Neuroprotective potential of phenolic extracts of <i>Capsicum frutescens</i> as an inhibitor of monoamine oxidase and cholinesterase activities

Abstract

In this study, we investigated the in vitro antioxidant activity of the extracts from ripe and unripe fruits of Capsicum frutescens. The effects of the extracts on three enzymes which are associated with Parkinson's disease (PD) were also investigated together with quantitation of total phenol, flavonoid and non-flavonoid contents of the extracts. Activities of mitochondrial monoamine oxidase (MAO), acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) from rat brain were determined in the presence of the extracts. 1, 1-diphenyl-2- picrylhydrazyl (DPPH) and OH radicals scavenging abilities, as well as membrane stabilizing effect of the extract via inhibition of Fe²⁺ -induced lipid peroxidation in rat brain tissue homogenate were assessed. The results revealed that the extracts exhibited mitochondrial MAO, AChE and BChE inhibitory effects in concentrationdependent manner, with the unripe fruit extract showing significantly higher (P<0.05) inhibitory effects than the ripe fruit extract. However, the ripe fruit extract had significantly higher total phenol and flavonoid contents, as well as exhibited significantly higher (P<0.05) DPPH free radical scavenging and membrane stabilizing effects. The observed antioxidant and enzyme inhibitory properties of ripe and unripe pepper (C. frutescens) fruits extracts could be an interplay among their constituent polyphenols. This could be a justification for their use as nutraceutical/dietary intervention in the management of neurodegenerative diseases, especially PD. Collectively, these findings suggest that C. frutescens could serve as a functional food/nutraceutical in the management of PD and our further studies will be directed towards characterization of the biomolecules involved and their mechanism(s) of action in appropriate models.

Keywords: Monoamine oxidase, Cholinesterases, Capsicum spp, Neurodegenerative diseases, Functional foods