In vitro induction of rat liver mitochondrial membrane permeability transition pore opening by solvent extracts of Momordica charantia leaves

Abstract

Alteration of mitochondrial functions such as permeability transition (PT), a process associated with the uncoupling of oxidative phosphorylation, has been found to play a vital role in the apoptotic process induced by certain anti-cancer agents. When triggered, PT facilitates the release of mitochondrial apoptogenic proteins which in turn activate the caspase cascade of apoptosis. Thus, this study investigated the in vitro effects of varying concentrations (0.2, 0.4, 0.6, 0.8 and 1.0 mg/ml) of different leaf extracts [Crude Water-Soluble Extract (CWSE), Decoction (DE) and Methanol Extract (ME)] of Momordica charantia (M. charantia), a purported anti-cancer plant of the family Cucurbitaceae on normal rat liver mitochondria. Opening of mitochondrial membrane permeability transition pore (MMPTP) was spectrophotometrically assayed under succinate-energized condition. Results obtained showed concentration-dependent and significant (P<0.05) increases in the extents to which MMPTP opening was induced by the three extract types when compared with the control group. Inductions caused by CWSE and DE increased with increasing concentrations while those caused by ME decreased with increasing concentrations, giving the maximum induction at 1.0 mg/ml (8.1-fold increase) of CWSE and the least induction at 1.0 mg/ml (4.3-fold increase) of ME, respectively. Spermine, a reference inhibitor of MMPTP opening, reversed all observed openings. These results indicate that the tested leaf extracts of M. charantia are potent (CWSE being the most potent) MMPTP opening inducers and the pathway by which M. charantia causes apoptosis in cancer cells is probably mitochondrial-mediated (intrinsic).

Keywords: Mitochondrial membrane permeability transition pore (MMPTP), Momordica charantia, Apoptosis, Spermine.