LPI 10th ANNIVERSARY COLLOQUIUM
In some of my earlier studies, I studied the colored compounds in henna, a traditional skin and hair dye. We were interested in lawsone, the compound that gives henna its orange color. Henna is traditionally prepared by mixing ground henna powder with water to make a paste, which sits for several hours before use. After analyzing traditionally prepared henna-water paste and a methanol extract of henna that did not turn orange, we noticed that lawsone is present in henna in a pro-dye form (dihydrolawsone glucoside), which is enzymatically converted to lawsone in the water paste. We also noticed that vitamin C, which naturally occurs in the henna plant, reacts with lawsone and creates a stable, new water-soluble vitamin C conjugate.
We wondered if this reaction with vitamin C also occurs in the human body. The oxidized form of lawsone has chemical reactivity similar to oxidized lipid (fat) compounds produced under conditions of oxidative stress. These oxidized lipids can lead to oxidative damage in the body, especially to DNA and to proteins. Similar to what we observed in the henna plant, we found that vitamin C reacts with oxidized lipids to form vitamin C conjugates in test-tube reactions, using vitamin C concentrations normally present inside cells. We are currently investigating the biological relevance of this previously unrecognized property of vitamin C by analyzing blood plasma and tissue homogenates. It is well known that oxidized lipids, which play a role in the initiation and progression of atherosclerosis and other age-related diseases, are detoxified by conjugation with glutathione, a natural antioxidant produced by the body. Our research will test the hypothesis that vitamin C contributes to the detoxification and elimination of oxidized lipids through conjugation with vitamin C.
Last updated May 2007