Studies On Alkaloids From Two Erythrina Species

Plants of the genus Erythrina are commonly found in parks and streets.The wood of Erythrina can be used as utensils or raw materials for papermaking.Their roots and barks can be used as medicine.The main chemical constituents of Erythrina genus are alkaloids,which have the same muscle-paralyzing effects as curare,anti-anxiety,sleep-promoting,acetylcholinesterase inhibition,and insecticidal activities.In this paper,the alkaloids of E.subumbrans and E.senegalensis,two medicinal plants from Xishuangbanna,Yunnan,were studied.A total of 34 alkaloids were isolated and identified,including 2 new alkaloids.The branches and leaves of E.subumbrans were extracted with methanol,and the extract was treated by acid dissolved and then base precipitated,and the base solution was extracted with chloroform to obtaine the crude alkaloids which was isolated by various separation techniques（silica gel,MCI,and Sephadex LH-20）.The purified compounds were characterized by spectral techniques（IR,NMR and MS）.Finally a total of 20 alkaloids were isolated and identified from the chloroform extracts,and their structures were elucidated as 3-demthoxylerythratine（1）,3-demthoxyl-11β-hydroxylerythratine（2）,11β-hydroxyerythratine（3）,erythratinone（4）,11β-hydroxyerythratinone（5）,8-oxoerythrinine（6）,virosecurinine（7）,（R）-2-propylhexyl-2H-1,2,3-triazole-4-carboxylate（8）,cristanine A（9）,erythraline（10）,erythrinine（11）,（+）-10,11-dioxoerythratine（12）,erythratine（13）,11-methoxyerythratine（14）,10-oxo-erythraline-11-O-β-D-glucose（15）,2-hydroxymethyl N-methyltryptaminel（16）,cristanine D（17）,erythratine N-oxide（18）,erythraline N-oxide（19）and erythraline-11β-O-glucopyranoside（20）respectively.Among them,1 and 2 were new Erythrina alkaloids,8 and 16 were isolated from the genus Erythrina for the first time,and 3,5,7,9,11,13,15 and18～20 were obtaine from E.subumbrans originally.The branches and leaves of E.senegalensis were extracted and isolated with the same method as that with E.subumbrans.As a result,14 alkaloids were isolated and identified from the chloroform extract,and their structures were identified as erytharbine（1’）,（+）-erysotramidine（2’）,erysotrine（3’）,erysotrine-N-oxide（4’）,（+）-11α-hydroxyerysotrine（5’）,（+）-11α-hydroxyerysotramidine（6’）,orientaline（7’）,erythrartine-11-O-β-D-glucose（8’）,（+）-11α-hydroxyerysotrine N-oxide（9’）,laudanidine（10’）,erythratinone（11’）,reticuline（12’）,（+）-10,11-dioxoerysotrine（13’）and 11β-hydroxyerythratine（14’）respectively.All the alkaloids were isolated from E.senegalensis for the first time.The inhibitory activity of the compound 11β-hydroxyerythratine（3）rich in E.subumbrans was tested for its inhibitory activity on Phytophthora infestans 88069,but no activity was shown.The tumor cytotoxicity,osteoclast proliferation and differentiation activity tests of some compounds are still in progress.