Life Extension Magazine®

Issue: Jul 2011


Differentiation of adipose stem cells.

The broad definition of a stem cell is a cell that has the ability to self-renew and differentiate into one or more specialized terminally differentiated cell types. It has become evident that stem cells persist in, and can be isolated from, many adult tissues. Adipose tissue has been shown to contain a population of cells that retain a high proliferation capacity in vitro and the ability to undergo extensive differentiation into multiple cell lineages. These cells are referred to as adipose stem cells and are biologically similar, although not identical, to mesenchymal stem cells derived from the bone marrow. Differentiation causes stem cells to adopt the phenotypic, biochemical, and functional properties of more terminally differentiated cells. This chapter will provide investigators with some background on stem cells derived from adipose tissue and then provide details on adipose stem cell multilineage differentiation along osteogenic, adipogenic, chondrogenic, and neurogenic lineages.

Methods Mol Biol. 2008;456:155-71

Adipose tissue development - Impact of the early life environment.

Increasing experimental and observational evidence in both animals and humans suggests that early life events are important in setting later fat mass. This includes both the number of adipocytes and the relative distribution of both brown and white adipose tissue. Brown adipose tissue is characterised as possessing a unique uncoupling protein (UCP)1 which enables the rapid generation of large amounts of heat and is most abundant in the newborn. In large mammals such as sheep and humans, brown fat that is located around the major internal organs, is largely lost during the postnatal period. However, it is retained in small and discrete areas into adulthood when it is sensitive to environmental cues such as changes in ambient temperature or day length. The extent to which brown adipose tissue is lost or replaced by white adipose tissue and/or undergoes a process of transdifferentiation remains controversial. Small amounts of UCP1 can also be present in skeletal muscle which now appears to share the same common precursor cell as brown adipose tissue. The functional consequences of UCP1 in muscle remain to be confirmed but it could contribute to dietary induced thermogenesis. Challenges in elucidating the primary mechanisms regulating adipose tissue development include changes in methylation status of key genes during development in different species, strains and adipose depots. A greater understanding of the mechanisms by which early life events regulate adipose tissue distribution in young offspring are likely to provide important insights for novel interventions that may prevent excess adiposity in later life.

Prog Biophys Mol Biol. 2010 Dec 14

Inhibition of adipocyte differentiation and adipogenesis by the traditional Chinese herb Sibiraea angustata.

Obesity has become a major health concern due to its strong association with the metabolic syndrome. Inhibition of adipocyte differentiation represents a key strategy to inhibit obesity. Sibiraea angustata (SA), a traditional Chinese herb, has a wide range of pharmacological effects, such as improving digestive functions. Here, we report a novel antiadipogenic effect of SA. By using the SA water extract (SAW), SA acetic ether extract (SAA) and the 3T3-L1 model of adipocyte differentiation and adipogenesis, we showed that both SAW and SAA impaired the proliferation and adipo-differentiation of 3T3-L1 in a dose- and time-dependent manner. At the molecular level, treatment of 3T3-L1 cells with SAW or SAA inhibited the expression of the key adipocyte differentiation regulator CCAAT enhancer binding protein β (C/EBPβ), as well as peroxisome proliferator activated receptor γ, adipocyte protein-2, lipoprotein lipase and glucose transporter 4. Cell cycle analysis showed that both SAW and SAA blocked cell cycle at the G1-S transition phase, causing cells to remain in the preadipocyte state. The expression of CyclinA and cyclin-dependent kinase 2 was also inhibited by SAW and SAA. Treatment with SAW also prevented the localization of C/EBPβ to the centromeres. Taken together, our results show that SA has a potent antiadipogenic effect in 3T3-L1 cells due to the inhibition of adipocyte differentiation and adipogenesis. We propose that SA may be used as a safe and effective neutraceutical to manage obesity.

Exp Biol Med (Maywood). 2010 Dec;235(12):1442-9

Xanthones from mangosteen inhibit inflammation in human macrophages and in human adipocytes exposed to macrophage-conditioned media.

Obesity-associated inflammation is characterized by recruitment of macrophages (MPhi) into white adipose tissue (WAT) and production of inflammatory cytokines, leading to the development of insulin resistance. The xanthones, alpha- and gamma-mangostin (MG), are major bioactive compounds found in mangosteen that are reported to have antiinflammatory and antioxidant properties. Thus, we examined the efficacy of MG to prevent lipopolysaccharide (LPS)-mediated inflammation in human MPhi (differentiated U937 cells) and cross-talk with primary cultures of newly differentiated human adipocytes. We found that alpha- and gamma-MG attenuated LPS-induced expression of inflammatory genes, including tumor necrosis factor-alpha, interleukin-6, and interferon gamma-inducible protein-10 in a dose-dependent manner in MPhi. We also found that alpha- and gamma-MG attenuated LPS-activated mitogen-activated protein kinases (MAPK) and activator protein (AP)-1, but only gamma-MG reduced nuclear factor-kappaB (NF-kappaB). In addition, alpha- and gamma-MG attenuated LPS suppression of PPARgamma gene expression in a dose-dependent manner. Notably, the ability of MPhi-conditioned media to cause inflammation and insulin resistance in primary cultures of human adipocytes was attenuated by pretreating MPhi with gamma-MG. Taken together, these data demonstrate that MG attenuates LPS-mediated inflammation in MPhi and insulin resistance in adipocytes, possibly by preventing the activation of MAPK, NF-kappaB, and AP-1, which are central to inflammatory cytokine production in WAT.

J Nutr. 2010 Apr;140(4):842-7

St. John’s Wort inhibits adipocyte differentiation and induces insulin resistance in adipocytes.

Adipocytes are insulin sensitive cells that play a major role in energy homeostasis. Obesity is the primary disease of fat cells and a major risk factor for the development of Type II diabetes, cardiovascular disease, and metabolic syndrome. Obesity and its related disorders result in dysregulation of the mechanisms that control adipocyte gene expression and function. To identify potential novel therapeutic modulators of adipocytes, we screened 425 botanical extracts for their ability to modulate adipogenesis and insulin sensitivity. We observed that less than 2% of the extracts had substantial effects on adipocyte differentiation of 3T3-L1 cells. Two of the botanical extracts that inhibited adipogenesis were extracts from St. John’s Wort (SJW). Our studies revealed that leaf and flower, but not root, extracts isolated from SJW inhibited adipogenesis as judged by examining PPARgamma and adiponectin levels. We also examined the effects of these SJW extracts on insulin sensitivity in mature 3T3-L1 adipocytes. Both leaf and flower extracts isolated from SJW substantially inhibited insulin sensitive glucose uptake. The specificity of the observed effects was demonstrated by showing that treatment with SJW flower extract resulted in a time and dose dependent inhibition of insulin stimulated glucose uptake. SJW is commonly used in the treatment of depression. However, our studies have revealed that SJW may have a negative impact on adipocyte related diseases by limiting differentiation of preadipocytes and significantly inducing insulin resistance in mature fat cells.

Biochem Biophys Res Commun. 2009 Oct 9;388(1):146-9

Adipose tissue fatty acid metabolism and cardiovascular disease.

Fatty acid and triacylglycerol metabolism in adipose tissue may be involved in the generation of risk factors for cardiovascular disease and type 2 diabetes. Pharmaceutical companies are targeting adipocyte metabolism in their search for drugs for treating, or reducing the risk of, these conditions. We review new developments in adipose tissue fatty acid metabolism and how that might relate to cardiovascular disease. Fatty acid release from human adipose tissue is oscillatory, with a period of about 12 min. Remarkably, oscillatory fatty acid release is also seen in isolated adipocytes. Further evidence has emerged that not all adipose depots are equal, and that lower-body adipose tissue may exert protective effects against cardiovascular disease. There have been a number of developments in the area of fatty acid handling by adipocytes. Fatty acid binding proteins are clearly important in regulating fatty acid metabolism, with striking protection against atherosclerosis in mice deficient in both the binding proteins expressed in adipocytes. The demonstration that adipocytes lacking hormone-sensitive lipase still display lipolysis has led to the identification of novel lipases that may play crucial roles in adipose tissue fatty acid metabolism. Further evidence has accrued of the interaction between hormone-sensitive lipase and perilipin, the protein that coats the adipocyte lipid droplet. Recent developments in our understanding of adipose tissue fatty acid metabolism open up the possibility of new pharmaceutical targets. However, interference with adipose tissue fatty acid metabolism is not to be undertaken lightly and needs a clear understanding of the normal role of adipocyte lipolysis.

Curr Opin Lipidol. 2005 Aug;16(4):409-15

Anti-adipogenesis by 6-thioinosine is mediated by downregulation of PPAR gamma through JNK-dependent upregulation of iNOS.

