Two masanane-type lactone alkaloids, named nobilisitine A and B, were isolated from Egyptian Clivia nobilis and characterized by spectroscopic and chemical methods. Both compounds showed contain the same [2]benzopyrano[3,4-g]indole ring system and therefore belong to the same subgroup of Amaryllidaceae alkaloids. In particular, nobilisitine A and B, reported as two new alkaloids, proved to be the 5 beta-hydroxy-3a,11c-epi-masan-7-one and the 3-hydroxybutanoyl ester of clivonine (5 alpha-hydroxy-5a-epi-masan-7-one), the alkaloid previously extracted from Clivia miniata and belonging to the same alkaloid subgroup. Nobilisitine B appears to be an epimer at the acyl side chain of clivatine. (C) 1999 Elsevier Science Ltd. All rights reserved.