Free amino acid and cysteine sulfoxide composition of 11 garlic (Allium sativum L.) cultivars by gas chromatography with flame ionization and mass selective detection

Two garlic subspecies (n = 11), Allium sativum L. var. opioscorodon (hardneck) and Allium sativum L. var. sativum (softneck), were evaluated for their free amino acid composition. The free amino acid content of garlic samples analyzed ranged from 1121.7 to 3106.1 mg/100 g of fresh weight (mean = 2130.7 +/- 681.5 mg/100 g). Hardneck garlic had greater methiin, alliin, and total free amino acids contents compared to softneck garlic. The major free amino acid present in all but one subspecies was glutamine (cv. Mother of Pearl had aspartic acid as the major free amino acid). Cv. Music Pink garlic (a rocambole hardneck variety) contained the most methiin, alliin, and total free amino acids. The solid-phase extraction, alkylchloroformate derivatization, GC-FID, and GC-MS methods used in this study were simple and rapid, allowing 18 free amino acids in garlic to be separated within 10 min.     

Allicin and allicin-derived garlic compounds increase breath acetone through allyl methyl sulfide: use in measuring allicin bioavailability

Progress in establishing systemic pharmacological effects for fresh, crushed garlic (Allium sativum L) in humans has been hindered by (1) the inability to measure allicin bioavailability, (2) lack of direct evidence that allicin has significant systemic activity at doses of garlic normally consumed, and (3) lack of a model for an acute effect. We have addressed these problems by quantifying the increases in breath acetone and breath allyl methyl sulfide (AMS). The area under the 48 h curve was measured in humans after consumption of standardized garlic preparations, allicin, and allicin-derived compounds, at the equivalent of 7 g of crushed garlic. It was shown that the allyl thiosulfinates (mainly allicin) are solely responsible for breath AMS and increased breath acetone. Diallyl trisulfide, diallyl disulfide, ajoene, and S-allylmercaptocysteine, at isomolar dithioallyl, showed the same quantitative effects as allicin. Consumption of AMS at isomolar allyl also gave the same effects as allicin, indicating that AMS is the main metabolite of allicin and is an active metabolite. In conclusion, allicin and allicin-derived compounds are rapidly metabolized to AMS, a compound which stimulates the production of acetone and which can be used to measure the bioavailability of allicin and, hence, the ability of garlic supplements to represent fresh garlic.     

Biological and chemical stability of garlic-derived allicin

This study verifies the instability of garlic ( Allium sativum L.)-derived allyl 2-propenylthiosulfinate (allicin) in various aqueous and ethanolic solutions as well as in vegetable oil through chemical and biological analyses performed simultaneously. Crushed fresh garlic cloves generated antibacterial activity and chemically detectable allicin, a major antibacterial principle, and both declined on a daily basis in aqueous and ethanolic solutions at room temperature, showing biological and chemical half-lives of about 6 and 11 days, respectively. Allicin was more stable in 20% alcohol than in water, but surprisingly unstable in vegetable oil, with an activity half-life 0.8 h, as estimated from its antibacterial activity toward Escherichia coli, and a chemical half-life of 3.1 h, based on chromatographic quantification. In alcoholic and aqueous extracts, the biological half-life of allicin tended to be longer than the chemical one, suggesting the occurrence of bioactive compounds other than allicin in the extracts.     

Model studies on precursor system generating blue pigment in onion and garlic

Reactions involved in blue-green discoloration in a mixture of onion (Allium cepa L.) and garlic (Allium sativum L.) were investigated. Vivid-blue color was successfully reproduced by using a defined model reaction system comprising only trans-(+)-S-(1-propenyl)-L-cysteine sulfoxide (1-PeCSO) from onion, S-allyl-L-cysteine sulfoxide (2-PeCSO) from garlic, purified alliinase (EC 4.4.1.4), and glycine (or some other amino acids). Four reaction steps identified and factors affecting the blue color formation were in good agreement with those suggested by earlier investigators. When crude onion alliinase was used in place of garlic alliinase, less pigment was formed. This result was explained by a difference in the amount of thiosulfinates, colorless intermediates termed color developers, yielded from 1-PeCSO by these enzymes.     

