Studies On Metabolism And Pharmacokinetics Of Radix Isatidis In Rats In Vivo

Object:Glucosinolates are the main active ingredients of Radix Isatidis,possessing antibacterial,antiviral and anti-endotoxin effects.R,S-goitrin,as one of glucosinolates,is a characteristic component and responsible for the medicinal properrities of Radix Isatidis.However,the metabolism of R,S-goitrin and its time course of blood concentration changes still remain unclear.Therefore,comprehensive identification of the metabolites and pharmacokinetics studies of R,S-goitrin to ascertain that its entry into the body process will be of great significance for revealing the pharmacodynamic basis of Radix Isatidis.Method:A complete metabolic investigation of R,S-goitrin was performed through ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry?UHPLC-Q/TOF-MS?.Urine samples of rats after administration were analyzed,and compared with blank samples to find possible metabolites.The structures of metabolites were ambigiously identified by using the elemental composition speculation,fragmentation patterns and the information of tandem mass spectrometry.Subsequently,quantification of R,S-goitrin in the plasma sample after after three doses of 20,25,30 mg/kg was established by using LC-MS/MS.And the pharmacokinetic parameters were calculated by DAS 3.1.Furthermore,the plasma concentration of R,S-goitrin in yeast-induced rats and normal rats were determined by using LC-MS/MS,and its pharmacokinetic parameters were calculated and compared.Result:The metabolic pathways of R,S-goitrin in rats mainly involved methylation,acetylation,hydroxylation,oxidation,reduction,glutathionylation and alanine.After intragastrically administration of different dose of R,S-goitrin,their pharmacokinetic parameters were conducted,t_1/2 of R,S-goitrin were 4.15 h,5.72 h and 5.18 h,respectively.AUC_0-t of three doses were 8444.69±2818.06?g/L*h,20907.09±6169.20?g/L*h and 32886.80±4018.04?g/L*h,respectively.These results suggested dose-independent pharmacokinetic characteristics.The T_max of the yeast-induced group and the normal group was similar after administration of R,S-goitrin,while C_max and AUC values were significantly different between the two groups.C_max of the yeast-induced group was 6174.50±395.11?g/L,and AUC_0-t was70354.29±6312.00?g/L*h,which was significantly higher than that of the normal group,indicating that R,S-goitrin entered the body exposure could increase under disease conditions.The half-life of the yeast-induced group was delayed 1 h comparision with the normal group,and the MRT was 7.80±0.51 h and CLz/F was0.33±0.04 L/h/kg.Conclusion:The result of metabolic pathways indicated that the ring structure of R,S-goitrin is not easily hydrolyzed in rats.C_max and AUC values of R,S-goitrin after oral administration in vivo were dose-dependent,while C_max and AUC values of the yeast-induced group were significantly higher than that of the normal group.Furthermore the half-life of R,S-goitrin in the yeast-induced group was delayed,and the plasma clearance rate was slowed down.And the average residence time was increased.The above results are suggested that the pathological state of fever will affect the pharmacokinetic behavior of R,S-goitrin.In this study,combined with the techniques of traditional Chinese medicine pharmacokinetics,chemistry of Chinese materia medica,analytical chemistry and pharmacology of Chinese materia medica,the metabolic and pharmacokinetic characteristics of R,S-goitrin were investigated to analysis the physiological disposition and major metabolites,to obtain its pharmacokinetics parameters,and to elucidate the plasma concentration-time change process,which can lay the foundation for further study of the mechanism of Radix Isatidis.