Zhang Zhiqiang, Chan Gallant Kar-Lun, Li Jieliang, Fong Wang-Fun, Cheung Hon-Yeung
Research Group for Bioactive Products, Department of Biology and Chemistry, City University of Hong Kong, Hong Kong, SAR, China.
Chem Pharm Bull (Tokyo). 2008 Sep;56(9):1229-33. doi: 10.1248/cpb.56.1229.
The intracellular level of glutathione (GSH) was significantly decreased after the addition of andrographolide (1) to cell cultures of HepG2. When the molecular interaction between andrographolide and GSH was investigated under a condition mimicking the in vivo environment, we observed that the level of GSH dropped in the presence of andrographolide. Stoichiometric analysis indicates that the reaction between these two reactants was 1 to 1 at pH 7 and followed second order kinetics. The activation energy of the overall reaction was 41.9+/-10 kJ x mol(-1) according to the Arrhenius equation. Using a micro-liquid-liquid extraction method followed by micellar electrokinetic chromatographic separation, two major products were isolated and identified, and their chemical structures were determined as 14-deoxy-12-(glutathione-amino)-andrographolide (2) and 14-deoxy-12-(glutathione-S-yl)-andrographolide (3). Based on these structural findings, a hypothetical mechanism of reaction between glutathione and andrographolide was proposed. It is concluded that the alpha,beta-unsaturated lactone moiety of andrographolide reacts with GSH through a Michael addition followed by dehydration of the adduct.
在向HepG2细胞培养物中添加穿心莲内酯（1）后，细胞内谷胱甘肽（GSH）水平显著降低。当在模拟体内环境的条件下研究穿心莲内酯与GSH之间的分子相互作用时，我们观察到在穿心莲内酯存在下GSH水平下降。化学计量分析表明，这两种反应物之间的反应在pH 7时为1比1，并遵循二级动力学。根据阿伦尼乌斯方程，总反应的活化能为41.9±10 kJ·mol⁻¹。采用微液-液萃取法，随后进行胶束电动色谱分离，分离并鉴定出两种主要产物，其化学结构确定为14-脱氧-12-（谷胱甘肽-氨基）-穿心莲内酯（2）和14-脱氧-12-（谷胱甘肽-S-基）-穿心莲内酯（3）。基于这些结构发现，提出了谷胱甘肽与穿心莲内酯之间反应的假设机制。得出的结论是，穿心莲内酯的α，β-不饱和内酯部分通过迈克尔加成反应与GSH反应，随后加合物脱水。
