Two New Monoterpene Glycosides from Qing Shan Lu Shui Tea with Inhibitory Effects on Leukocyte-Type 12-Lipoxygenase Activity

摘要

We evaluated the inhibitory effect of 12 Chinese teas on leukocyte-type 12-lipoxygenase (LOX) activity. Tea catechins such as epigallocatechin gallate have been known to exhibit leukocyte-type 12-LOX inhibition. Qing Shan Lu Shui, which contains lower catechin levels than the other tested teas, suppressed leukocyte-type 12-LOX activity. To characterize the bioactive components of Qing Shan Lu Shui, leukocyte-type 12-LOX inhibitory activity-guided fractionation of the aqueous ethanol extract of the tea was performed, resulting in the isolation of two new monoterpene glycosides: liguroside A (1) and B (2). The structures of compounds 1 and 2 were characterized as (2E,5E)-7- hydroperoxy-3,7-dimethyl-2,5-octadienyl-O-(α-L-rhamnopyranosyl)-(1″→3′)-(4′″-O-trans- p-coumaroyl)-β-D-glucopyranoside and (2E,5E)-7-hydroperoxy-3,7-dimethyl-2,5-octa-dienyl- O-(α-L-rhamnopyranosyl)-(1″→3′)-(4′″-O-cis-p-coumaroyl)-β-D-glucopyranoside, respectively, based on spectral and chemical evidence. Ligurosides A (1) and B (2) showed inhibitory effects on leukocyte-type 12-LOX activity, with IC50 values of 1.7 and 0.7 μM, respectively.