Prospection of pharmaceutical bioactive compounds in marine algae Rhodophyta and Heterokontophyta and cytotoxicity evaluation.

Several therapeutic drugs manufactured by the pharmaceutical industry are chemical structures isolated from organisms that are found in nature or molecules based on that. May be included at this group drugs isolated from marine organisms, like corals, sponges and seaweeds, known as great secondary metabolites producers. Based on this facts the objective of the present study is to perform a prospection study to achieve bioactive molecules with pharmaceutical purposes, on extracts made from red (Rhodophyta) and brown (Heterokontophyta) seaweed collected in the Brazilian shore. The prospection studies was performed by means of evaluation of the antioxidant, antibacterial, antifungal, anticancer and antiparasitic (against Leishmania and Schistosoma) potential. In the evaluation were tested the supercritical extracts of 5 different species, including 2 brown species: Dictyota dichotoma and D. menstrualis and 3 red species: Chondria littoralis, Spyridia hypnoides and Plocamium brasiliense. The extracts were evaluated by their potential bioactive compounds and the most promising results were selected for the following fractionation steps. Overall the extracts have shown good results and may be represent a potential source of bioactive molecules. The extracts of both D. dichotoma and D. menstrualis were submitted to a bioguided fractionation process by their antischistosomal activities. It was still included a third extract from D. mertensii to the studies and every step was monitored by LC-MS techniques. Comparing the detected mass for each active fraction, it was observed the presence of a substance with m/z 271,24 in all of the extracts, so the isolating procedures were directed to obtain that specific molecule, which was obtained in a biomass of 7 mg. Differently than expected the molecule when evaluated isolated do not show the antischistosomal activity, leading to the hypothesis that the activity was related to different molecules for each species or even the observed effect is resulted by an interaction mechanism with another substances by an additive or synergist mechanism. The overall evaluation of the whole work show some promising results and it represent a great support for future fractionation works. (AU)