The effects of ozone on resveratrol and quercetin: phytochemicals in grape berry skins

Many compounds in the epicuticular wax of grape berry skins are phytochemicals that have health benefits for people who consume either the grapes or products from grapes. These compounds also play a role in maintaining the health of the grape by regulating exchanges between the inside of the grape and the external environment. Since these compounds are in contact with the environment, any pollutants that can react with compounds in the wax could result in less healthy and less nutritious grapes. Ozone, a pollutant that can react with many of the phytochemicals in the wax, is especially high in agricultural areas and poses a threat to growing healthy grapes with maximum nutrition. To understand the extent to which ozone can affect grapes, we are studying the reaction between ozone and individual molecular components in the wax. Two of these molecular components, quercetin and resveratrol, contribute to the composition of the grape’s epicuticular wax. There is also evidence that these compounds help to reduce the risk of cancer and promote apoptosis in cancer cells in humans. The reaction between these individual compounds and ozone was studied by placing the compound, in sold form, in a PTFE bottle with excess ozone for a minimum of 1 week. These reactions were performed under dry and humid (with water present) conditions. Reaction products were characterized using IR, HPLC-QToF-MS, and various NMR techniques such as 1H, 13C, DEPT, HSQC, H2BC and HMBC by comparing spectra of the product with spectra of the unreacted compound. The differences in these spectra show changes in functional groups, mass, and structure between the unreacted compounds and the ozonolysis reaction products. Once the products were identified, reactions mechanisms were developed to explain product formation