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pubmed:abstractText |
The methanol extract from Dipsacus asper Wall (Dipsacaceae) was found to show antioxidant activity against free radical and Cu(2+)-mediated LDL oxidation. In further study, to identify active constituents from the plant, six caffeoyl quinic acid derivatives: 3,4-di-O-caffeoylquinic acid (1), methyl 3,4-di-O-caffeoyl quinate (2), 3,5-di-O-caffeoylquinic acid (3), methyl 3,5-di-O-caffeoyl quinate (4), 4,5-di-O-caffeoylquinic acid (5) and methyl 4,5-di-O-caffeoyl quinate (6) were isolated. Their structures were identified by spectroscopic methods including 2D-NMR. The isolated compounds, 1-6, were found to be potent scavengers of the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), and are more potent than butylated hydroxyl toluene (BHT) used as a positive control. The compounds 1-6 also inhibited Cu(2+)-mediated low-density lipoprotein (LDL) oxidation. They increased the lag time of conjugated dienes formation and inhibited the generation of thiobarbituric acid reactive substances (TBARS) in a dose-dependent manner. These results suggested that Dipsacus asper due to its antioxidant constituents, 1-6, may have a role to play in preventing the development and progression of atherosclerotic disease.
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