Determination of seven organosulfur compounds in garlic by high-performance liquid chromatography

The properties of garlic (Allium sativum L.) are attributed to organosulfur compounds. Although these compounds change during cultivation and storage, there is no report of their simultaneous analysis. Here, a newly developed analytical method with a rapid and simple sample preparation to determine four sulfoxides and three gamma-glutamyl peptides in garlic is reported. All garlic samples were simply extracted with 90% methanol solution containing 0.01 N hydrochloric acid and prepared for analysis. Alliin, isoalliin, methiin, cycloalliin, and gamma-l-glutamyl-S-methyl-l-cysteine were determined by normal-phase HPLC using an aminopropyl-bonded column. gamma-l-Glutamyl-S-(2-propenyl)-l-cysteine and gamma-l-glutamyl-S-(trans-1-propenyl)-l-cysteine were separated on an octadecylsilane column. The overall recoveries were 97.1-102.3%, and the relative standard deviation values of intra- and interday precision were lower than 2.6 and 4.6%, respectively. This newly developed method offers some advantages over the currently accepted techniques including specificity, speed, and ease of use and would be useful for chemical and biological studies of garlic and its preparations.     

Identification of two novel pigment precursors and a reddish-purple pigment involved in the blue-green discoloration of onion and garlic

By using a model reaction system representing blue-green discoloration that occurs when purees of onion (Allium cepa L.) and garlic (Allium sativum L.) are mixed, we isolated two pigment precursors (PPs) and a reddish-purple pigment (PUR-1) and determined their chemical structures. PPs were isolated from a heat-treated solution containing color developer (CD) and either l-valine or l-alanine, and their structures were determined as 2-(3,4-dimethylpyrrolyl)-3-methylbutanoic acid (PP-Val), and 2-(3,4-dimethyl-1H-pyrrolyl) propanoic acid (PP-Ala), respectively. Next, PUR-1 was isolated from a heat-treated solution containing PP-Val and allicin, and its structure was determined as (1E)-1-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-yl)-prop-1-enylene-3-(1-((1S)-1-carboxy-2-methylpropyl)-3,4-dimethyl-1H-pyrrol-2-ylidenium). The structure of PUR-1 suggested that PP molecules containing a 3,4-dimethyl pyrrole ring had been cross-linked by an allyl group of allicin to form conjugated pigments. While PUR-1 is a dipyrrole compound exhibiting a reddish-purple color, a color shift toward blue to green can be expected as the cross-linking reaction continues to form, for example, tri- or tetrapyrrole compounds.     

Chemical characterization of Allium ursinum L. depending on harvesting time

Sulfur-containing compounds of ramson (Allium ursinum L.) are responsible for its traditional use in terms of culinary and medicinal purposes. Leaves and bulbs were investigated for their contents of cysteine sulfoxides (volatile precursors) as well as volatile compounds released from minced plant material. Plants were analyzed during the whole vegetation period, focused on the months from March to June. Additionally, within the dormancy period bulbs were analyzed again and alliinase activity was determined. The pattern of volatile compounds was analyzed both by SPME/GC-MS and by SDE/GC-MS. Compared to each other, SDE exhibited a wider spectrum of detectable volatile compounds. The quality and quantity of volatiles significantly depended on the time of harvest. The highest amounts of volatile precursors can be gained in March and April, shortly before flowering time (up to 0.4% of total cysteine sulfoxides). The main cysteine sulfoxides were alliin and isoalliin. It has been found that alliinase of A. ursinum exhibited properties similar to those of alliinase of garlic (Allium sativum L.), but differing in terms of substrate specificity.     

硒对大蒜生理特性、含硒量及品质的影响

以金蒜3号为试材,采用盆栽试验,通过叶面喷施不同浓度、不同次数的亚硒酸钠研究了硒对大蒜生理特性、含硒量和品质的影响。结果表明:在生长期4月5日、15日和25日累计喷施1次、2次、3次3个浓度（5、10、15 mg/L）的亚硒酸钠溶液,均不同程度影响大蒜生理特性、含硒量和品质。与对照相比,叶面喷施2次10 mg/L的亚硒酸钠溶液,可显著提高叶片中光合色素含量和光合性能;能显著改善蒜薹和鳞茎品质,单薹鲜质量和单头鲜质量分别提高68.25%和29.00%,可溶性糖、可溶性蛋白、维生素C含量分别提高73.05%、104.66%、18.95%和82.01%、51.27%、69.82%;并可有效提高鳞茎中游离氨基酸含量（38.91%）,降低蒜薹中游离氨基酸含量（36.95%）;同时可降低蒜薹和鳞茎中大蒜素含量,但差异不显著。蒜薹和鳞茎硒含量随硒浓度和喷施次数的增加而显著提高,最高可达19.81和23.96 mg/kg,为对照的3.85和4.41倍。综合各因素指标,大蒜以叶面喷施2次10 mg/L的亚硒酸钠为宜。     

