Photochemistry of stilbene phytoalexins. The phytoalexins are compounds that accumulate at the site of plant injury and confer resistance to disease caused by invading microorganisms.
Resveratrol (Resv), a trihydroxystilene, and its dimethoxy derivative, pterostilbene (Pter), are phytoalexins found in plant tissues, and notably in red grapes and wine.
They have attracted attention because they are highly bioactive and may play a role in the prevention of human diseases. Resv may explain the “French paradox”, the beneficial effects of moderate wine consumption,
because it is an antioxidant that inhibits platelet aggregation. Pter, the major antioxidant in blueberries, is one of the active ingredients in the heartwood of Pterocarpus marsupium and is known to combat hyperglycemia by lowering
glucose levels. As stilbenes, Resv and Pter are expected to undergo photo-isomerization, - cyclization and -oxidation. As phenols, they should have enhanced Ka’s in their excited states and behave as photoacids. Except for a report of the photooxidation of the 4-methoxy derivative of Pter to the corresponding phenanthrene (Ppter), photochemical and photophysical studies have focused on trans-resveratrol (t-Resv), and its naturally occurring 2-O-glucoside piceid.
Published results are qualitative and contradictory. While formation of cis-resveratrol (c-Resv) is well established, as is its presence naturally in wine, its photoreactions are not well understood.
Irradiations have been in air-saturated solutions, conditions that should favor phenanthrene formation. The postdoctoral fellow will carry out a quantitative investigation of the photochemistry of Resv and Pter. Products will be identified and the mechanism of their formation and their quantum yields will be determined. UV absorption, fluorescence (static and time resolved), nuclear magnetic resonance, and mass spectroscopy will be some of the measurements employed.
Singular value decomposition will be used to treat spectral matrices and advanced separation methods will be relied upon to purify the photoproducts.
Special research AND career skills that you would be willing to provide training for a new postdoctoral scholar: PDFs are taught to safely make reliable photophysical and photochemical measurements, to plan experiments and interpret results. The PI corrects required periodic research reports and involves PDFs in the preparation of manuscripts for publication. PowerPoint talks and posters. Mentoring skills are developed by assisting in undergraduate research supervision.