Saito Samuel, Silva Givaldo, Santos Regineide Xavier, Gosmann Grace, Pungartnik Cristina, Brendel Martin
Laboratório de Biologia de Fungos, Centro de Biotecnologia e Genética, Universidade Estadual de Santa Cruz, Ilhéus, BA, 45662-900, Brazil.
Faculdade de Farmácia, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, 90610-000, Brazil.
Int J Mol Sci. 2012;13(3):2846-2862. doi: 10.3390/ijms13032846. Epub 2012 Mar 5.
Reverse phase-solid phase extraction from Cassia alata leaves (CaRP) was used to obtain a refined extract. Higher than wild-type sensitivity to CaRP was exhibited by 16 haploid Saccharomyces cerevisiae mutants with defects in DNA repair and membrane transport. CaRP had a strong DPPH free radical scavenging activity with an IC(50) value of 2.27 μg mL(-1) and showed no pro-oxidant activity in yeast. CaRP compounds were separated by HPLC and the three major components were shown to bind to DNA in vitro. The major HPLC peak was identified as kampferol-3-O-β-d-glucoside (astragalin), which showed high affinity to DNA as seen by HPLC-UV measurement after using centrifugal ultrafiltration of astragalin-DNA mixtures. Astragalin-DNA interaction was further studied by spectroscopic methods and its interaction with DNA was evaluated using solid-state FTIR. These and computational (in silico) docking studies revealed that astragalin-DNA binding occurs through interaction with G-C base pairs, possibly by intercalation stabilized by H-bond formation.
采用反相固相萃取法从翅荚决明叶中提取（CaRP），以获得精制提取物。16个在DNA修复和膜转运方面存在缺陷的单倍体酿酒酵母突变体对CaRP的敏感性高于野生型。CaRP具有较强的DPPH自由基清除活性，IC(50)值为2.27 μg mL(-1)，并且在酵母中未表现出促氧化活性。通过高效液相色谱法分离CaRP化合物，结果表明三种主要成分在体外与DNA结合。高效液相色谱的主要峰被鉴定为山奈酚-3-O-β-d-葡萄糖苷（紫云英苷），在对紫云英苷-DNA混合物进行离心超滤后，通过高效液相色谱-紫外测量发现其对DNA具有高亲和力。通过光谱方法进一步研究了紫云英苷与DNA相互作用，并使用固态傅里叶变换红外光谱对其与DNA的相互作用进行了评估。这些以及计算（计算机模拟）对接研究表明，紫云英苷与DNA的结合是通过与G-C碱基对相互作用发生的，可能是通过氢键形成稳定的嵌入作用。
