Pharmacokinetic Investigation Of Borneolum Syntheticum (Synthetic Bingpian) And Identification Of Bioactive Bingpian Compounds

Background and PurposeCompound Danshen tablet is a Chinese herbal medicine for angina pectoris in coronary heart disease.The tablet is prepared from Salvia miltiorrhiza roots(Danshen),Panax notoginseng roots(Sanqi),and Borneolum syntheticum(synthetic Bingpian).Coronary heart disease arising from atherosclerosis is a leading cause of morbidity and death worldwide.Foam cell,a hallmark of atherosclerosis,is prominently derived from monocyte-differentiated intimal macrophage through unlimitedly phagocytizing oxidized low-density lipoprotein(ox-LDL).As a part of our serial pharmacokinetic investigations of Compound Danshen formula,the current investigation focused on constituents originating from the component Bingpian,after dosing Compound Danshen tablet.Bingpian is widely used as a component herb in many Chinese herbal medicines for prevention and treatment of coronary heart disease.Cell-and animal-based studies have shown that borneol and isoborneol,the main constituents of Bingpian,exhibit vasorelaxant,anticoagulant,preventing lipids accumulation in the macrophages,sedative,and analgesic properties.However,which Bingpian compounds(unchanged and metabolized)are responsible for the Compound Danshen tablet’s therapeutic action remains inconclusive.Accordingly,this pharmacokinetic investigation aimed to identify potential therapeutic Bingpian compounds,after orally dosing Compound Danshen tablet in human,that are bioavailable(in their unchanged and/or metabolized forms)at loci responsible for the potency to protect against ox-LDL-induced macrophage foam cell formation and to characterizing the compounds’pharmacokinetics and disposition related to the therapeutic action.Experimental ApproachSystemic exposure to Bingpian compounds was determined in human volunteers receiving Compound Danshen tablets.Several rat studies and in vitro studies were performed to facilitate a better understanding of factors influencing systemic exposure to Bingpian compounds.Volatile Bingpian compounds in biomatrices were quantified by gas chromatography/mass spectrometry(GC-MS),and the non-volatile Bingpian metabolites were quantified by liquid chromatography with tandem mass spectrometry(LC-MS/MS).The macrophage-derived foam cells,stimulated by ox-LDL,were used to investigate the inhibitory effect of Bingpian compounds on the formation of foam cell.Key ResultsAlthough borneol(1)and isoborneol(2)were the major Bingpian constituents in Compound Danshen tablet,their extensive hepatic first-pass metabolism resulted in significant levels of their oxidized metabolite camphor(M1/2_O)and respective glucuronizedmetabolitesborneol-2-O-glucuronide(M1_G)and isoborneol-2-O-glucuronide(M2_G)in human plasma after dosing.In addition,Bingpian is mainly excreted by the kidneys in the form of glucuronides(M1_Gand M2_G).Bingpian compounds(1,2,M1/2_O,M1_G,and M2_G)exert the inhibitory activity of formation of foam cell at the concentration of 4 and 20μM.Circulating 1,2,and M1/2_O,having good membrane permeability,could pass through the vascular endothelial barrier to inhibit the formation of foam cells in the vascular endothelial layer;circulating M1_Gand M2_G,having poor membrane permeability,could also pass across the vascular endothelial barrier,due to the endothelial barrier’s destruction in atherosclerosis,to exert pharmacological activities.Conclusion and ImplicationsIn the current investigation,it was demonstrated for the first time that metabolites(M1/2_O,M1_G,and M2_G)rather than the unchanged Bingpian compounds(1 and 2),exhibited significant systemic exposure after dosing the tablet.These circulating Bingpian compounds(1,2,M1/2_O,M1_G,and M2_G)all have the activity of inhibiting the foam cell formation,which is associated with anti-atherosclerosis.The concentrations of Bingpian metabolites used to exert in vitro bioactivities related to the efficacy significantly are comparable to the compounds’clinically achievable concentrations,respectively.Additionally,the destruction of the endothelial barrier provides a favorable factor for compounds with poor membrane permeability to access the intima layer of arteries.The results of pharmacokinetic and pharmacodynamic studies suggest that Bingpian metabolites may play a more critical role in inhibiting macrophage foaming than the unchanged Bingpian compounds.This investigation,together with such investigations of other components,has implications for precisely defining therapeutic benefit of Compound Danshen tablet and other Bingpian-containing herbal medicines.Another part of the dissertation is the quality variability evaluation of Xue Bi Jing injection.On the basis of study of newly developed assays for quality evaluation of Xue Bi Jing,a LC/MS-MS-based assays using a one-point calibration,batch-to-batch quality variability among 33 batches of injection manufactured over three years was evaluated.Xue Bi Jing exhibited high overall quality consistency,which can be said to have contributed to its effective,safe,and growing medicinal use in sepsis care over the years.