Antioxidant phenolic compounds isolated from wild Pyrus ussuriensis Maxim. fruit peels and leaves

Thirteen phenolic compounds were isolated from pear (Pyrus ussuriensis Maxim.) peels and leaves extracts by using various column chromatography techniques with a guided DPPH (1,1-diphenyl-2-picrylhydrazyl) radical-scavenging assay, the result of antioxidant activity of phenolic compounds is then verified by measurement of ROS (reactive oxygen species). The isolated compounds were identified as rutin (1), (-)-catechin (2), orobol (3), daidzein (4), tricin 4'-O-[threo-beta-guaiacyl-(7 ''-O-methyl)-glyceryl] ether (5), tricin 4'-O-[ threo-beta-guaiacyl-(7.-Omethyl- 9 ''-O-acetyl)-glyceryl] ether (6), 5,7,3', 5'-tetrahydroxyflavanone (7), artselaeroside A (8), trilobatin (9), 3-(2,4,6-trihydroxyphenyl)-1-(4-hydroxyphenyl)-propan-1-one (10), quercetin-3-O-(3 ''-O-galloyl)-alpha-L-rhamnopyranoside (11), apigenin (12) and quercetin (13) on the basis of nuclear magnetic resonance spectroscopy along with comparison with literature data. Among these compounds, quercetin and quercetin-3-O-(3 ''-O-galloyl)- a-L-rhamnopyranoside exhibited potent DPPH radical-scavenging activity with IC50 (Half Maximal Inhibitory Concentration) value of 6.06 and 9.60 mu g/mL, respectively. The results revealed that P. ussuriensis could be used in the fields of food and medicine to prevent human aging diseases.