Abstract
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.
Highlights
Oxidative modification of low-density lipoprotein is the first key step in the development of atherosclerosis, and the role of leukocyte-type 12-lipoxygenase (LOX) in this process has been established using leukocyte-type 12-LOX-knockout mice [1,2]
We have investigated the inhibitory effects of 12 commercial Chinese teas on leukocyte-type
Bioassay-guided fractionation of Qing Shan Lu Shui led to the isolation of two new monoterpene glycosides, named liguroside A (1) and B (2)
Summary
Oxidative modification of low-density lipoprotein is the first key step in the development of atherosclerosis, and the role of leukocyte-type 12-lipoxygenase (LOX) in this process has been established using leukocyte-type 12-LOX-knockout mice [1,2]. We previously reported that guava leaf extracts showed anti-atherogenic activity by inhibiting leukocyte-type 12-LOX activity [3]. Chinese teas derived from various kinds of plants are drunk for health benefits in parts of South China such as the province of Sichuan. Tea catechins such as epigallocatechin gallate and epicatechin gallate are known to inhibit several enzyme activities and to show inhibitory effects on inflammation and cardiovascular disease [4]. We investigated the isolation and characterization of active constituents showing inhibitory effects on the leukocyte-type 12-LOX activity from Chinese teas
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