Inhibitory Effects of Caffeic Acid Ester Analogues on Free Radicals and Human Liver Microsome CYP1A2 Activities
作者:Churdsak Jaikang、Chaiyavat Chaiyasut、Paitoon Narongchai、Kanokporn Niwatananun、Siripun Narongchai、Winthana Kusirisin
DOI:10.2174/157340611794859316
日期:2011.3.1
Ethyl caffeate (EC), octyl caffeate(OC), benzyl caffeate(BC) and phenethyl caffeate(PC) were synthesized and evaluated for scavenging of superoxide anion, nitric oxide radical and 1,1-diphenyl-1-picrylhydrazyl radical(DPPH). Antioxidant activity was investigated with reducing power method. Pooled human liver microsome was used for investigating the effects on cytochrome P450 1A2 (CYP1A2) catalytic activities by using phenacetin as a substrate. Dixon and Cornish- Bowden plots were used for enzyme kinetic analysis. The EC, OC, BC and PC potentially inhibited superoxide anion, nitric oxide and DPPH radicals. IC50 values of superoxide anion scavenging of EC, OC, BC and PC were 16.42, 79.83, 123.69 and 123.69 μg/ml, respectively. EC was more potent than OC and BC in terms of nitric oxide radical scavenger: IC50 values of EC, OC and BC were 24.16, 37.34 and 52.64 μg/ml, respectively. In addition, the IC50 values of EC, OC, BC and PC on DPPH radical scavenging were 70.00, 184.56, 285.34 and 866.54 μg/ ml, respectively. The IC50 values of EC, OC, BC and PC on phenacetin O-deethylation were 124.98, 111.86, 156.68 and 31.05 μg/ml, respectively. Enzyme kinetics showed that the type of inhibition mechanism was mixed-type. The result of this study shows that caffeic acid ester analogues potentially scavenge free radicals and inhibit catalytic activity of CYP1A2. This may lead to important implications in the prevention of CYP1A2-mediated chemical carcinogenesis.
合成了乙基咖啡酸酯(EC)、辛基咖啡酸酯(OC)、苄基咖啡酸酯(BC)和苯乙基咖啡酸酯(PC),并评估了它们对超氧阴离子、氮氧自由基和1,1-二苯基-1-苦味唑自由基(DPPH)的清除能力。采用还原力法研究抗氧化活性。使用人类肝微粒体进行研究,以探讨对细胞色素P450 1A2(CYP1A2)催化活性的影响,使用对乙酰氨基酚作为底物。采用Dixon和Cornish-Bowden绘图法进行酶动力学分析。结果表明,EC、OC、BC和PC对超氧阴离子、氮氧和DPPH自由基具有潜在的抑制作用。EC、OC、BC和PC对超氧阴离子清除的IC50值分别为16.42、79.83、123.69和123.69 μg/ml。在氮氧自由基清除方面,EC的活性优于OC和BC,其IC50值分别为24.16、37.34和52.64 μg/ml。此外,EC、OC、BC和PC对DPPH自由基清除的IC50值分别为70.00、184.56、285.34和866.54 μg/ml。EC、OC、BC和PC对对乙酰氨基酚O-去乙基化的IC50值分别为124.98、111.86、156.68和31.05 μg/ml。酶动力学分析表明抑制机制为混合型抑制。该研究结果表明,咖啡酸酯类类化合物可能对自由基具有清除作用,并抑制CYP1A2的催化活性。这可能对预防CYP1A2介导的化学致癌有重要意义。