Antioxidant activity of capsinoids.

Hot peppers are a good source of dietary antioxidants, encompassing, apart from widespread compounds (flavonoids, phenolic acids, carotenoids, vitamin A, ascorbic acid, tocopherols), also specific constituents such as the pungent capsaicinoids (capsaicin, dihydrocapsaicin, and related analogues). We have shown that capsinoids also show remarkable antioxidant activity. These benign analogues of capsaicin could protect linoleic acid against free radical attack in simple in vitro systems, inhibiting both its autoxidation and its iron- or EDTA-mediated oxidation. These properties were retained in some simple synthetic analogues (vanillyl nonanoate and its dimerization products). Capsiate, dihydrocapsiate, and their analogues were devoid of pro-oxidant activity and showed a highly significant antioxidant activity in all systems investigated. Vanillyl nonanoate, a simple capsinoid mimic, was also tested on cell cultures for cytotoxic activity and the capacity to inhibit FeCl(3)-induced oxidation.