GLABRACIN-A AND GLABRACIN-B, 2 NEW ACETOGENINS FROM ANNONA-GLABRA

Two new bioactive bis-THF Annonaceous acetogenins, glabracins A (1) an d B (2), and two previously known acetogenins, javoricin (3) and bulla tanocin (4), have been isolated from the leaves of Annona glabra by ac tivity-directed fractionation using the brine shrimp lethality test (B ST). The structures of 1 and 2 were elucidated based on spectroscopic and chemical methods, and the absolute stereochemistries were partiall y determined by the advanced Mosher ester method. 1 and 2 showed selec tive cytotoxicities to certain human tumor cell lines, and 1 was signi ficantly more potent although 1 and 2 differ only in the stereochemist ry of their vicinal diols at C-23/24. (C) 1998 Elsevier Science Ltd. A ll rights reserved.