Chloroform Fraction of Methanol Extract of Funtumia elastica (Preuss) Stem Bark Induces Mitochondrial-Mediated Cell Death Via Mitochondrial Permeability Transition Pore Opening

Abstract

Aims: Funtumia elastica is a tropical medicinal plant traditionally used in the treatment of tumor. However, its mechanism of action via Mitochondrial Permeability Transition (mPT) Pore  is yet to be unraveled.  The mPT pore has become a significant target for drug development because its opening triggers cytochrome c release, ultimately leading to mitochondrial-mediated cell death. This study therefore aimed to explore the effects of the chloroform fraction of the methanol extract of Funtumia elastica (CFFE) on mitochondrial-dependent cell death through mPT pore opening. Methodology: The crude methanol extract (CMFE) was partitioned successively to obtain n-hexane (HFFE), chloroform (CFFE), ethyl acetate (EAFE) and methanol (MFFE) fractions. Two sets of the animals separately and equally divided into four groups were treated as follows; First set: Group I received corn oil(10 ml/kg) while groups II, III and IV received 200 mg/kg of CMFE, CFFE and MFFE, respectively. Second set: Groups I, II, III and IV were treated with corn oil(10 ml/kg), CFFE(50 mg/kg), CFFE(100 mg/kg) and CFFE(200 mg/kg), respectively. Rat liver mitochondria were isolated by differential centrifugation. The effects of the extract and fractions were investigated on mPT pore, mitochondrial ATPase (mATPase)activity, mitochondrial membrane lipid peroxidation(mLPO), Caspases 9 and 3 activation, and, hepatic DNA fragmentation. Histological examination on the liver was assessed. Data were analyzed using ANOVA at α 0.05. Results: Oral administration of CMFE, CFFE, EAFE and MFFE at 200 mg/kg gave induction folds of 2.9, 12.3, 8.3 and 6.3, respectively, related to the control. The CFFE at 50, 100 and 200mg/kg induced pore opening by 3.7, 10.0 and 13.0 folds, respectively, related to the control. The CFFE caused significant enhancement of mATPase activity, caspases 9 and 3 activation, dose-dependent induction of hepatic DNA fragmentation, and decrease in malondialdehyde generation. Histological assessment at lower doses showed normal morphology while mild congestion was observed at the highest dose. Conclusion: These results suggest the presence of phytochemicals in CFFE that can induce mitochondrial-dependent cell death via mPT pore opening. Further work is therefore necessary to characterize and isolate the active principle in CFFE that is responsible for this property.