s-allylmercaptocysteine and allicin

Allicin in garlic is the primary active compound known to rapidly interact with free thiols.. To examine the effect of allicin on gene expression and glutathione cellular level in vascular endothelial cells.. Cultured endothelial cells were exposed to allicin; mRNA was prepared and subjected to Micro-array and Real-Time PCR. Glutathione cellular level was determined on cell lysates.. Micro-array analysis demonstrated allicin-induced up- and down-regulation of 116 and 100 genes, respectively. Up-regulated genes included the phase II detoxifying enzymes thioredoxin reductase 1 and 2, heme oxygenase-1 and glutamate cysteine lygaze modifier subunit, the rate limiting enzyme in glutathione biosynthesis. Endothelial cells exposed to allicin and its derivatives containing glutathione or cysteine residues increased cellular glutathione. Allicin increased the glutathione level in a concentration and time-dependent manner up to 8-fold at a concentration of 10-20 microM after 28 h exposure. Furthermore, allicin derivative-treated cultures demonstrated a 50% decrease in tBuOOH cytotoxicity.. These results may suggest a putative role for allicin and its derivatives in preventing reactive oxygen species damage by up-regulating the phase II detoxifying enzymes and increasing the cellular glutathione level.

Topics: Animals; Antioxidants; Aorta; Cattle; Cells, Cultured; Cysteine; Disulfides; Endothelial Cells; Glutamate-Cysteine Ligase; Glutathione; Heme Oxygenase-1; Humans; Oligonucleotide Array Sequence Analysis; Polymerase Chain Reaction; RNA, Messenger; Sulfinic Acids; Thioredoxin-Disulfide Reductase; Umbilical Veins; Up-Regulation

Growth-inhibitory effects on DS19 mouse erythroleukemia cells were seen in the micromolar concentration range with allicin and S-allylmercaptocysteine and in the millimolar range with allyl butyrate, allyl phenyl sulfone, and S-allyl cysteine. Increased acetylation of histones was induced by incubation of cells with the allyl compounds at concentrations similar to those that resulted in the inhibition of cell proliferation. The induction of histone acetylation by S-allylmercaptocysteine was also observed in Caco-2 human colon cancer cells and T47D human breast cancer cells. In contrast to the effect on histone acetylation, there was a decrease in the incorporation of phosphate into histones when DS19 cells were incubated with 25 microM S-allylmercaptocysteine. Histone deacetylase activity was inhibited by allyl butyrate, but there was little or no effect with the allyl sulfur compounds examined in this study. A similar degree of downregulation of histone deacetylase and histone acetyltransferase was observed when DS19 cells were incubated with S-allylmercaptocysteine or allyl isothiocyanate. The induction of histone acetylation by S-allylmercaptocysteine was not blocked by a proteasome inhibitor. The mechanism by which S-allylmercaptocysteine induces histone acetylation remains to be characterized. It may be related in part to metabolism to allyl mercaptan, which is a more effective inhibitor of histone deacetylase.

Topics: Acetylation; Acetyltransferases; Allyl Compounds; Animals; Antineoplastic Agents; Breast Neoplasms; Colonic Neoplasms; Cysteine; Disulfides; Electrophoresis, Polyacrylamide Gel; Female; Histone Acetyltransferases; Histone Deacetylases; Histones; Humans; Leukemia, Erythroblastic, Acute; Leupeptins; Mice; Saccharomyces cerevisiae Proteins; Sulfinic Acids; Tumor Cells, Cultured

The reaction between allicin (diallylthiosulfinate), the active component of garlic and reduced glutathione was investigated. The product of this reaction, mixed disulfide S-allylmercaptoglutathione (GSSA) was separated by high performance liquid chromatography and identified by 1H and (13)C nuclear magnetic resonance and mass spectroscopy. The reaction is fast (with an apparent bimolecular reaction rate constant of 3.0 M(-1) s(-1)). It is pH-dependent, which reveals a direct correlation to the actual concentration of mercaptide ion (GS(-)). Both GSSA and S-allylmercaptocysteine (prepared from allicin and cysteine) reacted with SH-containing enzymes, papain and alcohol dehydrogenase from Thermoanaerobium brockii yielding the corresponding S-allylmercapto proteins, and caused inactivation of the enzymes. The activity was restored with dithiothreitol or 2-mercaptoethanol. In addition, GSSA also exhibited high antioxidant properties. It showed significant inhibition of the reaction between OH radicals and the spin trap 5,5'-dimethyl-1-pyroline N-oxide in the Fenton system as well as in the UV photolysis of H2O2. In ex vivo experiments done with fetal brain slices under iron-induced oxidative stress, GSSA significantly lowered the production levels of lipid peroxides. The similar activity of GSSA and allicin as SH-modifiers and antioxidants suggests that the thioallyl moiety has a key role in the biological activity of allicin and its derivatives.

Topics: Alcohol Dehydrogenase; Antioxidants; Chromatography, High Pressure Liquid; Cysteine; Disulfides; Enzyme Inhibitors; Garlic; Glutathione; Kinetics; Magnetic Resonance Spectroscopy; Papain; Plants, Medicinal; Sulfhydryl Compounds; Sulfinic Acids