Phenolic constituents and inhibitory effects of the leaf of Afzel on free radicals, cholinergic and monoaminergic enzymes in rat's brain .

Objectives: is a medicinal plant used traditionally in Africa in the management of several human diseases including psychosis. However, there is inadequate scientific information on the potency of the phenolic constituents of leaf in the management of neurodegeneration. Therefore, this study characterized the phenolic constituents and investigated the effects of aqueous and methanolic extracts of leaf on free radicals, Fe-induced lipid peroxidation, and critical enzymes linked to neurodegeneration in rat's brain .

Methods: The polyphenols were evaluated by characterizing phenolic constituents using high-performance liquid chromatography coupled with diode array detector (HPLC-DAD). The antioxidant properties were assessed through the extracts ability to reduce Fe to Fe; inhibit ABTS, DPPH, and OH radicals and Fe-induced lipid peroxidation. The effects of the extracts on AChE and MAO were also evaluated.

Results: The phenolic characterization of leaf revealed that there were more flavonoids present. Both aqueous and methanolic extracts of leaf had inhibitory effects with the methanolic extract having higher significant (p≤0.05) free radicals scavenging ability coupled with inhibition of monoamine oxidases. However, there was no significant (p≤0.05) difference obtained in the inhibition of lipid peroxidation and cholinesterases.

Conclusion: This study suggests that the rich phenolic constituents of leaf might contribute to the observed antioxidative and neuroprotective effects. The methanolic extract was more potent than the aqueous extract; therefore, extraction of leaf with methanol could offer better health-promoting effects in neurodegenerative condition.