[Erythrina alkaloids from stems of Erythrina corallodendron]

This study aims to investigate Erythrina alkaloids from the stems of Erythrina corallodendron. Eighteen Erythrina alkaloids were isolated from the 95% ethanol extract of the stems of E. corallodendron by silica gel,octadecyl silica( ODS),Sephadex LH-20 column chromatography and preparative HPLC. With nuclear magnetic resonance( NMR) spectroscopy and mass spectrometry( MS),their structures were identified as crstanine A( 1),erytharbine( 2),cristamine C( 3),( +)-erystramindine( 4),10,11-dioxoerythraline( 5),8-oxoerythraline( 6),8-oxo-11β-methoxyerythradine( 7),11-methoxyerythradine( 8),( ±)-11-epi-methoxyerythraline( 9),( +)-erythraline( 10),crystamidine( 11),8-oxoerythrinine( 12),( +)-11α-hydroxyerysotrine( 13),erythrinine( 14),erysodine( 15),erysotrine-N-oxide( 16),( +)-erythratidine( 17),erythratine( 18). Compounds 1-4,7,9,11,13,16 and 17 were isolated from E. corallodendron for the first time. Furthermore,the cytotoxic activities of these Erythrina alkaloids were screened by MTT assay. The results showed that all compounds had no obvious cytotoxic activity. The analgesic activities of compounds1,6 and 8 were evaluated using an acetic acid-induced writhing test in mice. The writhing inhibition rates of compounds 1,6 and 8 at20 mg·kg~(-1)( ip) were 69%,70% and 62%,respectively( P<0. 01),indicating they have significant analgesic activity.