Phenolic compositions of Viburnum dilatatum Thunb. fruits and their antiradical properties

The fruit of Viburnum dilatatum Thunb., called “gamazumi” in Japanese, has been shown to prevent oxidative injury in rats given gamazumi crude extract (GCE), a solid which was obtained from the squeezed juice. Crude protein and fat contents were very low in the squeezed juice, and GCE included 53.0 mg/g of total polyphenols. Therefore, five major phenolic compounds were isolated from GCE, which they were identified by NMR and liquid chromatography/mass spectrometry/MS. These chemical structures were as follows: cyanidin 3-sambubioside (Cy-3-sam), cyanidin 3-glucoside (Cy-3-glc), 5-O-caffeoyl-4-methoxyl quinic acid (4-MeO-5-CQA), quercetin and chlorogenic acid (5-CQA). These concentrations in the fruits were, in order, 5-CQA, 4-MeO-5-CQA, Cy-3-sam, quercetin and Cy-3-glc, and their total content was equal to 42.4% of total polyphenols. By the ESR method, the superoxide anion radical scavenging activity was in the following order: Cy-3-sam, 4-MeO-5-CQA, Cy-3-glc, 5-CQA, quercetin; and the activity on hydroxyl radicals was in the order of Cy-3-sam, 5-CQA, quercetin, 4-MeO-5-CQA, Cy-3-glc. Cy-3-sam had the most potent antiradical activity, since the activities of Cy-3-sam were similar or higher than those of ascorbic acid. Our results suggest that these phenolic compounds, especially Cy-3-sam and chlorogenic acids may contribute to the antiradical activity and physiological effects of V. dilatatum fruits.