Showing papers on "Allicin published in 1993"
TL;DR: In contrast, nicotinic acid and particularly adenosine caused moderate inhibition of HMG-CoA reductase activity and of cholesterol biosynthesis suggesting that these compounds participate, at least in part, in the early inhibition of sterol synthesis by garlic extracts.
Abstract: Exposure of primary rat hepatocytes and human HepG2 cells to water-soluble garlic extracts resulted in the concentration-dependent inhibition of cholesterol biosynthesis at several different enzymatic steps. At low concentrations, sterol biosynthesis from [14C]acetate was decreased in rat hepatocytes by 23% with an IC50 (half-maximal inhibition) value of 90μg/mL and in HepG2 cells by 28% with an IC50 value of 35 μg/mL. This inhibition was exerted at the level of hydroxymethylglutaryl-COA reductase (MHG-CoA reductase) as indicated by direct enzymatic measurements and the absence of inhibition if [14C]mevalonate was used as a precursor. At high concentrations (above 0.5 mg/mL), inhibition of cholesterol biosynthesis was not only seen at an early step where it increased considerably with dose, but also at later steps resulting in the accumulation of the precursors lanosterol and 7-dehydrocholesterol. No desmosterol was formed which, however, was a major precursor accumulating in the presence of triparanol. Thus, the accumulation of sterol precursors seem to be of less therapeutic significance during consumption of garlic, because it requires concentrations one or two orders of magnitude above those affecting HMG-CoA reductase. Alliin, the main sulfur-containing compound of garlic, was without effect itself. If converted to allicin, it resulted in similar changes of the sterol pattern. This suggested that the latter compound might contribute to the inhibition at the late steps. In contrast, nicotinic acid and particularly adenosine caused moderate inhibition of HMG-CoA reductase activity and of cholesterol biosynthesis suggesting that these compounds participate, at least in part, in the early inhibition of sterol synthesis by garlic extracts.
136 citations
TL;DR: Because garlic has been reported to beneficially affect serum lipid levels, platelet function, fibrinolysis and blood pressure, this additional effect of retarding lipoprotein oxidation may contribute to the potential antiatherosclerotic effect of garlic.
Abstract: Interventions which make serum lipoproteins less susceptible to oxidation may be antiatherogenic. The antioxidant properties of garlic which have been demonstratedin vitro led us to investigate the effects of garlic supplements on lipoprotein oxidation susceptibility in humans. Ten healthy volunteers were given 600 mg/d of garlic powder (6 tablets of Kwai®) for two weeks in a placebo-controlled, randomized, double-blind crossover trial. We found that although serum lipid and lipoprotein levels were not lowered in this short time period, theex vivo susceptibility of apolipoprotein B-containing lipoproteins to oxidation was significantly decreased (−34%). Because garlic has been reported to beneficially affect serum lipid levels, platelet function, fibrinolysis and blood pressure, this additional effect of retarding lipoprotein oxidation may contribute to the potential antiatherosclerotic effect of garlic.
122 citations
TL;DR: The results indicate that this garlic preparation can reduce blood pressure, particularly with more conventional doses, in patients with mild to moderate hypertension and under placebo‐controlled, double‐blind conditions.
Abstract: A popular garlic preparation containing 1.3% allicin at a large dose (2400 mg) was evaluated in this open-label study in nine patients with rather severe hypertension (diastolic blood pressure > or = 115 mm Hg). Sitting blood pressure fell 7/16 (+/- 3/2 SD) mm Hg at peak effect approximately 5 hours after the dose, with a significant decrease in diastolic blood pressure (p < 0.05) from 5-14 hours after the dose. No significant side effects were reported. Our results indicate that this garlic preparation can reduce blood pressure. Further controlled studies are needed, particularly with more conventional doses (e.g., < or = 900 mg/day), in patients with mild to moderate hypertension and under placebo-controlled, double-blind conditions.
97 citations
TL;DR: Ajoene was found to inhibit platelet aggregation induced by AA, adrenaline, collagen, adenosine diphosphate (ADP) and calcium ionophore A23187; the nature of the inhibition was irreversible.
