Simultaneous quantification and ADME prediction of AD-1 and its eight metabolites in rat feces, and screening of PARP-1 inhibitors through molecular docking

20( R )-25-methoxyl-dammarane-3 β ,12 β ,20-triol (CN Patent: 201,010,107,476.7, AD-1) is a promising antitumor compound, was isolated from total hydrolyzed saponins extracted from Panax notoginseng leaves. A sensitive and rapid method for the simultaneous detection of AD-1 and its 8 major metabolites in rat feces was developed in this study. AD-1 (20 mg/kg) was orally administered to male rats by gastric intubation. Then, the feces samples were collected. After addition of internal standard (Mifepristone), feces samples were pretreated by protein precipitation followed by liquid-liquid extraction. Chromatographic separation was performed on an Angela C 18 column with gradient elution using a mobile phase composed of acetonitrile and water (containing 5 mM ammonium acetate) at a flow rate of 0.3 mL/min. The analytes were detected without any interference from the multiple reaction monitoring (MRM) mode using positive electrospray ionization. Calibration curves offered satisfactory linearity ( r > 0.995) within the determined ranges. Both intra-day and inter-day variances were lower than 15%, and the accuracy was within 85–115%. The fecal excretion recoveries of AD-1 (M0), metabolite 1 (M1), M2, M3, M4, M5, M6, M7 and M8 were 41.36%, 0.62%, 6.20%, 0.50%, 6.99%, 2.07%, 1.86%, 0.41% and 0.29%, respectively. The observed excretion profiles for AD-1 and its metabolites after oral administration are helpful to understand the poor oral bioavailability of AD-1, and will aid further investigations of AD-1 as a pharmacologically active component. Moreover, the in silico ADME (Absorption, Distribution, Metabolism, Excretion) predictions indicated that the metabolites were nontoxic and present passive gastrointestinal absorption. In previous studies, we found that M5, a metabolite of AD-1, has strong cytotoxicity against ovarian cancer cells. Further molecular docking studies showed that the most potent metabolite, M5, effectively binds to poly ADP-ribose polymerase-1 (PARP-1), which may provide novel solutions for treating ovarian cancer.