Modulation of mitochondrial permeability transition pore opening by Myricetin and prediction of its-drug-like potential using in silico approach

Myricetin has been demonstrated to have multiple biological functions with promising research and development prospects. This study investigated the effect of myricetin on liver mitochondrial membrane permeability transition pores and its inhibitory potential on proteins that are important in the apoptotic process in silico. Mitochondrial swelling was assessed as changes in absorbance under succinate-energized conditions. Cytochrome c release, mitochondrial-lipid peroxidation, caspase 3 and 9 expressions, as well as calcium ATPase, were assessed. Pharmacokinetic properties of myricetin were predicted through the SwissADME server while the binding affinity of myricetin toward the proteins was computed using the AutodockVina Screening tool. The conformational stability of protein-ligand interactions was evaluated using molecular dynamics simulations analysis through the iMODS server. Myricetin inhibited the opening of the mitochondrial permeability transition pore and also reversed the increase in mitochondrial lipid peroxidation caused by calcium and other toxicants. Myricetin also caused a reduction in the expression of caspase 3 and 9 as well as calcium ATPase activity. The molecular docking results revealed that myricetin had a considerable binding affinity to the pocket site of caspase 3 and 9 as well as calcium ATPase. Myricetin showed a good drug-likeness based on the predicted pharmacokinetic properties as revealed by low CYP 450 inhibitory promiscuity and relatively low toxicity. It could therefore be suggested that myricetin could be useful in the management of diseases where too many apoptosis occur characterized by excessive tissue wastage such as neurodegenerative conditions and could as well play a role in protecting the physicochemical properties of membrane bilayers from free radical-induced severe cellular damage.

Modulatory potential of Citrus sinensis and Moringa oleifera extracts and epiphytes on rat liver mitochondrial permeability transition pore

BACKGROUND

Bioactive agents from medicinal and dietary plants have been reported to modulate the mitochondrial membrane permeability transition pores.

OBJECTIVE

This study investigated the in vitro effects of C. sinensis (CSE) and M. oleifera (MOE) methanol leaf extracts and their epiphytes (CEP and MEP) on mitochondria permeability transition pores.

METHODS

In vitro antioxidant activities of the extracts were determined using standard procedures and quantification of polyphenolic compounds in the extracts was done using HPLC-DAD. Opening of the mitochondrial permeability transition pores was assessed as mitochondrial swelling and observed spectrophotometrically as changes in absorbance under succinate-energized conditions. Cytochrome c release was also assessed spectrophotometrically.

RESULTS

From the results, CSE, MOE, CEP, and MEP inhibited lipid peroxidation and scavenged nitric oxide and DPPH radicals in a concentration-dependent manner. All extracts exhibited greater ferric reducing antioxidant potential. More so, the results showed that CSE, MOE, CEP, and MEP possess the substantive amount of total flavonoids and total phenolics. CSE and MOE had higher total flavonoids and total phenolic content when compared with the epiphytes. HPLC-DAD results revealed Tangeretin as the most abundant in CSE; Eriocitrin in citrus epiphytes; Moringine in MOE and Flavones in moringa epiphytes. All extracts inhibited calcium-induced opening of the pores in a concentration-dependent manner with C. sinensis leaf extract (CSE) and moringa epiphyte (MEP) being the most potent in this regard with no significant release of cytochrome c at all concentrations.

CONCLUSION

The results suggest that CSE and MEP have bioactive agents which could be useful in the management of diseases where too much apoptosis occurs characterized by excessive tissue wastage such as neurodegenerative conditions.

Anti-Acetylcholinesterase Compounds Isolated from the Leaves of Kigelia africana (LAM) Benth (Bignoniaceae)

Acetylcholinesterase (AChE) is an enzyme that is involved in the breakdown of some neurotransmitters. Its inhibition is one of the treatment strategies employed in the management Alzheimer diseases. Flavonoids isolated from the leaves of Kigelia africana were investigated for their comparative AChE inhibition. The extract of the leaves was subjected to vacuum liquid chromatography (VLC) to obtain four fractions using n-hexane (n-hex, 100%), n-hexane/dichloromethane (hex/DCM, 1:1), dichloromethane/ethyl acetate (DCM/EtOAc, 1:1) and ethyl acetate/methanol (EtOAc/MeOH, 1:1). The four fractions were subjected to AChE inhibitory study with DCM/EtOAc (1:1) fraction showing the highest inhibitory activity. Three flavonoids were isolated from this fraction and their structures were elucidated and characterised using 1D- and 2D-nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS) techniques. Their spectroscopic data compared well with literature. The compounds demonstrated considerable inhibition of AChE activity with luteolin (1), rutin (2) and quercetin (3) that showed IC50 of 945.0, 282.1, 254.8 μg/ml respectively as against the IC50 of 38.93 μg/ml for rivastigmine, a well-known cholinesterase agent. Compound 3 showed 17.89 ± 0.57 and 7.70 ± 0.64 μ/l/mg protein at 200 and 400 μg/ml respectively, for AChE activity as against 10.37 ± 0.99 and 6.24 ± 1.24 μ/l/mg protein showed by rivastigmine at 200 and 400 μg/ml respectively. This study showed that the phytochemical responsible for the AChE inhibition in the crude extract as reported by Falode et al., 2017 resided in the DCM/EtOAc (1:1) fraction. The structural-activity relationship of the flavonoids revolves around substitution in position 3 of the compounds.