Kweon M H, Hwang H J, Sung H C
Graduate School of Biotechnology, Korea University, 5-1 ka Anam-dong, Sungbuk-ku, Seoul 136-701, Korea.
J Agric Food Chem. 2001 Oct;49(10):4646-55. doi: 10.1021/jf010514x.
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.
从竹子（毛竹）中分离出了一种已知的抗氧化化合物和两种新型抗氧化化合物。竹叶的丁醇提取物被发现具有显著的抗氧化活性，这通过在黄嘌呤/黄嘌呤氧化酶测定系统中清除稳定的1,1 - 二苯基 - 2 - 苦基肼（DPPH）自由基和超氧阴离子自由基（O₂⁻）来衡量。提取物经抗氧化活性导向的分级分离，得到并鉴定了三种结构异构的绿原酸衍生物：3 - O -（3'-甲基咖啡酰）奎尼酸（1）、5 - O - 咖啡酰 - 4 - 甲基奎尼酸（2）和3 - O - 咖啡酰 - 1 - 甲基奎尼酸（3）。化合物2和3是首次从天然产物中分离并鉴定出来的。在DPPH清除试验以及铁诱导的大鼠微粒体脂质过氧化系统中，化合物2（IC₅₀ = 8.8和19.2 μM）和3（IC₅₀ = 6.9和14.6 μM）的抗氧化活性比绿原酸（IC₅₀ = 12.3和28.3 μM）以及其他相关的羟基肉桂酸如咖啡酸（IC₅₀ = 13.7和25.5 μM）和阿魏酸（IC₅₀ = 36.5和56.9 μM）高约2 - 4倍。在这三种化合物中，化合物1的抗氧化活性最弱，其DPPH清除和脂质过氧化抑制活性（IC₅₀ = 16.0和29.8 μM）低于绿原酸和咖啡酸。这三种化合物均表现出超氧阴离子清除活性以及对黄嘌呤氧化酶的抑制作用。它们的超氧阴离子（O₂⁻）清除活性（IC₅₀ = 1、4.3 μM；2、2.8 μM；3、1.2 μM）明显强于抗坏血酸（IC₅₀ = 56.0 μM）、α - 生育酚（IC₅₀ > 100 μM）和其他受试化合物，尽管它们对黄嘌呤氧化酶的抑制作用可能有助于其强大的清除活性。α - 生育酚对12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯诱导的人早幼粒细胞白血病HL - 60细胞中超氧阴离子的产生有显著抑制作用（为对照的65.5%），化合物3表现出中等活性（36.0%）。另一方面，包括1、2、绿原酸和其他抗氧化剂在内的其他化合物在抑制超氧阴离子产生方面活性较弱（24.8 - 10.1%）。
