Antioxidant activity of capsanthin and the fatty acid esters in paprika (Capsicum annuum)

The antioxidant ability of capsanthin and the fatty acid esters was examined by measuring the free radical-oxidation of methyl linoleate. To assess radical scavenging effect, the production of methyl linoleate hydroperoxides and the decomposition of capsanthins in reaction solution were measured by HPLC. Capsanthin suppressed hydroperoxide formation as well as B-carotene, lutein, and zeaxanthin. Interestingly, capsanthin decomposed more slowly than the other carotenoids, and the radical scavenging effect of capsanthin was found to last longer. Also, the capsanthin esterified partially and/or totally with fatty acids (mono- and/or diesterified capsanthin), isolated from paprika color, suppressed oxidation of methyl linoleate in a similar manner as nonesterified capsanthin. This finding suggests that the radical scavenging ability of capsanthin was not influenced by esterification, that is, the ability would contribute to the polyene chain, especially conjugated keto group. It was first found that esterified (monoesterified and diesterified) capsanthins also were good radical scavengers.