Antioxidant actions of fruit, herb and spice extracts

The antioxidant properties of extracts of five fruits (apple, pear, peach, plum and grapefruit), three herbs (rosemary, tarragon and basil) and one spice (black pepper) were evaluated in a series of assays involving reactive oxygen species (ROS). In general, the crude extracts possessed potent antioxidant properties in vitro. Rosemary extract was 50-times more effective at preventing microsomal lipid peroxidation of human liver microsomes induced by NADPH/iron compared to peroxidation induced by iron/ascorbate, but tarragon was more effective in the iron/ascorbate dependent peroxidation. Analysis of the content of hydroxycinnamic acids of the pear, apple, plum and peach extracts measured after hydrolysis with sodium hydroxide showed that caffeic acid, p-coumaric and ferulic acids were the principal hydroxycinnamic acids present. Although the hydroxycinnamic acids and naringin do not contribute to the inhibition of lipid peroxidation by fruit extracts, they were able to inhibit deoxyribose degradation by 30% suggesting ability to weakly scavenge hydroxyl radicals (OH^•). Nevertheless, extracts of herbs and spices are increasingly of interest in the food industry because they retard oxidative degradation to lipids.