The stem bark of Glycosmis mauritiana contained the acridone alkaloids noracronycine and des-N-methylacronycine, and two new carbazole alkaloids, 3,3,10-trimethyl-3,7-dihydropyrano[2,3clcarbazole (glycomaurin) and 6-methyl-4-(31-methyIbut-21-enyl)carbazol-3-ol (glycomaurrol), whose structures were confirmed by synthesis and by cyclization to dihydroglycomaurin respectively. Glycomaurin has a ring system which has not been previously found in nature.Glycosmis mauritiana (Lam.) Tanaka (Rutaceae) is a small tree growing in the dry zone of Sri Lanka.l Previous work on G. mauritiana includes the isolation of 4,8-dimethoxy-l-methyl-3-(31-methylbut-21-enyl)quinolin-2(lH)one, skimmianine, dictamnine, arborinine, the acridone alkaloid l-hydroxy-3-methoxy-lO-methyl-2-(31-methylbut-21-enyl)acridin-9(lOH)-one, the carbazole alkaloids glycozolidine and glycozoline from its root,2 and the pigment 8-C-P-glucopyranosylapigenin (vitexin) from its leaves and stem.3
Results and DiscussionThe dichloromethane extract of the dried, ground stem bark of Glycosmis mauritiana, collected in Giritale in north central Sri Lanka, contained two new carbazole alkaloids and two, more polar, acridone alkaloids noracronycine and des-N-methylacronycine, in addition to the acridone alkaloid isolated earlier.2 The physical and spectroscopic data of the acridone alkaloids were identical with those reported for noracronycine and des-N-methylacronycine previously isolated from G. p e n t a p h y l l~.~The least polar alkaloid (I), C1gH17N0, gave a violet colour with concentrated sulfuric acid; the colour turned green on dilution, indicating that a carbazole skeleton was present. Its U.V. spectrum, with A, , , at 215, 231, 262, 312, l Stone, B. C., in 'A Revised Handbook to the Flora of Ceylon' (Eds M. D. Dassanayake and F.
