Life Extension Magazine®

Issue: Apr 2012

Trimetazidine

Production of bioactive substances by intestinal bacteria as a basis for explaining probiotic mechanisms: bacteriocins and conjugated linoleic acid.

The mechanisms by which intestinal bacteria achieve their associated health benefits can be complex and multifaceted. In this respect, the diverse microbial composition of the human gastrointestinal tract (GIT) provides an almost unlimited potential source of bioactive substances (pharmabiotics) which can directly or indirectly affect human health. Bacteriocins and fatty acids are just two examples of pharmabiotic substances which may contribute to probiotic functionality within the mammalian GIT. Bacteriocin production is believed to confer producing strains with a competitive advantage within complex microbial environments as a consequence of their associated antimicrobial activity. This has the potential to enable the establishment and prevalence of producing strains as well as directly inhibiting pathogens within the GIT. Consequently, these antimicrobial peptides and the associated intestinal producing strains may be exploited to beneficially influence microbial populations. Intestinal bacteria are also known to produce a diverse array of health-promoting fatty acids. Indeed, certain strains of intestinal bifidobacteria have been shown to produce conjugated linoleic acid (CLA), a fatty acid which has been associated with a variety of systemic health-promoting effects. Recently, the ability to modulate the fatty acid composition of the liver and adipose tissue of the host upon oral administration of CLA-producing bifidobacteria and lactobacilli was demonstrated in a murine model. Importantly, this implies a potential therapeutic role for probiotics in the treatment of certain metabolic and immunoinflammatory disorders. Such examples serve to highlight the potential contribution of pharmabiotic production to probiotic functionality in relation to human health maintenance.

Int J Food Microbiol. 2012 Jan 16;152(3):189-205

Probiotics and pharmabiotics: alternative medicine or an evidence-based alternative?

That commensal bacteria play an important role in human health is beyond doubt, and it is now widely accepted that humans function as super organisms, whose collective metabolic potential exceeds the sum of our individual eukaryotic and prokaryotic components. However, while it is has been established that the prokaryotic component of the human superorganism is amenable to manipulation by chemotherapeutic, dietary or microbial interventions, the significance of such alterations in terms of human health or well being is less well established. Prebiotics (non- digestible food ingredients that stimulate the growth and/or activity of bacteria in the digestive system) and probiotics (live microorganisms that when administered in adequate amounts, confer a health benefit on the host) are often bracketed among ‘alternative’ approaches to influencing human health, such as homeopathy, naturopathy, acupuncture and hypnotherapy. Others believe that prebiotics and probiotics have proven their effectiveness in properly conducted, clinically controlled human trials and therefore can be considered as evidence-based alternatives or adjuncts to conventional medicines. My journey from a position of total skepticism to ‘reluctant convert’ is the basis of this article, which should not be considered in any sense as a review of the literature but simply a personal account of this transition. While I am not bent on converting other doubters, I will recount some of the thought processes and evidence that has helped to form my current opinion.

Bioeng Bugs. 2010 Mar-Apr;1(2):79-84

The potential for probiotic manipulation of the gastrointestinal microbiome.

Multiple internal and external sites of the healthy human body are colonized by a diversity of symbiotic microbes. The microbial assemblages found in the intestine represent some of the most dense and diverse of these human-associated ecosystems. Unsurprisingly, the enteric microbiome, that is the totality of microbes, their combined genomes, and their interactions with the human body, has a profound impact on physiological aspects of mammalian function, not least, host immune response. Lack of early-life exposure to certain microbes, or shifts in the composition of the gastrointestinal microbiome have been linked to the development and progression of several intestinal and extra-intestinal diseases, including childhood asthma development and inflammatory bowel disease. Modulating microbial exposure through probiotic supplementation represents a long-held strategy towards ameliorating disease via intestinal microbial community restructuring. This field has experienced somewhat of a resurgence over the past few years, primarily due to the exponential increase in human microbiome studies and a growing appreciation of our dependence on resident microbiota to modulate human health. This review aims to review recent regulatory aspects related to probiotics in food. It also summarizes what is known to date with respect to human gastrointestinal microbiota - the niche which has been most extensively studied in the human system - and the evidence for probiotic supplementation as a viable therapeutic strategy for modulating this consortium.

Curr Opin Biotechnol. 2011 Nov 30

The colonic microflora and probiotic therapy in health and disease.

PURPOSE OF REVIEW: Host-microbe dialogue is involved not only in maintenance of mucosal homeostasis but also in the pathogenesis of several infectious, inflammatory, and neoplastic disorders of the gut. This has led to a resurgence of interest in the colonic microbiota in health and disease. Recent landmark findings are addressed here. RECENT FINDINGS: Reciprocal signalling between the immune system and the microbiota plays a pivotal role in linking alterations in gut microbiota with risk of metabolic disease in the host, notably insulin resistance, obesity, and chronic low-grade inflammation. Loss of ancestral indigenous organisms consequent upon a modern lifestyle may contribute to an increased frequency of various metabolic and immuno-allergic diseases. The potential to address this underpins the science of pharmabiotics. SUMMARY: Advances in understanding host-microbe interactions within the gut can inform rational probiotic or pharmabiotic selection criteria. In addition, the gut microbiota may be a repository for drug discovery as well as a therapeutic target.

Curr Opin Gastroenterol. 2011 Jan;27(1):61-5

Probiotics-host communication: Modulation of signaling pathways in the intestine.

The intestinal microbiota includes a diverse group of functional microorganisms, including candidate probiotics or viable microorganisms that benefit the host. Beneficial effects of probiotics include enhancing intestinal epithelial cell function, protecting against physiologic stress, modulating cytokine secretion profiles, influencing T lymphocyte populations, and enhancing antibody secretion. Probiotics have demonstrated significant potential as therapeutic options for a variety of diseases, but the mechanisms responsible for these effects remain to be fully elucidated. Accumulating evidence demonstrates that probiotics communicate with the host by modulating key signaling pathways, such as NFkB and MAPK, to either enhance or suppress activation and influence downstream pathways. Beneficial microbes can profoundly alter the physiology of the gastrointestinal tract, and understanding these mechanisms may result in new diagnostic and therapeutic strategies.

Gut Microbes. 2010 May-Jun;1(3):148-63

Mechanisms of probiotic action: Implications for therapeutic applications in inflammatory bowel diseases.

Probiotics are defined as nonpathogenic living microorganisms, including some commensal bacterial flora, which have beneficial effects on host health and disease prevention and/or treatment. Clinical trials have shown beneficial effects of probiotics on several human diseases, such as inflammatory bowel diseases (IBDs), which are among the most-studied diseases testing probiotics as a potential therapy. However, a significant question regarding clinical use of probiotics is the mechanism underlying the wide range of actions. Studies discussed in this review suggest 3 distinct cellular and molecular mechanisms for probiotic regulation in IBD therapy: 1) Probiotics block pathogenic bacterial effects by producing bactericidal substances and competing with pathogens and toxins for adherence to the intestinal epithelium; 2) Probiotics regulate immune responses by enhancing the innate immunity and modulating pathogen-induced inflammation via toll-like receptor-regulated signaling pathways; and 3) Probiotics regulate intestinal epithelial homeostasis by promoting intestinal epithelial cell survival, enhancing barrier function, and stimulating protective responses. Probiotics modulate host cell signaling pathways, including Akt, mitogen-activated protein kinases, and nuclear factor-kappaB to mediate these intestinal epithelial functions. It is hoped that developing a mechanistic understanding of probiotic action will provide the rationale to support the development of new hypothesis-driven studies to define the clinical efficacy in preventive, adjunctive, or alternative treatments for IBD.

Inflamm Bowel Dis. 2008 Nov;14(11):1585-96

Indications for the use of probiotics in gastrointestinal diseases.

