Köhler T, Heinisch M, Kirchner M, Peinhardt G, Hirschelmann R, Nuhn P
Department of Pharmacy, Martin-Luther-University, Halle, Germany.
Biochem Pharmacol. 1992 Aug 18;44(4):805-13. doi: 10.1016/0006-2952(92)90419-j.
3-(4-Alkylbenzoyl)acrylic acids (ABAAs) were synthesized by acylation of alkylbenzenes with maleic anhydride and then screened in vitro for inhibition of phospholipase A2 (PLA2) from snake venom and from porcine pancreas. The inhibitory potency of ABAAs increased with the length of the alkyl residues resulting in IC50 values of between 10(-7) and 10(-4) mol/L. The most potent inhibitors of the snake venom PLA2 were the 4-(n)-hexadecyl and octadecyl (OBAA) derivatives. Kinetic experiments referred to a time-dependent inhibitory reaction. Irreversibility was examined by dilution and dialysis. A molar ratio of inactivation of OBAA of nearly 20 was estimated. Double reciprocal replots of the apparent inactivation constants to the concentration of OBAA gave a (pseudo) first order rate constant of inactivation of 2.3 min-1. For the dissociation constant of the enzyme-inhibitor intermediate, a value of 6 x 10(-6) mol/L was obtained. On the other hand, the PLA2 from porcine pancreas seemed hardly to be inhibited by ABAAs. The present data are discussed in relation to the proposed model for PLA2 inactivation by manoalide. In human PMNs leukotriene B4 and 5-HETE production was essentially reduced. In human platelets the thrombin-induced TxA2 production was reduced. Since these effects disappeared after addition of arachidonic acid, these findings refer to a PLA2 inhibition. The immunologically induced bronchospasm in guinea pigs was significantly and dose-dependently inhibited by OBAA. This indicates that ABAAs might be useful in treating allergic diseases, such as asthma, eczema, allergic shock and others.
通过用马来酸酐对烷基苯进行酰化反应合成了3-(4-烷基苯甲酰基)丙烯酸(ABAA)，然后在体外筛选其对蛇毒和猪胰磷脂酶A2(PLA2)的抑制作用。ABAA的抑制效力随烷基残基长度的增加而增强，IC50值在10^(-7)至10^(-4)mol/L之间。蛇毒PLA2最有效的抑制剂是4-(正)-十六烷基和十八烷基(OBAA)衍生物。动力学实验表明这是一种时间依赖性抑制反应。通过稀释和透析检测其不可逆性。估计OBAA的失活摩尔比接近20。将表观失活常数与OBAA浓度的双倒数重绘图得到失活的(伪)一级速率常数为2.3 min^(-1)。对于酶-抑制剂中间体的解离常数，得到的值为6×10^(-6)mol/L。另一方面，猪胰PLA2似乎几乎不受ABAA的抑制。结合曼诺酰胺使PLA2失活的模型对目前的数据进行了讨论。在人中性粒细胞中，白三烯B4和5-羟基二十碳四烯酸的产生基本减少。在人血小板中，凝血酶诱导的血栓素A2产生减少。由于添加花生四烯酸后这些作用消失，这些发现表明是PLA2受到了抑制。豚鼠免疫诱导的支气管痉挛被OBAA显著且剂量依赖性地抑制。这表明ABAA可能对治疗过敏性疾病如哮喘、湿疹、过敏性休克等有用。
