Abstract
Seven new phenylhexanoids, (S)-(+)-3,4-dihydroxy-11-methoxyphenylhex-9-one (1), (E) 3,4-dihydroxy-phenylhex-10-en-9-one (2), (E)-4-hydroxyphenylhex-10-en-9-one (3), (R)-(-)-3,4,11-trihydroxyphenylhex-9-one 11-O-β-d-glucopyranoside (4), (R)-(-)-4,11-dihydroxyphenylhex-9-one 11-O-β-d-glucopyranoside (5), phenylhex-4,9,11-triol 11-O-β-d-glucopyranoside (6), and 9-O-acetyl-phenylhex-4,9,11-triol 11-O-β-d-glucopyranoside (7), were isolated and identified from Tibetan medicine Saxifraga umbellulata var. pectinate. The antioxidant activities of these compounds were evaluated using the DPPH and ABTS radical scavenging experiments. In the ABTS experiment, compounds 1 (IC(50) 13.99 ± 2.53 μM) and 2 (IC(50) 13.11 ± 0.94 μM) exhibited significantly better antioxidant activity than L-ascorbic acid (IC(50) 23.51 ± 0.44 μM).