Secondary metabolites from the cnidarian Cavernularia sp.: structures of the new briaranes cavernulin A and B1,2

Department of Chemistry, University College of Science, University of Calcutta, 92, Acharya Prafulla Chandra Road,

Kolkata-700 009, India

Drug Research & Development Centre, 1078, Jessore Road, Kolkata-700 028, India

General Non-Chordata Section, Zoological Survey of India, 27, J. L. Nehru Road, Kolkata-700 016, India

Manuscript received 30 March 2001

Novel cyclized cernbranoids (briantnes) cavernulin A and cavernulin B along with ubiquitous wax esters (derived from saturated fatty acids and some analogous unsaturated fatty acids), cholesterol, ceramides as well as 1-0-alkylglycerols have been isolated from the cnidarian Cavemularia sp., the extract of which shows some toxicity to guppy fingerlings and in brineshrimp assays. The structures of cavernulin A as (1S*,2S*,5Z,7S*,8R*,9S*,10S*,11R*,12R*,17R*)-2,9-diacetoxy-12- buta noyloxy-8-hyd roxybria ra-5, 13-dien-18-one and cavern ulin B as (1S* ,2S* ,5Z, 7S* ,8R * ,9S*, 10S* ,11R* ,12R* ,17R* )-2,9- diacetoxy-8,12-dihydroxybl"iara-5,13-dien-18-one are established f.-om one-dimensional [ ¹H and homodecoupling as well as ¹³C (NDC and DEPT-135)] and two-dimensional (COSY-90, X-H correlation optimized for ¹J_C-H and NOESY) NMR and other· (IR and Mass) spectral and some chemical studies. The lengths of the alkyl chains in wax esters, ceramidcs and 1-O- alkylglyccrols are established by appropriate gas chromatographic studies.