[Interaction and mechanism between poinicidin and BSA]

To establish a sensitive and specific LC-MS/MS method for determination of the binding conditions of ponicidin with bovine serum albumin (BSA) and analysis of its mechanism. The protein binding rates and related binding constants of ponicidin in BSA samples were determined by ultrafiltration and LC-MS/MS. Scatchard equation was used to calculate the binding constant (Ka) of ponicidin in BSA samples as well as the number of binding sites (n), and the mechanism on ponicidin binding with BSA was explored. The results showed that the average protein binding rate of ponicidin with BSA was 57.2%, mainly as grade Ⅰ intensive binding, and the relevant binding constant was 2.54×104 L•μg⁻¹, with a binding site number of n=0.75. The binding of ponicidin with BSA had no concentration dependence within the investigated concentrations. The established method in this study showed high sensitivity, specificity, simple operation and met the analysis requirements, and the calculation of binding constant laid foundation for the clinical drug interactions and pharmacokinetics research.