No abstract

No abstract

No abstract

Resveratrol (3,5,4'-trihydroxylstilbene), a phytoalexin in response to injury or fungal attack, is found in grapes and other food products. It has been well documented that the compound has beneficial effects as hypolipidemic, anticancer, antiviral, neuroprotective, antiaging, and anti-inflammatory natural active principle. It was observed that both trans-and cis-resveratrols undergo hydrogen-deuterium (H/D) exchange at H-2,6 and H-4 positions of the A-ring. The exchange rates were determined by 1 H NMR spectroscopy. The results reveal that the exchange rates are configuration and pH dependent. Derivative of 2-O-β-D-glucoside can significantly speed up the H/D exchange reactions for both isomers. The trans-resveratrol experiences faster H/D exchanging than the cis-resveratrol. Such isomeric effect is possibly due to the factor that the trans-resveratrol is in favor of forming larger/super conjugative system and has less spatial interference. Theoretical calculation shows that electronegativity at these positions is in the order of H-2,6＞H-4, which is in consistent with the exchange rates observed by NMR. The results may be of help in understanding the properties of resveratrol, and in analysis of resveratrol in natural products or body fluids using mass spectroscopy that occasionally requires stable deuterium isotope labeling.