Allium species from Central and Southwest Asia are rich sources of marasmin

Marasmin, which is especially known from the two South African species Tulbaghia alliacea and Tulbaghia violacea , but was also described for the garlic mushroom Marasmius alliaceus , is the precursor of the thiosulfinate marasmicin. Marasmicin has attracted considerable attention because of its antifungal and tuberculostatic activities. However, many Allium species of the subgenus Melanocrommyum, especially Allium suworowii , are also very rich in marasmin. A. suworowii revealed concentrations of marasmin up to 1.6%, related to the fresh weight of bulbs, and up to 3.0%, related to air-dried fruiting bodies, of the corresponding γ-glutamylmarsmin was found in M. alliaceus. Both species show much higher amounts of marasmin as Tulbaghia and could be considered as natural sources for the isolation of this compound. Further promising Allium species with considerable amounts of marasmin besides other cysteine sulfoxides are Allium stipitatum and Allium altissimum . (R(S),R(C))-Marasmin is typical for the investigated species of the subgenus Melanocrommyum, whereas γ-glutamyl-(S(S),R(C))-marasmin is the only cysteine sulfoxide for the genus Marasmius known until now. Both cysteine sulfoxides were isolated and described as o-phthaldialdehyde (OPA) derivatives. Furthermore, the cysteine sulfoxides methiin, propiin, S-(2-pyrrolyl)-cysteine sulfoxide, eventually S-(2-pyridyl)-cysteine sulfoxide and S-(2-pyridyl)-L-cysteine N-oxide were found.     

Comparison of the bioactive compounds and antioxidant potentials of fresh and cooked Polish, Ukrainian, and Israeli garlic

Garlic (Allium sativum L.) is an essential part of Polish, Ukrainian, and Israeli cuisine. The aim of this investigation was to compare the changes in bioactive compounds, proteins, and antioxidant potentials in fresh Polish, Ukrainian, and Israeli garlic samples after subjection to cooking temperature. Dietary fiber and essential trace elements were comparable. The antioxidant potentials were determined by four scavenging methods using beta-carotene, 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide (NO), and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS(*)(+)) radical cation with K(2)S(2)O(8) or MnO(2) assays. Polyphenols, tocopherols, proteins, and antioxidant potentials were higher in Polish garlic, but not significantly (P > 0.05). The SDS- and native-PAGE electrophoretic patterns of all three fresh garlic samples were without significant differences. Most of the proteins were in the molecular mass range of 24-97 kDa, and the more intensive major bands were concentrated at 50 and 12 kDa. The 50 kDa protein nearly disappears and the intensity of the 12 kDa lectin bands slightly decreases during cooking. It was observed that the bioactive compounds, antioxidant potential, and proteins in garlic decrease significantly after 20 min of cooking at 100 degrees C (P < 0.05). In conclusion, (a) the bioactive compounds, electrophoretic patterns, and antioxidant potential of fresh Polish, Ukrainian, and Israeli garlic samples are comparable; (b) garlic samples subjected to 100 degrees C during 20 min preserve their bioactive compounds, antioxidant potential, and protein profile and are comparable with fresh garlic; and (c) fresh garlic should be added to dishes cooked at 100 degrees C in the last 20 min of the cooking process.     

Differential inhibition of human platelet aggregation by selected Allium thiosulfinates

Thiosulfinates (TSs) have been implicated as a principle source of the antiplatelet property of raw onion and garlic juice. The in vitro responses of human platelets to dosages of four TSs were measured using whole blood aggregometry and compared by regression analysis. Of the compounds evaluated, methyl methane-TS (MMTS), propyl propane-TS (PPTS), and 2-propenyl 2-propene-TS (allicin) are present in freshly cut Allium vegetables, whereas ethyl ethane-TS (EETS) has not been detected. All TSs were synthesized using a model reaction system. PPTS and allicin had the strongest antiplatelet activity at 0.4 mM, inhibiting aggregation by 90 and 89%, respectively. At the same concentration, EETS and MMTS were significantly weaker, inhibiting 74 and 26%, respectively. Combinations of TSs were not additive in their inhibition of aggregation, indicating that the antiplatelet potential of Allium extracts cannot be easily predicted by quantifying organosulfur components. EETS, PPTS, and allicin were significantly more potent platelet inhibitors than aspirin at nearly equivalent concentrations.     