Probiotics are live microbial organisms that are present in foods or dietary supplements and that confer health benefits to the host when ingested in sufficient quantities. Probiotics can be bacterial (e.g. Bifidobacteria spp. and Lactobacillus spp.) or yeasts (e.g. Saccharomyces boulardii). The administration of probiotics is often believed to be by and large beneficial for individuals with inflammatory or infectious diseases of the gastrointestinal tract. These positive effects are generally attributed to the ability of probiotics to regulate intestinal permeability, normalize host intestinal flora, improve gut immune barrier function, and equilibrate the balance between proinflammatory and anti-inflammatory cytokines. Of note, however, these claims are not always substantiated by findings from properly conducted clinical trials. Of particular importance, even when results from randomized controlled trials support the beneficial effects of a particular probiotic for a specific indication, the benefits achieved by the probiotic are generally not translatable to other probiotic formulations. This review discusses the gastrointestinal indications for probiotic use and describes the level of evidence that supports the use of specific probiotics for these indications. Several indications are addressed, including enteric infections, gastritis caused by Helicobacter pylori infection, necrotizing enterocolitis, inflammatory bowel diseases, and irritable bowel syndrome.

Dig Dis. 2011;29(6):574-87

Gut microbiota, probiotics, and vitamin D: interrelated exposures influencing allergy, asthma, and obesity?

Current evidence supports a role for gut colonization in promoting and maintaining a balanced immune response in early life. An altered or less diverse gut microbiota composition has been associated with atopic diseases, obesity, or both. Moreover, certain gut microbial strains have been shown to inhibit or attenuate immune responses associated with chronic inflammation in experimental models. However, there has been no fully adequate longitudinal study of the relation between the neonatal gut microbiota and the development of allergic diseases (eg, atopic asthma) and obesity. The emergence of promising experimental studies has led to several clinical trials of probiotics (live bacteria given orally that allow for intestinal colonization) in human subjects. Probiotic trials thus far have failed to show a consistent preventive or therapeutic effect on asthma or obesity. Previous trials of probiotics have been limited by small sample size, short duration of follow-up, or lack of state-of-the art analyses of the gut microbiota. Finally, there is emerging evidence that the vitamin D pathway might be important in gut homeostasis and in signaling between the microbiota and the host. Given the complexity of the gut micriobiota, additional research is needed before we can confidently establish whether its manipulation in early life can prevent or treat asthma, obesity, or both.

J Allergy Clin Immunol. 2011 May;127(5):1087-94

Regulation of tight junction permeability by intestinal bacteria and dietary components.

The human intestinal epithelium is formed by a single layer of epithelial cells that separates the intestinal lumen from the underlying lamina propria. The space between these cells is sealed by tight junctions (TJ), which regulate the permeability of the intestinal barrier. TJ are complex protein structures comprised of transmembrane proteins, which interact with the actin cytoskeleton via plaque proteins. Signaling pathways involved in the assembly, disassembly, and maintenance of TJ are controlled by a number of signaling molecules, such as protein kinase C, mitogen-activated protein kinases, myosin light chain kinase, and Rho GTPases. The intestinal barrier is a complex environment exposed to many dietary components and many commensal bacteria. Studies have shown that the intestinal bacteria target various intracellular pathways, change the expression and distribution of TJ proteins, and thereby regulate intestinal barrier function. The presence of some commensal and probiotic strains leads to an increase in TJ proteins at the cell boundaries and in some cases prevents or reverses the adverse effects of pathogens. Various dietary components are also known to regulate epithelial permeability by modifying expression and localization of TJ proteins.

J Nutr. 2011 May;141(5):769-76

An intimate tête-à-tête - how probiotic lactobacilli communicate with the host.

Pharmaceutical agents are routinely used in the treatment of gastrointestinal disorders and their role as modulators of host cell responses is well characterized. In contrast, the understanding of the molecular mechanisms, which determine the role of probiotics, i.e. health-promoting bacteria, as host cell modulators is still in its infancy. Both in vitro and in vivo studies are just starting to reveal the capability of probiotic lactobacilli to modulate host cell-signaling networks and the associated influences on downstream regulatory pathways, including modulation of mucosal cytokine profiles that dictate host immune functions. The communication between probiotic lactobacilli and intestinal host cells is multifactorial and involves an integrative repertoire of receptors on the host side that recognize multiple effector molecules on the bacterial side, of which most have been found to be cell wall- or cell surface-associated compounds and proteins. This review describes the discovery of these bacterial effector molecules and their role in strain- and species-specific modulation of host signaling pathways. Unraveling the mechanisms responsible for probiotic-host interactions will progress this research field towards molecular science and will provide markers for probiotic product quality control as well as host-response efficacy. These developments can ultimately lead to a more dedicated, personalized application of probiotics with strong molecular and scientific support for health promotion.

Eur J Pharmacol. 2011 Sep;668 Suppl 1:S33-42

Microbes, intestinal inflammation and probiotics.

Inflammatory bowel disease (IBD) is known for causing disturbed homeostatic balance among the intestinal immune compartment, epithelium and microbiota. Owing to the emergence of IBD as a major cause of morbidity and mortality, great efforts have been put into understanding the sequence of intestinal inflammatory events. Intestinal macrophages and dendritic cells act in a synergistic fashion with intestinal epithelial cells and microbiota to initiate the triad that governs the intestinal immune responses (whether inflammatory or regulatory). In this review, we will discuss the interplay of intestinal epithelial cells, bacteria and the innate immune component. Moreover, whether or not genetic intervention of probiotic bacteria is a valid approach for attenuating/mitigating exaggerated inflammation and IBD will also be discussed.

Expert Rev Gastroenterol Hepatol. 2012 Feb;6(1):81-94

Probiotics in the treatment of human inflammatory bowel diseases: update 2011.

Crohn’s disease, ulcerative colitis, and pouchitis after ileal pouch anal anastomosis in ulcerative colitis patients are often refractory to standard therapy. Over the last decade, the rational to use probiotics and its beneficial efficacy in the treatment of chronic inflammatory bowel disease (IBD) is increasingly under scrutiny. Although it has become clear that intestinal epithelial-mucosal immune interactions and enteric bacteria play a critical role in the development of IBD, the substantial clinical efficacy of probiotics in these disorders is less evident. This review outlines the clinical studies regarding probiotics before October 2007. These studies formed the foundation of probiotic clinical trials in IBD, but they also indicated the need of larger and better-controlled studies than the past experimental approaches. Furthermore, this review also examines in-depth the probiotic clinical trials published between 2007 and December 2010, providing new insights into the role of probiotics for inducing and maintaining remission of IBD, and highlighting some of the breakthroughs, especially regarding induction of remission for ulcerative colitis.

J Clin Gastroenterol. 2011 Nov;45 Suppl:S139-44

Probiotics and prebiotics in primary care for colon cancer.

CONTEXT: Colon neoplasias are presently the third most common cancer type. Its treatment is still associated with high risk of complications, thus emphasizing the need to design new treatment strategies. The ingestion of probiotics and prebiotics, or the combination of both (symbiotics), represents a new therapeutic choice. In front of the importance among qualitative and quantitative balance in intestinal microbiota for human’s health and with the purpose to evaluate the application of probiotics and prebiotics, this study tries to approach the importance of these in both the prevention and treatment of colon cancer. EVIDENCE ACQUISITION: A study was conducted on scientific databases (Medline, Lilacs, PubMed, Ovid, SciELO), and a review was made of recent scientific articles in the literature, from 2003 to 2008. Additional informations were taken from sites in the internet. RESULTS: Studies point out the inverse relation between the consumption of probiotics and prebiotics in colon cancer diagnosis through various action mechanisms, including: immune response stimulation, reduction in inflammation, for directly inhibiting the formation of tumor cells and for converting pre-carcinogenic substances into carcinogenic ones. CONCLUSION: Through this literature review, it was possible to achieve positive answers as regards the use of probiotics and prebiotics in carcinogenesis, which can be adequately recommended.

