12,34-Oxamanzamines, novel biocatalytic and natural products from manzamine producing Indo-Pacific sponges

ent-12,34-Oxamanzamines E (1) and F (2), as well as 12,34-oxamanzamine A (4) were isolated from three Indo-Pacific sponges and their structures were assigned on the basis of spectroscopic data. The biocatalytic transformation of ent-8-hydroxymanzamine A (3) to 2, using Nocardia sp. ATCC 21145 and Fusarium oxysporium ATCC 7601, has also been achieved. These compounds possess a novel ring system generated through a new ether bridge formed between carbons 12 and 34 of the typical manzamine structure. Ten heterotrophic bacterial isolates, including actinomycetes and alpha-proteobacteria, were isolated from one of these sponges in a preliminary effort to identify a possible microbial origin for these compounds. The potent activity of the manzamines against malaria and the AIDS 01 pathogen, Mycobacterium tuberculosis, is also presented. (C) 2002 Elsevier Science Ltd. All rights reserved.