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January 2008

Phytosterol composition of nuts and seeds commonly consumed in the United States.

Phytosterols were quantified in nuts and seeds commonly consumed in the United States. Total lipid extracts were subjected to acid hydrolysis and then alkaline saponfication, and free sterols were analyzed as trimethylsilyl derivatives by capillary GC-FID and GC-MS. Delta5-Avenasterol was quantified after alkaline saponification plus direct analysis of the glucoside. Sesame seed and wheat germ had the highest total phytosterol content (400-413 mg/100 g) and Brazil nuts the lowest (95 mg/100 g). Of the products typically consumed as snack foods, pistachio and sunflower kernel were richest in phytosterols (270-289 mg/100 g). beta-Sitosterol, Delta5-avenasterol, and campesterol were predominant. Campestanol ranged from 1.0 to 12.7 mg/100 g. Only 13 mg/100 g beta-sitosterol was found in pumpkin seed kernel, although total sterol content was high (265 mg/100 g). Phytosterol concentrations were greater than reported in existing food composition databases, probably due to the inclusion of steryl glycosides, which represent a significant portion of total sterols in nuts and seeds.

J Agric Food Chem. 2005 Nov 30;53(24):9436-45

Modulation of blood pressure, lipid profiles and redox status in hypertensive patients taking different edible oils.

BACKGROUND: Free oxygen radicals and insufficiency of antioxidants have been implicated in the pathogenesis of hypertension. We determined the effect of edible oils on blood pressure, lipid profiles and redox status in hypertensive patients given antihypertensive therapy (nifedipine-calcium channel blocker). METHODS: 530 patients medicated with nifedipine were divided into 3 groups (356 patients-sesame oil; 87 patients-sunflower oil; 47 patients-groundnut oil) and the control group (n=40) received only the drug, nifedipine. The respective oils were supplied to the patients and instructed to use as the only edible oil for 60 days, which comes to 35 g of oil/day/person. Blood pressure, lipid profiles [total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and triglycerides (TG)], lipid peroxidation [thiobarbituric acid reactive substances (TBARS)], enzymatic [superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx)] and nonenzymatic [(vitamin C, vitamin E, beta-carotene and reduced glutathione (GSH)] in blood were measured at baseline and after 60 days of oil substitution. RESULTS: Patients with nifedipine alone or with respective oils had significantly lowered blood pressure. TC, LDL-C and TG decreased while HDL-C elevated in sesame and sunflower oil groups. Increases of HDL-C and TG were noted in groundnut oil group. TBARS levels reduced in all the groups whereas the reduction was remarkable in sesame oil group. Activities of SOD elevated in the 3 oil groups whereas GPx and CAT increased only in sesame oil group. Levels of vitamin C, vitamin E, beta-carotene and GSH increased in sesame oil group whereas vitamin E and beta-carotene were elevated only in sunflower and groundnut oil groups. GSH increased in drug control group also. CONCLUSION: Among the 3 oils, sesame oil offers better protection over blood pressure, lipid profiles and lipid peroxidation and increases enzymatic and nonenzymatic antioxidants.

Clin Chim Acta. 2005 May;355(1-2):97-104

Sesame ingestion affects sex hormones, antioxidant status, and blood lipids in postmenopausal women.

Sesame ingestion has been shown to improve blood lipids in humans and antioxidative ability in animals. Sesamin, a sesame lignan, was recently reported to be converted by intestinal microflora to enterolactone, a compound with estrogenic activity and also an enterometabolite of flaxseed lignans, which are known to be phytoestrogens. Whether sesame can be a source of phytoestrogens is unknown. This study was designed to investigate the effect of sesame ingestion on blood sex hormones, lipids, tocopherol, and ex vivo LDL oxidation in postmenopausal women. Twenty-six healthy subjects attended, and 24 completed, this randomized, placebo-controlled, crossover study. Half of them consumed 50 g sesame seed powder daily for 5 wk, followed by a 3-wk washout period, then a 5-wk 50-g rice powder placebo period. The other half received the 2 supplements in reverse order. After sesame treatment, plasma total cholesterol (TC), LDL-C, the ratio of LDL-C to HDL-C, thiobarbituric acid reactive substances in oxidized LDL, and serum dehydroepiandrosterone sulfate decreased significantly by 5, 10, 6, 23, and 18%, respectively. The ratio of alpha- and gamma-tocopherol to TC increased significantly by 18 and 73%, respectively. All of these variables differed significantly between the 2 treatments. Serum sex hormone-binding globulin and urinary 2-hydroxyestrone (n = 8) increased significantly by 15 and 72%, respectively, after sesame treatment, and these concentrations tended to differ (P = 0.065 and P = 0.090, respectively) from those after the placebo treatment. These results suggest that sesame ingestion benefits postmenopausal women by improving blood lipids, antioxidant status, and possibly sex hormone status.

J Nutr. 2006 May;136(5):1270-5

Sesamol induces nitric oxide release from human umbilical vein endothelial cells.