Arq Gastroenterol. 2010 Jan-Mar;47(1):93-8

Probiotics Prevent the Development of 1,2-Dimethylhydrazine (DMH)-Induced Colonic Tumorigenesis through Suppressed Colonic Mucosa Cellular Proliferation and Increased Stimulation of Macrophages.

Probiotics modulate immunity and inhibit colon carcinogenesis in experimental models, but these effects largely depend on the bacterial strain, and the precise mechanisms are not well understood. Therefore, we studied the effect of Bifidobacterium longum and/or Lactobacillus gasseri on the development of 1,2-dimethylhydrazine (DMH)-induced colonic precancerous lesions and tumors in mice while delineating the possible mechanisms involved. The results suggest that dietary consumption of probiotics (B. longum and L. gasseri) resulted in a significant inhibition of DMH-induced aberrant crypt foci (ACF) formation in male ICR mice. Long-term (24 weeks) dietary consumption of probiotics resulted in a reduction of colon tumor multiplicity and the size of the tumors. Administration of B. longum and L. gasseri suppressed the rate of colonic mucosa cellular proliferation in a manner correlating with the inhibition of tumor induction by DMH. In addition, the phagocytic activity of peritoneal macrophages was significantly increased in the DMH-treated mice that were fed various doses of B. longum, but not with L. gasseri or combined probiotics (B. longum + L. gasseri). We also found that L. gasseri significantly increased the proliferation of RAW264.7 macrophage cells through an increase in S phase DNA synthesis, which was related to the up-regulation of proliferating cell nuclear antigen (PCNA) and cyclin A. Taken together, these results demonstrate the in vivo chemopreventive efficacy and the immune stimulating mechanisms of dietary probiotics against DMH-induced colonic tumorigenesis.

J Agric Food Chem. 2011 Dec 28;59(24):13337-45

Procyanidins from apples (Malus pumila Mill.) extend the lifespan of Caenorhabditis elegans.

Apple polyphenols (AP) mainly consist of procyanidins (PC), which are composed of (-)-epicatechins and (+)-catechins. In order to investigate the antiageing effects of PC, we measured the life span of CAENORHABDITIS ELEGANS worms treated with PC. Treatment with 65 µg/mL PC extended the mean life span of wild-type N2 and FEM-1 worms by 12.1 % and 8.4 %, respectively, i.e., to a similar extent as resveratrol. In addition, treatment with 100 µg/mL AP also significantly prolonged the mean life span of the same worms by 12.0 % and 5.3 %, respectively, i.e., to a similar extent as PC. In contrast, treatment with (-)-epicatechin did not extend the life span of the worms. PC did not modify the growth, food intake, or fecundity of C. elegans. Treatment with PC did not extend the life span of MEV-1 worms, which show excessive oxidative stress, indicating that PC had no antioxidant ability in the MEV-1 mutant. Moreover, treatment with PC had no effect on the longevity of SIR-2.1 worms, which lack the activity of SIR-2, a member of the sirtuin family of NAD (+)-dependent protein deacetylases. These results indicated that PC has SIR-2.1-dependent antiageing effects on C. elegans.

Planta Med. 2011 Jan;77(2):122-7

Apple polyphenols modulate expression of selected genes related to toxicological defence and stress response in human colon adenoma cells.

Apples contain significant amounts of flavonoids that are potentially cancer risk reducing by acting antioxidative or antiproliferative and by favorably modulating gene expression. The purpose of this study was to investigate whether polyphenols from apples modulate expression of genes related to colon cancer prevention in preneoplastic cells derived from colon adenoma (LT97). For this, LT97 cells were treated with effective concentrations of apple extracts (AEs). RNA was isolated and used for synthesis and labeling of cDNA that was hybridized to cDNA-arrays. Gene expression studies were performed using a commercial cDNA-array from Superarray that contains a limited number of genes (96 genes) related to drug metabolism, and a custom-made cDNA microarray that contains a higher number of genes (300 genes, including some genes from Superarray) related to mechanisms of carcinogenesis or chemoprevention. Real-time PCR and enzyme activity assays were additionally performed to confirm selected array results. Treatment of cells with AE resulted in 30 and 46 genes expressed over cut-off values (>or=1.5- or <or=0.7-fold) in Superarray and custom array, respectively. Of 87 genes spotted on both arrays, 4 genes (CYP3A7, CYP4F3, CHST7, GSTT2) were regulated with similar directional changes. Expression of selected phase II genes (GSTP1, GSTT2, GSTA4, UGT1A1, UGT2B7), regulated on either array, was confirmed by real-time PCR. The enzyme activities of glutathione S-transferases and UDP-glucuronosyltransferases were altered by treatment of LT97 cells with AE. The observed altered gene expression patterns in LT97 cells, resulting from AE treatment, points to a possible protection of the cells against some toxicological insults.

Int J Cancer. 2008 Jun 15;122(12):2647-55

Impact of apple polyphenols on GSTT2 gene expression, subsequent protection of DNA and modulation of proliferation using LT97 human colon adenoma cells.

Apple extract (AE) enhances expression of glutathione S-transferases (e.g., GSTT2) in human colon cells (LT97). Therefore, aim of the present study was to identify functional consequences of GSTT2 induction by AE and to determine the relation of AE effects to isolated compounds. Polyphenol composition of AE was analyzed. LT97 cells were treated with AE or synthetic polyphenol mixture (SPM) under conditions that induced GSTT2, and challenged with GSTT2-2 substrate cumene hydroperoxide (CumOOH) to determine DNA damage using comet assay. Modulation of GSTT2 expression (real-time PCR) was reassessed, and the influence on cell proliferation and pro-oxidative potential of AE and SPM were assessed to understand additional mechanisms. Induction of GSTT2 by AE was accompanied by protection of LT97 cells from CumOOH-induced genotoxicity. Although SPM was unable to reflect AE-specific bioactivity related to GSTT2 modulation and anti-genotoxicity, inhibition of LT97 cell proliferation by SPM was comparable. Storage of AE caused changes in phenolic composition along with loss of activity regarding GSTT2 induction and amplified growth inhibition. At the applied concentrations, no H(2)O(2) formation was detectable with any of the substances. AE can protect against oxidatively induced DNA damage. Nevertheless, chemopreventive effects of AE strongly depend on the specific composition, which is modified by storage.

Mol Nutr Food Res. 2009 Oct;53(10):1254-62

Apple juice intervention modulates expression of ARE-dependent genes in rat colon and liver.

BACKGROUND: The risk of cancer and other degenerative diseases is inversely correlated with consumption of fruits and vegetables. This beneficial effect is mainly attributed to secondary plant constituents such as polyphenols, supposed to play a major role in protection against ROS (reactive oxygen species)-associated toxicity. AIM OF THE STUDY: To elucidate the potential of differently manufactured apple juices (clear AJ/cloudy AJ/smoothie, in comparison with a polyphenol-free control juice) to modulate expression of ARE-dependent genes. METHODS: In male Sprague-Dawley rats (n = 8/group; 10d juice intervention, 4d wash-out; 4 treatment cycles), expression of target genes (superoxide dismutase, SOD1/SOD2; glutathione peroxidase, GPX1/GPX2; γ-glutamylcysteine ligase, GCLC/GCLM; glutathione reductase, GSR; catalase, CAT; NAD(P)H:quinone oxidoreductase-1, NQO1 and transcription factor erythroid-derived 2-like-2, Nrf2) was quantified with duplex RT-PCR, using glyceraldehyde-3-phosphate dehydrogenase (GAPDH) as control. RESULTS: In colon and liver of rats consuming polyphenol-free control juice, rather similar basic expressions were observed (relative GAPDH ratios ranging from 2 to 0.7 and 2.5-0.3, respectively). In the distal colon, apple juice intervention slightly but significantly induced most genes (e.g. GPX2, GSR, CAT, Nrf2; p < 0.001), whereas in the liver only GPX1 and NQO1 mRNA were up-regulated; other hepatic target genes were not affected or down-regulated (SOD1, SOD2, GCLC/M, GSR), concomitant with the absence of Nrf2 induction. Induction of antioxidant gene expression differed with juice type (cloudy AJ > clear AJ ~ smoothie). CONCLUSION: Taken together, the results underline the potential of polyphenol-rich apple juice to increase the expression of ARE-dependent antioxidant genes.