Adipocyte dysfunction is associated with the development of obesity. This study shows that 6-thioinosine inhibits adipocyte differentiation. The mRNA levels of PPAR gamma and C/EBPalpha, but not C/EBPbeta and delta, were reduced by 6-thioinosine. Moreover, the mRNA levels of PPAR gamma target genes (LPL, CD36, aP2, and LXRalpha) were down-regulated by 6-thioinosine. We also demonstrated that 6-thioinosine inhibits the transactivation activity and the mRNA level of PPAR gamma. Additionally, attempts to elucidate a possible mechanism underlying the 6-thioinosine-mediated effects revealed that 6-thioinosine induced iNOS gene expression without impacting eNOS expression, and that this was mediated through activation of AP-1, especially, JNK. In addition, 6-thioinosine was found to operate upstream of MEKK-1 in JNK activation signaling. Taken together, these findings suggest that the inhibition of adipocyte differentiation by 6-thioinosine occurs primarily through the reduced expression of PPAR gamma, which is mediated by upregulation of iNOS via the activation of JNK.

Cell Mol Life Sci. 2010 Feb;67(3):467-81

Molecular mechanisms of adipocyte differentiation and inhibitory action of pref-1.

Commitment and differentiation of adipocytes is governed by transcription factors that are under the control of the combinatorial effects of hormonal and cell-cell and cell-matrix interaction. Established preadipocyte cell lines, such as 3T3-L1, 3T3-F442A, and Ob 17, have made it possible to examine the molecular details of the differentiation process. Differentiation is accompanied by dramatic increases in adipocyte genes, including adipocyte fatty acid-binding protein and lipid-metabolizing enzymes. Transcription factors PPAR gamma and C/EBP have been shown to transactivate some of the adipocyte-expressed genes. By integrating hormonal and metabolic cues, these nuclear factors may synergistically function in adipocyte lineage determination and differentiation. Adipocyte differentiation involves drastic cell shape alterations that are accompanied by changes in expression of cytoskeletal and extracellular matrix proteins, including decreases in actin and tubulin levels. Pref-1, an EGF-repeat containing transmembrane protein, is highly expressed in preadipocytes; this expression is totally abolished after differentiation to adipocytes. Pref-1 is inhibitory for adipocyte differentiation and processing of transmembrane pref-1 generates a biologically active soluble from corresponding to the ectodomain. Interaction of the EGF-repeats of pref-1 with an as yet unidentified receptor may mediate the inhibitory effects of pref-1 in adipocyte differentiation, thereby affecting nuclear events accompanying adipogenesis.

Crit Rev Eukaryot Gene Expr. 1997;7(4):281-98

The relationship between adipocyte fatty acid binding protein-4, retinol binding protein-4 levels and early diabetic nephropathy in patients with type 2 diabetes.

Adipocyte fatty acid binding protein-4 (A-FABP4) and retinol binding protein-4 (RBP4) have recently been linked to type 2 diabetes mellitus (DM). Serum A-FABP4 and RBP4 levels and their relationships with early diabetic nephropathy were examined in 87 type 2 diabetic patients. The patients with diabetic nephropathy showed high A-FABP4 levels compared to the patients without diabetic nephropathy (p=0.0001). Log A-FABP4 correlated positively with age (p=0.02), log duration of diabetes (p=0.04), log body mass index (BMI) (p=0.0001), log creatinine (p=0.007), log C-reactive protein (CRP) (p=0.01), log albumin excretion rate (AER) (p=0.001), and negatively with MDRD-GFR (p=0.0001). Serum RBP4 levels were similar between the patients with and without diabetic nephropathy. RBP4 correlated positively with triglycerides (p=0.001), log creatinine (p=0.009), and negatively with MDRD-GFR (p=0.04). In regression analysis, log A-FABP4 was associated with age, sex, log BMI, and log AER (r(2)=0.43) and RBP4 was associated with triglycerides and log creatinine (r(2)=0.22). In conclusion, we found high serum A-FABP4 but unchanged RBP4 concentrations and their associations with renal function and early diabetic nephropathy in type 2 DM.

Diabetes Res Clin Pract. 2011 Feb;91(2):203-7

Momordica charantia (bitter melon) inhibits primary human adipocyte differentiation by modulating adipogenic genes.

Escalating trends of obesity and associated type 2 diabetes (T2D) has prompted an increase in the use of alternative and complementary functional foods. Momordica charantia or bitter melon (BM) that is traditionally used to treat diabetes and complications has been demonstrated to alleviate hyperglycemia as well as reduce adiposity in rodents. However, its effects on human adipocytes remain unknown. The objective of our study was to investigate the effects of BM juice (BMJ) on lipid accumulation and adipocyte differentiation transcription factors in primary human differentiating preadipocytes and adipocytes. METHODS: Commercially available cryopreserved primary human preadipocytes were treated with and without BMJ during and after differentiation. Cytotoxicity, lipid accumulation, and adipogenic genes mRNA expression was measured by commercial enzymatic assay kits and semi-quantitative RT-PCR (RT-PCR). RESULTS: Preadipocytes treated with varying concentrations of BMJ during differentiation demonstrated significant reduction in lipid content with a concomitant reduction in mRNA expression of adipocyte transcription factors such as, peroxisome proliferator-associated receptor gamma (PPARgamma) and sterol regulatory element-binding protein 1c (SREBP-1c) and adipocytokine, resistin. Similarly, adipocytes treated with BMJ for 48 h demonstrated reduced lipid content, perilipin mRNA expression, and increased lipolysis as measured by the release of glycerol. CONCLUSION: Our data suggests that BMJ is a potent inhibitor of lipogenesis and stimulator of lipolysis activity in human adipocytes. BMJ may therefore prove to be an effective complementary or alternative therapy to reduce adipogenesis in humans.

BMC Complement Altern Med. 2010 Jun 29;10:34

Signalling role of adipose tissue: adipokines and inflammation in obesity.

White adipose tissue (WAT) is a major endocrine and secretory organ, which releases a wide range of protein signals and factors termed adipokines. A number of adipokines, including leptin, adiponectin, tumour necrosis factor alpha, IL-1beta (interleukin 1beta), IL-6, monocyte chemotactic protein-1, macrophage migration inhibitory factor, nerve growth factor, vascular endothelial growth factor, plasminogen activator inhibitor 1 and haptoglobin, are linked to inflammation and the inflammatory response. Obesity is characterized by a state of chronic mild inflammation, with raised circulating levels of inflammatory markers and the expression and release of inflammation-related adipokines generally rises as adipose tissue expands (adiponectin, which has anti-inflammatory action is an exception). The elevated production of inflammation-related adipokines is increasingly considered to be important in the development of diseases linked to obesity, particularly Type II diabetes and the metabolic syndrome. WAT is involved in extensive cross-talk with other organs and multiple metabolic systems through the various adipokines.

Biochem Soc Trans. 2005 Nov;33(Pt 5):1078-81

Inhibition of Irvingia gabonensis seed extract (OB131) on adipogenesis as mediated via down regulation of the PPARgamma and leptin genes and up-regulation of the adiponectin gene.

BACKGROUND: Endeavors to manage obesity have been heavily reliant on controlling energy intake and expenditure equilibrium, but have failed to curtail the overweight and obesity epidemic. This dynamic equilibrium is more complex than originally postulated and is influenced by lifestyle, calorie and nutrient intake, reward cravings and satiation, energy metabolism, stress response capabilities, immune metabolism and genetics. Fat metabolism is an important indicator of how efficiently and to what extent these factors are competently integrating. We investigated whether an Irvingia gabonensis seed extract (IGOB131) would provide a more beneficial comprehensive approach influencing multiple mechanisms and specifically PPAR gamma, leptin and adiponectin gene expressions, important in anti-obesity strategies. METHODS: Using murine 3T3-L1 adipocytes as a model for adipose cell biology research, the effects of IGOB131 were investigated on PPAR gamma, adiponectin, and leptin. These adipocytes were harvested 8 days after the initiation of differentiation and treated with 0 to 250 microM of IGOB131 for 12 and 24 h at 37 degree C in a humidified 5 percent CO2 incubator. The relative expression of PPAR gamma, adiponectin, and leptin in 3T3-L1 adipocytes was quantified densitometrically using the software LabWorks 4.5, and calculated according to the reference bands of beta-actin. RESULTS: The IGOB131 significantly inhibited adipogenesis in adipocytes. The effect appears to be mediated through the down-regulated expression of adipogenic transcription factors (PPAR gamma) [P less than 0.05] and adipocyte-specific proteins (leptin) [P less than 0.05], and by up-regulated expression of adiponectin [P less than 0.05]. CONCLUSION: IGOB131 may play an important multifaceted role in the control of adipogenesis and have further implications in in-vivo anti obesity effects by targeting the PPAR gamma gene, a known contributory factor to obesity in humans.

