Camptothecin and Thiocamptothecin: the Role of Sulfur in Shifting the Hydrolysis Equilibrium towards the Closed Lactone Form
作者:Marco Pistolozzi、Greta Varchi、Alessandra Degli Esposti、Andrea Guerrini、Giovanna Sotgiu、Marco Ballestri、Claudia Ferroni、Alessandro Venturini、Carlo Bertucci
DOI:10.1002/cmdc.201100206
日期:2011.9.5
presence of HSA. Specifically, HSA caused a shift in the hydrolysis equilibrium of TCPT towards the carboxylate form, but the proportion of lactone form remained higher than that observed for CPT under the same conditions, and also in the presence of a higher excess of the protein. The role of the sulfur atom in the stability of the open and closed lactone derivatives was investigated by theoretical
不良反应限制了20-(S)-喜树碱(CPT)的临床潜力,并导致人们对开发具有较小严重缺陷并保持其治疗活性的CPT类似物的兴趣日益增长。最近,CPT的硫代吡啶酮等排物20-(S)-喜树碱(TCPT)的开发在H460,HT29和IGROV-1细胞系中比母体化合物产生更有效的作用。TCPT相对于CPT的活性提高可能是由于内酯环的稳定性更高。在此,在有或没有人血清白蛋白(HSA)的情况下,通过HPLC研究了CPT和TCPT的可逆水解为开环羧酸盐形式。发现在缓冲溶液(24 h)处于平衡状态时以内酯形式存在的TCPT量显着高于CPT,并且在存在HSA的情况下观察到相同的趋势。具体而言,HSA导致TCPT的水解平衡向羧酸盐形式转移,但内酯形式的比例仍然高于在相同条件下以及在存在过量蛋白质的情况下CPT所观察到的比例。通过使用稳定能的理论计算以及实验吸收光谱和计算吸收光谱之间的比较,研究了硫原子在开环和闭