Efeito antitumoral de extratos das macroalgas antárticas Cystosphaera jacquinotti, Desmaretia anceps e Iridaea cordata sobre a linhagem celular tumoral

Abstract

Colorectal cancer is one of the most prevalent in the world, with high mortality rates. Despite advances in the diagnostic area in recent decades, mortality rates remain high due to tumor cell resistance to conventional drugs. Therefore, the search for new compounds with antitumor activity is extremely important. Antarctic macroalgae are adapted to a hostile environment and are considered promising sources of compounds with anticancer activity. In this work, the tumor cell line HCT 116 was exposed to increasing concentrations of extracts obtained from the antarctic seaweeds Iridaea cordata, Cystosphaera jacquinotii and Desmarestia anceps by ultrasound technique. For the macroalgae D. anceps, extraction was also carried out by the maceration technique, using the chloroform extract. This extract was fractionated and the cytotoxicity of the extract and fractions against the HCT 116 cell line was evaluated. The extracts and fractions were also characterized chemically. The death induction pathway and the effect on the cell cycle of the HCT 116 cell line were analyzed after exposure to the DACM extract at IC50 and double concentration rate. The hexanic and chloroform extracts of the I. cordata seaweed and the hexane, chloroform and methanolic extracts of D. anceps obtained by the ultrasound technique inhibited the growth of the tumor cell line HCT 116 in a dose-dependent manner. The chloroform extract of D. anceps obtained by the maceration technique (DACM) showed cytotoxicity against the HCT 116 cell line in a dose-dependent manner. Fractions were analyzed by thin layer chromatography (TLC) and nuclear magnetic resonance (1H NMR). With the exception of fraction 1, all fractions revealed cytotoxic effects against HCT 116 cell line. The DACM extract was also caused a reduction in the number of XVI cells in the G1 phase of the cell cycle and the increase population of multinucleated cells. The mechanism of induced cell death after exposure of the HCT 116 tumor cells to the DACM extract for 24 hours was related to the apoptotic process. These data suggest that the hexanic and chloroform extracts of I. cordata and the hexane, chloroform and methanolic extracts of D. anceps obtained by the ultrasound and the chloroform extract of D. anceps obtained by maceration are candidates for further studies for the identification of compounds with antitumor activity. This was the first study to report the anticancer activity of extracts and fractions of D. anceps brown seaweed, as well as the mechanism of death and effect caused in the cell cycle of the HCT 116 strain after exposure to the extract, suggesting that this alga is a promising candidate to future studies for the identification and isolation of molecules with antitumor activity.