Induction of Mitochondrial-Mediated Apoptosis by Solvent Fractions of Methanol Extract of Heliotropium indicum in Rat Liver Cells

Aim: Mitochondrial Membrane Permeability Transition (MMPT) pore has emerged as a promising target for drug development because the release of cytochrome c upon the opening of the pore is a point of no return for mitochondrial-mediated apoptosis to occur. Heliotropium indicum (HI) is as an anti-tumor and wound healing agent in traditional medicine. It is not known whether its mode of action involves the induction of apoptosis via the opening of the MMPT pore.

Methodology: Mitochondria, isolated from male albino rat liver (about 100 g), were exposed to varying concentrations (10, 30, 50, 70, and 90 µg/ml) of solvent fractions of methanol extract of HI i.e Chloroform (CFHI), Ethylacetate (EFHI), Methanol (MFHI) and crude Methanol Extract (MEHI) of HI. Opening of the pore, cytochrome c release, mitochondrial ATPase activity and extent of mitochondrial lipid peroxidation were assessed spectrophotometrically in vitro. Activation of caspases 9 and 3 were also assessed using ELISA kits.

Results: In the absence of Ca2+, CFHI, EFHI, MFHI and MEHI induced the opening of the pore in a concentration-dependent manner with CFHI having the highest induction fold of 26 and MFHI as the lowest having 6.6. All the fractions inhibited lipid peroxidation in a concentration-dependent manner. Also, these fractions induced the release of cytochrome c with CFHI having the highest effect and the least by MFHI. Mitochondrial ATPase activity was enhanced by all the fractions with CFHI having the highest stimulatory effect. Interestingly, intra-peritoneal administration of CFHI and MEHI at 2, 5, 10 and 20 mg/kg body weight for 21 days resulted in significant opening of the pore, the release of cytochrome c and activation of caspases 9 and 3. All these effects were highest with 20 mg/kg body weight.

Conclusion: These findings therefore suggest that Chloroform Fraction of Heliotropium indicum is the most potent of all these fractions and therefore contains the bioactive agent that induces mitochondrial-mediated apoptosis in normal liver cells. The fraction will therefore be useful for further studies for drug development in diseases requesting up-regulation of apoptosis.