Snijman Petra W, Joubert Elizabeth, Ferreira Daneel, Li Xing-Cong, Ding Yuanqing, Green Ivan R, Gelderblom Wentzel C A
Departments of Chemistry, Stellenbosch University, Private Bag X1, Matieland (Stellenbosch) 7602, South Africa.
J Agric Food Chem. 2009 Aug 12;57(15):6678-84. doi: 10.1021/jf901417k.
The antioxidant activity of rooibos flavonoids, including the dihydrochalcones aspalathin and nothofagin and their corresponding flavone glycosides, was evaluated using the ABTS radical cation, metal chelating, and Fe(II)-induced microsomal lipid peroxidation assays. Epigallocatechin gallate (EGCG) and Trolox were used as reference standards. Optimized geometric conformers of aspalathin and nothofagin, in addition to calculated physicochemical properties, were considered to explain interaction with the microsomal membrane structure and thus relative potency of the dihydrochalcones. The most potent radical scavengers were aspalathin (IC50 = 3.33 microM) and EGCG (IC50 = 3.46 microM), followed by quercetin (IC50 = 3.60 microM) and nothofagin (IC50 = 4.04 microM). The least effective radical scavengers were isovitexin (IC50 = 1224 microM) and vitexin (IC50 > 2131 microM). Quercetin (IC50 = 17.5 microM) and EGCG (IC50 = 22.3 microM) were the most effective inhibitors of lipid peroxidation. Aspalathin (IC50 = 50.2 microM) and catechin (IC50 = 53.3 microM) displayed similar potencies. Nothofagin (IC50 = 1388 microM) was almost as ineffective as its flavone glycoside analogues.
使用ABTS自由基阳离子、金属螯合和铁（II）诱导的微粒体脂质过氧化试验，评估了路易波士黄酮类化合物的抗氧化活性，其中包括二氢查耳酮阿斯塔汀和诺托法金及其相应的黄酮苷。表没食子儿茶素没食子酸酯（EGCG）和Trolox用作参考标准。除了计算的物理化学性质外，还考虑了阿斯塔汀和诺托法金的优化几何构象，以解释与微粒体膜结构的相互作用，从而解释二氢查耳酮的相对效力。最有效的自由基清除剂是阿斯塔汀（IC50 = 3.33 microM）和EGCG（IC50 = 3.46 microM），其次是槲皮素（IC50 = 3.60 microM）和诺托法金（IC50 = 4.04 microM）。最无效的自由基清除剂是异荭草素（IC50 = 1224 microM）和荭草素（IC50 > 2131 microM）。槲皮素（IC50 = 17.5 microM）和EGCG（IC50 = 22.3 microM）是脂质过氧化最有效的抑制剂。阿斯塔汀（IC50 = 50.2 microM）和儿茶素（IC50 = 53.3 microM）表现出相似的效力。诺托法金（IC50 = 1388 microM）与其黄酮苷类似物几乎一样无效。
