Macroalgas da Antártica: Propriedades Químicas e Avaliação Biológica

Abstract

The Antarctic continent reached its current position for 45 million years (Ma) and has been geographically isolated from other continents since the breakup of the Antarctic Peninsula from South America (30 Ma ago). Due to the high degree of endemism in Antarctica, resulting from such isolation, and extreme environmental conditions to which the species, particularly macroalgae, are exposed, they needed to develop evolutionary adaptation mechanisms and therefore are able to produce a variety of secondary metabolites. The search for biologically active substances with potential pharmacological application has attracted the interest to the marine environment, particularly in the treatment of cancer, as a disease that presents many challenges to healing, besides affecting large portion of the world population. Regarding the Antarctic Peninsula, particularly given the limited study of local diversity, we seek to characterize biological materials from the region. In this perspective, the objective of this study was to characterize chemically five endemic seaweeds of the Antarctic continent and the subantarctic islands and assess their potential antitumor activities. Extract with different degrees of polarity (hexane, chloroform and ethanol) were prepared in order to extract different classes of molecules algae and tested on tumor cell lines of rat glioma (C6), human glioblastoma multiforme (U87) and adenocarcinoma lung (A549). In order to evaluate the cytotoxicity of the extracts were evaluated the effects of the extracts on non-tumor cell lines of mouse astrocytes and human lung fibroblasts. Macroalgae, except Palmaria decipiens showed considerable antitumor activity, and the most promising extracts were nonpolar, demonstrating selective effect. Among the best results in the treatment of A549, the chloroform extracts of algae Pyropia endiviifolia, Desmarestia anceps and Iridaea cordata showed concentrations that inhibit 50% of cells (IC50) 45.66 μg.mL-1 ; 61.16 μg.mL-1 and 67.54 μg.mL-1 , respectively; while the IC50 of hexane extract of chlorophyte Prasiola crispa was 93.02 μg.mL-1 . In relation to treatment with gliomas, which are more aggressive and malignant cells, the brown alga D. anceps showed inhibition of growth in all extracts analyzed, whereas effects were enhanced after 48 hours of exposure reaching 50% inhibition in 250μg.mL-1 (hexane), 45% (chloroform) and 50% of inhibition in 500μg.mL-1 at ethanolic extract. The crude chloroform extract of the red alga I. cordata inhibit 40% of growth in glioma 250μg.mL-1 , while and the hexane extract of the Pyropia endiviifolia inhibited in 10μg.mL-1 . Thus, the isolation of biologically active nonpolar molecules present in these extracts with potential antineoplastic effect becomes a next target for study of our research group.