Eur J Nutr. 2011 Mar;50(2):135-43

Cloudy apple juice decreases DNA damage, hyperproliferation and aberrant crypt foci development in the distal colon of DMH-initiated rats.

Clear (CleA) and cloudy (CloA) apple juices containing different amounts of analyzed procyanidins and pectin were investigated for preventive effects of colon cancer and underlying molecular mechanisms in F344 rats given intraperitoneal injections of 1,2-dimethylhydrazine (DMH; 20 mg/kg body wt) once a week for 4 weeks. Rats received either water (Cont), CleA or CloA (ad libitum) for 7 weeks starting 1 week before the first DMH injection. CloA inhibited DMH induced genotoxic damage in mucosa cells of the distal colon compared with Cont as investigated by single-cell microgel electrophoresis assay. The mean tail intensity in mucosa cells of DMH-treated controls (Cont/DMH: 6.1+/-0.9%) was significantly reduced by CloA (2.4+/-0.8%; P<0.01) but not by CleA intervention (4.1+/-1.2%; P>0.05). The crypt cell proliferation index induced by DMH (Cont/NaCl: 10.0+/-0.7%; Cont/DMH: 19.9+/-1.0%; P<0.001) was significantly decreased by CleA (15.7+/-0.7%; P<0.001) and CloA intervention (11.9+/-0.4%; P<0.001). CloA but not CleA significantly reduced the number of large aberrant crypt foci (ACF) consisting of more than four aberrant crypts (AC) (Cont/DMH: 37.4+/-5.4; CleA/DMH: 32.8+/-4.4, P>0.05; CloA/DMH: 18.8+/-2.5 ACF; P<0.05) and the overall mean ACF size in the distal colon (Cont/DMH: 2.31+/-0.09; CleA/DMH: 2.27+/-0.05; CloA/DMH: 2.04+/-0.03 AC/ACF; P<0.05). After treatment with DMH and/or apple juices there were no changes in transcript levels of colonic cyclooxygenase isoforms (COX-1, COX-2) or glutathione-associated enzymes (GST-M2, gamma-GCS, GST-P), the splenocyte natural killer cell activity and plasma antioxidant status. However, CloA but not CleA prevented the DMH-induced reduction of splenocyte CD4/CD8 (T-helper cells to cytotoxic lymphocytes) ratio. Since both formulations contained comparable concentrations and types of monomeric polyphenols, complex polyphenols or non-polyphenolic compounds, such as pectin might be responsible for the stronger cancer-preventive effect by CloA.

Carcinogenesis. 2005 Aug;26(8):1414-21

Apple polyphenol extracts prevent aspirin-induced damage to the rat gastric mucosa.

Aspirin causes gastroduodenal ulcers and complications. Food bioactive compounds could exert beneficial effects in the gastrointestinal tract. We evaluated whether apple polyphenol extract (APE) reduced aspirin-induced injury to the rat gastric mucosa. Rats were treated with APE (10(-4) m catechin equivalent) before oral aspirin (200 mg/kg). Cyclo-oxygenase-2 (COX-2), transforming growth factor-alpha (TGF alpha) and heparin-binding epidermal-growth-factor-like growth factor (HB-EGF) mRNA and protein expression were assessed by RT-PCR and Western blot analysis, respectively; malondialdehyde (MDA) was determined by HPLC; gastric secretion was evaluated in pylorus-ligated rats. APE decreased acute and chronic aspirin injury both macroscopically and microscopically (approximately 50 % decrease in lesion score; P < 0.05). Aspirin up-regulated mRNA and protein expression of COX-2 and HB-EGF, but not of TGF alpha; APE reduced aspirin-induced mRNA and protein over-expression of COX-2 and HB-EGF; aspirin significantly increased gastric MDA and this effect was counteracted by APE pre-treatment. APE did not significantly affect gastric acid secretion. In conclusion, APE reduces aspirin-induced gastric injury independently of acid inhibition. We speculate that APE might be of therapeutic use in the prophylaxis of aspirin-related gastropathy.

Br J Nutr. 2008 Dec;100(6):1228-36

Influence of apple polyphenols on inflammatory gene expression.

Apples (Malus spp., Rosaceae) and products thereof contain high amounts of polyphenols which show diverse biological activities and may contribute to beneficial health effects, like protecting the intestine against inflammation initiated by chronic inflammatory bowel diseases (IBD). IBD are characterized by an excessive release of several proinflammatory cytokines and chemokines by different cell types which results consequently in an increased inflammatory response. In the present study we investigated the preventive effectiveness of polyphenolic juice extracts and single major constituents on inflammatory gene expression in immunorelevant human cell lines (DLD-1, T84, MonoMac6, Jurkat) induced with specific stimuli. Besides the influence on proinflammatory gene expression, the effect on NF-kappaB-, IP-10-, IL-8-promoter-, STAT1-dependent signal transduction, and the relative protein levels of multiple released cytokines and chemokines were studied. DNA microarray analysis of several genes known to be strongly regulated during gastrointestinal inflammation, combined with quantitative real-time PCR (qRT-PCR) revealed that the apple juice extract AE04 (100-200 microg/mL) significantly inhibited the expression of NF-kappaB regulated proinflammatory genes (TNF-alpha, IL-1beta, CXCL9, CXCL10), inflammatory relevant enzymes (COX-2, CYP3A4), and transcription factors (STAT1, IRF1) in LPS/IFN-gamma stimulated MonoMac6 cells without significant effects on the expression of house-keeping genes. A screening of some major compounds of AE04 revealed that the flavan-3-ol dimer procyanidin B(2 )is mainly responsible for the anti-inflammatory activity of AE04. Furthermore, the dihydrochalcone aglycone phloretin and the dimeric flavan-3-ol procyanidin B(1 )significantly inhibited proinflammatory gene expression and repressed NF-kappaB-, IP-10-, IL-8-promoter-, and STAT1-dependent signal transduction in a dose-dependent manner. The influence on proinflammatory gene expression by the applied polyphenols thereby strongly correlated with the increased protein levels investigated by human cytokine array studies. In summary, we evaluated selected compounds responsible for the anti-inflammatory activity of AE04. In particular, procyanidin B(1), procyanidin B(2), and phloretin revealed anti-inflammatory activities in vitro and therefore may serve as transcription-based inhibitors of proinflammatory gene expression.

Mol Nutr Food Res. 2009 Oct;53(10):1263-80

GSTT2, a phase II gene induced by apple polyphenols, protects colon epithelial cells against genotoxic damage.

The potential protective effect of a polyphenol-rich diet for colon carcinogenesis is of great scientific and medical interest. Apples are a main source of polyphenols, and apple juice has been shown to attenuate chemically induced colon carcinogenesis in animal models. In addition to an antioxidant and antiproliferative activity, apple polyphenols have been shown to elevate expression of the phase II gene glutathione S-transferase T2 (GSTT2) in colon epithelial cells. We hypothesized that apple polyphenols may thereby provide protection against oxidant-induced DNA damage. Using GSTT2 promoter constructs and luciferase reporter assays, we found that polyphenolic apple extracts (AE) can directly enhance GSTT2 promoter activity. Comet assays demonstrated that the genotoxicity of the GSTT2 substrate cumene hydroperoxide (CumOOH) was significantly reduced when HT29 colon epithelial cells were pretreated with AE. Overexpression of GSTT2 in HT29 cells significantly reduced CumOOH induced DNA damage, whereas shRNA mediated knockdown of GSTT2 gene expression resulted in higher damage. Our results causally link GSTT2 levels with protection from genotoxic stress, and provide evidence that the antigenotoxic effects of apple polyphenols in vitro are at least in part due to an induction of GSTT2 expression. Induction of phase II genes may contribute to primary chemoprevention of colon cancer by apple polyphenols.

