Efeito do extrato hidroalcoólico de Orbygnia martiana (Babaçu) sob os mecanismos de estresse oxidativo e indução de morte celular em células de câncer de mama (MCF-7)

Abstract

Oxidative stress mechanisms are closely linked to the death and survival of normal and tumor cells. Due to this important role, many treatments used in cancer aim to alter the balance between pro and antioxidant substances in order to induce cell death of tumor cells and prevent their escape mechanisms. Previous studies have demonstrated the ability of Orbygnia martiana to alter the rates of apoptosis and necrosis in tumor cells, another feature of this extract found in the literature is the modulation in the release of superoxide anion in mononuclear phagocytes incubated with bacteria. Thus this work aims to evaluate the influence of Orbygnia martiana under the mechanisms of oxidative stress in cocultures between human peripheral blood mononuclear cells and breast tumor cells and also its association with the mechanisms of cell death. The extract was obtained by the Orbygnia martiana leaves at a concentration of 0.2g/mL and, after previous concentration-response tests, it was diluted to the concentration of 100pg/mL. Incubations were made for 18 hours between human peripheral blood mononuclear cells from healthy patients and culture of mammary tumor cells of the MCF-7 strain with and without the stimulus of the extract, and subsequently were evaluated the release of superoxide anion by the cytochrome C method and the activity of superoxide dismutase (SOD) by the inhibition of NBT reduction method. The rates of apoptosis, necrosis and Fas expression were also evaluated by flow cytometry and the cell viability of the extract under normal human peripheral blood cells by fluorescence microscopy. It was observed that the extract did not alter the viability of normal cells, increased the rate of apoptosis and reduced necrosis of tumor cells, increased superoxide anion release in coculture and reduced superoxide dismutase activity in the spontaneous control group carrying only tumor cells . Therefore, the hydroalcoholic extract of Orbygnia martiana appears as a possible treatment of breast cancer by inducing death of mammary tumor cells and the possible mechanism linked to this effect is the imbalance of the oxidative balance.