Lipids Health Dis. 2008 Nov 13;7:44

Ethanolic extracts of Brassica campestris spp. rapa roots prevent high-fat diet-induced obesity via beta(3)-adrenergic regulation of white adipocyte lipolytic activity.

The influence of ethanolic extracts of Brassica campestris spp. rapa roots (EBR) on obesity was examined in imprinting control region (ICR) mice fed a high-fat diet (HFD) and in 3T3-L1 adipocytes. The ICR mice used were divided into regular diet, HFD, EBR (50 mg/kg/day EBR administered orally), and orlistat (10 mg/kg/day orlistat administered orally) groups. The molecular mechanism of the anti-obesity effect of EBR was investigated in 3T3-L1 adipocytes as well as in HFD-fed ICR mice. In the obese mouse model, both weight gain and epididymal fat accumulation were highly suppressed by the daily oral administration of 50 mg/kg EBR for 8 weeks, whereas the overall amount of food intake was not affected. EBR treatment induced the expression in white adipocytes of lipolysis-related genes, including beta(3)-adrenergic receptor (beta(3)-AR), hormone-sensitive lipase (HSL), adipose triglyceride lipase, and uncoupling protein 2. Furthermore, the activation of cyclic AMP-dependent protein kinase, HSL, and extracellular signal-regulated kinase was induced in EBR-treated 3T3-L1 cells. The lipolytic effect of EBR involved beta(3)-AR modulation, as inferred from the inhibition by the beta(3)-AR antagonist propranolol. These results suggest that EBR may have potential as a safe and effective anti-obesity agent via the inhibition of adipocyte lipid accumulation and the stimulation of beta(3)-AR-dependent lipolysis.

J Med Food. 2010 Apr;13(2):406-14

Adiponectin: a link between excess adiposity and associated comorbidities?

Adiponectin is a novel polypeptide that is highly specific to adipose tissue. In contrast to other adipocytokines, adiponectin levels are decreased in obesity and associated comorbidities, such as type 2 diabetes. Decreased expression of adiponectin is correlated with insulin resistance. It has been suggested that several agents, such as tumor necrosis factor alpha, could mediate their effects on insulin metabolism through modulating adiponectin secretion from adipocytes. The mechanisms for the development of atherosclerotic vascular disease in obese individuals are largely unknown. Several findings support the interesting hypothesis that adiponectin could be a link between obesity and related atherosclerosis. First, adiponectin levels are lower in patients with coronary artery disease. Second, adiponectin modulates endothelial function and has an inhibitory effect on vascular smooth muscle cell proliferation. Moreover, adiponectin is accumulated more preferably to the injured vascular wall than intact vessels and has been shown to suppress macrophage-to-foam cell transformation. Adiponectin may also be involved in the modulation of inflammation. Thiazolidinediones, antiatherogenic and other effects have been explained by their direct enhancing effect on adiponectin. In conclusion, adiponectin has anti-inflammatory and antiatherogeneic effects as well as multiple beneficial effects on metabolism. Therefore it is not a surprise that adiponectin therapy has been tested in animal models of obesity, and it has been shown to ameliorate hyperglycemia and hyperinsulinemia without inducing weight gain or even inducing weight loss in some studies. Unlike agents that exert their effects centrally, adiponectin’s effects seem to be peripherally mediated. The evidence of an association between adiponectin and the metabolic and cardiovascular complications of obesity is growing all the time.

J Mol Med. 2002 Nov;80(11):696-702

Visceral adiposity, not abdominal subcutaneous fat area, is associated with high blood pressure in Japanese men: the Ohtori study.

Visceral adiposity is considered to have a key role in cardiometabolic diseases. The purpose of this study is to investigate cross-sectionally the association between intra-abdominal fat area (IAFA) measured by computed tomography (CT) and high blood pressure independent of abdominal subcutaneous fat area (ASFA) and insulin resistance. Study participants included 624 Japanese men not taking oral hypoglycemic medications or insulin. Abdominal, thoracic and thigh fat areas were measured by CT. Total fat area (TFA) was calculated as the sum of abdominal, thoracic and thigh fat area. Total subcutaneous fat area (TSFA) was defined as TFA minus IAFA. Hypertension and high normal blood pressure were defined using the 1999 criteria of the World Health Organization. Multiple-adjusted odds ratios of hypertension for tertiles of IAFA were 2.64 (95% confidence interval, 1.35-5.16) for tertile 2, and 5.08 (2.48-10.39) for tertile 3, compared with tertile 1 after adjusting for age, fasting immunoreactive insulin, diabetes status, ASFA, alcohol consumption, regular physical exercise and smoking habit. IAFA remained significantly associated with hypertension even after adjustment for ASFA, TSFA, TFA, body mass index or waist circumference, and no other measure of regional or total adiposity was associated with the odds of hypertension in models, which included IAFA. Similar results were obtained for the association between IAFA and the prevalence of high normal blood pressure or hypertension. In conclusion, greater visceral adiposity was associated with a higher odds of high blood pressure in Japanese men.

Hypertens Res. 2011 May;34(5):565-72

Visceral adiposity and the severity of coronary artery disease in middle-aged subjects with normal waist circumference and its relation with lipocalin-2 and MCP-1.

OBJECTIVE: Visceral adipose tissue has emerged as a key organ contributing to the development of coronary artery disease (CAD). However, defining central obesity by waist circumference (WC) may underestimate visceral adiposity in lean patients. The aim of this study was to investigate the relationship between visceral adiposity and severity of CAD in subjects with normal WC. METHODS: Among 365 patients with documented CAD, 90 male subjects with normal WC (<90 cm) were selected and their visceral fat areas (VFA) were examined using computed tomography. Lipid profiles and levels of adipokines including lipocalin-2, high molecular weight adiponectin, and monocyte chemoattractant protein (MCP)-1 were measured. Patients were divided into tertiles based on VFA at the L4 vertebra level. RESULTS: Patients with single-vessel disease had significantly lower VFA than those with multi-vessel disease (P<0.05; 86.0 vs. 97.5 vs. 99.6 cm(2) for single- , double- , and triple-vessel diseases, respectively). Positive association between the extent of CAD and VFA was clearly demonstrated and logistic regression analysis showed that subjects in the upper tertile for VFA had a 4.5-fold higher risk of having multi-vessel disease compared with those in the lowest tertile (P<0.05; odds ratio=4.51; 95% confidence interval=1.10-18.45). Circulating levels of lipocalin-2 and MCP-1 were significantly higher in the upper tertiles of VFA. CONCLUSION: Increased visceral adiposity is significantly associated with the severity of CAD, even in subjects without central obesity as determined by WC measurements. Abnormalities in adipokine regulation may provide a novel mechanistic connection between visceral adiposity and associated cardiovascular complications.

Atherosclerosis. 2010 Dec;213(2):592-7

Astaxanthin-enriched-diet reduces blood pressure and improves cardiovascular parameters in spontaneously hypertensive rats.

The aim of this study was to investigate the effects of astaxanthin-enriched diet on blood pressure, cardiac hypertrophy, both vascular structure and function and superoxide ((*)O(2-)) production in spontaneously hypertensive rats (SHR). Twelve-week-old SHR were treated for 8 weeks with an astaxanthin-enriched diet (75 or 200 mg/kg body weight per day). Systolic blood pressure was monitorized periodically during the study by the tail cuff method. At the end of the study animals were sacrificed and heart, kidneys and aorta were removed. Left ventricular weight/body weight ratio was used as left ventricular hypertrophy index (LVH). Vascular function and structure were studied in conductance (aortic rings) and resistance (renal vascular bed) arteries. Also (*)O(2-) production was evaluated by lucigenin-enhanced chemiluminescence. Systolic blood pressure was lower in astaxanthin-treated groups than the control group from the first week of treatment, and LVH was significantly reduced. Astaxanthin improved endothelial function on resistance arteries, but had no effect on aorta. These effects were accompanied by a decrease in oxidative stress and improvements in NO bioavailability. Taken together, these results show that diet supplemented with astaxanthin has beneficial effects on hypertension, by decreasing blood pressure values, improving cardiovascular remodeling and oxidative stress.

Pharmacol Res. 2011 Jan;63(1):44-50

Alpha-tocopherol and astaxanthin decrease macrophage infiltration, apoptosis and vulnerability in atheroma of hyperlipidaemic rabbits.