Effect of genetic characteristics and environmental factors on organosulfur compounds in garlic ( Allium sativum L.) grown in Andalusia, Spain

The content of organosulfur compounds was determined in selected garlic cultivars grown at four locations in Andalusia, Spain. The organosulfur compounds studied were three γ-glutamyl peptides, namely, γ-l-glutamyl-S-(2-propenyl)-l-cysteine (GSAC), γ-l-glutamyl-S-(trans-1-propenyl)-l-cysteine (GSPC), and γ-l-glutamyl-S-methyl-l-cysteine (GSMC), and four cysteine sulfoxides (alliin, isoalliin, methiin, and cycloalliin). There was a significant effect of the location, cultivar, and garlic ecotype on individual organosulfur compound contents. Purple-type cultivars showed on average the highest contents of GSMC, GSAC, alliin, and methiin but the lowest isoalliin content. The impact of genotype was relatively high for GSAC, whereas this factor hardly contributed to the total variability in alliin and isoalliin content. Planting date had a significant effect on the content of alliin and isoalliin. Discriminant analysis evidenced the ability of organosulfur compounds to distinguish among garlic bulbs from different locations or ecotypes with 81 or 86% accuracy, respectively.     

适宜的氮硫配施提高基质栽培大蒜鳞茎品质

试验采用蛭石-珍珠岩盆栽方式,研究了不同浓度氮(5、10、20 mmol/L,记作N1、N2、N3)、硫(2、4、8 mmol/L,记作S1、S2、S3)配施条件对大蒜鳞茎品质的影响,并采用隶属函数法对大蒜品质进行综合评价,分析鳞茎品质与氮硫互作水平的响应关系。试验结果表明,氮素、硫素对大蒜主要营养成分含量影响不尽相同,氮硫配施能够不同程度提高大蒜鳞茎中可溶性蛋白、VC、大蒜多糖、游离氨基酸的含量,且氮、硫单一因素对大蒜鳞茎品质影响远低于元素间交互作用。但在氮素适宜水平下(10~20 mmol/L),硫素水平对大蒜鳞茎中大蒜辣素含量有显著影响,提高硫浓度能够显著增加大蒜辣素含量,而在硫素浓度过高时(8 mmol/L)则明显抑制该物质合成。隶属函数法综合评价以N3S2处理组大蒜鳞茎品质最优,隶属函数值为0.81,对照组(CK)最差。综合分析可见,无机基质栽培条件下氮硫配施显著影响大蒜鳞茎品质,氮素浓度20 mmol/L(N3)、硫素浓度4 mmol/L(S2)时最利于大蒜鳞茎品质的提升,为大蒜无机基质栽培最佳氮、硫配施水平,且两元素配施存在明显的互作效应。该结论为大蒜栽培氮、硫元素合理配施提供试验指导。     

Composition, stability, and bioavailability of garlic products used in a clinical trial

In support of a new clinical trial designed to compare the effects of crushed fresh garlic and two types of garlic supplement tablets (enteric-coated dried fresh garlic and dried aged garlic extract) on serum lipids, the three garlic products have been characterized for (a) composition (14 sulfur and 2 non-sulfur compounds), (b) stability of suspected active compounds, and (c) availability of allyl thiosulfinates (mainly allicin) under both simulated gastrointestinal (tablet dissolution) conditions and in vivo. The allyl thiosulfinates of blended fresh garlic were stable for at least 2 years when stored at -80 degrees C. The dissolution release of thiosulfinates from the enteric-coated garlic tablets was found to be >95%. The bioavailability of allyl thiosulfinates from these tablets, measured as breath allyl methyl sulfide, was found to be complete and equivalent to that of crushed fresh garlic. S-Allylcysteine was stable for 12 months at ambient temperature. The stability of the suspected active compounds under the conditions of the study and the bioavailability of allyl thiosulfinates from the dried garlic supplement have validated the use of these preparations for comparison in a clinical trial.     

