Dihydrochalcone glucosides and antioxidant activity from the roots of Anneslea fragrans var. lanceolata

Bioassay-guided fractionation of the roots of Anneslea fragrans var. lanceolata led to the isolation of four dihydrochalcone glucosides, davidigenin-2'-O-(6″-O-4″'-hydroxybenzoyl)-β-glucoside (1), davidigenin-2'-O-(2″-O-4″'-hydroxybenzoyl)-β-glucoside (2), davidigenin-2'-O-(3″-O-4″'-hydroxybenzoyl)-β-glucoside (3), and davidigenin-2'-O-(6″-O-syringoyl)-β-glucoside (4), and 13 known compounds. The structures were identified by means of spectroscopic analysis. Davidigenin-2'-O-(6″-O-syringoyl)-β-glucoside (4), 1-O-3,4-dimethoxy-5-hydroxyphenyl-6-O-(3,5-di-O-methylgalloyl)-β-glucopyranoside (5), lyoniresinol (10), and syringic acid (13) showed ABTS [2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid)] cation radical scavenging activity, with SC(50) values of 52.6 ± 5.5, 26.0 ± 0.7, 6.0 ± 0.2, and 27.5 ± 0.6 μg/mL in 20 min, respectively. Lyoniresinol (10), isofraxidin (12), and syringic acid (13) also showed DPPH [1,1-diphenyl-2-picrylhydrazyl] radical scavenging activity, with SC(50) values of 8.4 ± 1.8, 51.6 ± 2.2, and 4.3 ± 0.7 μg/mL in 30 min, respectively.