Mol Nutr Food Res. 2009 Oct;53(10):1245-53

Polyphenolic apple extracts: effects of raw material and production method on antioxidant effectiveness and reduction of DNA damage in Caco-2 cells.

A diet rich in fruits and vegetables is commonly perceived to be associated with reduced cancer risk, attributed to its high content of polyphenols. As apples represent a major polyphenol source in Western countries, we studied differentially produced extracts (1-100 microg/mL): two from different apple juices (AEs), one from pomace (APE), and one peel extract (PE) on their potential to reduce DNA oxidation damage and induce antioxidant defense in Caco-2 cells. Additionally, we measured direct antioxidant capacity (TEAC/ORAC) of the extracts. Quercetin-rich PE and APE most effectively diminished DNA damage and ROS level after 24 h incubation (PE > APE), whereas the AEs were only moderately effective. GPx activity was diminished for all extracts, with AEs > APE > PE. Direct antioxidant activity decreased in the order AEs > PE > APE, displaying no significant correlation with cellular markers. In conclusion, apple phenolics at low, nutritionally relevant concentrations may protect intestinal cells from ROS-induced DNA damage, mediated by cellular defense mechanisms rather than by antioxidant activity.

J Agric Food Chem. 2010 Jun 9;58(11):6636-42

Annurca apple polyphenols have potent demethylating activity and can reactivate silenced tumor suppressor genes in colorectal cancer cells.

The CpG island methylator phenotype is characterized by DNA hypermethylation in the promoters of tumor suppressor genes with silencing of transcription. Hypermethylation of the promoter of hMLH1 and subsequent microsatellite instability occurs in approximately 12% of sporadic colorectal cancers (CRC). Annurca apple, a variety of southern Italy, is rich in polyphenols that are associated with anticancer properties. Populations in southern Italy have lower incidences of CRC than elsewhere in the western world. We evaluated the mechanisms of putative anticancer effects of Annurca polyphenol extract (APE) in in vitro models of CRC. We extracted polyphenols from Annurca apples and treated RKO, SW48, and SW480 cells with APE and assessed the cell viability, apoptosis, and cell cycle. DNA methylation of selected tumor suppressor genes was evaluated after treatment with APE and was compared with the synthetic demethylating agent 5-aza-2’deoxycytidine (5-aza-2dC). DNA methyltransferase (DNMT)-1 and -3b levels were evaluated. Decreased cell viability and induction of apoptosis was evident after treatment. We found no significant changes in cell cycle dynamics. We observed significant increases of p53 protein expression in RKO after treatment. APE treatment strongly reduced DNA methylation in the promoters of hMLH1, p14(ARF), and p16(INK4a) with consequent restoration of normal expression. These effects were qualitatively comparable with those obtained with 5-aza-2dC. We observed a significant reduction in expression of DNMT proteins after treatment without changes in messenger RNA. In conclusion, APE have potent demethylating activity through the inhibition of DNMT proteins. The lack of toxicity in Annurca extracts makes them excellent candidates for the chemoprevention of CRC.

J Nutr. 2007 Dec;137(12):2622-8

Apple polyphenols affect protein kinase C activity and the onset of apoptosis in human colon carcinoma cells.

Polyphenol-rich apple extracts have been reported to suppress human colon cancer cell growth in vitro. The protein kinase C (PKC) is among the signaling elements known to play an important role in colon carcinogenesis. In the present study, we investigated whether apple polyphenols affect PKC activity and induce apoptosis in the human colon carcinoma cell line HT29. A polyphenol-rich apple juice extract (AE02) was shown to inhibit cytosolic PKC activity in a cell-free system. In contrast, incubation of HT29 cells for 1 or 3 h with AE02 up to 2 mg/mL did not affect the cytosolic PKC activity. After prolonged incubation (24 h), cytosolic PKC activity was modulated, albeit a u-shaped curve of effectiveness was observed, with an initial inhibitory effect followed by the recurrence and even induction of enzyme activity. Concomitantly, in the cytosol, a significant decrease of the protein levels of PKCalpha, PKCbetaII, and PKCgamma together with a significant increase of a proapoptotic PKCdelta fragment was observed. However, the effects on the protein levels of these PKC isoforms in the cytosol were not associated with translocation between the different cellular compartments but might instead result from the onset of apoptosis. Indeed, the treatment with AE02 was shown to induce apoptosis by the activation of caspase-3, DNA fragmentation, and cleavage of poly(ADP ribose) polymerase. So far, identified and available constituents of the apple extract did not contribute substantially to the observed effects on PKC and apoptosis induction. In summary, apple polyphenols were found to inhibit PKC activity in a cell-free system. However, our results indicate that within intact cells PKC does not represent the primary target of apple polyphenols but appears to be affected in the course of apoptosis induction.

J Agric Food Chem. 2007 Jun 27;55(13): 4999-5006

Chemopreventive properties of apple procyanidins on human colon cancer-derived metastatic SW620 cells and in a rat model of colon carcinogenesis.

Apples contain several classes of polyphenols: monomers (catechins, epicatechins) and oligomers/polymers, such as the procyanidins. Our aim was (i) to study anti-proliferative mechanisms on human metastatic colon carcinoma (SW620 cells) of apple polyphenol fractions (monomers or procyanidins) and (ii) to evaluate their anti-carcinogenic properties in vivo. Two polyphenol-enriched fractions were isolated from apples. Fraction non-procyanidins contained 73% phenolic monomers and no procyanidins, while fraction procyanidins contained 78% procyanidins and no monomers. Inhibition of SW620 cell growth was only observed with fraction P (IC50 = 45 microg/ml). After a 24-h exposure of cells to fraction P, protein kinase C activity was inhibited by 70% and a significant increase in extracellular signal-regulated kinases 1 and 2 and c-jun N-terminal kinases expression was observed together with the down-regulation of polyamine biosynthesis and the activation of caspase-3. Colon carcinogenesis was induced in rats by intraperitoneal injections of azoxymethane, once a week for 2 weeks. Seven days after the last injection, Wistar rats received fraction P (0.01%) dissolved in drinking water. After 6 weeks of treatment, the colon of rats receiving procyanidins showed a significant (P < 0.01) reduction of the number of preneoplastic lesions when compared with controls receiving water. The total number of hyperproliferative crypts and of aberrant crypt foci was reduced by 50% in rats receiving 0.01% apple procyanidins in their drinking water. Our results show that apple procyanidins alter intracellular signaling pathways, polyamine biosynthesis and trigger apoptosis in tumor cells. These compounds antagonize cancer promotion in vivo. In contrast with absorbable drugs, these natural, non toxic, dietary constituents reach the colon where they are able to exert their antitumor effects.

Carcinogenesis. 2005 Jul;26(7):1291-5

Chemoprevention of intestinal polyps in ApcMin/+ mice fed with western or balanced diets by drinking annurca apple polyphenol extract.

The Western diet (WD) is associated with a higher incidence of colorectal cancer (CRC) than the Mediterranean diet. Polyphenols extracted from Annurca apple showed chemopreventive properties in CRC cells. A multifactorial, four-arm study by using wild-type (wt) and Apc(Min/+) mice was carried out to evaluate the effect on polyp number and growth of APE treatment (60 μmol/L) ad libitum in drinking water combined with a WD or a balanced diet (BD) for 12 weeks. Compared with APE treatment, we found a significant drop in body weight (P < 0.0001), severe rectal bleeding (P = 0.0076), presence of extraintestinal tumors, and poorer activity status (P = 0.0034) in water-drinking Apc(Min/+) mice, more remarkably in the WD arm. In the BD and WD groups, APE reduced polyp number (35% and 42%, respectively, P < 0.001) and growth (60% and 52%, respectively, P < 0.0001) in both colon and small intestine. Increased antioxidant activity was found in wt animals fed both diets and in Apc(Min/+) mice fed WD and drinking APE. Reduced lipid peroxidation was found in Apc(Min/+) mice drinking APE fed both diets and in wt mice fed WD. In normal mucosa, mice drinking water had lower global levels of DNA methylation than mice drinking APE. APE treatment is highly effective in reducing polyps in Apc(Min/+) mice and supports the concept that a mixture of phytochemicals, as they are naturally present in foods, represent a plausible chemopreventive agent for CRC, particularly in populations at high risk for colorectal neoplasia.

