Antiprotozoan activity of Brazilian marine cnidarian extracts and of a modified steroid from the octocoral Carijoa riisei

In the present investigation, we have evaluated the antileishmanial and antitrypanosomal activity of methanolic crude extracts obtained from eight species of cnidarians and of a modified steroid isolated from the octocoral Carijoa riisei. The antileishmanial activity of cnidarians crude extracts showed 50% inhibitory concentration ( IC50) values in the concentration range between 2.8 and 93.3 mu g/mL. Trypomastigotes of Trypanosoma cruzi were less susceptible to the crude extracts, with IC50 values in the concentration range between 40.9 and 117.9 mu g/mL. The steroid (18-acetoxipregna-1,4,20-trien-3-one) displayed a strong antileishmanial activity, with an IC50 value of 5.5 mu g/mL against promastigotes and 16.88 mu g/mL against intracellular amastigotes. The steroid also displayed mammalian cytotoxicity (IC50 of 10.6 mu g/mL), but no hemolytic activity was observed at the highest concentration of 12.5 mu g/mL. The antileishmanial effect of the steroid in macrophages suggested other mechanism than macrophage activation, as no upregulation of nitric oxide was observed. The antitrypanosomal activity of the steroid resulted in an IC50 value of 50.5 mu g/mL. These results indicate the potential of cnidarian natural compounds as antileishmanial drug candidates.

Chemical variability within the marine sponge Aplysina fulva

Dibromotyrosine-derived metabolites are of common occurrence within marine sponges belonging to the order Verongida. However, previous chemical analysis of crude extracts obtained from samples of the verongid sponge Aplysina fulva collected in Brazil did not provide any dibromotyrosine-derived compounds. In this investigation, five samples of A. fulva from five different locations along the Brazilian coastline and one sample from a temperate reef in the South Atlantic Bight (SAB) (Georgia, USA) were investigated for the presence of bromotyrosine-derived compounds. All six samples collected yielded dibromotyrosine-derived compounds, including a new derivative, named aplysinafulvin, which has been identified by. analysis of spectroscopic data. These results confirm previous assumptions that dibromotyrosine-derived metabolites can be considered as chemotaxonomic markers of verongid sponges. The isolation of aplysinafulvin provides additional support for a biogenetic pathway involving an arene oxide intermediate in the biosynthesis of Verongida metabolites. It cannot yet be established if the chemical variability observed among the six samples of A.fulva collected in Brazil and the SAB is the result of different environmental factors, distinct chemical extraction and isolation protocols, or a consequence of hidden genetic diversity within the postulated morphological plasticity of this species. (C) 2007 Elsevier Ltd. All rights reserved.

Antiparasitic, antineuroinflammatory, and cytotoxic polyketides from the marine sponge Plakortis angulospiculatus collected in Brazil

Investigation of the bioactive crude extract from the sponge Plakortis angulospiculatus from Brazil led to the isolation of plakortenone (1) as a new polyketide, along with five known polyketides (2-6) previously isolated from other Plakortis sponges. The known polyketides were tested in antileishmanial, antitrypanosomal, antineuroinflammatory, and cytotoxicity assays. The results show that plakortide P (3) is a potent antiparasitic compound, against both Leishmania chagasi and Trypanosona cruzi, and exhibited antineuroinflammatory activity. The known polyketides 2-6 were tested for cytotoxicity against four human cancer cell lines, but displayed only moderate cytotoxic activity.

Biotransformation of alpha-Bromoacetophenones by the Marine Fungus Aspergillus sydowii

The biotransformation reactions of alpha-bromoacetophenone (1), p-bromo-alpha-bromoacetophenone (2), and p-nitro-alpha-bromoacetophenone (3) by whole cells of the marine fungus Aspergillus sydowii Ce19 have been investigated. Fungal cells that had been grown in artificial sea water medium containing a high concentration of chloride ions (1.20 M) catalysed the biotransformation of 1 to 2-bromo-1-phenylethanol 4 (56%), together with the alpha-chlorohydrin 7 (9%), 1-phenylethan-1,2-diol 9 (26%), acetophenone 10 (4%) and phenylethanol 11 (5%) identified by GC-MS analysis. In addition, it was observed that the enzymatic reaction was accompanied by the spontaneous debromination of 1 to yield alpha-chloroacetophenone 5 (9%) and alpha-hydroxyacetophenone 6 (18%) identified by GC-FID analysis. When 2 and 3 were employed as substrates, various biotransformation products were detected but the formation of halohydrins was not observed. It is concluded that marine fungus A. sydowii Ce19 presents potential for the biotransformations of bromoacetophenone derivatives.

Pyrodysinoic Acid Derivatives from the Marine Sponge Dysidea robusta

Three new nitrogen-containing terpenes related to pyrodysinoic acid (1) have been isolated from the sponge Dysidea robusta collected in Brazil. Isopyrodysinoic acid (2), 13-hydroxyisopyrodysinoic acid (3), and pyrodysinoic acid B (4) were obtained from the crude extract of D. robusta and identified by analysis of spectroscopic data. Pyrodysinoic acid B (4) is the first furodysin or furodysinin sesquiterpene derivative with a trans junction between the two six-membered rings of the 1,2,3,4,4a,7,8,8a-octahydro-1,1,6-trimethylnaphthalene moiety.