Abstract: When garlic cloves are chopped or crushed several dialkyl thiosulfinates are rapidly formed by the action of the enzyme alliin lyase or alliinase (EC 4.4.1.4) on S(+)-alkyl-L-cysteine sulfoxides. Allicin (diallyl thiosulfinate or allyl 2-propene thiosulfinate) is the dominant thiosulfinate released. A variety of sulfur containing compounds are formed from allicin and other thiosulfinates depending on the way in which garlic is handled. One such compound identified recently is ajoene which has been reported to possess antithrombotic properties. We present here data on the antiplatelet properties of ajoene together with its effects on the metabolism of arachidonic acid (AA) in intact platelets. Thus, ajoene was found to inhibit platelet aggregation induced by AA, adrenaline, collagen, adenosine diphosphate (ADP) and calcium ionophore A23187; the nature of the inhibition was irreversible. In washed platelets stimulated by labelled arachidonate, ajoene inhibited the formation of thromboxane A2; 12-lipoxygenase product(s) were reduced at higher ajoene concentrations. This garlic-derived substance inhibited the incorporation of labelled AA into platelet phospholipids at higher concentration. In labelled platelets, on stimulation with either calcium ionophore A23187 or collagen, reduced amounts of thromboxane and 12-HETE (12-hydroxyeicosatetraenoic acid) were produced in ajoene-treated platelets compared to control platelets. This substance had no effect on the deacylation of platelet phospholipids. The results suggest that at least one of the mechanisms by which ajoene shows antiplatelet effects could be related to altered metabolism of AA.
89 citations
TL;DR: In this article, the authors used HPLC, "cryogenic" GC-MS and proton Nh4R spectroscopy to analyze extracts of wild garlic, leek, scallion, shallot, elephant (or great-headed) garlic, chive, and Chinese chive.
Abstract: Room temperature vacuum distillates and extracts of onion, garlic, and other genus Allium plants (wild garlic, leek, scallion, shallot, elephant (or great-headed) garlic, chive, Chinese chive) were analyzed by HPLC, "cryogenic" GC-MS and proton Nh4R spectroscopy, using authentic samples of suspected thiosulfinate components to evaluate the methods. Eight thiosulfinates (RS(0)SR') and related organosulfur compounds (cisand trans-2,3-dimethy1-5,6-dithiabicyclo[2.1. llhexane 5-oxides; (Z,Z)-d,l-2,3-dimethyl-1,4-butanedithid S,S'-dioxide) were separated and identified in each plant extract, several for the first time. Garlic grown in cooler climates was found to show enhanced ally1 to methyl thiosulfinate levels in extracts. INTRODUCTION AND BACKGROUND Garlic (Allium sativum) and onion (Allium cepa) were among the earliest of cultivated foods and spices, easily identified by primitive food-seekers by their distinctive smell, now known to be associated with organosulfur compounds. The popularity of garlic and onions in folk medicine through the centuries for treatment of such varied disorders as dog bites, insect stings, earaches, burns and wounds, baldness, headaches, chest colds, respiratory ailments, asthma, pneumonia, diabetes, cardiovascular disorders, and rheumatism, among others, can be attributed to their pungent aroma, strong taste and, in the case of onion, its potent lachrymatory effect. These plants are members of the well known and widely appreciated genus allium, comprising more than 600 different species, other common members being leek, chive, shallot, and scallion. Common allium species were valued by early civilizations both as important dietary constituents and as medicinals for the treatment of many disorders, for example as recorded in the Bible, "...