Studies On Antitumor Bioactive Constituents Of Gelsemium Elegans Benth. And Metabolism Of Gelsemine In Vitro And In Vivo

Gelsemium elegans Benth.,as one specie of Gelsemium genus of Loganiaceae family,is widely distributed in Fujian,Yunnan,Guizhou,Guangdong,Guangxi provinces in South China and over southeast Asia.Gelsemium elegans,which has other names,such as Gou wen, Duan changcao,Zhu renshen,and so on,is known as a toxic plant in the world.The whole plant has severe toxicity,especially in young leaves.According to Traditional Chinese Medicine theory,this plant is bitter in taste,warm-natured,and has been used as a remedy for certain kinds of skin ulcers.Recently,some pharmacological effects of it,including analgesic, anti-tumor,anti-inflammatory effects,had been reported.By means of macroporous resin,silica gel,ODS,Sephadex LH-20,and preparative HPLC and so on,40 compounds were obtained from the water extract of Gelsemium elegans and the structures of 33 compounds were indentified by the physico-chemical characters and spectral data(UV,IR,1D-NMR,2D-NMR,et al).These compounds including 11 alkaloids were identified as:gelsenine(1),11-methoxyhumantenmine(2),14-hydroxy-19-oxogelsenicine(3), 19-hydroxy-dihydrogelsevirine(4),koumine(5),humantenmine(6),gelsemoxonine(7), humantenine(8),gelsevirine(9),gelsemine(10),akuammidine(11) respectively,and twenty-five were nonalkaloids,consisting of gelsemiunoside A(12),gelsemiunoside B(13), (7R,8S)-7,8-dihydro-7-(4-hydroxy-3-methoxyphenyl)-8-hydroxylmethyl-3'-methoxybenzo furan carboxylic acid(14),gelsemoside A(15),3β-hydroxy-27-p-(E)-coumaroyloxy -ursan-12-en-28-oic acid(16),3β-hydroxy-27-p-(Z)-coumaroyloxy -ursan-12-en-28-oic acid (17),uncarinic acid E(18),gelsemoside B(19),4-O-caffeoylquininic acid(20),1-O-caffeoyl-quininic acid methyl ester(21),1-O-caffeoylquininic acid(22),vanillic acid(23), 3,4-dihydroxylphenyl aldehyde(24),ferulic acid(25),caffeic acid(26),3,4-dihydroxyl benzonic acid(27),syringic acid(28),p-hydroxylbenzonic acid(29), 6-methoxyl-7-hydroxylcoumarin(30),6,7-dimethoxyl-8-hydroxylcoumarin(31),scoparon (32),β-sitosterol(33).Among these compounds,compound 1,2,12,13,15,19 were new compounds,while compound 14,16-18,20,21,24,26,29,30,31,32 were isolated from the Gelsemium genus for the first time.By MTT methods,the anti-inhibitory on cell growth activity of some compounds from Gelsemium elegans were investigated in vitro with A375-S2 cell line.The result indicated that alkaloids from G.elegans showed little cytotoxic bioactivities,and compared with that of them,the nonalkaloids compounds 16,17,18 showed the significant activities,contrarily.According to the references,more than forty indole alkaloid derivatives from G.elegans had been reported,but the metabolism in vivo or in vitro of these alkaloids have not been found.For the purpose of finding the difference,the metabolism of compound 10(gelsemine), the main compound in this plant,in vitro by liver microsome was studied.After metabolism in liver microsome in vitro,5 metabolites were obtained.By means of physico-chemical characters and spectral data,the structures of two metabolites were identified as 4-N-demethoxygelsemine(Ml) and 21-oxogelsemine(M2),Furthermore,the cell growth inhibitory bioactivities of the parent compound and its corresponding metabolites were compared in both HepG₂ and HeLa cells.The result showed that two metabolites exhibited much more activity than that of the parent.