RESUMO
Objective To study the enzyme kinetics of brucine (BRU) and strychnine (STR), total alkaloids, and monomers active components of BRU and STR in extracts of Strychnos nux-vomica in rat liver microsomes, and investigate metabolic differences between BRU and STR monomer, total alkaloids, and BRU and STR in extracts in rat liver microsomes. Methods The contents of BRU and STR in the monomers, total alkaloids, and extracts in the metabolic system in vitro were measured by LC-MS/MS method, and the kinetic parameters of the enzyme were calculated. Results Compared with monomer group, Km and Vmax value of BRU and STR in total alkaloids and extracts of S. nux-vomica were obviously decreased; Compared with total alkaloids, Km and Vmax value of BRU and STR monomers in S. nux-vomica were obviously increased. The CLint of BRU among total alkaloids and monomer extracts groups had no significantly difference; And the CLint of STR in three groups was successively decreased. Conclusion Total alkaloids, BRU and STR in S. nux-vomica extracts, and BRU and STR monomer can be metabolized by the liver microsomes, and the pharmacokinetical parameters of BRU and STR in all groups have significant differences in metabolism.