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The fatty acid composition of whole phospholipids from marine sponges collected from the Colombian Caribbean Sea was determined as part of our studies on the order Halichondrida: Halichondria magniconulosa , Halichondria lutea, Petromica ciocalyptoides, Axinyssa ambrosia, Didiscus oxeata and Dragmaxia undata . Structure elucidation was accomplished by means of gas chromatography retention parameters and GCMS. Eight new fatty acids were identified by their methyl esters and N-acylpyrrolidide derivatives (i.e. 5-methyl-6-octadecenoic, 16-methyl-11-heptadecenoic, 8-methyl-4-tetracosenoic, 8,17-dimethyl-5-octadecenoic, 23-methyl-8-tetracosenoic, 20-methyl-18-tetracosenoic, 4,17-tetracosadienoic and 22,27-dimethyl-5,9-octacosadienoic acids). These findings establish alternative fatty acid biosynthetic possibilities for these organisms.

The antifungal activity of the sesquiterpenoids (+)-curcuphenol and (+)-curcudiol isolated from the Caribbean sponge Didiscus oxeata was evaluated against several filamentous fungi.

8 pages, figures, and tables statistics., New semisynthetic sesquiterpene derivatives (3-7, 10), together with two known ones (8-9) were prepared from (S)-(+)- curcuphenol (1), isolated from the Caribbean sponge Didiscus oxeata. The natural sesquiterpenes 1 and (S)-(+)-curcudiol (2), as well as semisynthetic derivatives 3-10, were evaluated against the herbivorous insect species Spodoptera littoralis, Leptinotarsa decemlineata and Rhopalosiphum padi. All compounds had an antifeedant effect on L. decemlineata. With R. padi, a structure-dependent antifeedant response was observed, with 1 being the most active, followed by 4 and 5. Furthermore, compounds 1, 4, 5, 7, 8 and 10 reduced S. littoralis larval weight, with 10 also reducing ingestion by S. littoralis larvae. Of the derivatives studied here, none showed stronger effects (either antifeedant or postingestive) than the parent compound 1. It can, therefore, be concluded that the structure of the side chain and the presence of the phenol ring of curcuphenol are important structural requirements for its insect antifeedant and growth regulation effects.

Three bromopyrrole alkaloids (1–3) were isolated from the acetone extracts of Didiscus oxeata during chemical and biological investigation of Caribbean and Indo-Pacific marine sponges. The structures were established by spectroscopic methods. Mukanadin D (3) was obtained for the first time as a naturally-occurring C11 bromopyrrole alkaloid.

New semisynthetic sesquiterpene derivatives (3–7, 10), together with two known ones (8–9) were prepared from ( S)-(+)-curcuphenol (1), isolated from the Caribbean sponge Didiscus oxeata. The natural sesquiterpenes 1 and ( S)-(+)-curcudiol (2), as well as semisynthetic derivatives 3–10, were evaluated against the herbivorous insect species Spodoptera littoralis, Leptinotarsa decemlineata and Rhopalosiphum padi. All compounds had an antifeedant effect on L. decemlineata. With R. padi, a structure-dependent antifeedant response was observed, with 1 being the most active, followed by 4 and 5. Furthermore, compounds 1, 4, 5, 7, 8 and 10 reduced S. littoralis larval weight, with 10 also reducing ingestion by S. littoralis larvae. Of the derivatives studied here, none showed stronger effects (either antifeedant or postingestive) than the parent compound 1. It can, therefore, be concluded that the structure of the side chain and the presence of the phenol ring of curcuphenol are important structural requirements for its insect antifeedant and growth regulation effects.

The methanolic extract of several marine sponges (Topsentia Oenitrjx, Dysidea tupha, Acanthella acuta, Didiscus oxeata and two Agelas species) have been found to be ichthyotoxic. The metabolites responsible %or this toxicity have been isolated and their structuresdetermined on the basis of their chemical and spectral properties. The total synthesis of some of these metabolites is presented. Among marine invertebrates, sponges appear to be one of the richest phyla in toxicogenic species. In an increasing number of cases it has been demonstrated that this toxicity is associated with the presence of specific secondary metabolites which may act to minimize predation by mobile animals and (or) to serve as weapons in spatial competition (1tz). During the last few years our laboratory, in collaboration with spongologists, has been involved in a research program whose objective is to isolate and identify sponge toxic metabolites and to evaluate their role in the defense mechanism of these animals, as well as their use as chemotaxonomic markers. To this end about 100 different species of sponges have been collected in the Mediterranean sea and more recently in the Southern Caribbean. They have been extracted and their extracts evaluated for their ichthyo- and spongiotoxicities. Several species have been found to be toxic and we will present here some of the recent chemical results we have obtained.