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Alcoholic beverages are enjoyed together with meals worldwide, but their excessive intake is associated with an increased risk of various diseases. We investigated whether S-allyl-L-cysteine sulfoxide (ACSO), a sulfuric odor precursor of garlic, suppresses elevation in plasma ethanol concentration by accelerating ethanol metabolism and preventing ethanol absorption from the gut in rats. ACSO and garlic extract with a high ACSO content (Garlic-H) suppressed elevation in concentrations of ethanol and acetaldehyde in plasma and promoted the activities of alcohol dehydrogenase and aldehyde dehydrogenase. However, ACSO and Garlic-H did not affect plasma acetate so much. Furthermore, we examined the change in plasma ethanol concentration by injecting ACSO or Garlic-H into the ligated stomach or jejunum together with ethanol solution. ACSO and Garlic-H suppressed the absorption of ethanol from the stomach and jejunum, but suppression in the jejunum was less than in the stomach. In conclusion, ACSO inhibits ethanol absorption and accelerates ethanol metabolism.

S-Allyl-L-cysteine sulfoxide (ACSO) is an odour precursor in garlic bulbs. One plausible pathway for the biosynthesis of ACSO involves S−2-carboxypropyl glutathione produced from glutathione and methacrylic acid via valine or from γ-glutamyl cysteine. The elimination of glycine and glutamic acid from S−2-carboxypropyl glutathione produces S-2-carboxypropyl cysteine, which is converted to S-allyl cysteine by decarboxylation and oxidation. S-Allyl cysteine is also biosynthesized via the elimination of glutamic acid from γ-glutamyl S-allyl cysteine by γ-glutamyl transpeptidase. The sulfur oxidation of S-allyl cysteine by flavin-containing monooxygenase forms ACSO. When cells are damaged by slicing or grating, ACSO in the cytoplasm or cytoplasmic vesicle is immediately converted to allylsulfenic acid, pyruvic acid, and ammonia by alliinase (C-S lyase), which is located in the vacuoles of vascular bundle sheath cells. Two molecules of allylsulfenic acid form diallyl thiosulfinate (allicin), which exhibits potent antimicrobial activity. Allicin eventually yields garlic odour compounds, such as diallyl disulfide (DADS) and diallyl trisulfide (DATS). Although these sulfides are known to exert various physiological functions, their strong odour limits their use in foods. On the other hand, ACSO is water-soluble and odourless and enhances sweet, salty, and umami tastes, characteristics of which are desirable for food additives. Upon consumption, ACSO is primarily absorbed from the small intestine in the intact form, but is also partly decomposed to allylsulfenic acid, pyruvic acid and ammonia. Allylsulfenic acid is then further converted to DADS and diallyl monosulfide (DAS). ACSO has numerous in vivo functions, such as the prevention of diabetes, myocardial ischaemia, hepatic injury, platelet aggregation and blood ethanol elevation. Although some of these effects may be attributed to its metabolites, ACSO itself contributes to many of these physiological functions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Orally administered S -allyl- L -cystine sulfoxide (ACSO/alliin) suppressed melanoma growth in xenografted mice. • ACSO suppressed B16F1 melanoma cells viability in vitro. • Only ACSO exhibited both in vivo and in vitro effects, different from other garlic odor precursors. Certain foods modify the risk of developing melanoma. Various garlic compounds, including odor precursors and their derivatives, inhibit tumor growth; thus, garlic could protect against melanoma. However, it is unclear if S -allyl- L -cystine sulfoxide (ACSO/alliin), which is the most abundant (>10 mg/g) odor precursor in fresh raw garlic, has anti-melanoma effect. We investigated if ACSO and the related compounds suppress tumor growth in vivo and in vitro. We orally administered ACSO, S -methyl- L -cystine sulfoxide (MCSO), and S -allyl- L -cystine (ACS) to mice with xenografted melanoma and observed the effect of these administrations on tumor size and lactate dehydrogenase activity. The effect of ACSO, MCSO, and ACS on B16F1 melanoma cells viability was also studied. We found that only ACSO suppressed tumor growth in vivo and in vitro. In addition, the sera collected from rats after oral administration of ACSO suppressed melanoma proliferation in vitro. ACSO may be the key anti-melanoma compound in garlic. [ABSTRACT FROM AUTHOR]

The combination of the garlic-derived amino acid, S-allyl-l-cysteine sulfoxide (ACSO), and ornithine or arginine on CCl4-induced hepatic injury was examined. After investigating the effectiveness of the mixture of ACSO and ornithine or arginine in preventing hepatic injury in vivo, an extract rich in ACSO and ornithine was prepared by converting arginine in garlic to ornithine by arginase from Hypsizygus marmoreus (buna-shimeji), after screening the productivity of ornithine among 12 kinds of mushrooms. Co-administration of ACSO with ornithine or arginine suppressed the increase in aspartate transaminase, alanine transaminase, and thiobarbituric acid reactive substance, and the decrease in glutathione S-transferase and cytochrome p450 2E1 activities after CCl4 injection more effectively than a single administration of ACSO. All extracts prepared from garlic and buna-shimeji with low and high contents of ACSO and arginine or ornithine significantly suppressed CCl4-induced hepatic injury in rats. Considering that ACSO is tasteless, odourless, and enhances taste, and ornithine has a flat or sweet taste and masks bitterness, the extract rich in ACSO and ornithine from garlic and buna-shimeji could be considered a potential antioxidant food material that can be added to many kinds of food to prevent hepatic injury. [ABSTRACT FROM AUTHOR]

S-Allyl-l-cysteine sulfoxide (ACSO) is a precursor of garlic-odor compounds like diallyl disulfide (DADS) and diallyl trisulfide (DATS) known as bioactive components. ACSO has suitable properties as a food material because it is water-soluble, odorless, tasteless and rich in bulbs of fresh garlic. The present study was conducted to examine the preventive effect of ACSO on hepatic injury induced by CCl4 in rats. ACSO, its analogs and garlic-odor compounds were each orally administered via gavage for five consecutive days before inducing hepatic injury. Then, biomarkers for hepatic injury and antioxidative state were measured. Furthermore, we evaluated the absorption and metabolism of ACSO in the small intestine of rats and NF-E2-related factor 2 (Nrf2) nuclear translocation by ACSO using HepG2 cells. As a result, ACSO, DADS and DATS significantly suppressed the increases in biomarkers for hepatic injury such as the activities of aspartate transaminase (AST), alanine transaminase (ALT) and lactate dehydrogenase (LDH), and decreases in antioxidative potency such as glutathione (GSH) level and the activities of glutathione S-transferase (GST) and glutathione peroxidase (GPx). We also found ACSO was absorbed into the portal vein from the small intestine but partially metabolized to DADS probably in the small intestine. In in vitro study, ACSO induced Nrf2 nuclear translocation in HepG2 cells, which is recognized as an initial trigger to induce antioxidative and detoxifying enzymes. Taken together, orally administered ACSO probably reached the liver and induced antioxidative and detoxifying enzymes by Nrf2 nuclear translocation, resulting in prevention of hepatic injury. DADS produced by the metabolism of ACSO in the small intestine might also have contributed to the prevention of hepatic injury. These results suggest potential use of ACSO in functional foods that prevent hepatic injury and other diseases caused by reactive oxygen species (ROS). [ABSTRACT FROM AUTHOR]