Dabrowiak James C, Goodisman Jerry, Souid Abdul-Kader
Department of Chemistry, Syracuse University, Syracuse, New York 13210, USA.
Drug Metab Dispos. 2002 Dec;30(12):1378-84. doi: 10.1124/dmd.30.12.1378.
The reactions of cisplatin [cis-diamminedichloroplatinum(II), CDDP] with glutathione (GSH) and drug thiols were investigated at 37 degrees C in 100 mM Tris-NO(3), pH approximately 7.4, using a clinically relevant concentration of CDDP (33 micro M), a large excess of GSH (16.5 mM), and [NaCl] of 4.62 mM. The conditions were designed to mimic passage of CDDP through the cytosol. The reactions were studied by UV-absorption spectroscopy, high-pressure liquid chromatography (HPLC), and atomic absorption spectroscopy. The initial rates, detected by UV absorbance, confirmed that the reactions are first order in [CDDP]. The HPLC peak corresponding to CDDP was analyzed for platinum content by atomic absorption spectroscopy, which decreased exponentially with time, confirming that the reactions are first order in [CDDP] and allowing determination of the pseudo first order rate constants (k(1)). For reaction of the dichloro form of CDDP with GSH, the k(1) value was approximately 2.2 x 10(-4) s(-1) (t(1/2) of approximately 53 min), giving the second order rate constant value (k(2)) of approximately 1.3 x 10(-2) M(-)1 s(-1). Reaction of a mixture of the aquated forms of CDDP with GSH gave a lower k(1) value ( approximately 0.9 x 10(-4) s(-1)). Reaction of CDDP with sodium 2-mercaptoethanesulfonate (mesna) gave a k(1) value of approximately 1.8 x 10(-4) s(-1) (t(1/2) of approximately 65 min and k(2) of approximately 1.1 x 10(-2) M(-1) s(-1)). Reaction of CDDP with S-2-(3-aminopropylamino)ethanethiol (WR-1065) gave a k(1) value of approximately 12.0 x 10(-4) s(-1) (t(1/2) of approximately 10 min and k(2) of approximately 7.3 x 10(-2) M(-)1 s(-1)). The relatively slow reaction rate of CDDP with GSH is consistent with the efficient DNA platination by CDDP in the presence of millimolar concentration of GSH in the cytosol.
在37摄氏度下，于100 mM Tris-NO₃（pH约7.4）中，使用临床相关浓度的顺铂（33 μM）、大量过量的谷胱甘肽（16.5 mM）以及4.62 mM的[NaCl]，研究了顺铂[顺二氨二氯铂(II)，CDDP]与谷胱甘肽（GSH）及药物硫醇的反应。设计这些条件以模拟顺铂在细胞质中的传递过程。通过紫外吸收光谱、高压液相色谱（HPLC）和原子吸收光谱对反应进行了研究。通过紫外吸光度检测到的初始速率证实反应对[CDDP]为一级反应。通过原子吸收光谱分析了对应于CDDP的HPLC峰中的铂含量，其随时间呈指数下降，证实反应对[CDDP]为一级反应，并允许确定伪一级速率常数（k₁）。对于CDDP的二氯形式与GSH的反应，k₁值约为2.2×10⁻⁴ s⁻¹（半衰期约为53分钟），二级速率常数（k₂）值约为1.3×10⁻² M⁻¹ s⁻¹。CDDP的水合形式混合物与GSH的反应给出较低的k₁值（约0.9×10⁻⁴ s⁻¹）。CDDP与2-巯基乙磺酸钠（美司钠）的反应给出的k₁值约为1.8×10⁻⁴ s⁻¹（半衰期约为65分钟，k₂约为1.1×10⁻² M⁻¹ s⁻¹）。CDDP与S-2-(3-氨丙基氨基)乙硫醇（WR-1065）的反应给出的k₁值约为12.0×10⁻⁴ s⁻¹（半衰期约为1分钟，k₂约为7.3×10⁻² M⁻¹ s⁻¹）。在细胞质中存在毫摩尔浓度的GSH时，CDDP与GSH相对较慢的反应速率与CDDP对DNA的有效铂化作用是一致的。
