The mode of action of allicin: its ready permeability through phospholipid membranes may contribute to its biological activity.
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Allicin (diallyl thiosulfinate) is the main biologically active component of the freshly crushed garlic extracts. In the present work the ability of allicin to cross through membranes (artificial and biological) was studied. Partition coefficients of allicin in water/octanol, water/hexadecane and water/phospholipids mixtures were determined. Using phospholipid vesicles loaded with hydrophilic thiols (reduced glutathione or 2-nitro-5-thiobenzoate), we observed that allicin freely permeates through phospholipid bilayers and interacts with the SH groups. The reaction rate of allicin with SH containing molecules after crossing the membrane was the same as in solution. Fast diffusion and permeation of allicin across human red blood cell membranes was also demonstrated. Allicin does not induce leakage, fusion or aggregation of membrane. The high permeability of allicin through membranes may greatly enhance the intracellular interaction with thiols. (+info)
Garlic powder, effect on plasma lipids, postprandial lipemia, low-density lipoprotein particle size, high-density lipoprotein subclass distribution and lipoprotein(a).
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OBJECTIVES: To test the hypothesis that a garlic supplement alters plasma lipoproteins, postprandial lipemia, low-density lipoprotein (LDL) size and high-density lipoprotein (HDL) subclass distribution differently in 50 moderately hypercholesterolemic subjects classified as LDL subclass pattern A or B. BACKGROUND: Garlic has been variably reported to reduce or not affect plasma cholesterol values. Low-density lipoprotein pattern B is a common inherited disorder of lipoprotein metabolism that has been shown to have a significantly greater response to several lipid lowering treatments including low fat diet when compared with LDL pattern A individuals. METHODS: A double blind, randomized, placebo controlled trial in an outpatient lipid research clinic was performed and included fifty moderately hypercholesterolemic subjects (mean LDL cholesterol = 166 +/- 22 mg/dl) classified as LDL subclass pattern A (predominantly large LDL, n = 22) or B (predominantly small LDL, n = 28). Following a two-month stabilization period, subjects were randomly assigned to a placebo or 300 mg three times a day of a standardized garlic tablet for three months. RESULTS: For all subjects, LDL pattern A and B subjects combined, garlic treatment for three months resulted in no significant change in total cholesterol, LDL cholesterol, HDL cholesterol, HDL subclass distribution, postprandial triglycerides, apolipoprotein B, lipoprotein (a) (Lp[a]), LDL peak particle diameter or LDL subclass distribution. There was no significant difference in response for the same parameters among subjects classified as LDL pattern A or B with the exception of significantly greater (p = 0.01) reduction in mean peak particle diameter in pattern A subjects treated with either garlic or placebo. There was no significant change in LDL subclass distribution. CONCLUSIONS: This investigation confirms that garlic therapy has no effect on major plasma lipoproteins and further, that it has no impact on HDL subclasses, Lp(a), apolipoprotein B, postprandial triglycerides or LDL subclass distribution. Garlic may have a greater effect on LDL particle diameter in LDL pattern A compared with pattern B subjects. This difference was not reflected in other plasma lipid measurements. (+info)
Effects of allitridi on intracellular Ca2+ concentration in isolated rat brain cells.
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AIM: To study actions of allitridi extracted from garlic on intracellular calcium in isolated rat brain cells. METHODS: Brain cells were isolated from newborn rat brain with Fura 2-AM measurements of intracellular Ca2+ concentration ([Ca2+]i). RESULTS: Allitridi 1-100 mumol.L-1 concentration-dependently blocked increases of [Ca2+]i caused by potassium chloride and sodium glutamate (Glu) with IC50 of 59.7 and 69.9 mumol.L-1 respectively. Allitridi 100 mumol.L-1 blocked norepinephrine (Nor)-induced [Ca2+]i elevation. CONCLUSION: Allitridi is an effective agent for blocking the [Ca2+]i increase caused by potassium chloride, Nor and Glu. (+info)
Activities of garlic oil, garlic powder, and their diallyl constituents against Helicobacter pylori.
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Chronic Helicobacter pylori disease is reduced with Allium vegetable intake. This study was designed to assess the in vivo anti-H. pylori potential of a variety of garlic substances. The garlic materials all showed substantial but widely differing anti-H. pylori effects against all strains and isolates tested. The MICs (range, 8 to 32 microg/ml) and minimum bactericidal concentrations (MBCs) (range, 16 to 32 microg/ml) of undiluted garlic oil (GO) were smaller than those of garlic powder (GP) (MIC range, 250 to 500 microg/ml; MBC range, 250 to 500 microg/ml) but greater than the MIC of allicin (4. 0 microg/ml) (Table 2) present in GP. Allicin (MIC, 6 microg/ml; MBC, 6 microg/ml) was more potent than diallyl disulfide (MIC range, 100 to 200 microg/ml; MBC range, 100 to 200 microg/ml), its corresponding sulfide, but of a strength similar to that of diallyl tetrasulfide (MIC range, 3 to 6 microg/ml; MBC range, 3 to 6 microg/ml). Antimicrobial activity of the diallyl sulfides increased with the number of sulfur atoms. Time course viability studies and microscopy showed dose-dependent anti-H. pylori effects with undiluted GO, GP, allicin, and diallyl trisulfide after a lag phase of ca. 1 to 2 h. Substantial in vitro anti-H. pylori effects of pure GO and GP and their diallyl sulfur components exist, suggesting their potential for in vivo clinical use against H. pylori infections. (+info)
Analysis of responses of garlic derivatives in the pulmonary vascular bed of the rat.
