Allyl sulfides are characteristic flavor components obtained from garlic. These sulfides are thought to be responsible for their epidemiologically proven anticancer effect on garlic eaters. This study was aimed at clarifying the molecular basis of this anticancer effect of garlic by using human colon cancer cell lines HCT-15 and DLD-1. The growth of the cells was significantly suppressed by diallyl trisulfide (DATS, HCT-15 IC 50 ‫؍‬ 11.5 M, DLD-1 IC 50 ‫؍‬ 13.3 M); however, neither diallyl monosulfide nor diallyl disulfide showed such an effect. The proportion of HCT-15 and that of DLD-1 cells residing at the G 1 and S phases were decreased by DATS, and their populations at the G 2 /M phase were markedly increased for up to 12 h. The cells with a sub-G 1 DNA content were increased thereafter. Caspase-3 activity was also dramatically increased by DATS. Fluorescence-activated cell sorter analysis performed on the cells arrested at the G 1 /S boundary revealed cell cycle-dependent induction of apoptosis through the transition of the G 2 /M phase to the G 1 phase by DATS. DATS inhibited tubulin polymerization in an in vitro cell-free system. DATS disrupted microtubule network formation of the cells, and microtubule fragments could be seen at the interphase. Peptide mass mapping by liquid chromatography-tandem mass spectrometry analysis for DATS-treated tubulin demonstrated that there was a specific oxidative modification of cysteine residues Cys-12␤ and Cys-354␤ to form S-allylmercaptocysteine with a peptide mass increase of 72.1 Da. The potent antitumor activity of DATS was also demonstrated in nude mice bearing HCT-15 xenografts. This is the first paper describing intracellular target molecules directly modified by garlic components.Allyl sulfides, e.g. diallyl monosulfide (DAS), 4 diallyl disulfide (DADS), and diallyl trisulfide (DATS), are characteristic flavor components of the essential oil prepared from garlic (Allium sativum L.). Garlic is widely served around the world, and it has been reported that allyl sulfides inhibit both the initiation and promotion stages of tumorigenesis in experimental carcinogenesis models for various types of cancer (1-5). Recently, several lines of investigation have shown that allyl sulfides suppress cell growth and induce apoptosis in multiple cancer cell lines (6 -12). We previously reported that the sulfur-containing volatile oils prepared from garlic and onion inhibit proliferation and induce differentiation of the human promyelocytic leukemia cell line HL-60 (13). However, the molecular mechanisms underlying the antitumorigenesis of allyl sulfides are still not fully understood.Microtubules are ubiquitous proteins present in eukaryotes as components of the cytoskeleton and play pivotal roles in a variety of cellular processes involving cell division, motility, and intracellular trafficking (14). The microtubules are dynamic polymers composed of ␣␤-tubulin heterodimers, and they form the mitotic spindles, which are known to introduce the replicated DNA molecules to the res...

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Diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DATS) are principal constituents of garlic oil. We studied the effect of these sulfides on the phase II drug-metabolizing enzymes, and on the rat model of acute liver injury induced by carbon tetrachloride (CCl4). A highly purified form of each sulfide (more than 99% purity) was administered i.p. to rats at a concentration of 10 or 100 micromol/kg body weight for 14 consecutive days. DATS (10 micromol/kg) and DADS at a 10-fold higher dose (100 micromol/kg) significantly increased the activities of glutathione S-transferase (GST) and quinone reductase (QR); whereas DAS did not. In the CCl4-induced acute liver injury model of rats, DATS (10 micromol/kg) significantly suppressed the increase in plasma lactate dehydrogenase (LDH) and aspartate aminotransferase (AST) activities. In conclusion, hepatic phase II enzymes were induced strongly by the trisulfide and weakly by the disulfide, but not by DAS. DATS significantly reduced the liver injury caused by CCl4. DATS may be one of the important factors in garlic oil that protects our body against the injury caused by radical molecules.