Induction of Mitochondrial-Mediated Apoptosis by Solvent Fractions of Methanol Extract of Heliotropium indicum in Rat Liver Cells | Chapter 10 | Recent Advances in Biological Research Vol. 4
Introduction:
The biochemical process of apoptosis may occur by a number of mechanism
including; extrinsic or death-receptor pathway, intrinsic or
mitochondrial-mediated pathway which involves the opening of Mitochondrial
Membrane Permeability Transition (MMPT) pore in situations of intracellular
calcium overload or oxidative stress or cellular insult and by the
perforin/granzyme pathway. There is considerable evidence that bioactive agents
in some plants (sulforaphane in cruciferous vegetables, genistein in soybeans and
epigallocatechin gallate in green tea etc.) were able to induce MMPT pore
opening. Quite a number of these agents have been identified and they currently
under preclinical and clinical trials.
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.
Author(s) Details
Adeola O. Olowofolahan
Laboratories for Biomembrane
Research and Biotechnology, Department of Biochemistry, College of Medicine,
University of Ibadan, Nigeria.
Yemisi D. Adeoye
Laboratories for Biomembrane
Research and Biotechnology, Department of Biochemistry, College of Medicine,
University of Ibadan, Nigeria.
Olufunso O. Olorunsogo
Laboratories for Biomembrane
Research and Biotechnology, Department of Biochemistry, College of Medicine,
University of Ibadan, Nigeria.
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