Cancer Prev Res (Phila). 2011 Jun;4(6):907-15

Effects of metabolic modulation by trimetazidine on left ventricular function and phosphocreatine/adenosine triphosphate ratio in patients with heart failure.

AIMS: The addition of trimetazidine to standard treatment has been shown to improve left ventricular (LV) function in patients with heart failure. The aim of this study is to non-invasively assess, by means of in vivo 31P-magnetic resonance spectroscopy (31P-MRS), the effects of trimetazidine on LV cardiac phosphocreatine and adenosine triphosphate (PCr/ATP) ratio in patients with heart failure. METHODS AND RESULTS: Twelve heart failure patients were randomized in a double-blind, cross-over study to placebo or trimetazidine (20 mg t.i.d.) for two periods of 90 days. At the end of each period, all patients underwent exercise testing, 2D echocardiography, and MRS. New York Heart Association (NYHA) class, ejection fraction (EF), maximal rate-pressure product, and metabolic equivalent system (METS) were evaluated. Relative concentrations of PCr and ATP were determined by cardiac 31P-MRS. On trimetazidine, NYHA class decreased from 3.04+/-0.26 to 2.45+/-0.52 (P = 0.005), whereas EF (34+/-10 vs. 39+/-10%, P = 0.03) and METS (from 7.44+/-1.84 to 8.78+/-2.72, P = 0.03) increased. The mean cardiac PCr/ATP ratio was 1.35+/-0.33 with placebo, but was increased by 33% to 1.80+/-0.50 (P = 0.03) with trimetazidine. CONCLUSION: Trimetazidine improves functional class and LV function in patients with heart failure. These effects are associated to the observed trimetazidine-induced increase in the PCr/ATP ratio, indicating preservation of the myocardial high-energy phosphate levels.

Eur Heart J. 2006 Apr;27(8):942-8

Modulation of fatty acids oxidation in heart failure by selective pharmacological inhibition of 3-ketoacyl coenzyme-A thiolase.

A direct approach to manipulate cardiac energy metabolism consists in modifying substrate utilization by the heart. Pharmacological agents that directly inhibit fatty acid oxidation include inhibitors of 3-ketoacyl coenzyme A thiolase (3-KAT), the last enzyme involved in ss-oxidation. The most extensively investigated agents of this group of drugs are trimetazidine and ranolazine. Clinical studies have shown that these agents can substantially increase the ischemic threshold in patients with effort angina. However, the results of current research is also supporting the concept that shifting the energy substrate preference away from fatty acid metabolism and toward glucose metabolism by 3-KAT inhibitors could be an effective adjunctive treatment in patients with heart failure, in terms of left ventricular function and glucose metabolism improvement. In fact, these agents have also been shown to improve overall glucose metabolism in diabetic patients with left ventricular dysfunction. In this paper, the recent literature on the beneficial effects of this new class of drugs on left ventricular dysfunction and glucose metabolism is reviewed and discussed.

Curr Clin Pharmacol. 2007 Sep;2(3):190-6

The effects of chronic trimetazidine treatment on mechanical function and fatty acid oxidation in diabetic rat hearts.

Clinical and experimental evidence suggest that increased rates of fatty acid oxidation in the myocardium result in impaired contractile function in both normal and diabetic hearts. Glucose utilization is decreased in type 1 diabetes, and fatty acid oxidation dominates for energy production at the expense of an increase in oxygen requirement. The objective of this study was to examine the effect of chronic treatment with trimetazidine (TMZ) on cardiac mechanical function and fatty acid oxidation in streptozocin (STZ)-diabetic rats. Spontaneously beating hearts from male Sprague-Dawley rats were subjected to a 60-minute aerobic perfusion period with a recirculating Krebs-Henseleit solution containing 11 mmol/L glucose, 100 muU/mL insulin, and 0.8 mmol/L palmitate prebound to 3% bovine serum albumin (BSA). Mechanical function of the hearts, as cardiac output x heart rate (in (mL/min).(beats/min).10-2), was deteriorated in diabetic (73 +/- 4) and TMZ-treated diabetic (61 +/- 7) groups compared with control (119 +/- 3) and TMZ-treated controls (131 +/- 6). TMZ treatment increased coronary flow in TMZ-treated control (23 +/- 1 mL/min) hearts compared with untreated controls (18 +/- 1 mL/min). The mRNA expression of 3-ketoacyl-CoA thiolase (3-KAT) was increased in diabetic hearts. The inhibitory effect of TMZ on fatty acid oxidation was not detected at 0.8 mmol/L palmitate in the perfusate. Addition of 1 mumol/L TMZ 30 min into the perfusion did not affect fatty acid oxidation rates, cardiac work, or coronary flow. Our results suggest that higher expression of 3-KAT in diabetic rats might require increased concentrations of TMZ for the inhibitory effect on fatty acid oxidation. A detailed kinetic analysis of 3-KAT using different concentrations of fatty acid will determine the fatty acid inhibitory concentration of TMZ in diabetic state where plasma fatty acid levels are increased.

Can J Physiol Pharmacol. 2007 May;85(5):527-35

Trimetazidine revisited: a comprehensive review of the pharmacological effects and analytical techniques for the determination of trimetazidine.

Trimetazidine (TMZ) is an effective and well-tolerated antianginal drug that possesses protective properties against ischemia-induced heart injury. Growing interest in metabolic modulation in recent years urged an up-to-date review of the literature on TMZ. This review consists of two major sections: (1) comprehensive and critical information about the pharmacological effects, mechanism of action, pharmacokinetics, side effects, and current usage of TMZ, and (2) developments in analytical techniques for the determination of the drug in raw material, pharmaceutical dosage forms, and biological samples.

Cardiovasc Ther. 2008 Summer;26(2):147-65

The antianginal drug trimetazidine shifts cardiac energy metabolism from fatty acid oxidation to glucose oxidation by inhibiting mitochondrial long-chain 3-ketoacyl coenzyme A thiolase.

Trimetazidine is a clinically effective antianginal agent that has no negative inotropic or vasodilator properties. Although it is thought to have direct cytoprotective actions on the myocardium, the mechanism(s) by which this occurs is as yet undefined. In this study, we determined what effects trimetazidine has on both fatty acid and glucose metabolism in isolated working rat hearts and on the activities of various enzymes involved in fatty acid oxidation. Hearts were perfused with Krebs-Henseleit solution containing 100 microU/mL insulin, 3% albumin, 5 mmol/L glucose, and fatty acids of different chain lengths. Both glucose and fatty acids were appropriately radiolabeled with either (3)H or (14)C for measurement of glycolysis, glucose oxidation, and fatty acid oxidation. Trimetazidine had no effect on myocardial oxygen consumption or cardiac work under any aerobic perfusion condition used. In hearts perfused with 5 mmol/L glucose and 0.4 mmol/L palmitate, trimetazidine decreased the rate of palmitate oxidation from 488+/-24 to 408+/-15 nmol x g dry weight(-1) x minute(-1) (P<0.05), whereas it increased rates of glucose oxidation from 1889+/-119 to 2378+/-166 nmol x g dry weight(-1) x minute(-1) (P<0.05). In hearts subjected to low-flow ischemia, trimetazidine resulted in a 210% increase in glucose oxidation rates. In both aerobic and ischemic hearts, glycolytic rates were unaltered by trimetazidine. The effects of trimetazidine on glucose oxidation were accompanied by a 37% increase in the active form of pyruvate dehydrogenase, the rate-limiting enzyme for glucose oxidation. No effect of trimetazidine was observed on glycolysis, glucose oxidation, fatty acid oxidation, or active pyruvate dehydrogenase when palmitate was substituted with 0.8 mmol/L octanoate or 1.6 mmol/L butyrate, suggesting that trimetazidine directly inhibits long-chain fatty acid oxidation. This reduction in fatty acid oxidation was accompanied by a significant decrease in the activity of the long-chain isoform of the last enzyme involved in fatty acid beta-oxidation, 3-ketoacyl coenzyme A (CoA) thiolase activity (IC(50) of 75 nmol/L). In contrast, concentrations of trimetazidine in excess of 10 and 100 micromol/L were needed to inhibit the medium- and short-chain forms of 3-ketoacyl CoA thiolase, respectively. Previous studies have shown that inhibition of fatty acid oxidation and stimulation of glucose oxidation can protect the ischemic heart. Therefore, our data suggest that the antianginal effects of trimetazidine may occur because of an inhibition of long-chain 3-ketoacyl CoA thiolase activity, which results in a reduction in fatty acid oxidation and a stimulation of glucose oxidation.