[the Jews who fled Egypt to wander the Sinai wilderness for forty years fondly remembered] the fish which we did eat in Egypt so freely, and the pumpkins and melons, and the leeks, onions and garlic," and as documented by discovery of dried garlic cloves and wooden models of onions among the relics found in the burial chambers of the pharoahs, and by references to medicinal uses of these plants in the writings of Aristotle, Hippocrates, Aristophanes, and Pliny the Elder (Ref. 1). Both the popularity of allium plants as foodstuff as well as the reputation of garlic and onion as "cure-alls" stimulated scientific investigations, such as the early work by Pasteur in France (ca. 1858) into garlic's antibacterial activity and by Wertheim (1844) and later Semmler (1892) in Germanyinto the composition of distilled garlic and onion oils (mainly diallyl disulfide, CH2=CHCH2SSCH2CH=CH2,1, in the former case, and propenyl propyl disulfide in the latter case). Only with the advent of modem spectroscopic and chromatographic techniques has it become possible to determine the molecular basis for the odor, taste and biological activity of the fresh or processed plants. Key early discoveries on this subject were made by Cavallito (1944) and Wilkens (1962) in the United States, by Stoll and Seebeck in Switzerland (1948) and by Virtanen in Finland (1960) (Ref. 2,3). Cavallito discovered an unstable, odoriferous liquid substance in extracts of fresh garlic he termed allicin (CH2=CHCH2S(O)SCH2CH=CH2 i AllS(O)SAlI, 2-propene1-sulfinothioic acid S-Zpropenyl ester; 2) possessing antibacterial properties, while Stoll and Seeback identified the immediate precursor of allicin as alliin, (CH2=CHCH2S(O)CH2CH(NH2)COOH, (+)-S-allyl-Lcysteine S-oxide; 3). Present evidence indicates that allicin 2 is formed by action of the C-S lyase enzyme alliinase (released by cutting or crushing garlic cloves) on the stable precursor alliin 3 by way of the intermediate 2-propenesulfenic acid (4, Scheme 1). Alliin 3 occurs abundantly in garlic, up to 0.76 f0.40% of fresh weight. From onion preparations Virtanen isolated three homologues of ,
71 citations
TL;DR: Allicin at 25 ppm for 5 min as a root‐dip treatment for tomato seedlings is effective against M. incognita.
Abstract: Allicin—an active nematicidal principle in garlic—has been isolated and tested against Meloidogyne incognita infesting tomato Allicin resulted in 11–75 eggs hatched at 5–05 ppm compared with 146 hatched at 0 ppm after 120 h A juvenile kill of 87–100% at 25–50 ppm allicin was recorded within 72 h Concentrations of 200 and 100 ppm allicin as bare‐root dips for 30 min killed 83% and 87% of tomato seedlings, respectively Penetration of tomato roots by juveniles was 13%, 14% and 18% in seedlings which had been dipped in allicin at 200, 100 and 25 ppm for 5 min, respectively, compared with 36% in untreated seedlings Allicin at 25 ppm for 5 min as a root‐dip treatment for tomato seedlings is effective against M incognita
35 citations
TL;DR: This study suggests that allicin lowered intraocular pressure (IOP) in normal rabbits, in part, by dual actions at the neuroeffector junction.
Abstract: The intent of this work was to examine the actions of allicin on 1) intraocular pressure(IOP) in normal and unilaterally sympathectomized (SX) rabbits; 2) cAMP accumulation in the rabbit i...
18 citations
01 Jan 1993
TL;DR: The aqueous extract and the polar fraction increased interleukin-1 production, and the thiosulfinate fraction enhanced natural killer cell activity, and neither the agueour nor the fractions stimulated lymphocyte blastogenesis.
Abstract: Aqueous garlic (Allium sativum L.) extract and the polar and thiosulfinate fractions were evaluated for their effects on the immune function of human peripheral blood mononuclear cells in vitro. The thiosulfinate fraction was found to contain diallyl thiosulfinate (allicin), allyl methyl and methyl allyl thiosulfinates and tranj-l-propenyl allyl thiosulfinate. The aqueous extract and the polar fraction increased interleukin-1 production, and the thiosulfinate fraction enhanced natural killer cell activity. The aqueous garlic extract, polar and thiosulfinate fractions increased interlenkin-2 production. Neither the agueour nor the fractions stimulated lymphocyte blastogenesis.
13 citations
TL;DR: In this paper, a simple GLC procedure was developed to examine the profile of sulphur compounds in garlic-based health products, namely alliin, allicin and sulphides.
