Effects of allyl mercaptan and various allium-derived compounds on cholesterol synthesis and secretion in Hep-G2 cells

The present study was undertaken to compare the effects of allyl mercaptan (AM), a major metabolite of garlic, with several garlic constituents and extracts on cytotoxicity, cholesterol synthesis and its secretion in Hep-G2 cells. The cells were grown in Dulbecco's modified Eagle's medium (DMEM) supplemented with 10% fetal bovine serum (FBS), and treated with 5, 25, 50, 125, 250 and 500 mu g/ml of AM, diallyl disulfide (DD), diallyl trisulfide (DT), steam-distilled garlic oil (SD) or vinyl-dithiin oil of garlic (VD) for 4 h. At concentrations up to 50 mu g/ml: no significant cytotoxic effect was found in any group, but at concentrations above 250 mu g/ml, the cell viability decreased drastically in all groups compared to the control. The treatment of cells with 25 mu g/ml (non-cytotoxic concentration) of AM, DD, DT, SD for 4 h significantly inhibited [H-3]acetate incorporation into cholesterol compared to that of the control (P < 0.05). The secretion of cholesterol into the medium was also significantly decreased in all groups except for VD. The treatment of cells with those allium constituents had no effect on either [H-3]acetate incorporation into fatty acids or [H-3]glycerol incorporation into triglyceride or phospholipid. (C) 2000 Elsevier Science S.A. All rights reserved.