棉酚抗生育新机制——对磷脂酶A_2活力的抑制作用(英文)

A New Antifertility Mechanism of Gossypol: Inhibition on Phospholipase A_2

采用微孔比色法及荧光分析法 ,研究抗男性生育化合物棉酚与猪胰腺磷脂酶A2 (phospho lipaseA2 ,PLA2 ,EC3 1 1 4 )温育并透析前后对酶活力及荧光的影响 .结果表明 ,棉酚与PLA2 不可逆地结合明显地降低了PLA2 活力及荧光强度 .棉酚对酶活力抑制作用的IC50 为 35μmol L ;当其浓度达到 80 μmol L时 ,能够完全抑制PLA2 ( 4 11μmol L)对合成底物 2 硫代十六酰乙基磷酸胆碱(HEPC ,0 .2 5mmol L)的水解作用 .PLA2 的最大激发波长与发射波长分别为 2 75nm ,34 3nm ,荧光强度与酶浓度呈良好的线性关系 .棉酚对PLA2 的荧光具有较强的淬灭作用 .由于PLA2 与男性生育密切相关 ,棉酚对PLA2

The effect of a male antifertility compound gossypol on the enzymatic activity and fluorescence of porcine pancreatic phospholipase A 2(ppⅠ PLA 2,EC 3 1 1 4)has been studied by microplate assay and fluorescence assay on the incubated mixture with or without dialysis.Gossypol interacted with ppⅠ PLA 2 resulting in forming a complex and diminishing enzymatic activity and fluorescence intensity.The drug enzyme interaction was irreversible by aqueous dialysis.The hydrolysis activity of ppⅠ PLA 2(4 11 μmol/L)toward a synthesized substrate 2 hexadecanoylthio 1 ethyl phosphorylcholine(HEPC,0 25 mmol/L)was completely inhibited by 80 μmol/L gossypol with an apparent IC 50 of 35 μmol/L.There was a good linearity between fluorescence intensities and concentrations of ppⅠ PLA 2 with maximal excitation and emission wavelength at 275 nm and 343 nm,respectively.Gossypol caused a red shift in the maximal emission of about 5 nm and strongly quenched the fluorescence intensity of ppⅠ PLA 2.Since PLA 2 is very important to male fertility,the influence of gossypol on PLA 2 probably correlates with its mechanism of male antifertility and adverse effect.