New records of demosponges (Porifera) from the South Orkney Islands (Antarctica) with a checklist for the region.

The South Orkney Islands (SOI) is a poorly studied Antarctic archipelago located in the Scotia Arc. In this study, we added 25 Demospongiae species to the SOI known sponge richness, which was previously represented by only 16 species. Of these, 22 species represent new records for SOI region, although they were previously recorded from other Antarctic sectors.

Antifouling Diterpenoids from the Sponge Dendrilla antarctica.

Two nor-diterpenes, 9,11-dihydrogracilin A (1) and the previously unreported 9,11-dihydrogracillinone A (2), were isolated from the sponge Dendrilla antarctica. The sponge was collected by trawling at a depth of 49 m, from the research vessel Puerto Deseado, near the coast of Tierra del Fuego, farther north than the reported habitat for this species. Since these compounds were particularly abundant and the sponge was free from epibionts, both 1 and 2 were included in soluble-matrix paints and tested for antifouling activity in the ocean.

Isolation and Antifouling Activity of Azulene Derivatives from the Antarctic Gorgonian Acanthogorgia laxa.

Three azulenoid sesquiterpenes (1 - 3) were isolated from the Antarctic gorgonian Acanthogorgia laxa collected by bottom trawls at -343 m. Besides linderazulene (1), and the known ketolactone 2, a new brominated C linderazulene derivative (3) was also identified. This compound has an extra carbon atom at C(7) of the linderazulene framework.

Isolation of acetylated bile acids from the sponge Siphonochalina fortis and DNA damage evaluation by the comet assay.

From the organic extracts of the sponge Siphonochalina fortis, collected at Bahía Bustamante, Chubut, Argentina, three major compounds were isolated and identified as deoxycholic acid 3, 12-diacetate (1), cholic acid 3, 7, 12-triacetate (2) and cholic acid, 3, 7, 12-triacetate. (3). This is the first report of acetylated bile acids in sponges and the first isolation of compound 3 as a natural product.

Dolabellane Diterpenoids from the South Atlantic Gorgonian Convexella magelhaenica.

Two new dolabellane diterpenoids (1 and 2) were isolated from a small sample of the deep water gorgonian octocoral Convexella magelhaenica collected as a nontarget by-catch by dredging (-93 m) in commercial Patagonian scallop fishing grounds in the South Atlantic. The structures of the new compounds, which are major metabolites in the extract, were established by spectroscopic techniques and chemical transformations. Both compounds were cytotoxic against a human pancreatic adenocarcinoma cell line at micromolar concentrations.