The composition of atherosclerotic plaques, not just macroscopical lesion size, has been implicated in their susceptibility to rupture and the risk of thrombus formation. By focusing on the quality of lipids, macrophages, apoptosis, collagen, metalloproteinase expression and plaque integrity, we evaluated the possible anti-atherosclerotic effect of the antioxidants alpha-tocopherol and astaxanthin in Watanabe heritable hyperlipidemic (WHHL) rabbits. Thirty-one WHHL rabbits were divided into three groups and were fed a standard diet, as controls (N =10), or a standard diet with the addition of 500 mg alpha-tocopherol per kg feed (N =11) or 100 mg astaxanthin per kg feed (N =10) for 24 weeks. We found that both antioxidants, particularly astaxanthin, significantly decreased macrophage infiltration in the plaques although they did not affect lipid accumulation. All lesions in the astaxanthin-treated rabbits were classified as early plaques according to the distribution of collagen and smooth muscle cells. Both antioxidants also improved plaque stability and significantly diminished apoptosis, which mainly occurred in macrophages, matrix metalloproteinase three expressions and plaque ruptures. Although neither antioxidant altered the positive correlations between the lesion size and lipid accumulation, the lesion size and apoptosis were only positively correlated in the control group. Astaxanthin and alpha-tocopherol may improve plaque stability by decreasing macrophage infiltration and apoptosis in this atherosclerotic setting. Apoptosis reduction by alpha-tocopherol and astaxanthin may be a new anti-atherogenic property of these antioxidants.

J Mol Cell Cardiol. 2004 Nov;37(5):969-78

Cytoprotective role of astaxanthin against glycated protein/iron chelate-induced toxicity in human umbilical vein endothelial cells.

Astaxanthin (ASX), a red carotenoid pigment with no pro-vitamin A activity, is a biological antioxidant that occurs naturally in a wide variety of plants, algae and seafoods. This study investigated whether ASX could inhibit glycated protein/iron chelate-induced toxicity in human umbilical-vein endothelial cells (HUVEC) by interfering with ROS generation in these cells. Glycated fetal bovine serum (GFBS) was prepared by incubating fetal bovine serum (FBS) with high-concentration glucose. Stimulation of cultured HUVECs with 50 mm 1 mL of GFBS significantly enhanced lipid peroxidation and decreased antioxidant enzyme activities and levels of phase II enzymes. However, preincubation of the cultures with ASX resulted in a marked decrease in the level of lipid peroxide (LPO) and an increase in the levels of antioxidant enzymes in an ASX concentration-dependent manner. These results demonstrate that ASX could inhibit LPO formation and enhance the antioxidant enzyme status in GFBS/iron chelate-exposed endothelial cells by suppressing ROS generation, thereby limiting the effects of the AGE-RAGE interaction. The results indicate that ASX could have a beneficial role against glycated protein/iron chelate-induced toxicity by preventing lipid and protein oxidation and increasing the activity of antioxidant enzymes.

Phytother Res. 2010 Jan;24(1):54-9

Effect of astaxanthin on hepatocellular injury following ischemia/reperfusion.

This study investigated the effect of astaxanthin (ASX; 3,3-dihydroxybeta, beta-carotene-4,4-dione), a water-dispersible synthetic carotenoid, on liver ischemia-reperfusion (IR) injury. Astaxanthin (5 mg/kg/day) or olive oil was administered to rats via intragastric intubation for 14

consecutive days before the induction of hepatic IR. On the 15th day, blood vessels supplying the median and left lateral hepatic lobes were occluded with an arterial clamp for 60 min, followed by 60 min reperfusion. At the end of the experimental period, blood samples were obtained from the right ventricule to determine plasma alanine aminotransferase (ALT) and xanthine oxidase (XO) activities and animals were sacrificed to obtain samples of nonischemic and postischemic liver tissue. The effects of ASX on IR injury were evaluated by assessing hepatic ultrastructure via transmission electron microscopy and by histopathological scoring. Hepatic conversion of xanthine dehygrogenase (XDH) to XO, total GSH and protein carbonyl levels were also measured as markers of oxidative stress. Expression of NOS2 was determined by immunohistochemistry and Western blot analysis while nitrate/nitrite levels were measured via spectral analysis. Total histopathological scoring of cellular damage was significantly decreased in hepatic IR injury following ASX treatment. Electron microscopy of postischemic tissue demonstrated parenchymal cell damage, swelling of mitochondria, disarrangement of rough endoplasmatic reticulum which was also partially reduced by ASX treatment. Astaxanthine treatment significantly decreased hepatic conversion of XDH to XO and tissue protein carbonyl levels following IR injury. The current results suggest that the mechanisms of action by which ASX reduces IR damage may include antioxidant protection against oxidative injury.

Toxicology. 2010 Jan 12;267(1-3):147-53

Disodium Disuccinate Astaxanthin (Cardax) attenuates complement activation and reduces myocardial injury following ischemia/reperfusion.

Carotenoids are a naturally occurring group of compounds that possess antioxidant properties. Most natural carotenoids display poor aqueous solubility and tend to form aggregates in solution. Disodium disuccinate astaxanthin (DDA; Cardax) is a water-dispersible synthetic carotenoid that rapidly and preferentially associates with serum albumin, thereby preventing the formation of supramolecular complexes and facilitating its efficacy after parenteral administration. This study investigated the ability of DDA to reduce inflammation and myocardial injury in a rabbit model of ischemia/reperfusion. DDA (50 mg/kg/day) or saline was administered i.v. for 4 consecutive days before the initiation of the protocol for induction of myocardial ischemia/reperfusion. On the 5th day, rabbits underwent 30 min of coronary artery occlusion, followed by a 3-h reperfusion period. Myocardial infarct size, as a percentage of the area at risk, was calculated for both groups. Infarct size was 52.5 +/- 7.5% in the vehicle-treated (n = 9) and 25.8 +/- 4.7% in the DDA-treated (n = 9) animals (p < 0.01 versus vehicle; mean myocardial salvage = 51%). To evaluate the anti-inflammatory effects of DDA, complement activity was assessed at the end of reperfusion using a red blood cell lysis assay. DDA administration significantly reduced (p < 0.01) the activation of the complement system in the serum. The current results, coupled with the well established antioxidant ability of carotenoids, suggest that the mechanism(s) of action by which DDA reduces the tissue damage associated with reperfusion injury may include both antioxidant and anticomplement components.

J Pharmacol Exp Ther. 2005 Aug;314(2):686-92

Cardioprotection and myocardial salvage by a disodium disuccinate astaxanthin derivative (Cardax).

Cardioprotection in humans by carotenoids has been inferred from observational and epidemiologic studies, however, direct studies of cardioprotection and myocardial salvage by carotenoids are lacking. In the current study, intravenous (I.V.) pre-treatment with a novel carotenoid derivative (disodium disuccinate astaxanthin; Cardax) was evaluated as a myocardial salvage agent in a Sprague-Dawley rat infarct model. Animals were dosed once per day I.V. by tail vein injection for 4 days at one of 3 doses (25, 50, and 75 mg/kg) prior to the infarct study carried out on day 5. The results were compared with control animals treated with saline vehicle. Thirty (30) minutes of occlusion of the left anterior descending (LAD) coronary artery was followed by 2 hours of reperfusion prior to sacrifice, a regimen which resulted in a mean infarct size (IS) as a percent (%) of the area at risk (AAR) of 59 +/- 3%. Area at risk was quantified by Patent blue dye injection, and infarct size (IS) was determined by triphenyltetrazolium chloride (TTC) staining. Cardax at 50 and 75 mg/kg for 4 days resulted in a significant mean reduction in IS/AAR to 35 +/- 3% (41% salvage) and 26 +/- 2% (56% salvage), respectively. Infarct size and myocardial salvage were significantly, and linearly, correlated with plasma levels of non-esterified, free astaxanthin at the end of reperfusion. These results suggest that parenteral Cardax may find utility in those clinical applications where pre-treatment of patients at risk for myocardial infarction is performed.

Life Sci. 2004 May 28;75(2):215-24

Astaxanthin vs placebo on arterial stiffness, oxidative stress and inflammation in renal transplant patients (Xanthin): a randomised controlled trial.

