Cerebrosides in grapevine leaves: distinct composition of sphingoid bases among the grapevine species having different tolerances to freezing temperature.
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Cerebrosides from leaves of three grapevine species were analyzed in detail. The relative proportions of 8-E/Z isomers of 4-hydroxy-8-sphingenines [i.e. 8-E/Z t18:1(8E) and (8Z)] differed amongst the species in respect to freezing tolerance. This suggests that the occurrence of high levels of t18:1(8Z) in cerebrosides is correlated with freezing tolerance in these species. (+info)
Nonalcoholic red wine extract and quercetin inhibit LDL oxidation without affecting plasma antioxidant vitamin and carotenoid concentrations.
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BACKGROUND: Antioxidant enrichment of LDL can increase its resistance to oxidation and hence reduce its atherogenicity. The objective of the present study was to investigate whether in vivo supplementation with nonalcoholic red wine extract and quercetin can increase the oxidative resistance of LDL, and also whether the supplementation has any effect on other antioxidative micronutrients present in the blood. METHODS: Twenty-one male subjects were supplemented with a placebo drink for 2 weeks and randomized into two groups. One group (n = 11) received the red wine extract (1 g/day, equivalent to 375 mL of red wine) and the other group (n = 10) quercetin (30 mg/day) for 2 weeks, followed by a 5-week washout period. RESULTS: In the red wine extract-supplemented group, ex vivo copper-initiated oxidation of LDL (lag phase, mean +/- SD) was 40 +/- 11 min at the baseline, and increased significantly to 47 +/- 6 min [P <0.05 compared with placebo (38 +/- 4 min) and the washout values (40 +/- 5 min)]. In the quercetin-supplemented group, the lag phase was 44 +/- 11 and 40 +/- 5 min for the baseline and placebo, respectively, and increased significantly to 51 +/- 7 min [P <0.05 compared with placebo and washout (41 +/- 9 min)] after supplementation. Plasma lipids (triglycerides, total cholesterol, LDL- and HDL-cholesterol) did not change during the study period. Supplementation with red wine extract or quercetin had no effect on plasma vitamin C and E, retinol, and carotenoid concentrations. CONCLUSIONS: Alcohol-free red wine extract and one of its components, quercetin, can inhibit LDL oxidation after in vivo supplementation; such "inhibition" is unrelated to changes in antioxidant vitamin and carotenoid concentrations. (+info)
Red wine intake prevents nuclear factor-kappaB activation in peripheral blood mononuclear cells of healthy volunteers during postprandial lipemia.
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BACKGROUND: Several epidemiological studies have demonstrated the beneficial effect of red wine intake in reducing total and cardiovascular mortality. This effect has been attributed in part to its antioxidant properties. Because the monocytes/macrophages and the nuclear transcription factor kappaB (NF-kappaB) are implicated in the pathogenesis of atherosclerotic lesions, we examined the effect of red wine intake on the activation of NF-kappaB in peripheral blood mononuclear cells. METHODS AND RESUTLS: Sixteen healthy volunteers were studied 3 times each: after a moderate dose, a low dose, and no wine with a fat-enriched breakfast. Lipid profile and NF-kappaB activation (electrophoretic mobility shift assay) were examined in blood samples taken before and 3, 6, and 9 hours after wine intake. In addition, mononuclear cells were incubated with VLDL in the presence of some antioxidants (quercetin and alpha-tocopherol succinate) contained in red wine to study their effects on NF-kappaB activation. Subjects receiving a fat-enriched breakfast had increased NF-kappaB activation in peripheral blood mononuclear cells coinciding with the augmentation in total triglycerides and chylomicrons. Red wine intake prevented NF-kappaB activity even though it induced a certain increase in serum lipids, particularly VLDL, that did not increase after the fat ingestion alone. However, another form of alcohol intake (vodka) did not modify the NF-kappaB activation provided by postprandial lipemia. In cultured mononuclear cells, isolated human VLDL caused NF-kappaB activation in a time-dependent manner that did not occur in the presence of the red wine antioxidants quercetin and alpha-tocopherol. CONCLUSIONS: Our results provide a new potential mechanism to explain the beneficial effects of red wine intake in the reduction of cardiovascular mortality. (+info)
Diet and prevention of coronary heart disease: the potential role of phytochemicals.
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Epidemiological studies, and some clinical trials, demonstrate that a proper diet reduces the rate of occurrence of cardiovascular disorders. Several in vitro studies suggest that some components of plant foods, most of which sharing a phenolic structure, are endowed with interesting 'pharmacological activities'. This article reviews the evidence that links a high dietary intake of phytochemicals from various sources with a reduced incidence of coronary heart disease. (+info)
MET17 and hydrogen sulfide formation in Saccharomyces cerevisiae.
