Efeito citotóxico de extratos das macroalgas antárticas Monostroma hariotii e Iridaea cordata sobre a linhagem celular tumoral HCT - 116

Abstract

Colorectal cancer (CRC) is the third most prevalent malignant neoplasm in the world population. In the last decades, the marine environment has aroused the curiosity of researchers due to its immense biodiversity. This work aimed to chemically characterize extracts from two species of Antarctic seaweed and to evaluate the antioxidant and cytotoxic activity of these extracts against the HCT-116 cell line. It was also investigated mechanisms of programmed cell death in cells after exposure of extracts with macroalgae. The extracts were obtained by depletion, in which the samples remained in contact with the solvent for 24 hours and were identified by gas chromatography associated with mass spectrometry (GC-MS). The antioxidant action was determined by the DPPH radical inhibition method and cell viability was determined by the MTT assay. Cell morphology was determined by Giemsa stain and cell apoptosis was identified by staining with acridine orange / ethidium bromide (AO / EB) and flow cytometry. Eight extracts were obtained: MHE / MHM / MHH / MHC (M. hariotii - ethanol / methanol / hexane and chloroform), ICE / ICM / ICH / ICC (I. cordata - ethanol / methanol / hexane / chloroform). The MHM, MHH and MHC extracts were not able to inhibit cell proliferation in 24 hours of treatment, on the other hand, the MHE demonstrated to have activity against the cell line (IC50 577.44 ± 95.39 µg.mL-1). For I. cordata only the ICH and ICC extracts showed cytotoxicity, with ICC being the most sensitive (IC50 268.63 ± 11.11 µg.mL-1). Two main compounds were identified in the extracts of MHE and ICC: phytol and palmitic acid, characteristics of seaweed. The 24-hour treatment with extracts of MHE and ICC caused morphological changes in the cell line at the tested concentrations. Apoptosis and necrosis were identified after exposure of the cells to the extracts. The tests in fluorescence microscopy (AO / EB) and flow cytometry (annexin-V / PI) showed these effects after 24 hours exposure with the extracts of MHE and ICC. M. hariotii and I. cordata seaweeds extracts revealed to be promissing coumponds and should be explored in antitumor models against CRC. [resumo fornecido pelo autor]