Investigating the Photochemistry of Resveratrol

Resveratrol (3,4’,5-trihydroxystilbene) is a phytoalexin found in a variety of plants and food items that has been reported to have antioxidant, anti-inflammatory, and anti-tumor effects.  It is a light sensitive compound, undergoing a photoisomerization from trans-resveratrol to the cis- form upon irradiation with UV light.  With continued exposure to UV a third compound is observed, increasing in concentration as exposure time is increased.  The structure of this compound is evaluated using HPLC with fluorescence detection, UV-Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance spectroscopy (NMR).  This new compound appears to be occurring through a photocyclization reaction of the cis-isomer to form a tri-substituted phenanthrene system.