Improving knowledge of garlic paste greening through the design of an experimental strategy

The furthering of scientific knowledge depends in part upon the reproducibility of experimental results. When experimental conditions are not set with sufficient precision, the resulting background noise often leads to poorly reproduced and even faulty experiments. An example of the catastrophic consequences of this background noise can be found in the design of strategies for the development of solutions aimed at preventing garlic paste greening, where reported results are contradictory. To avoid such consequences, this paper presents a two-step strategy based on the concept of experimental design. In the first step, the critical factors inherent to the problem are identified, using a 2(III)(7-4) Plackett-Burman experimental design, from a list of seven apparent critical factors (ACF); subsequently, the critical factors thus identified are considered as the factors to be optimized (FO), and optimization is performed using a Box and Wilson experimental design to identify the stationary point of the system. Optimal conditions for preventing garlic greening are examined after analysis of the complex process of green-pigment development, which involves both chemical and enzymatic reactions and is strongly influenced by pH, with an overall pH optimum of 4.5. The critical step in the greening process is the synthesis of thiosulfinates (allicin) from cysteine sulfoxides (alliin). Cysteine inhibits the greening process at this critical stage; no greening precursors are formed in the presence of around 1% cysteine. However, the optimal conditions for greening prevention are very sensitive both to the type of garlic and to manufacturing conditions. This suggests that optimal solutions for garlic greening prevention should be sought on a case-by-case basis, using the strategy presented here.     

Influence of Nitrogen and Sulfur Fertilization on the Alliin Content of Onions and Garlic

Abstract

Onion (Allium cepa L.) and garlic (Allium sativum L.) were among the earliest cultivated crops and have been popular in folk medicine for centuries. Alliins (cysteine sulfoxides) are the characteristic sulfur (S) containing secondary metabolites of Allium species like onions, shallot, garlic, leek and chives and they cause taste and sharpness and are criteria for the pharmaceutical quality. The influence of the S nutritional status on the content of secondary S containing metabolites was shown for different crops such as oilseed rape, mustard, nasturtium, and allium species. It was the aim of this study to investigate the influence of the S and nitrogen (N) supply on the alliin content of onion and garlic and to evaluate the significance for crop quality. In a greenhouse experiment three levels of N and S were applied in factorial combinations of 0, 50, and 250 mg pot^?1 S and 250, 500, and 1000 mg pot^?1 N. 8 plants were grown in a Mitscherlich pot containing 8 kg sand. Leaves and bulbs were sampled twice during the growth period in order to follow up translocation processes. The first sampling was carried out when leaves were developed, but bulb growth had not yet started and the second one during main bulb growth. An increasing S supply was related to an increasing alliin content in leaves and bulbs of both crops, whereas nitrogen fertilization had only a minor influence. The alliin content in bulbs could be doubled by S fertilization. A translocation of alliin from leaves to bulbs was found so that time of harvest has a strong influence on the alliin content. At the beginning of plant development high alliin contents were found in leaves, while with bulb development they were translocated into this plant organ. The results show that the potential health benefits of Allium species could be distinctly improved by S fertilization.     

超高压和超声波预处理对蒜片热风干燥过程及品质的影响

为缩短蒜片热风干燥时间,提高干制蒜片品质,将超高压与超声波技术应用到蒜片干燥前处理,并利用低场核磁共振技术(Low Field Nuclear Magnetic Resonance, LF-NMR)分析预处理对蒜片干燥过程中内部不同状态水分迁移的影响。结果表明:干燥前超声或超高压预处理有利于加快干燥过程,超声、超高压和超高压-超声预处理的干燥时间分别比没有预处理的对照组降低了37.50%、43.75%、62.50%;三种预处理均可以降低干燥能耗,尤以超高压-超声最为显著(P0.05),相比对照降低了32.31%。低场核磁共振测定结果表明,预处理后蒜片中存在三种状态的水分,自由水占的比例最大,不易流动水次之,结合水最少。干燥过程中脱除的主要是自由水,超声和超高压均降低了自由水的脱除时间,超高压-超声预处理脱除自由水的时间最少,为90 min,说明超高压和超声联合更有利于减弱蒜片组织对水分的束缚并增强水分的流动性。通过扫描电镜发现,超高压使蒜片细胞间隙增大,细胞壁破坏严重,而经超声预处理的蒜片组织出现疏松多孔的结构,超高压-超声扩增了蒜片的显微通道,验证了超高压-超声更有利于提高水分的流动性。经超高压或超声预处理后,干制蒜片的色差降低,复水比和蒜素含量显著提高(P0.05),超高压与超声联合预处理得到的干制蒜片品质较优,色差值为16.11,大蒜素含量为2.67 mg/g,复水比为2.90 g/g。研究结果为高效节能、高品质的大蒜干燥技术提供理论参考。     

