9r-(9alpha(z)-10alpha)-of-3--angeloyloxy-4--acetoxy-3--4--dihydroseselin and khellactone

Many chiral drugs are used as the racemic mixtures in clinical practice. The occurrence of enantioselectively pharmacological activities calls for the development of enantiospecific analytical approaches during pharmacokinetic studies of enantiomers. Sample preparation plays a key role during quantitative analysis of biological samples. In current study, a rapid and reliable online solid phase extraction-chiral high performance liquid chromatography-tandem mass spectrometry (online SPE-chiral LC-MS/MS) method was developed for the simultaneously enantiospecific quantitation of (+)-trans-khellactone (dTK), (+/-)-cis-khellactone (d/lCK), (+/-)-praeruptorin A (d/lPA), (+/-)-praeruptorin B (d/lPB) and (+)-praeruptorin E (dPE), the main active angular-type pyranocoumarins (APs) in Peucedani Radix (Chinese name: Qian-hu) or the major metabolites of those APs, in rat plasma. The validation assay results described here show good selectivity and enantiospecificity, extraction efficiency, accuracy and precision with quantification limits (LOQs) of 2.57, 1.28, 1.28, 1.88, 4.16, 4.16 and 4.18ngmL(-1) for dTK, lCK, dCK, dPA, dPB, lPB and dPE, respectively, while lPA was not detected in rat plasma due to the carboxylesterase(s)-mediated hydrolysis. In addition, the validated system was satisfactorily applied to characterize the pharmacokinetic properties of those components in normal and chronic obstructive pulmonary disease (COPD) rats following oral administration of Qian-hu extract. dCK and lCK were observed as the main herb-related compounds in plasma. Enantioselectively pharmacokinetic profiles occurred for dCK vs lCK, dPA vs lPA, and dPB vs lPB in either normal or COPD rats. The proposed whole system is expected to be a preferable analytical tool for in vivo study of chiral drugs, in particular for the characterization of enantioselectively pharmacokinetic profiles.

Topics: Administration, Oral; Animals; Calibration; Chromatography, High Pressure Liquid; Coumarins; Disease Models, Animal; Hydrolysis; Linear Models; Male; Pulmonary Disease, Chronic Obstructive; Rats; Rats, Wistar; Reproducibility of Results; Stereoisomerism; Tandem Mass Spectrometry

Angular-type pyranocoumarins (APs) show attractive prospects in anti-hypertension, chemotherapy and anti-HIV treatment. Previous studies revealed extensive hepatic metabolisms of several APs following similar pathways. This study investigated the enzyme kinetics and the main CYP450 isozyme(s) involved in metabolism of (+)-praeruptorin A (dPA), an AP with significant cardio-protective activities, in human liver microsomes (HLMs) using ultra high-performance liquid chromatography coupled with a hybrid quadrupole-linear ion trap mass spectrometry (UHPLC-QT-MS/MS). dPA produced 6 metabolites via hydrolysis (M1-M3), oxidation (M4-M6), and hydrolysis followed by acyl migration (M2 or M3). Oxidation at the C-3' side chain instead of the coumarin ring was consolidated with the aromatic proton signal in NMR spectra. The major metabolite (-)-cis-khellactone (M1) followed biphasic kinetics in HLMs with high affinity (Km1 0.02μM) and intrinsic clearance (CLint1, invitro1.29mL/min/mg protein), whereas other metabolites (M2-M6) fitted typical Michaelis-Menten kinetics with lower affinity (Km 3.85-39.13μM). Recombinant human CYP3A4 showed the highest activity toward M1 and M4 formation, while it was CYP2C19 for M2/M3 and M5 and CYP2B6 for M6. Principal component analysis of the metabolite formation profile of dPA also revealed the highest similarity between CYP3A4 and HLMs. Both quercetin (CYP2C8 inhibitor) and ketoconazole (CYP3A4 inhibitor) showed 60-100% inhibition of M1-M4 and M6 formations in HLMs, while M5 formation was mainly inhibited by α-naphthoflavone (CYP1A2 inhibitor, 70-80%) and quercetin (90%). Moreover, formations of all metabolites were predominantly inhibited by CYP3A4 antibody (37-68%). These findings shed a light on main involvement of CYP3A4 in human hepatic elimination of APs, indicating potential drug interactions.

Topics: Calcium Channel Blockers; Chromatography, High Pressure Liquid; Coumarins; Cytochrome P-450 Enzyme System; Humans; Hydrolysis; Kinetics; Liver; Microsomes, Liver; Oxidation-Reduction; Tandem Mass Spectrometry