Polyunsaturated fatty acids (PUFA) are vulnerable to peroxidative attack. Protecting PUFA from peroxidation is essential to utilize their beneficial effects in health and in preventing disease. The antioxidants vitamin E, t-butylhydroxy toluene (BHT) and t-butylhydroxy anisole (BHA) inhibited ascorbate/Fe(2+)-induced lipid peroxidation in rat liver microsomes. In addition, a number of spice principles, for example, curcumin (5-50 microM) from turmeric, eugenol (25-150 microM) from cloves and capsaicin (25-150 microM) from red chillies inhibited lipid peroxidation in a dose-dependent manner. Zingerone from ginger inhibited lipid peroxidation at high concentrations (greater than 150 microM) whereas linalool (coriander), piperine (black pepper) and cuminaldehyde (cumin) had only marginal inhibitory effects even at high concentrations (600 microM). The inhibition of lipid peroxidation by curcumin and eugenol was reversed by adding high concentrations of Fe2+.