title: Identification and antioxidant activity of novel chlorogenic acid derivatives from bamboo (Phyllostachys edulis).
abstract: One known and two novel antioxidant compounds have been isolated from bamboo (Phyllostachys edulis). The butanol-soluble extract of the bamboo leaves was found to have a significant antioxidant activity, as measured by scavenging the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and the superoxide anion radical (O(2)(-)) in the xanthine/xanthine oxidase assay system. Antioxidant activity-directed fractionation of the extract led to the isolation and characterization of three structural isomeric chlorogenic acid derivatives: 3-O-(3'-methylcaffeoyl)quinic acid (1), 5-O-caffeoyl-4-methylquinic acid (2), and 3-O-caffeoyl-1-methylquinic acid (3). Compounds 2 and 3 were isolated and characterized for the first time from the natural products. In the DPPH scavenging assay as well as in the iron-induced rat microsomal lipid peroxidation system, compounds 2 (IC(50) = 8.8 and 19.2 microM) and 3 (IC(50) = 6.9 and 14.6 microM) showed approximately 2-4 times higher antioxidant activity than did chlorogenic acid (IC(50) = 12.3 and 28.3 microM) and other related hydroxycinnamates such as caffeic acid (IC(50) =13.7 and 25.5 microM) and ferulic acid (IC(50) = 36.5 and 56.9 microM). Among the three compounds, compound 1 yielded the weakest antioxidant activity, and the DPPH scavenging and lipid peroxidation inhibitory activity (IC(50) = 16.0 and 29.8 microM) was lower than those of chlorogenic and caffeic acids. All three compounds exhibited both superoxide scavenging activities and inhibitory effects on xanthine oxidase. Their superoxide anion (O(2)(-)) scavenging activities (IC(50) = 1, 4.3 microM; 2, 2.8 microM; and 3, 1.2 microM) were markedly stronger than those of ascorbic acid (IC(50) = 56.0 microM), alpha-tocopherol (IC(50) > 100 microM), and other test compounds, although their inhibition effects on xanthine oxidase may contribute to the potent scavenging activity. alpha-Tocopherol exerted a significant inhibitory effect (65.5% of the control) on superoxide generation in 12-O-tetradecanoylphorbol-13-acetate-induced human promyelocytic leukemia HL-60 cells, and compound 3 showed moderate activity (36.0%). On the other hand, other compounds including 1, 2, chlorogenic acid, and other antioxidants were weakly active (24.8-10.1%) in the suppression of superoxide generation.
authors.affiliation: Graduate School of Biotechnology, Korea University, 5-1 ka Anam-dong, Sungbuk-ku, Seoul 136-701, Korea.
authors.forename: M H
authors.initials: MH
authors.lastname: Kweon
authors.forename: H J
authors.initials: HJ
authors.lastname: Hwang
authors.forename: H C
authors.initials: HC
authors.lastname: Sung
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000032:analysis* / Q000737:chemistry / Q000494:pharmacology; D015764:Bepridil / Q000031:analogs & derivatives* / Q000737:chemistry; D001713:Biphenyl Compounds; D002726:Chlorogenic Acid / Q000031:analogs & derivatives* / Q000032:analysis / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016166:Free Radical Scavengers; D015227:Lipid Peroxidation; D008862:Microsomes, Liver / Q000378:metabolism; D010851:Picrates; D018515:Plant Leaves / Q000737:chemistry*; D006109:Poaceae / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013481:Superoxides / Q000737:chemistry; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D004791:Enzyme Inhibitors; D016166:Free Radical Scavengers; D010851:Picrates; D013481:Superoxides; D002726:Chlorogenic Acid; D015764:Bepridil; C004931:1,1-diphenyl-2-picrylhydrazyl; D014969:Xanthine Oxidase