BACKGROUND: There is evidence that renal transplant recipients have accelerated atherosclerosis manifest by increased cardiovascular morbidity and mortality. The high incidence of atherosclerosis is, in part, related to increased arterial stiffness, vascular dysfunction, elevated oxidative stress and inflammation associated with immunosuppressive therapy. The dietary supplement astaxanthin has shown promise as an antioxidant and anti-inflammatory therapeutic agent in cardiovascular disease. The aim of this trial is to investigate the effects of astaxanthin supplementation on arterial stiffness, oxidative stress and inflammation in renal transplant patients. METHOD AND DESIGN: This is a randomised, placebo controlled clinical trial. A total of 66 renal transplant recipients will be enrolled and allocated to receive either 12 mg/day of astaxanthin or an identical placebo for one-year. Patients will be stratified into four groups according to the type of immunosuppressant therapy they receive: 1) cyclosporine, 2) sirolimus, 3) tacrolimus or 4) prednisolone+/-azathioprine, mycophenolate mofetil or mycophenolate sodium. Primary outcome measures will be changes in 1) arterial stiffness measured by aortic pulse wave velocity (PWV), 2) oxidative stress assessed by plasma isoprostanes and 3) inflammation by plasma pentraxin 3. Secondary outcomes will include changes in vascular function assessed using the brachial artery reactivity (BAR) technique, carotid artery intimal medial thickness (CIMT), augmentation index (AIx), left ventricular afterload and additional measures of oxidative stress and inflammation. Patients will undergo these measures at baseline, six and 12 months. DISCUSSION: The results of this study will help determine the efficacy of astaxanthin on vascular structure, oxidative stress and inflammation in renal transplant patients. This may lead to a larger intervention trial assessing cardiovascular morbidity and mortality.

BMC Nephrol. 2008 Dec 18;9:17

Astaxanthin protects neuronal cells against oxidative damage and is a potent candidate for brain food.

Astaxanthin (AST) is a powerful antioxidant that occurs naturally in a wide variety of living organisms. Based on the report claiming that AST could cross the brain-blood barrier, the aim of this study was to investigate the neuroprotective effect of AST by using an oxidative stress-induced neuronal cell damage system. The treatment with DHA hydroperoxide (DHA-OOH) or 6-hydroxydopamine (6-OHDA), either of which is a reactive oxygen species (ROS)-inducing neurotoxin, led to a significant decrease in viable dopaminergic SH-SY5Y cells by the MTT assay, whereas a significant protection was shown when the cells were pretreated with AST. Moreover, 100 nM AST pretreatment significantly inhibited intracellular ROS generation that occurred in either DHA-OOH- or 6-OHDA-treated cells. The neuroprotective effect of AST is suggested to be dependent upon its antioxidant potential and mitochondria protection; therefore, it is strongly suggested that treatment with AST may be effective for oxidative stress-associated neurodegeneration and a potential candidate for natural brain food.

Forum Nutr. 2009;61:129-35

Astaxanthin inhibits glutamate release in rat cerebral cortex nerve terminals via suppression of voltage-dependent Ca(2+) entry and mitogen-activated protein kinase signaling pathway.

The purpose of this study was to examine the effect and mechanism of astaxanthin, a natural carotenoid, on endogenous glutamate release in nerve terminals of rat cerebral cortex (synaptosomes). Results showed that astaxanthin exhibited a dose-dependent inhibition of 4-aminopyridine (4-AP)-evoked release of glutamate. The effect of astaxanthin on the evoked glutamate release was prevented by chelating the intrasynaptosomal Ca(2+) ions and by the vesicular transporter inhibitor, but was insensitive to the glutamate transporter inhibitor. Astaxanthin decreased depolarization-induced increase in [Ca(2+)](C), whereas it did not alter the resting synaptosomal membrane potential or 4-AP-mediated depolarization. The effect of astaxanthin on evoked glutamate release was abolished by the N-, P- and Q-type Ca(2+) channel blockers, but not by the ryanodine receptor blocker or the mitochondrial Na(+)/Ca(2+) exchanger blocker. In addition, the inhibitory effect of astaxanthin on evoked glutamate release was prevented by the mitogen-activated protein kinase (MAPK) inhibitors PD98059 and U0126. Western blot analyses showed that astaxanthin significantly decreased the 4-AP-induced phosphorylation of MAPK, and this effect was blocked by PD98059. On the basis of these results, it was concluded that astaxanthin inhibits glutamate release from rat cortical synaptosomes through the suppression of presynaptic voltage-dependent Ca(2+) entry and MAPK signaling cascade.

J Agric Food Chem. 2010 Jul 28;58(14):8271-8

Astaxanthine secured apoptotic death of PC12 cells induced by beta-amyloid peptide 25-35: its molecular action targets.

Astaxanthine (ASTx) is a novel carotenoid nutraceutical occurring in many crustaceans and red yeasts. It has potent antioxidant, photoprotective, hepatodetoxicant, and anti-inflammatory activities. Documented effect of ASTx on treatment of neurodegenerative disease is still lacking. We used the beta-amyloid peptide (Abeta) 25-35-treated PC12 model to investigate the neuron-protective effect of ASTx. The parameters examined included cell viability, caspase activation, and various apoptotic biomarkers that play their critical roles in the transduction pathways independently or synergistically. Results indicated that Abeta25-35 at 30 microM suppressed cell viability by 55%, whereas ASTx was totally nontoxic below a dose of 5.00 microM. ASTx at 0.1 microM protected PC12 cells from damaging effects of Abeta25-35 in several ways: (1) by securing the cell viability; (2) by partially down-regulating the activation of caspase 3; (3) by inhibiting the expression of Bax; (4) by completely eliminating the elevation of interleukin-1beta and tumor necrosis factor-alpha; (5) by inhibiting the nuclear translocation of nuclear factor kappaB; (6) by completely suppressing the phosphorylation of p38 mitogen-activated protein kinase; (7) by completely abolishing the calcium ion influx to effectively maintain calcium homeostasis; and (8) by suppressing the majority (about 75%) of reactive oxygen species production. Conclusively, ASTx may have merit to be used as a very potential neuron protectant and an anti-early-stage Alzheimer’s disease adjuvant therapy.

J Med Food. 2010 Jun;13(3):548-56

Down-regulation of IL-6 production by astaxanthin via ERK-, MSK-, and NF-κB-mediated signals in activated microglia.

In this study, we investigated the effect of astaxanthin on IL-6 in activated microglial cells because excessive interleukin-6 (IL-6) production by activated brain microglia has been linked to many neurological disorders and proper regulation of IL-6 is critical for maintaining brain homeostasis. Astaxanthin inhibited lipopolysaccharide (LPS)-stimulated IL-6 mRNA and protein in BV-2 microglial cells. Moreover, LPS-induced p-IKKα, p-IκBα, and p-NF-κB p65 levels were all suppressed by astaxanthin. The translocation of p-NF-κB p65 from the cytosol into the nucleus and transcriptional activity were inhibited by astaxanthin. IL-6 expression and NF-κB transcriptional activation were inhibited by astaxanthin, as well as inhibitors of NF-B and MAPK in LPS-stimulated BV-2 microglial cells. Consistent with these findings, astaxanthin down-regulated the activation of p-extracellular signal-regulated kinase 1/2 (p-ERK1/2) and p-mitogen- and stress-activated protein kinase 1(p-MSK1), but not of p-c-jun N-terminal kinase (p-JNK). Astaxathin also decreased IL-6 mRNA and protein levels in LPS-stimulated primary microglial cells, RAW264.7 macrophages, and peritoneal macrophages. In addition, IL-6 suppression through astaxanthin-induced down-regulation of p-ERK1/2, p-MSK1, and p-NF-B p65 occurred in microglial cells stimulated with LPS or stromal derived factor (SDF)-1α. Astaxathin also inhibited the secretion and mRNA expression of IL-6 in SDF-1α-stimulated microglial cells. SDF-1α-stimulated ERK1/2, MSK1, and NF-B p65 phosphorylation were reduced by astaxanthin. Therefore, our results suggest that astaxanthin regulates IL-6 production through a p-ERK1/2-MSK-1- and p-NF-B p65-dependent pathway in activated microglial cells.

Int Immunopharmacol. 2010 Dec;10(12):1560-72

Astaxanthin reduces ischemic brain injury in adult rats.

Astaxanthin (ATX) is a dietary carotenoid of crustaceans and fish that contributes to their coloration. Dietary ATX is important for development and survival of salmonids and crustaceans and has been shown to reduce cardiac ischemic injury in rodents. The purpose of this study was to examine whether ATX can protect against ischemic injury in the mammalian brain. Adult rats were injected intracerebroventricularly with ATX or vehicle prior to a 60-min middle cerebral artery occlusion (MCAo). ATX was present in the infarction area at 70-75 min after onset of MCAo. Treatment with ATX, compared to vehicle, increased locomotor activity in stroke rats and reduced cerebral infarction at 2 d after MCAo. To evaluate the protective mechanisms of ATX against stroke, brain tissues were assayed for free radical damage, apoptosis, and excitoxicity. ATX antagonized ischemia-mediated loss of aconitase activity and reduced glutamate release, lipid peroxidation, translocation of cytochrome c, and TUNEL labeling in the ischemic cortex. ATX did not alter physiological parameters, such as body temperature, brain temperature, cerebral blood flow, blood gases, blood pressure, and pH. Collectively, our data suggest that ATX can reduce ischemia-related injury in brain tissue through the inhibition of oxidative stress, reduction of glutamate release, and antiapoptosis. ATX may be clinically useful for patients vulnerable or prone to ischemic events.

