Determination of products derived from trans-resveratrol UV photoisomerisation by means of HPLC–APCI-MS

Resveratrol, a phenolic compound found in plant tissues, berries, and wine exists in trans and cis stereo isomeric forms. Naturally, due to differences in energetic state the trans form is the more common, but in wines the cis form is also present, resulting from photoisomerisation reactions. It is thought that from this reaction the only product arising is the cis-resveratrol. After UV irradiation of the trans-resveratrol solution for 10 min a third component appears with a growing concentration till 1 h of irradiation. From the MS/MS results we can assert that this compound is a product derived from oxidation, where the double bond at the centre of the resveratrol molecule, changes into a triple bond, forming a diphenylacetylene derivative (3,4′,5-trihydroxy-diphenylacetylene).