[Purine and carboline alkaloids from ascidian Symplegma oceania].

Five purine and carboline alkaloids were isolated from the methanol extract of the ascidian Symplegma oceania. Classic chromatographies including preparative HPLC were used for isolation and purification of the compounds. The structures were established as 6-methoxy-7-methyl-8-oxoguanine (1), 2-methylimino-3-methyl-6-methylamino- 9H-purine (2), 1,2,3,4-tetrahydro-betacarboline (3), 1,2,3,4-tetrahydro-1-methyl-beta-carboline (4) and 1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (5) by comparison the spectroscopic data (MS, 1H, 13C-NMR) with those reported in the literatures. Compounds 2-5 were reported from the the genus Symplegma for the first time. The purine and carboline were the major alkaloid types of S. oceania.