FASEB J. 2009 Jun;23(6):1958-68

Modified citrus pectin (MCP) increases the prostate-specific antigen doubling time in men with prostate cancer: a phase II pilot study.

This trial investigated the tolerability and effect of modified citrus pectin (Pecta-Sol) in 13 men with prostate cancer and biochemical prostate-specific antigen (PSA) failure after localized treatment, that is, radical prostatectomy, radiation, or cryosurgery. A total of 13 men were evaluated for tolerability and 10 for efficacy. Changes in the prostate-specific antigen doubling time (PSADT) of the 10 men were the primary end point in the study. We found that the PSADT increased (P-value<0.05) in seven (70%) of 10 men after taking MCP for 12 months compared to before taking MCP. This study suggests that MCP may lengthen the PSADT in men with recurrent prostate cancer.

Prostate Cancer Prostatic Dis. 2003;6(4):301-4

Inhibition of human cancer cell growth and metastasis in nude mice by oral intake of modified citrus pectin.

BACKGROUND: The role of dietary components in cancer progression and metastasis is an emerging field of clinical importance. Many stages of cancer progression involve carbohydrate-mediated recognition processes. We therefore studied the effects of high pH- and temperature-modified citrus pectin (MCP), a nondigestible, water-soluble polysaccharide fiber derived from citrus fruit that specifically inhibits the carbohydrate-binding protein galectin-3, on tumor growth and metastasis in vivo and on galectin-3-mediated functions in vitro. METHODS: In vivo tumor growth, angiogenesis, and metastasis were studied in athymic mice that had been fed with MCP in their drinking water and then injected orthotopically with human breast carcinoma cells (MDA-MB-435) into the mammary fat pad region or with human colon carcinoma cells (LSLiM6) into the cecum. Galectin-3-mediated functions during tumor angiogenesis in vitro were studied by assessing the effect of MCP on capillary tube formation by human umbilical vein endothelial cells (HUVECs) in Matrigel. The effects of MCP on galectin-3-induced HUVEC chemotaxis and on HUVEC binding to MDA-MB-435 cells in vitro were studied using Boyden chamber and labeling assays, respectively. The data were analyzed by two-sided Student’s t test or Fisher’s protected least-significant-difference test. RESULTS: Tumor growth, angiogenesis, and spontaneous metastasis in vivo were statistically significantly reduced in mice fed MCP. In vitro, MCP inhibited HUVEC morphogenesis (capillary tube formation) in a dose-dependent manner. In vitro, MCP inhibited the binding of galectin-3 to HUVECs: At concentrations of 0.1% and 0.25%, MCP inhibited the binding of galectin-3 (10 micro g/mL) to HUVECs by 72.1% (P =.038) and 95.8% (P =.025), respectively, and at a concentration of 0.25% it inhibited the binding of galectin-3 (1 micro g/mL) to HUVECs by 100% (P =.032). MCP blocked chemotaxis of HUVECs toward galectin-3 in a dose-dependent manner, reducing it by 68% at 0.005% (P<.001) and inhibiting it completely at 0.1% (P<.001). Finally, MCP also inhibited adhesion of MDA-MB-435 cells, which express galectin-3, to HUVECs in a dose-dependent manner. CONCLUSIONS: MCP, given orally, inhibits carbohydrate-mediated tumor growth, angiogenesis, and metastasis in vivo, presumably via its effects on galectin-3 function. These data stress the importance of dietary carbohydrate compounds as agents for the prevention and/or treatment of cancer.

J Natl Cancer Inst. 2002 Dec 18;94(24):1854-62

Effects of natural complex carbohydrate (citrus pectin) on murine melanoma cell properties related to galectin-3 functions.

Citrus pectin (CP) and pH-modified citrus pectin (MCP) are highly branched and non-branched complex polysaccharides, respectively, rich in galactoside residues, capable of combining with the carbohydrate-binding domain of galectin-3. We reported previously that intravenous injection of B16-F1 murine melanoma cells with CP or MCP into syngeneic mice resulted in a significant increase or decrease of lung colonization, respectively (Platt D, Raz A (1992) J Natl Cancer Inst 84:438-42). Here we studied the effects of these polysaccharides on cell-cell and cell-matrix interactions mediated by carbohydrate-recognition. MCP, but not CP, inhibited B16-F1 melanoma cells adhesion to laminin and asialofetuin-induced homotypic aggregation. Both polysaccharides inhibited anchorage-independent growth of B16-F1 cells in semisolid medium, i.e. agarose. These results indicate that carbohydrate-recognition by cell surface galectin-3 may be involved in cell-extracellular matrix interaction and play a role in anchorage-independent growth as well as the in vivo embolization of tumour cells.

Glycoconj J. 1994 Dec;11(6):527-32

Modified citrus pectin anti-metastatic properties: one bullet, multiple targets.

In this minireview, we examine the ability of modified citrus pectin (MCP), a complex water soluble indigestible polysaccharide obtained from the peel and pulp of citrus fruits and modified by means of high pH and temperature treatment, to affect numerous rate-limiting steps in cancer metastasis. The anti-adhesive properties of MCP as well as its potential for increasing apoptotic responses of tumor cells to chemotherapy by inhibiting galectin-3 anti-apoptotic function are discussed in the light of a potential use of this carbohydrate-based substance in the treatment of multiple human malignancies.

Carbohydr Res. 2009 Sep 28;344(14):1788-91

Extraction of green labeled pectins and pectic oligosaccharides from plant byproducts.

Green labeled pectins were extracted by an environmentally friendly way using proteases and cellulases being able to act on proteins and cellulose present in cell walls. Pectins were isolated from different plant byproducts, i.e., chicory roots, citrus peel, cauliflower florets and leaves, endive, and sugar beet pulps. Enzymatic extraction was performed at 50 degrees C for 4 h, in order to fulfill the conditions required for microbiological safety of extracted products. High methoxy (HM) pectins of high molar mass were extracted with three different enzyme mixtures. These pectins were subsequently demethylated with two pectin methyl esterases (PMEs), either the fungal PME from Aspergillus aculeatus or the orange PME. It was further demonstrated that high molar mass low methoxy (LM) pectins could also be extracted directly from cell walls by adding the fungal PME to the mixture of protease and cellulase. Moreover, health benefit pectic oligosaccharides, the so-called modified hairy regions, were obtained after enzymatic treatment of the residue recovered after pectin extraction. The enzymatic method demonstrates that it is possible to convert vegetable byproducts into high-added value compounds, such as pectins and pectic oligosaccharides, and thus considerably reduce the amount of these residues generated by food industries.

J Agric Food Chem. 2008 Oct 8;56(19):8926-35

Effects of daily oral administration of quercetin chalcone and modified citrus pectin on implanted colon-25 tumor growth in Balb-c mice.

The health benefits of fruits and vegetables have been the subject of numerous investigations over many years. Two natural substances, quercetin (a flavonoid) and citrus pectin (a polysaccharide found in the cell wall of plants) are of particular interest to cancer researchers. Two modified versions of these substances - quercetin chalcone (QC) and a pH-modified citrus pectin (MCP) - are the focus of this study. Previous research has confirmed that quercetin exhibits antitumor properties, likely due to immune stimulation, free radical scavenging, alteration of the mitotic cycle in tumor cells, gene expression modification, anti-angiogenesis activity, or apoptosis induction, or a combination of these effects. MCP has inhibited metastases in animal studies of prostate cancer and melanoma. To date, no study has demonstrated a reduction in solid tumor growth with MCP, and there is no research into the antitumor effect of QC. This study examines the effects of MCP and QC on the size and weight of colon-25 tumors implanted in balb-c mice. Fifty mice were orally administered either 1 ml distilled water (controls), low-dose QC (0.8 mg/ml), high-dose QC (1.6 mg/ml), low-dose MCP (0. 8 mg/ml) or high-dose MCP (1.6 mg/ml) on a daily basis, beginning the first day of tumor palpation (usually eight days post-implantation). A significant reduction in tumor size was noted at day 20 in all groups compared to controls. The groups given low-dose QC and MCP had a 29% (NS) and 38% (p<0.02) decrease in size, respectively. The high-dose groups had an even more impressive reduction in size; 65% in the QC group and 70% in the mice given MCP (both p<0.001). This is the first evidence that MCP can reduce the growth of solid primary tumors, and the first research showing QC has antitumor activity. Additional research on these substances and their effect on human cancers is warranted.

Altern Med Rev. 2000 Dec;5(6):546-52

Inhibitory effect of modified citrus pectin on liver metastases in a mouse colon cancer model.

