Antioxidative and antiglycative effects of six organosulfur compounds in low-density lipoprotein and plasma

Low-density lipoprotein (LDL) and plasma were isolated from patients with non-insulin-dependent diabetes. The protective effects of six organosulfur compounds (DAS, diallyl sulfide; DADS, diallyl disulfide; SAC, S-allylcysteine; SEC, S-ethylcysteine; SMC, S-methylcysteine; SPC, S-propylcysteine) against further oxidation and glycation in these already partially oxidized and glycated samples were studied. DAS and DADS showed significantly greater oxidative-delaying effects than four cysteine-containing compounds in both partially oxidized LDL and plasma samples (P < 0.05). However, cysteine-containing agents were superior to DAS and DADS in delaying glycative deterioration in already partially glycated LDL (P < 0.05). The observed delays of oxidative and glycative effects from each agent were significantly concentration-dependent (P < 0.05). Furthermore, six organosulfur agents significantly decreased the loss of catalase and glutathione peroxidase activities in plasma and increased α-tocopherol retention in LDL and plasma (P < 0.05). These results suggested that the use of these organosulfur agents derived from garlic at these concentrations could protect partially oxidized and glycated LDL or plasma against further oxidative and glycative deterioration, which might benefit patients with diabetic-related vascular diseases.