The oceans cover about 2/3 of the surface of the planet and occupy most of the Earth's biosphere. Moreover, the oceans are also recognized as being a great source of organic compounds, which drove evolution of species and the development of life. These compounds began to be considered a useful source of bioactive compounds in the early 1960s and, since then, more than 10.000 marine metabolites have been isolated and characterized. Despite this, bioprospection of marine organisms is still incipient when compared to terrestrial sources - only 14% of known all natural products come from marine origins. In this context, the objective of the present study was to evaluate the anticancer potential of organic extracts obtained from the sponge Phorbas amaranthus collected in Fernando de Noronha Archipelago, Pernambuco – Brazil, further demonstrating the biotechnological value of the region, as well as the therapeutic value of the marine environment.
A sustainable prospecting protocol was applied to a small aliquot of the sponge Phorbas amaranthus, collected during and expedition carried out in 1998 to the Fernando de Noronha Archipelago. In the laboratory, the sponge was crushed, the material obtained was heated in a water bath at 55 °C and inoculated into Petri dishes containing 3 different culture media (one rich and two poor in nutrients). The methods and the different media employed favored the growth of actinomycetes, a group of gram positive bacteria known to be producers of pharmacologically useful molecules. Individualized colonies were recognized by phenotypic characteristics, reinoculated separately in a new Petri dish and encoded. Each new purified strain was grown in liquid medium, an aliquot of this culture was homogenized in glycerol for cryopreservation at -80 °C, and most of the samples were extracted in ethyl acetate. After the solvent removal, the extracts obtained were tested for cytotoxicity in HCT-116 (human colorectal carcinoma) tumor cells in culture and it was considered active those that reduced at least 70% of the growth of cells in the concentration of 50g/mL.
So far, 10 strains of actinomycetes have been isolated from the studied sponge, cryopreserved and their extracts tested for cytotoxicity. Of these, 1 extract was considered active, inhibiting over 80% of the cells proliferation or inducing cell death, followed by two other strains, which inhibited 70% of the cells proliferation. It was also observed that the relatively poor culture media were more advantageous than the rich one. The project also intends to continue isolating new strains and the next steps are the taxonomic identification of the active strains, as well as the main molecules present in these extracts. However, these results can already highlight the biotechnological value found in the region, as well as the pharmacological potential present in bacteria recovered from the sponge Phorbas amaranthus.