Background and Aims: Stilbenes are an important group of phenolic substances that exist in roots, stems, leaves, skins and seeds. But little work has been performed to characterise the composition of grape root or to measure the antioxidant capacity of several stilbenes with hydroxyl radicals,1,1-diphenyl-2-picrylhydrazyl and nitric oxide free radicals. Methods and Results: Stilbenes were analysed by HPLC-MS/MS, and the radicals scavenging ability was determined by electron paramagnetic resonance. The root contained the highest concentration of stilbenes, followed by the stem and grape skin. The concentration of the following stilbenes increased in the order: piceatannol, δ-viniferin, trans-piceid, trans-resveratrol and ε-viniferin. All stilbenes had a high hydroxyl radical scavenging ability, with the scavenging rate above 50% for stilbenes at a concentration of 5 μmol/L; the same concentration of stilbenes had the lowest scavenging capacity for the nitric oxide free radicals model, with the rate below 50%. Conclusions: Five stilbenes were determined in three grape tissues. The root contained the highest concentration of stilbenes. All stilbenes had radical scavenging ability. The highest antioxidant activity was found in piceatannol. Significance of the Study: The results provide a more detailed tissue-specific profile for where these health-promoting substances can be extracted from in the grape.

No abstract