12 citations
TL;DR: Though this episode of myocardial infarction cannot be documented to be due to garlic overuse, circumstantial evidence and lack of any risk factors in this patient, make us feel that probably excess consumption of garlic could have caused some hemodynamic and/or hemorrheological changes which were harmful.
6 citations
DOI•
01 Jan 1993
TL;DR: In this article, the garlic extract was extracted by extraction with ethylacetate or ethanol and the extracted oil obtained was tested for their antibacterial capacity, which indicated that the isolated oil were active against Staphylococcus aureus, Bacillus cereus and Escherichia coli.
Abstract: Garlic oil is known to have medicinal effect on hypertension, heart desease, anemia and various infections. The active principles are reported to be allicin, diallil disulfide, allilpropyl disulfide, scorduun, selenium and germanium in addition to the presence of anticoagulant, anuhaemolytic and arulthrombotic agents. The methods applied for isolation and other conditions during the isolation affect the yield or the compositions of the oil, for instance with steam distillation the allicin will decompose whereas extraction at room temperature will yield oil with allicin as the main component. In the present study isolation was conducted by extraction with ethylacetate or ethanol and the oil obtained was tested for their antibacterial capacity. Tests against Staphylococcus aureus, Bacillus cereus and Escherichia coli indicated that the isolated oil were active. On the other hand, commercial garlic extract (KGE) and garlic oil capsule (GOC) gave negative test. This may have been due to either insufficient concentration. of the biologically active component present in the commercial drugs or different method of extraction process. investigation with thin layer chromatography (TLC) of the drugs On silica gel plate ustngn-hexane and ethyl acetate as eluents showed six components in the GOC and none in KGE whereas for the isolated oil 13 components were identified with iodine vapour. Although the oils indicated antibacterial activity, it is somehow less active compared with oxytetracycline which is used as reference.
Journal Article•
TL;DR: The activity of chicken liver fructose 1,6-bisphosphatase increases dramatically after incubation with allicin, a major biologically active compound produced by garlic, and can be reversed by dithiothreitol or tris(2-carboxyethyl)phosphine, the latter being much more effective.
Abstract: The activity of chicken liver fructose 1,6-bisphosphatase increases dramatically after incubation with allicin, a major biologically active compound produced by garlic. Activation is more pronounced when the enzyme is assayed with Mn2+ than Mg2+. Maximum activation is accompanied by the disappearance of 4 highly reactive sulfhydryl groups per molecule of enzyme. This modification also leads to loss of activation by K+, and reduced sensitivity to inhibition by AMP, fructose 2,6-bisphosphate, and high concentration of fructose 1,6-bisphosphate. All the altered properties induced by allicin can be reversed by dithiothreitol or tris(2-carboxyethyl)phosphine, the latter being much more effective.
01 Jan 1993
TL;DR: The results demonstrate that the effects of water-soluble extracts of garlic powder on cholesterol biosynthesis in rat hepatocytes are due to distinct compounds present in garlic which may contribute to the hypocholesterolemic effect of garlic observed in rats and man.
Abstract: Water-soluble extracts of garlic powder inhibit cholesterol-biosynthesis at early and late steps of the pathway. In this study we have tried to identify garlic compounds associated with these different inhibitory actions wh ich are predominant at low and high concentrations, respectively. Alliin, neither alone nor after incubation with alliinase, was able to inhibit sterol synthesis from 14C-acetate in cultured rat hepatocytes at the early step. Likewise, allicin caused no reduction, while ajoen diminished sterol synthesis by maximally 16 %. Other compounds containing allyl- and/or sulphur-groups (including y glutamyl-peptides) did not inhibit, whereas nicotinamide and particularly adenosine caused some inhibition. From all these compounds only allicin and ajoen at high concentrations interacted with the conversion of lanosterol to cholesterol. 80th substances led to the accumulation of lanosterol as weil as some 7-dehydrocholesterol at the expense of cholesterol. Desmosterol was not accumulating. These results demonstrate that the effects of water-soluble extracts of garlic powder on cholesterol biosynthesis in rat hepatocytes are due to distinct compounds present in garlic which may contribute to the hypocholesterolemic effect of garlic observed in rats and man.