Cytotoxicity of xyloglucan from Copaifera langsdorffii and its complex with oxovanadium (IV/V) on B16F10 cells

Abstract The aim of this study was to investigate the effects of xyloglucan extracted from Copaifera langsdorffii seeds (XGC) and its complex with oxovanadium (XGC:VO) in murine melanoma B16F10 cells. The formation of complexes was followed by potentiometric titration and further demonstrated by 51 V RMN. The viability and proliferation of B16F10 cells were reduced up 50% by the xyloglucan and its complex, both at 200 μg/mL, from 24 to 72 h. Cytotoxic effects of XGC and XGC:VO do not involve changes in cell cycle progression. Only XGC:VO (200 μg/mL) promoted the cell death evidenced by annexin V stain. XGC increased the respiration and lactate levels in melanoma cells, while XGC:VO reduced about 50% the respiration and levels of pyruvate, without alter the lactate levels, indicating that both xyloglucan preparations interfere with the metabolism of B16F10 cells. No change in activity of the enzyme hexokinase and expression of pyruvate kinase M2 was observed. XGC:VO (200 μg/mL) negatively modulated the expression of the β subunit of ATP synthase. The results demonstrate that the cytotoxicity of XGC and XGC:VO on murine melanoma B16F10 cells can be related to the impairment of the mitochondrial functions linked to energy provision.