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Commercial isolates of Saccharomyces cerevisiae differ in the production of hydrogen sulfide (H(2)S) during fermentation, which has been attributed to variation in the ability to incorporate reduced sulfur into organic compounds. We transformed two commercial strains (UCD522 and UCD713) with a plasmid overexpressing the MET17 gene, which encodes the bifunctional O-acetylserine/O-acetylhomoserine sulfhydrylase (OAS/OAH SHLase), to test the hypothesis that the level of activity of this enzyme limits reduced sulfur incorporation, leading to H(2)S release. Overexpression of MET17 resulted in a 10- to 70-fold increase in OAS/OAH SHLase activity in UCD522 but had no impact on the level of H(2)S produced. In contrast, OAS/OAH SHLase activity was not as highly expressed in transformants of UCD713 (0.5- to 10-fold) but resulted in greatly reduced H(2)S formation. Overexpression of OAS/OAH SHLase activity was greater in UCD713 when grown under low-nitrogen conditions, but the impact on reduction of H(2)S was greater under high-nitrogen conditions. Thus, there was not a good correlation between the level of enzyme activity and H(2)S production. We measured cellular levels of cysteine to determine the impact of overexpression of OAS/OAH SHLase activity on sulfur incorporation. While Met17p activity was not correlated with increased cysteine production, conditions that led to elevated cytoplasmic levels of cysteine also reduced H(2)S formation. Our data do not support the simple hypothesis that variation in OAS/OAH SHLase activity is correlated with H(2)S production and release. (+info)
Internal trehalose protects endocytosis from inhibition by ethanol in Saccharomyces cerevisiae.
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Endocytosis in Saccharomyces cerevisiae is inhibited by concentrations of ethanol of 2 to 6% (vol/vol), which are lower than concentrations commonly present in its natural habitats. In spite of this inhibition, endocytosis takes place under enological conditions when high concentrations of ethanol are present. Therefore, it seems that yeast has developed some means to circumvent the inhibition. In this work we have investigated this possibility. We identified two stress conditions under which endocytosis was resistant to inhibition by ethanol: fermentation during nitrogen starvation and growth on nonfermentable substrates. Under these conditions, yeast accumulates stress protectors, primarily trehalose and Hsp104, a protein required for yeast to survive ethanol stress. We found the following. (i) The appearance of ethanol resistance was accompanied by trehalose accumulation. (ii) Mutant cells unable to synthesize trehalose also were unable to develop resistance. (iii) Mutant cells that accumulated trehalose during growth on sugars were resistant to ethanol even under this nonstressing condition. (iv) Mutant cells unable to synthesize Hsp104 were able to develop resistance. We conclude that trehalose is the major factor in the protection of endocytosis from ethanol. Our results suggest another important physiological role for trehalose in yeast. (+info)
Neuroprotective abilities of resveratrol and other red wine constituents against nitric oxide-related toxicity in cultured hippocampal neurons.
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Animal and epidemiological studies suggest that polyphenol constituents of red wine possess antioxidant activities that favour protection against cardiovascular disease - the so-called. 'French paradox' - and possibly, central nervous system disorders such as Alzheimer's disease (AD) and ischaemia. In the present study, the potential of three major red wine derived-polyphenols to protect against toxicity induced by the nitric oxide free radical donors sodium nitroprusside (SNP) and 3-morpholinosydnonimine (SIN-1) was examined in cultured rat hippocampal cells. Both co- and post-treatments with either the stilbene resveratrol (5 - 25 microM) or the flavonoids quercetin (5 - 25 microM) and (+)-catechin (1 - 10 microM) were capable of attenuating hippocampal cell death and intracellular reactive oxygen species accumulation produced by SNP (100 microM and 1 mM, respectively). However, among the phenolic compounds tested, only the flavonoids afforded significant protection against 5 mM SIN-1-induced toxicity. The effects of phenolic constituents were shared by Trolox (100 microM), a vitamin E analogue, but not by selective inhibitors of cyclo-oxygenases (COX) and lipoxygenases (LOX). Among the phenolic compounds tested, only quercetin (10 microM) inhibited 100 microM SNP-stimulated protein kinase C (PKC) activation, whereas none of them were able to attenuate nitrite accumulation caused by SNP (100 microM). Taken together, these data suggest that the neuroprotective abilities of quercetin, resveratrol, and (+)-catechin result from their antioxidant properties rather than their purported inhibitory effects on intracellular enzymes such as COX, LOX, or nitric oxide synthase. Quercetin, however, may also act via PKC to produce its protective effects. (+info)
Synthesis of alpha-D-glucosylglycerol by alpha-glucosidase and some of its characteristics.
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It has been found that alpha-D-glucosylglycerol (GG) is contained in such traditional Japanese foods brewed by using koji as sake, miso and mirin, and that GG is formed by transglucosylation to glycerol that is produced by yeast with alpha-glucosidase (EC 3.2.1.20) from koji in the sake mash. GG has also been found to consist of three components, 2-O-alpha-D-glucosylglycerol (GG-II), (2R)-1-O-alpha-D-glucosylglycerol (R-GG-I) and (2S)-1-O-alpha-D-glucosylglycerol (S-GG-I). GG was synthesized from a mixture of maltose and glycerol by the batch method, using alpha-glucosidase (transglucosidase L-AMANO). alpha-Glucosidase seemed to be so stable that the amount of GG increased about 5-fold compared with that in the first reaction by the daily addition of maltose for 10 d. Syrupy GG obtained was found to have the following characteristics: about 0.55-fold sweetness compared with sucrose, high thermo-stability, low heat-colorability, low Maillard reactivity, low hygroscopicity, high water-holding capacity, non-cariogenicity and low digestibility. (+info)