Circ Res. 2000 Mar 17;86(5):580-8

Trimetazidine-induced enhancement of myocardial glucose utilization in normal and ischemic myocardial tissue: an evaluation by positron emission tomography.

Trimetazidine has an anti-ischemic effect in angina pectoris. This agent has no hemodynamic effects, and its benefit is presumed to be based on a metabolic mechanism of action. A group of 33 dogs undergoing openchest left anterior descending coronary artery (LAD) ligation causing prolonged ischemia were imaged with quantitative positron emission tomography (PET) using 2-[18F]fluoro-2-deoxy-D-glucose (18FDG) to measure regional glucose metabolic utilization (rGMU) and [11C]acetate to measure regional monoexponential washout rate constant (Kmono) for oxidative metabolism in nonrisk and ischemic-risk myocardium. A total of 20 dogs were pretreated with trimetazidine at low dose (n = 10, 1 mg/kg) and high dose (n = 10, 5 mg/kg) and compared with 13 control dogs. Microsphere-measured myocardial blood flow (mL/min/g) was measured preocclusion and repeated hourly after occlusion and expressed as a ratio of preocclusion myocardial blood flow to verify a stable level of ischemia during PET. No differences were seen in postocclusion ischemic risk/nonrisk myocardial blood flow between treatment groups (p = not significant [NS]). Preocclusion and hourly measurements of heart rate and blood pressure corrected for baseline revealed no difference in control dogs versus trimetazidine (low-dose and high-dose) groups (p = NS). 18FDG-derived rGMU (micromol/min/g) was increased in high-dose trimetazidine versus control dogs in nonrisk and ischemic risk groups, respectively (1.16+/-0.57 vs 0.51+/-0.38 and 0.43+/-0.29 vs 0.20+/-0.14; p <0.05). rGMU was increased proportionately in nonrisk and ischemic risk in all groups without significant differences when corrected for nonrisk rGMU (ischemic risk/nonrisk was 0.92+/-1.3 vs 0.64+/-0.66 vs 0.40+/-0.22 for control dogs, all trimetazidine and high-dose trimetazidine groups). Kmono (min(-1) was not altered in any group (nonrisk = 0.13+/-0.03 vs 0.13+/-0.03 vs 0.14+/-0.02 and ischemic risk = 0.18+/-0.05 vs 0.17+/-0.06 vs 0.16+/-0.06 for control dogs, all trimetazidine and high-dose trimetazidine groups, respectively; p = NS for nonrisk vs ischemic risk, between and within groups). Our data verify that trimetazidine does not alter hemodynamic porameters. It increases total glucose utilization (oxidative and glycolytic) in myocardium without preferential increase in ischemic tissue. Absence of change in total oxidative metabolism suggests increased glucose metabolism is predominantly glycolysis or an increase in glucose oxidation with similar decrease in fatty acid oxidation.

Am J Cardiol. 1998 Sep 3;82(5A):42K-49K

Improvement of long-term preservation of the isolated arrested rat heart by trimetazidine: effects on the energy state and mitochondrial function.

Rat hearts, arrested in situ after intracaval injection of a cardioplegic solution, were preserved for 15 hours at 4 degrees C either by simple immersion or by low-flow (0.3 mL/min) perfusion. After preservation under both conditions, the left ventricular pressure developed by the reperfused hearts reached 8% and 43% of the control value (80 mm Hg), respectively. The addition of trimetazidine (TMZ; 10(-6) M) to the cardioplegic solution induced an improvement in functional recovery (by 2.4 and 1.5, respectively). This effect of TMZ was accompanied by a better energy profile illustrated by a 2-fold increase in the adenosine triphosphate to inorganic phosphate ratio and a reduction of intracellular acidosis as determined by 31P nuclear magnetic resonance spectroscopy. The function of the mitochondria (state 3, reduced nicotinamide-adenine dinucleotide [NADH] formation) isolated from the preserved hearts was significantly depressed in the stored hearts. The addition of TMZ to the cardioplegic solution partially protected oxoglutarate (and succinate) mitochondrial respiration and induced an increase in Ca2+ triggered NADH formation. These results show that the bioenergy status of the myocardial cell in isolated arrested stored rat heart is improved by the presence of TMZ in the preservation solution. Moreover, the experiments demonstrate that this effect includes protection of mitochondrial function and suggest that the drug could exert some control in the Ca2+ regulation of mitochondria.

Am J Cardiol. 1995 Aug 24;76(6):45B-49B

Effects of trimetazidine on metabolic and functional recovery of postischemic rat hearts.

The objective of this study was to test the hypothesis that the beneficial effect of trimetazidine during reflow of ischemic hearts is mediated by energy sparing and ATP pool preservation during ischemia. Isolated rat hearts (controls and rats treated with 10(-6) M trimetazidine, n = 17 per group) underwent the following protocol: baseline perfusion at normal coronary flow (20 minutes), low-flow ischemia at 10% flow (60 minutes), and reflow (20 minutes). We measured contractile function, O2 uptake, lactate release, venous pH and PCO2, and the tissue content of high-energy phosphates and their metabolites. During baseline, trimetazidine induced higher venous pH and lower PCO2 without influencing performance and metabolism. During low-flow ischemia, trimetazidine reduced myocardial performance (P = 0.04) and ATP turnover (P = 0.02). During reflow, trimetazidine improved performance (91 +/- 6% versus. 55 +/- 6% of baseline), prevented the development of diastolic contracture and coronary resistance, and reduced myocardial depletion of adenine nucleotides and purines. ATP turnover during low-flow ischemia was inversely related to recovery of the rate-pressure product (P = 0.002), end-diastolic pressure (P = 0.007), and perfusion pressure (P = 0.05). We conclude that trimetazidine-induced protection of ischemic-reperfused hearts is also mediated by energy sparing during ischemia, which presumably preserves the ATP pool during reflow.

Cardiovasc Drugs Ther. 1998 Dec;12(6):543-9

Effects of trimetazidine on ischemic contracture in isolated perfused rat hearts.

Trimetazidine (1-[2,3,4-trime-thoxibenzyl)]-piperazine, TMZ) is a drug with a proposed metabolically based antiischemic action. Because ischemic contracture is a serious complication of ischemia and is considered metabolic in origin, we studied the effect of trimetazidine (TMZ) on development of ischemic contracture in experimental low-flow ischemia. TMZ was either added to the perfusion fluid or given as pretreatment to the donor rats. Langendorff-perfused isolated rat hearts were submitted to 30-min subtotal global ischemia (residual flow = 0.2 ml/min, n = 6 per group) (normal flow = 12.4 +/- 0.8 ml/min, heart fresh weight = 0.9 +/- 0.3 g). Ischemic contracture was measured by a water-filled intraventricular balloon. Thereafter, the hearts were reperfused for 20 min and recovery of intraventricular pressure was monitored. Furthermore, because the mechanisms of action of TMZ may involve cellular energy metabolism, we assessed throughout glycolytic flux by collecting the coronary effluent every 5 min during control perfusion, ischemia, and reperfusion periods. Animals from the pretreated groups received TMZ [3 mg/kg orally (p.o.) twice daily] for 5 days. Animals from the control group received placebo for the same time period. Concentrations of 10(-6) and 10(-4) M were used when the drug was added to the perfusate. In our experimental conditions, TMZ pretreatment alone had no measurable cardioprotective effect, but addition to the perfusate of TMZ 10(-6) M, approximately a therapeutic concentration in humans, reduced ischemic contracture in both pretreated and control groups and improved postischemic recovery of developed pressure.