Characterization of some Allium hybrids by aroma precursors, aroma profiles, and alliinase activity

Various Allium hybrids, obtained by the crossbreeding of Allium cepa (onion) as the mother plant and six taxonomically distant wild species obtained by embryo rescue, were investigated with special respect to their individual profiles of cysteine sulfoxides as well as enzymically and nonenzymically formed aroma substances. Alliinase (EC 4.4.1.4) catalyzes the conversion of odorless (+)-S-alk(en)yl-L-cysteine sulfoxides into volatile thiosulfinates. These thiosulfinates were converted to a variety of sulfides by steam distillation. SPME-gas chromatography (GC) and high-performance liquid chromatography (HPLC) used for the analysis of aroma components and their precursors permitted a high sample throughput, so that numerous gene bank accessions and Allium breeding materials were analyzed within a comparatively short time. Cysteine sulfoxides as well as alliinase activity were found in all investigated samples at different levels, but (+)-S-methyl-L-cysteine sulfoxide (methiin) was the most abundant sulfoxide present. (+)-S-(trans-1-Propenyl)-L-cysteine sulfoxide (isoalliin) is typical for onion and was found in all investigated hybrids. The pattern of the other cysteine sulfoxides depended strongly on the parent plants used. The profile of aroma components corresponded with the related pattern of aroma precursors (cysteine sulfoxides). Successful hybridization was proven by randomly amplified polymorphic DNA analysis. Together with these established marker techniques, HPLC and SPME-GC analysis provide support to breeding projects designed to improve the health and aroma properties of Allium hybrids.     

紫色土增施单质硫对大蒜生长发育和硫素营养的影响

对紫色土施用单质硫条件下大蒜生长发育及硫素营养吸收和代谢进行了研究。结果表明,大蒜株高、叶面积、经济产量(蒜头)和经济系数以中等供硫水平最高,而茎粗和生物产量则以高硫水平最大。大蒜能耐高浓度的硫素供应,在0～120kghm-2供硫情况下,其全硫(TS)、水溶性硫(SS)和无机硫(Io-S)含量均随供硫量的增加而上升,小分子水溶性含硫氨基酸含量(Ws-S)以低硫水平最高,而大分子蛋白质硫含量(Wis-S)以中等供硫水平时最高,与大蒜素含量的变化一致。大蒜素含量与不同硫组分比率的关系分析发现,大蒜素含量与Ws-S/TS呈极显著的正相关(r=0.752 ),与Io-S/SS呈显著的正相关(r=0.702 )。全氮含量与全硫含量变化趋势一致,全磷含量以低硫水平时最高,全钾含量以中等供硫水平时最高。     

Effects of garlic powders with varying alliin contents on hepatic drug metabolizing enzymes in rats

The anticarcinogenic effect of garlic has been demonstrated in both epidemiologic and experimental studies. In this study, possible mechanisms involved in the anticarcinogenic effect of garlic consumption were assessed by determining its capacity to alter drug metabolizing enzymes, in relation with its alliin content. Rats were fed a diet for 2 weeks containing 5% garlic powders produced from bulbs grown on soils with different levels of sulfate fertilization and therefore containing differing amounts of alliin. Activities of several hepatic enzymes, which are important in carcinogen metabolism such cytochromes P450 (CYP) and phase II enzymes, were determined. Garlic consumption slightly increased ethoxyresorufin O-deethylase and CYP 1A2 levels. In contrast, garlic consumption decreased CYP 2E1 activity and the level of the corresponding isoform. UDP glucuronosyl transferase and glutathion S-transferase activities were increased by garlic powders. The alliin content of the garlic powders was positively correlated with UGT activity although not with other activities. Effects produced by garlic consumption were qualitatively similar to that of diallyl disulfide, a sulfur compound that has been extensively studied. These data could partially explain the chemoprotective effect of garlic.