Sesamol, which is derived from sesame seed lignans, is reportedly an antioxidant. Nitric oxide (NO), the most important vascular relaxing factor, is regulated in the endothelium. In addition, NO is involved in protecting endothelium and has antiatherosclerotic and antithrombotic activities. The endothelium produces NO through the regulation of both endothelial NO synthase (eNOS) expression and activity in endothelial cells. This study sought to investigate the effect of sesamol on NO released from human umbilical vein endothelial cells (HUVEC) and to examine the expression and activity of eNOS. Sesamol induced NO release from endothelial cells in a dose-dependent manner (from 1 to 10 microM), as measured 24 h after treatment; the expression of the eNOS gene at both transcription and translation levels; and NOS activity in endothelial cells. The content of cGMP was also increased by sesamol through NO signaling. The transcription of eNOS induced by sesamol was confirmed through the activation of PI-3 kinase-Akt (protein kinase B) signaling. The results demonstrate that sesamol induces NOS signaling pathways in HUVEC and suggest a role for sesamol in cardiovascular reactivity in vivo.

Lipids. 2005 Sep;40(9):955-61

Sesamin metabolites induce an endothelial nitric oxide-dependent vasorelaxation through their antioxidative property-independent mechanisms: possible involvement of the metabolites in the antihypertensive effect of sesamin.

Sesamin, a major lignan in sesame seeds and oil, has been known to lower blood pressure in several types of experimental hypertensive animals. A recent study demonstrated that sesamin metabolites had in vitro radical-scavenging activities. Thus, we determined whether the antioxidative effect of sesamin metabolites modulate the vascular tone and contribute to the in vivo antihypertensive effect of sesamin. We used four demethylated sesamin metabolites: SC-1m (piperitol), SC-1 (demethylpiperitol), SC-2m [(1R,2S,5R,6S)-6-(4-hydroxy-3-methoxyphenyl)-2-(3,4-dihydroxyphenyl)-3,7-dioxabicyclo[3,3,0]octane], and SC-2 [(1R,2S,5R, 6S)-2,6-bis(3,4-dihydroxyphenyl)-3,7-dioxabicyclo-[3,3,0]octane]. SC-1, SC-2m, and SC-2, but not SC-1m, exhibited potent radical-scavenging activities against the xanthine/xanthine oxidase-induced superoxide production. On the other hand, SC-1m, SC-1, and SC-2m produced endothelium-dependent vasorelaxation in phenylephrine-precontracted rat aortic rings, whereas SC-2 had no effect. The SC-1m- and SC-1-induced vasorelaxations were markedly attenuated by pretreatment with a nitric oxide synthase (NOS) inhibitor, NG-nitro-L-arginine (NOARG), or a soluble guanylate cyclase inhibitor, 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one. Neither SC-1m nor SC-1 changed the expression level of endothelial NOS protein in aortic tissues. The antihypertensive effects of sesamin feeding were not observed in chronically NOARG-treated rats or in deoxycorticosterone acetate-salt-treated endothelial NOS-deficient mice. These findings suggest that the enhancement of endothelium-dependent vasorelaxation induced by sesamin metabolites is one of the important mechanisms of the in vivo antihypertensive effect of sesamin.

J Pharmacol Exp Ther. 2006 Jul;318(1):328-35

Dietary sesame seeds elevate alpha-tocopherol concentration in rat brain.

We have previously reported that dietary sesame lignan elevates alpha-tocopherol concentration and decreases lipid peroxidation in tissues and serum of rats fed alpha-tocopherol. In this study, the effect of dietary sesame seeds on alpha-tocopherol concentration and lipid peroxidation in rat brain was examined. In experiment 1, male Wistar rats (4 wk old) were fed a vitamin E-free diet, or a diet containing alpha-tocopherol with or without sesame seeds for 1, 4 and 8 wk. The dietary sesame seeds elevated the alpha-tocopherol and lowered the thiobarbituric acid-reactive substance (TBARS) concentrations in the brain of the rats fed alpha-tocopherol for 4 and 8 wk. The dietary sesame seeds maintained the high alpha-tocopherol concentration in the brain during the experimental period, while the concentration of the rats fed alpha-tocopherol without sesame seeds was lowered after 8 wk. Then, the alpha-tocopherol concentration in various regions of the brain of rats fed a basal level of alpha-tocopherol with sesame seeds was compared with that of rats fed an excess amount of alpha-tocopherol in experiment 2. The alpha-tocopherol concentration in the cerebrum, cerebellum, brain stem and hippocampus of the rats fed 50 mg alpha-tocopherol/kg with sesame seeds was higher than those of the rats fed 500 mg alpha-tocopherol/kg without sesame seeds. These results suggest that the dietary sesame seeds are more useful than the intake of an excess amount of alpha-tocopherol, for maintaining a high alpha-tocopherol concentration and inhibiting lipid peroxidation in the various regions of the rat brain.

J Nutr Sci Vitaminol (Tokyo). 2005 Aug;51(4):223-30

Whole sesame seed is as rich a source of mammalian lignan precursors as whole flaxseed.

