The Metabolism And Distribution Of Three Kinds Of Gelsemium Alkaloids In Vivo And Vitro

Gelsemium(Gelsemium elegans Benth)is a highly toxic plant,which is mainly distributed in the southeast coastal areas of China.The toxicity of Gelsemium varies among different species.It is recorded in compendium of Materia Medica that "people who eat its leaves by mistake all die,while goat eat its seedlings will fat".The chemical composition of Gelsemium is complex,among which the main active component is indole alkaloids.In this paper,three main alkaloids in Gelsemium,namely koumine,gelsemine and gelsenicine,were studied to systematically elucidate the plasma protein binding,tissue distribution and in vitro and in vivo metabolism of them.This study provides a scientific basis for further exploring the mechanism of Gelsemium toxicity and the difference of Gelsemium toxicity basis.(1)The results of ultrafiltration showed that the binding rates of koumine(2 μg/m L)with human,pig,goat and rat plasma protein were 90.33±0.50%、86.71±0.90%、85.67±0.59%、87.10±1.23%,respectively;the binding rates of gelsemine(2 μg/m L)with human,pig,goat and rat plasma protein were 66.98±2.18%、46.86±2.93%、40.62±1.17%、69.91±0.39%,respectively;the binding rates of gelsenicine(2 μg/m L)with human,pig,goat and rat plasma protein were 92.76±0.23%、96.70±0.29%、86.48±2.07%、92.76±0.23%,respectively,which indicated that the plasma protein binding rates of koumine and gelsenicine were higher,but the plasma protein binding rates of gelsemine were lower,and there was significant difference among species.(2)The results of in vitro metabolism showed that the metabolic pathway of gelsenicine in different species was mainly demethylation and oxidation,but the elimination rate of gelsenicine in pig and goat liver microsomes was higher than that in human and rat liver microsomes.Therefore,the difference of toxicity of gelsenicine may be related to the degree of elimination.After metabolism,the elimination rate of gelsenicine in human and goat liver microsomes was much higher than that in pig and rat liver microsomes.The elimination rate of gelsenicine was the highest in human liver microsomes,and the lowest in rat liver microsomes.(3)By inhibiting and inducing the activity of CYP3A4/5,the metabolism in mice was studied.It was found that the three Gelsemium alkaloids could be detected in various tissues of mice after 5 min of administration,and the highest concentration was found in spleen and pancreas,indicating that the monomer of Gelsemium alkaloids was absorbed rapidly,widely distributed and can pass through the blood brain barrier.In the normal group,the concentrations of koumine,gelsemine and gelsenicine(0.24 mg/kg)in the brain were 794.3±171.7 ng/g,34.1±5.9 ng/g and 74.59±8.25 ng/g,respectively.After inducing the metabolism of gelsenicine,the content of gelsenicine in the brain of mice decreased to below the limit of quantitation,indicating that inhibiting or inducing CYP3A4/5 has an effect on the metabolism of Gelsemium alkaloids,and promoting the metabolism of gelsenicine can reduce death in mice.In this paper,the plasma protein binding rate,metabolism,and tissue distribution of three main alkaloid in Gelsemium were studied systematically.It was found that the plasma protein binding rate of Gelsemium alkaloid was high,and they were absorbed rapidly,distributed widely,and metabolized rapidly in vivo.Gelsenicine and other Gelsedine-type alkaloids were the main toxic components in Gelsemium,and these compounds may also be the main toxic components in Gelsemium which is one of the reasons for the difference in toxicity of Gelsemium.This study laid a foundation for further development and elucidation of its toxic mechanism and provided a scientific basis.