J Cardiovasc Pharmacol. 1994 Jul;24(1):45-9

Effects of trimetazidine administration before thrombolysis in patients with anterior myocardial infarction: short-term and long-term results.

Reperfusion may prevent or reduce the development and extent of necrosis, but may also lead to an increase in reperfusion damage. Experimental studies performed in various animal models of myocardial ischemia have demonstrated the anti-ischemic properties of trimetazidine (TMZ) and have suggested that TMZ has antioxidant properties, without any direct hemodynamic effects. Our study was aimed at investigating the effects of TMZ before thrombolysis in acute anterior myocardial infarction and included 81 patients, hospitalized within 4 hours of the onset of symptoms. Patients were randomly (double-blind) subdivided in two groups The first group (40 patients, Group A, TMZ-pretreatment), received 40 mg TMZ orally about 15 minute before thrombolysis and, subsequently, 20 mg every 8 hours. The second group (41 patients, Group B) received placebo before thrombolysis. Ventricular arrhythmias (VA) due to reperfusion were evaluated in the first 2 hours. VA occurred in 15 of patients in group A, versus 29 in group B, p<0.05. Creatine kinase (CK) normalization time was achieved after 55.7+/-12.5 hours in group A, versus 61.2+/-12.1 hour in group B, p = 0.048. CK peak was 1772+/-890 in group A vs. 2285+/-910 Ul/l in group B, (p = 0.012). In the follow-up (range 6-22 months), there were 4 deaths, two patients in each group. After 180 days from treatment, the TMZ group showed a smaller end systolic volume than the placebo group (echocardiographic data), 46.2+/-12 and 52.8+/-13 ml/m2, respectively, p = 0.037. Our data suggest that TMZ probably reduces reperfusion damage and/or infarct size in patients with anterior AMI subjected to thrombolysis and affects the post-AMI remodeling. Our data must be interpreted with caution because of the selection of patients. These findings require further extensive trials.

Cardiovasc Drugs Ther. 1999 Sep;13(5):423-8

Effects of chronic trimetazidine treatment on myocardial preconditioning in anesthetized rats.

Trimetazidine is a widely used anti-ischemic agent, but effects of its chronic treatment on myocardial preconditioning in anesthetized animals have not been investigated. The aim of this study was to examine the effects of 15-day treatment of trimetazidine on ischemic preconditioning and carbachol-induced preconditioning in anesthetized rats. Ischemic preconditioning, induced by 5 min of coronary artery occlusion and 5 min of reperfusion, significantly decreased the total number of ventricular ectopic beats, the incidence of ventricular tachycardia and abolished the occurrence of ventricular fibrillation (VF) during 30 min of ischemia. Trimetazidine (10 mg/kg/day, i.p. for 15 days and 10 mg/kg, i.v.) itself attenuated these arrhythmia parameters with no marked effect on hemodynamic effects. In the presence of trimetazidine, anti-arrhythmic effects of ischemic preconditioning were present. Carbachol infusion induced preconditioning with a marked depression of mean arterial blood pressure, heart rate and the total number of ventricular ectopic beats. No VF was observed in carbachol-induced preconditioning. The marked reductions in arrhythmia parameters that induced carbachol-induced preconditioning were also preserved in the presence of trimetazidine. Arrhythmia scores and myocardial infarct size were reduced significantly with ischemic preconditioning or carbachol-induced preconditioning and were not modified by trimetazidine. Lactate and malondialdehyde levels were suppressed significantly with preconditioning or trimetazidine + preconditioning groups. These results show that chronic treatment of trimetazidine protects the heart against ischemia-induced arrhythmias, reduces myocardial infarct size, plasma lactate and malondialdehyde levels, and preserves the effects of ischemic and pharmacological preconditioning in anesthetized rats.

Fundam Clin Pharmacol. 2006 Oct;20(5):449-59

Effects of trimetazidine on myocardial preconditioning in anesthetized rats.

Trimetazidine is a widely used anti-ischemic agent, but its effect on myocardial preconditioning in anesthetized animals has not been investigated. The aim of this study was to examine the effects of trimetazidine on ischemic preconditioning and carbachol preconditioning in anesthetized rats. Ischemic preconditioning, induced by 5-min coronary artery occlusion and 5-min reperfusion, decreased the incidence of ventricular tachycardia and abolished the occurrence of ventricular fibrillation during 30-min ischemia. Trimetazidine (10 mg/kg, i.v.) alone attenuated these parameters of arrhythmia. Carbachol infusion induced preconditioning with a marked depression of mean arterial blood pressure, heart rate and ventricular tachycardia. The marked reductions in parameters of arrhythmia induced by ischemic preconditioning and carbachol preconditioning were preserved in the presence of trimetazidine. Arrhythmia scores and myocardial infarct size were significantly reduced with ischemic preconditioning or carbachol preconditioning and were not inhibited by trimetazidine. These results show that trimetazidine protects the heart against ischemia-induced arrhythmias, reduces myocardial infarct size, preserves the effects of ischemic preconditioning and pharmacological preconditioning, and is able to mimic ischemic preconditioning in anesthetized rats.

Eur J Pharmacol. 2004 Oct 25;503(1-3):135-45

Effects of trimetazidine on in vivo coronary arterial platelet thrombosis.

We used Folts’ model of critical coronary artery stenosis with endothelial damage, which measures platelet-rich thrombus accumulation from cyclic flow reductions (CFRs). This paper reports results applied to trimetazidine, a member of the piperazine group. Trimetazidine at a dose of 1 mg/kg completely abolished CFRs caused by accumulating thrombus in the circumflex coronary artery in 4 of 8 open-chest anesthetized beagles. More trimetazidine (up to 5 mg/kg) abolished CFRs in two more and attenuated them in the remaining two dogs. There were no systemic hemodynamic effects observed. Adrenaline was then infused to stimulate platelet activation. At a rate of 0.4 microgram/kg/min, CFRs were restored in one dog only. Adrenaline given at 1.6 micrograms/kg/min resulted in restoration or increase in the slope of CFRs in all animals. A further six nonoperated dogs were anesthetized and given trimetazidine 3 mg/kg. Routine coagulation studies were not altered. However, aspirin 5 mg/kg significantly increased bleeding time, whereas trimetazidine alone did not. These findings suggest that trimetazidine is effective in preventing intracoronary platelet aggregation in this model. Because of its demonstrated sparing of coagulation factors and its lack of effect on bleeding time, the cause is unlikely to be inhibition of the fibrinogen or thrombin receptors, or interference with arachidonic acid metabolism.

Cardiovasc Drugs Ther. 1993 Feb;7(1):149-57

Chronic treatment with trimetazidine reduces the upregulation of atrial natriuretic peptide in heart failure.

Trimetazidine (TMZ) is effective for the treatment of ischemic cardiomyopathy; however, little is known about the effect of TMZ in established injury-induced heart failure. When rats with established infarct-induced heart failure were treated for 12 weeks with TMZ there was no effect on left ventricular function or dilation, or on mRNA expression of fatty acid oxidation enzymes. On the other hand, TMZ significantly reduced atrial natriuretic peptide mRNA levels compared with untreated rats.

Fundam Clin Pharmacol. 2006 Oct;20(5):503-5

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