Fiore Cristina, Bordin Luciana, Pellati Donatella, Armanini Decio, Clari Giulio
Department of Medical and Surgical Sciences-Endocrinology University of Padua, Via Ospedale 105, Padova, Italy.
Arch Biochem Biophys. 2008 Nov 1;479(1):46-51. doi: 10.1016/j.abb.2008.08.011. Epub 2008 Aug 24.
Glycyrrhetinic acid (GA) is a hydrolytic product of the triterpene glycoside of glycyrrhizic acid, one of the main constituents of licorice root, which has long been studied, due to its several biological and endocrine properties. In this paper, GA was tested on human erythrocytes, and GA-induced alterations were compared with those caused by diamide, a mild oxidant inducing well-characterized cell/membrane alterations, and n-ethylmaleimide (NEM), as alkylating agent. In order to verify the biochemical steps underlying the action of GA, band 3 Tyr-phosphorylation level, enzyme recruitment and band 3 clustering in cells pre-incubated with GA before diamide treatment were all examined. Results show that GA, in a dose-dependent manner, prevents both diamide and NEM-induced band 3 Tyr-phosphorylation, but not GSH decrease caused by both compounds. In addition, diamide-induced band 3 clustering and IgG binding to altered cells were also completely reversed by GA pre-treatment. Also, when membrane sensitivity toward proteolytic digestion was tested, GA-treated cells showed high resistance to proteolysis. In conclusion, in human erythrocytes, GA is proposed to strengthen membrane integrity against both oxidative and proteolytic damage.
甘草次酸（GA）是甘草根的主要成分之一甘草酸三萜糖苷的水解产物，由于其多种生物学和内分泌特性，长期以来一直受到研究。在本文中，对人红细胞进行了GA测试，并将GA诱导的变化与由二酰胺（一种诱导特征明确的细胞/膜变化的温和氧化剂）和N-乙基马来酰亚胺（NEM，作为烷基化剂）引起的变化进行了比较。为了验证GA作用的生化步骤，在二酰胺处理前用GA预孵育的细胞中，检测了带3酪氨酸磷酸化水平、酶募集和带3聚集情况。结果表明，GA以剂量依赖性方式阻止二酰胺和NEM诱导的带3酪氨酸磷酸化，但不阻止这两种化合物引起的谷胱甘肽（GSH）减少。此外，GA预处理也完全逆转了二酰胺诱导的带3聚集以及IgG与改变细胞的结合。而且，当测试膜对蛋白水解消化的敏感性时，经GA处理的细胞对蛋白水解具有高度抗性。总之，在人红细胞中，GA被认为可增强膜的完整性，抵抗氧化和蛋白水解损伤。