The mammalian lignans enterolactone and enterodiol, which are produced by the microflora in the colon of humans and animals from precursors in foods, have been suggested to have potential anticancer effects. This study determined the production of mammalian lignans from precursors in food bars containing 25 g unground whole flaxseed (FB), sesame seed (SB), or their combination (FSB; 12.5 g each). In a randomized crossover study, healthy postmenopausal women supplemented their diets with the bars for 4 wk each separated by 4-wk washout periods, and urinary mammalian lignan excretion was measured at baseline and after 4 wk as a marker of mammalian lignan production. Results showed an increase with all treatments (65.1-81.0 mumol/day; P < 0.0001), which did not differ among treatments. Lignan excretion with the whole flaxseed was similar to results of other studies using ground flaxseed. An unidentified lignan metabolite was detected after consumption of SB and FSB but not of FB. Thus, we demonstrated for the first time that 1) precursors from unground whole flaxseed and sesame seed are converted by the bacterial flora in the colon to mammalian lignans and 2) sesame seed, alone and in combination with flaxseed, produces mammalian lignans equivalent to those obtained from flaxseed alone.

Nutr Cancer. 2005;52(2):156-65

Chemopreventive effect of resveratrol, sesamol, sesame oil and sunflower oil in the Epstein-Barr virus early antigen activation assay and the mouse skin two-stage carcinogenesis.

Resveratrol, sesamol, sesame oil and sunflower oil are known natural dietary components with intrinsic cancer chemopreventive potentials. As a part of our study of dietary constituents as potential cancer chemopreventive agents, we have assessed the anti-cancer potentials of these products in the promotion stage of cancer development employing the in vitro Epstein-Barr virus early antigen activation assay induced by the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA). Further, we studied the activities of these compounds in the brine shrimp cytotoxicity assay as well as on the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging bioassay with a view to comparing some of the mechanisms of their anti-cancer activity. Finally, we compared the observed chemoprotective capabilities of the four products in the in vivo 7,12 dimethylbenz(a)anthracene initiated and TPA-promoted mouse skin two-stage carcinogenesis protocols. All the products tested showed a profound inhibitory effect on the Epstein-Barr virus early antigen induction using Raji cells. Comparatively, sesame oil was the most potent followed by sesamol and then resveratrol. Only sesamol and resveratrol showed a remarkable cytotoxic activity in the brine shrimp lethality assays as well as profound free radical scavenging activity in the DPPH bioassay. In both test systems, sesamol exhibited a more remarkable activity than resveratrol while sesame oil and sunflower oil did not exhibit any appreciable activity even at the highest concentrations tested (4000 microg ml(-1) ). In our in vivo assay at a 50-fold molar ratio to TPA, sesamol offered 50% reduction in mouse skin papillomas at 20 weeks after promotion with TPA. Under an identical molar ratio to TPA, resveratrol offered a 60% reduction in the papillomas in mouse at 20 weeks. Thus sesamol seems to be an almost equally potent chemopreventive agent. Sesame oil and sunflower oil offered 20 and 40% protection, respectively, in the mouse skin tumor model. The anti-oxidant capabilities of these compounds could not solely explain the observed anti-cancer characteristics. Resveratrol is present in grapes. Sesamol, a constituent of sesame oil and sunflower oil are regularly consumed dietary natural products. The observed chemopreventive effect of these products particularly warrants more attention since they already exist in the population with no known adverse effects.

Pharmacol Res. 2002 Jun;45(6):499-505

Comparative effects of flaxseed and sesame seed on vitamin E and cholesterol levels in rats.

Flaxseed and sesame seed both contain more than 40% fat, about 20% protein, and vitamin E, mostly gamma-tocopherol. Furthermore, both contain considerable amounts of plant lignans. However, flaxseed contains 54% alpha-linolenic acid, but sesame seed only 0.6%, and the chemical structures of flaxseed and sesame lignans are different. In this study, we investigated the differential effects of flaxseed and sesame seed on plasma and tissue gamma-tocopherol, TBARS, and cholesterol concentrations. Rats were fed experimental diets for 4 wk: vitamin E-free, (-VE), gamma-tocopherol, flaxseed (FS), sesame seed (SS), flaxseed oil (FO), FO with sesamin (FOS), and defatted flaxseed (DFF). SS and FOS diets induced significantly higher gamma-tocopherol concentrations in plasma and liver compared with FS, FO, and DFF diets. Groups fed FS, FO, and FOS showed lower plasma total cholesterol compared with the SS and DFF groups. Higher TBARS concentrations in plasma and liver were observed in the FS and FO groups but not in the FOS group. These results suggest that sesame seed and its lignans induced higher gamma-tocopherol and lower TBARS concentrations, whereas flaxseed lignans had no such effects. Further, alpha-linolenic acid produced strong plasma cholesterol-lowering effects and higher TBARS concentrations.

Lipids. 2003 Dec;38(12):1249-55