Production of Auroxanthins from Violaxanthin and 9-cis-Violaxanthin by Acidic Treatment and the Antioxidant Activities of Violaxanthin, 9-cis-Violaxanthin, and Auroxanthins

Violaxanthin and 9-cis-violaxanthin (major epoxycarotenoids in fruit) were prepared from mango fruit, purified, and converted to other carotenoids under acidic conditions. The resulting carotenoid structures were then analyzed in detail. Not only violaxanthin but also 9-cis-violaxanthin were found to be converted to (8S,8'S)-, (8S,8'R)-, and (8R,8'R)-auroxanthin at an approximate ratio of 4:6:1. Antioxidant activities of violaxanthin, 9-cis-violaxanthin, (8S,8'S)-auroxanthin, and (8S,8'R)-auroxanthin were examined. They possessed potent lipid peroxidation inhibitory and very weak 1O2 quenching activities.