AIM: To discuss the expression of glactin-3 in liver metastasis of colon cancer and its inhibition by modified citrus pectin (MCP) in mice. METHODS: Seventy-five Balb/c mice were randomly divided into negative control group (n = 15), positive control group (n = 15), low MCP concentration group (n = 15), middle MCP concentration group (n = 15) and high MCP concentration group (n = 15). CT26 colon cancer cells were injected into the subcapsule of mouse spleen in positive control group, low, middle and high MCP concentrations groups, except in negative control, to set up a colon cancer liver metastasis model. The concentration of MCP in drinking water was 0.0%, 0.0%, 1.0%, 2.5% and 5.0% (wt/vol), respectively. Liver metastasis of colon cancer was observed after 3 wk. Enzyme-linked immunosorbent assay (ELISA) was used to detect the concentration of galectin-3 in serum. Expression of galectin-3 in liver metastasis was detected by immunohistochemistry. RESULTS: Except for the negative group, the percentage of liver metastasis in the other 4 groups was 100%, 80%, 73.3% and 60%, respectively. The number of liver metastases in high MCP concentration group was significantly less than that in positive control group (P = 0.008). Except for the negative group, the median volume of implanted spleen tumor in the other 4 groups was 1.51 cm(3), 0.93 cm(3), 0.77 cm(3) and 0.70 cm(3), respectively. The volume of implanted tumor in middle and high MCP concentration groups was significantly smaller than that in positive control group (P = 0.019; P = 0.003). The concentration of serum galectin-3 in positive control and MCP treatment groups was significantly higher than that in the negative control group. However, there was no significant difference between them. Except for the negative control group, the expression of galectin-3 in liver metastases of the other 4 groups showed no significant difference. CONCLUSION: Expression of galetin-3 increases significantly in liver metastasis of colon cancer, which can be effectively inhibited by MCP.

World J Gastroenterol. 2008 Dec 28;14(48):7386-91

Expression of galectin-3 in liver metastasis of colon cancer and the inhibitory effect of modified citrus pectin.

OBJECTIVE: To observe the expression of galectin-3 in the liver metastasis of colon cancer in mice and the inhibitory effect of modified citrus pectin (MCP) on galectin-3 expression. METHODS: Seventy-five Balb/c mice were randomized into 5 groups, namely the negative control, positive control, low-concentration MCP, moderate-concentration MCP and high-concentration MCP groups. CT26 colon cancer cells were injected into the subcapsule of the mouse spleen to establish liver metastasis models of colon cancer, but the mice in the negative control group received no tumor cell injection. MCP was added into the drinking water of the mice at the concentrations of 0, 1.0%, 2.5% and 5.0% (m/V). The liver metastasis was observed 3 weeks after tumor cell inoculation. Enzyme-linked immunosorbent assay was performed to determine the serum galectin-3 level. A tissue microarray of the liver metastasis was prepared for immunohistochemical detection of galectin-3 expression in the liver metastasis. RESULTS: In the positive control, low-, moderate- and high-concentration MCP groups, the rates of liver metastasis were 100%, 80%, 73.3% and 60%, respectively. The number of liver metastases in high-concentration MCP group was significantly smaller than that in the positive control group (P<0.05). In the 4 groups with tumor cell inoculation, the median volume of the primary lesions in the spleen was 1.51, 0.93, 0.77 and 0.70 cm(3), respectively, which were significantly smaller in the moderate- and high-concentration MCP groups than in the positive control group (P<0.05). The serum galectin-3 level in the positive control group and MCP-treated groups were significantly higher than that in the negative control group (P<0.01), but similar between the positive control group and the MCP-treated groups (P>0.05). In the positive control and the MCP-treated groups, the expression of galectin-3 in the liver metastases showed no significant differences (P>0.05). CONCLUSION: The expression of galetin-3 is significantly increased in the liver metastasis of colon cancer, and MCP can effectively inhibit the liver metastasis.

Nan Fang Yi Ke Da Xue Xue Bao. 2008 Aug;28(8):1358-61

Mechanical entrapment is insufficient and intercellular adhesion is essential for metastatic cell arrest in distant organs.

In this report, we challenge a common perception that tumor embolism is a size-limited event of mechanical arrest, occurring in the first capillary bed encountered by blood-borne metastatic cells. We tested the hypothesis that mechanical entrapment alone, in the absence of tumor cell adhesion to blood vessel walls, is not sufficient for metastatic cell arrest in target organ microvasculature. The in vivo metastatic deposit formation assay was used to assess the number and location of fluorescently labeled tumor cells lodged in selected organs and tissues following intravenous inoculation. We report that a significant fraction of breast and prostate cancer cells escapes arrest in a lung capillary bed and lodges successfully in other organs and tissues. Monoclonal antibodies and carbohydrate-based compounds (anti-Thomsen-Friedenreich antigen antibody, anti-galectin-3 antibody, modified citrus pectin, and lactulosyl-l-leucine), targeting specifically beta-galactoside-mediated tumor-endothelial cell adhesive interactions, inhibited by >90% the in vivo formation of breast and prostate carcinoma metastatic deposits in mouse lung and bones. Our results indicate that metastatic cell arrest in target organ microvessels is not a consequence of mechanical trapping, but is supported predominantly by intercellular adhesive interactions mediated by cancer-associated Thomsen-Friedenreich glycoantigen and beta-galactoside-binding lectin galectin-3. Efficient blocking of beta-galactoside-mediated adhesion precludes malignant cell lodging in target organs.

Neoplasia. 2005 May;7(5):522-7

Death receptor agonists as a targeted therapy for cancer.

Apoptosis is integral to normal, physiologic processes that regulate cell number and results in the removal of unnecessary or damaged cells. Apoptosis is frequently dysregulated in human cancers, and recent advancements in our understanding of the regulation of programmed cell death pathways has led to the development of novel agents to reactivate apoptosis in malignant cells. The activation of cell surface death receptors by tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) and death receptor agonists represent an attractive therapeutic strategy to promote apoptosis of tumor cells through the activation of the extrinsic pathway. The observation that Apo2L/TRAIL can eliminate tumor cells preferentially over normal cells has resulted in several potential therapeutics that exploit the extrinsic pathway, in particular, the soluble recombinant human (rh)Apo2L/TRAIL protein and agonist monoclonal antibodies that target death receptors 4 or 5. Many of these agents are currently being evaluated in phase 1 or 2 trials, either as a single agent or in combination with cytotoxic chemotherapy or other targeted agents. The opportunities and challenges associated with the development of death receptor agonists as cancer therapeutics, the status of ongoing clinical evaluations, and the progress toward identifying predictive biomarkers for patient selection and pharmacodynamic markers of response are reviewed.

Clin Cancer Res. 2010 Mar 15;16(6):1701-8

PectaSol-C modified citrus pectin induces apoptosis and inhibition of proliferation in human and mouse androgen-dependent and- independent prostate cancer cells.

AIM: To demonstrate the efficacy of PectaSol-C modified citrus pectin (MCP) on prostate cancer in vitro. METHOD: Cytotoxicity analysis of PectaSol-C was performed by MTT assay, as were parallel studies with the former brand version of MCP called PectaSol. Apoptosis and inhibition of cell growth were investigated by Western blotting. RESULTS: Androgen-dependent and -independent human prostate cancer cell lines (LNCaP and PC3, respectively), androgen-dependent and -independent murine prostate cancer cell lines (CASP2.1 and CASP1.1, respectively), as well as noncancerous human benign prostate hyperplasia BPH-1 cell line, were used in the study. MTT assay revealed that 1.0% PectaSol exerted cytotoxicity on LNCaP, PC3, CASP2.1, CASP1.1, and BPH-1 cells for 4-day treatment by 48.0% +/- 2.1%, 54.4% +/- 0.3%, 15.4% +/- 0.8%, 46.1% +/- 1.7%, and 27.4% +/- 1.6%, respectively; whereas 1.0% PectaSol-C showed cytotoxity by 52.2% +/- 1.8%, 48.2% +/- 2.9%, 23.0% +/- 2.6%, 49.0% +/- 1.3%, and 26.8% +/- 2.6%, respectively. Western blotting further confirmed that both MCPs inhibit MAP kinase activation, increase the expression level of its downstream target Bim, a pro-apoptotic protein, and induce the cleavage of Caspase-3 in PC3 and CASP1.1 prostate cancer cells. CONCLUSION: PectaSol MCP and PectaSol-C MCP can inhibit cell proliferation and apoptosis in prostate cancer cell lines. Our data suggested that 1.0% PectaSol-C can be used for further chemopreventive and chemotherapeutic analysis in vivo.

Integr Cancer Ther. 2010 Jun;9(2):197-203

Characterization of the convulsant action of pregnenolone sulfate.

