Sachindra Nakkarike M, Sato Emiko, Maeda Hayato, Hosokawa Masashi, Niwano Yoshimi, Kohno Masahiro, Miyashita Kazuo
Faculty of Fisheries, Hokkaido University, 3-1-1 Minato, Hakodate 041-8611, Japan.
J Agric Food Chem. 2007 Oct 17;55(21):8516-22. doi: 10.1021/jf071848a. Epub 2007 Sep 26.
Antioxidant activity of carotenoids is suggested to be one of the factors for their disease preventing effects. Marine carotenoids fucoxanthin and its two metabolites, fucoxanthinol and halocynthiaxanthin, have been shown to exhibit several biological effects. The antioxidant activities of these three carotenoids were assessed in vitro with respect to radical scavenging and singlet oxygen quenching abilities. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of fucoxanthin and fucoxanthinol was higher than that of halocynthiaxanthin, with the effective concentration for 50% scavenging (EC 50) being 164.60, 153.78, and 826.39 microM, respectively. 2,2'-Azinobis-3-ethylbenzo thizoline-6-sulphonate radical scavenging activity of fucoxanthinol (EC 50, 2.49 microM) was stronger than that of fucoxanthin (EC 50, 8.94 microM). Hydroxyl radical scavenging activity as measured by the chemiluminescence technique showed that the scavenging activity of fucoxanthin was 7.9 times higher than that by fucoxanthinol, 16.3 times higher than that by halocynthiaxanthin, and 13.5 times higher than that by alpha-tocopherol. A similar trend was observed when the hydroxyl radical scavenging was assessed by the electron spin resonance (ESR) technique. ESR analysis of the superoxide radical scavenging activity also showed the superiority of fucoxanthin over the other two carotenoids tested. Singlet oxygen quenching ability of the three carotenoids was lower than that of beta-carotene, with quenching rate constants ( k Q, x10 (10) M (-1) s (-1)) being 1.19, 1.81, 0.80, and 12.78 for fucoxanthin, fucoxanthinol, halocynthiaxanthin, and beta-carotene, respectively. The higher radical scavenging activity of fucoxanthin and fucoxanthinol compared with halocynthiaxanthin is assumed to be due to presence of the allenic bond.
类胡萝卜素的抗氧化活性被认为是其预防疾病作用的因素之一。海洋类胡萝卜素岩藻黄质及其两种代谢产物，岩藻黄醇和海鞘黄质，已被证明具有多种生物学效应。对这三种类胡萝卜素的抗氧化活性进行了体外自由基清除和单线态氧猝灭能力的评估。岩藻黄质和岩藻黄醇的1,1-二苯基-2-苦基肼自由基清除活性高于海鞘黄质，50%清除的有效浓度（EC50）分别为164.60、153.78和826.39微摩尔。岩藻黄醇的2,2'-偶氮二（3-乙基苯并噻唑啉-6-磺酸）自由基清除活性（EC50，2.49微摩尔）强于岩藻黄质（EC50，8.94微摩尔）。通过化学发光技术测定的羟基自由基清除活性表明，岩藻黄质的清除活性比岩藻黄醇高7.9倍，比海鞘黄质高16.3倍，比α-生育酚高13.5倍。当通过电子自旋共振（ESR）技术评估羟基自由基清除时，观察到类似的趋势。ESR对超氧阴离子自由基清除活性的分析也表明岩藻黄质优于其他两种受试类胡萝卜素。这三种类胡萝卜素的单线态氧猝灭能力低于β-胡萝卜素，岩藻黄质、岩藻黄醇、海鞘黄质和β-胡萝卜素的猝灭速率常数（kQ，x10(10) M(-1) s(-1)）分别为1.19、1.81、0.80和12.78。岩藻黄质和岩藻黄醇与海鞘黄质相比具有更高的自由基清除活性，被认为是由于存在联烯键。