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Allicin, an extract from garlic, has been shown to be a systemic and pulmonary arterial vasodilator that acts by an unknown mechanism. In the present experiments, pulmonary vascular responses to allicin (10-100 microg), allyl mercaptan (0.3-1 mg), and diallyl disulfide (0.3-1 mg) were studied in the isolated lung of the rat under constant-flow conditions. When baseline tone in the pulmonary vascular bed of the rat was raised to a high-steady level with the thromboxane A(2) mimic U-46619, dose-related decreases in pulmonary arterial pressure were observed. In terms of the mechanism of action of allicin vasodilator activity in the rat, responses to allicin were not significantly different after administration of the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester, the K(ATP)(+) channel antagonist U-37883A, or the cyclooxygenase inhibitor sodium meclofenamate, or when lung ventilation was interrupted. These data show that allicin has significant vasodilator activity in the pulmonary vascular bed of the rat, whereas allyl mercaptan and diallyl disulfide produced no significant changes in pulmonary arterial perfusion pressure. The present data suggest that pulmonary vasodilator responses to allicin are independent of the synthesis of nitric oxide, ATP-sensitive K(+) channels, activation of cyclooxygenase enzyme, or changes in bronchomotor tone in the pulmonary vascular bed of the rat. (+info)
Pregnadienolone glycoside from wild garlic Allium ursinum L.
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A thorough investigation of saponin fraction from the underground parts of wild garlic--Allium ursinum L. (Liliaceae) has led to the isolation of 3-[O-alpha-rhamnopyranosyl-(1-->4)-alpha-rhamnopyranosyl-(1-->4)- alpha-rhamnopyranosyl-(1-->4)-beta-glucopyranoside-(1-->)]-3 beta-hydroxypregna-5,16-dien-20-one [1]. The structure of 1 was established by chemical and spectroscopic methods. Compound 1 is reported for the first time. (+info)
Garlic consumption and cancer prevention: meta-analyses of colorectal and stomach cancers.
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BACKGROUND: Animal and in vitro studies have provided evidence of an anticarcinogenic effect of active ingredients in garlic. OBJECTIVE: The objective was to conduct meta-analyses of the epidemiologic literature on the association between garlic consumption and risk of stomach, colon, head and neck, lung, breast, and prostate cancers. DESIGN: Meta-analyses were conducted for all cancers mutually and separately for colorectal and stomach cancers in relation to consumption of exclusively raw garlic, cooked garlic, or both (RC garlic). Eighteen studies reported a relative risk estimate for RC garlic consumption and cancer risk. RESULTS: In the meta-analyses of colorectal and stomach cancer, the reference categories ranged from no consumption to consumption of 3.5 g/wk, whereas the highest categories ranged from any consumption to >28.8 g/wk. The average difference between the highest and lowest categories was 16 g/wk. The random-effects relative risk (RR) estimate of colorectal cancer and RC garlic consumption, excluding garlic supplements, was 0.69 (95% CI: 0.55, 0.89). For stomach cancer, the random-effects RR estimate was 0.53 (95% CI: 0.31, 0.92). The heterogeneity among studies for the latter outcome (P: = 0.0002) indicates the questionableness of the generalizability of this summary estimate. An indication of publication bias for all cancers combined is evident from a funnel plot of RC garlic consumption and cancer risk and from the results of the Begg and Mazumdar test (P: = 0.049). CONCLUSIONS: High intake of RC garlic may be associated with a protective effect against stomach and colorectal cancers. Heterogeneity of effect estimates, differences in dose estimation, publication bias, and possible alternative hypotheses (eg, confounding by total vegetable consumption) preclude sole reliance on summary effect estimates. (+info)
Effects of allyl sulfur compounds and garlic extract on the expression of Bcl-2, Bax, and p53 in non small cell lung cancer cell lines.
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Allyl sulfur compounds play a major role in the chemoprevention against carcinogenesis. The present study compared the antiproliferative effects of diallyl sulfide (DAS), diallyl disulfide (DADS) and garlic extract on p53-wild type H460 and p53-null type H1299 non small cell lung cancer cells (NSCLC). The DAS and DADS treatment of both H460 and H1299 cells resulted in the highest numbers of cells in apoptotic state as measured by acridine orange staining, however, garlic extract treatment did not induce any significant apoptotic cells by MTT assay. DADS was found to be more effective in inducing apoptosis on NSCLC. The level of p53 protein in H460 cell was increased following DADS treatment. DAS and garlic extract treatment of H460 cells induced a rise in the level of Bax and a fall of Bcl-2 level. These results demonstrate that DAS, DADS and garlic extract are effective in reduction of anti-proliferative gene in NSCLC and suggest that modulation of apoptosis-associated cellular proteins by DAS, DADS and garlic extract may be the mechanism for apoptosis which merit further investigation as potential chemoprevention agents. (+info)