Pregnenolone sulfate (PS) is an endogenous neurosteroid synthesized by glial cells, which acts as a potent convulsant when injected intracerebroventricularly and intraperitoneally. PS is found in relatively high concentrations in the hippocampus. But its convulsant action in the hippocampus has not been characterized. A range of PS doses were infused directly into the right hippocampus of 42 rats, which were subsequently monitored for behavioral and electrographic seizures. At the highest dose (4 micromol), PS produced status epilepticus (SE) and severe behavioral convulsions. As the dose of PS was reduced, the fraction of rats having SE diminished (ED50 for SE = 2.7 micromol). At doses lower than 300 nmol, PS infusion produced discrete electrographic seizures (ED50 = 68 nmol) associated with mild behavioral seizures. Both the behavioral seizure score (BSS) and the total number of seizures during the observation period changed in a dose-dependent manner. In separate experiments in cultured hippocampal neurons, PS enhanced NMDA-evoked whole-cell currents (EC50 = 16 microM). The results demonstrate that the hippocampus is highly sensitive to the convulsant effects of PS and that the enhancement of NMDA currents could contribute to the convulsant action of PS.

Neuropharmacology. 2004 May;46(6):856-64

Associated hormonal declines in aging: DHEAS.

DHEA and its sulfate prohormone DHEAS are the most abundant circulating adrenal steroid hormones in humans. DHEA exerts its actions on peripheral target tissues either indirectly, following its conversion to androgens, estrogens or both, or directly, as a steroid hormone interacting with either a nuclear or a membrane receptor. In humans, DHEA shows a characteristic pattern of secretion throughout life. Serum DHEA concentrations decline with advancing age and vary with gender, ethnicity, and environmental factors. Epidemiological studies show an inverse relationship between plasma DHEA(S) levels in men and age-related illnesses, including cardiovascular and metabolic diseases, immune disorders, malignancies, and neurological dysfunction. This has generated great interest on the putative role of DHEA in age-associated illnesses. Administration of DHEA to rats and mice reduces visceral fat accumulation, and improves insulin resistance in experimental models of diet-induced obesity and/or type 2 diabetes. In addition, recent studies in vitro have shown that DHEA has the capacity to improve endothelial function by increasing nitric oxide (NO) synthesis. Replacement of DHEA in patients with adrenal insufficiency has been shown to exert beneficial effects on well-being, mood, and sexuality. By contrast, in healthy individuals, the physiological age-associated decline in circulating DHEA(S) per se does not justify DHEA supplementation, since the effects of this hormone on metabolic abnormalities, endothelial function in vivo, and cardiovascular events are contradictory. However, these results do not exclude the possibility that DHEA treatment may prove beneficial in specific subgroups of elderly subjects.

J Endocrinol Invest. 2005;28(3 Suppl):85-93

Uses of DHEA in aging and other disease states.

Dehydro-3-epiandrosterone is a steroid hormone synthesized in large quantities by the adrenal gland whose physiologic role remains unclear. The effects of DHEA could be estrogenic or androgenic, depending on the hormonal milieu. Low levels of DHEA are associated with aging, cardiovascular disease in men, and an increased risk of pre-menopausal breast and ovarian cancer. High levels of DHEA might increase the risk of postmenopausal breast cancer. Therapeutically DHEA might be useful for improving psychological well-being in the elderly, reducing disease activity in people with mild to moderate systemic lupus erythematosus and myotonic dystrophy, improving mood in those clinically depressed, and improving various parameters in women with adrenal insufficiency. Although many other claims have been made for DHEA in diverse conditions, such as aging, dementia, and AIDS, no well-designed clinical trials have clearly substantiated the utility and safety of long-term DHEA supplementation.

Ageing Res Rev. 2002 Feb;1(1):29-41

Pregnenolone sulfate enhances neurogenesis and PSA-NCAM in young and aged hippocampus.

Age-dependent cognitive impairments have been correlated with functional and structural modifications in the hippocampal formation. In particular, the brain endogenous steroid pregnenolone-sulfate (Preg-S) is a cognitive enhancer whose hippocampal levels have been linked physiologically to cognitive performance in senescent animals. However, the mechanism of its actions remains unknown. Because neurogenesis is sensitive to hormonal influences, we examined the effect of Preg-S on neurogenesis, a novel form of plasticity, in young and old rats. We demonstrate that in vivo infusion of Preg-S stimulates neurogenesis and the expression of the polysialylated forms of NCAM, PSA-NCAM, in the dentate gyrus of 3- and 20-month-old rats. These influences on hippocampal plasticity are mediated by the modulation of the gamma-aminobutyric acid receptor complex A (GABA(A)) receptors present on hippocampal neuroblasts. In vitro, Preg-S stimulates the division of adult-derived spheres suggesting a direct influence on progenitors. These data provide evidence that neurosteroids represent one of the local secreted signals controlling hippocampal neurogenesis. Thus, therapies which stimulate neurosteroidogenesis could preserve hippocampal plasticity and prevent the appearance of age-related cognitive disturbances.

Neurobiol Aging. 2005 Jan;26(1):103-14

Pregnenolone, dehydroepiandrosterone, and their sulfate and fatty acid esters in the rat brain.

The rat brain contains large amounts of pregnenolone (P) and dehydroepiandrosterone (D) arising from local biosynthetic pathways. We have devised a procedure for the measurement of both “neurosteroids” either unconjugated or released from their sulfate (S) or fatty acid (L) esters. The measurements were performed at the acrophase of the circadian variation of neurosteroids, and confirmed the large accumulation of P (25 +/- 8 ng/g, mean +/- SD) and of PS (19 +/- 6 ng/g) and DS (2.1 +/- 0.5 ng/g) in the brain of adult male rats. We found that fatty acid esters constitute the major species of neurosteroids in brain (PL 46 +/- 14, and DL 36 +/- 7 ng/g, in adult males). The levels of P and DS were increased by daily injection of vehicle to intact males, whereas castration, without or with testosterone or estradiol supplementation (2 mg daily for 7 days), did not produce a significant change of neurosteroids concentrations. Measurements of neurosteroids had not been previously reported in cyclic females. The levels of P, PL, and DS were identical in proestrous females and in intact males, whereas PS (26 +/- 6 ng/g) and DL (50 +/- 16 ng/g) were increased in females. Compared to proestrous females, diestrous females had lower levels of PS (19 +/- 6 ng/g), DS (1.7 +/- 0.4 ng/g), and PL (43 +/- 19 ng/g). These differences suggested a modulatory role of ovarian secretions on the metabolism of neurosteroids.

Steroids. 1989 Sep;54(3):287-97

Endogenous neuroprotective factors: neurosteroids.

Neurosteroids are a group of steroid hormones synthesized by the brain in the presence of steroidogenic enzymes. Specific neurosteroids modulate function of several receptors, and also regulate growth of neurons, myelinization and synaptogenesis in the central nervous system. Some neurosteroids have been shown to display neuroprotective properties, which may have important implications for their potential use in the treatment of various neuropathologies such as: age-dependent dementia, stroke, epilepsy, spinal cord injury, Alzheimer’s disease (AD), Parkinson’s disease (PD) and Niemann-Pick type C disease (NP-C). This paper focuses on neuroprotection afforded by neurosteroids.

Pharmacol Rep. 2006 May-Jun;58(3):335-40

Pregnenolone sulphate attenuates AMPA cytotoxicity on rat cortical neurons.

Neuroactive steroids can modulate brain excitability by interaction with several neurotransmitter receptor-associated channels. These compounds may thus exert profound influences on excitotoxic injury, i.e. neuronal cell death triggered by over-activation of glutamate receptors. It has been reported that pregnenolone sulphate (PS) and pregnenolone hemisuccinate (PHS) augment N-methyl-D-aspartate (NMDA) neurotoxicity in rat cultured neurons. Here we show that the effects of neuroactive steroids on AMPA cytotoxicity display features distinct from those on NMDA cytotoxicity. Concomitant application of PS (30-300 microm) attenuated, rather than augmented, AMPA neurotoxicity in cortical slice cultures in a concentration-dependent manner, whereas various other steroids including pregnenolone and PHS had no effect. Inhibition of steroid sulphatase by estrone-3-O-sulphamate led to a shift of the minimum effective concentration of PS against AMPA cytotoxicity from 30 to 10 microm. The protective action of PS was not affected by inhibition of protein synthesis or by blockade of glucocorticoid receptors, GABAA receptors or sigma-receptors. In dissociated cortical neurons, PS attenuated AMPA-induced inward currents whereas pregnenolone and PHS exhibited no significant effect. Thus, with strict structural specificity, PS but not pregnenolone or PHS attenuates AMPA cytotoxicity, probably by inhibiting activities of AMPA receptor-associated channels.

Eur J Neurosci. 2005 May;21(9):2329-35

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