Background The development of cholinesterase (ChE) and monoamine oxidase (MAO) inhibitors for management of neurodegenerative diseases such as Alzheimer's disease (AD) has come with their undesirable side effects. Hence, research for potent but natural ChE and MAO inhibitors with little or no side effects is essential. This study investigated the potentials of alkaloid extracts from two Cola species as nutraceuticals for prevention and management of AD. Methods Alkaloid extracts were obtained from two Cola species (Cola nitida [KN] and Cola acuminata [KA]) by solvent extraction method. The extracts were characterized for their alkaloid contents using gas chromatography (GC). The effects of the extracts on ChE and MAO activities were investigated in vitro. Also, the extracts' ability to inhibit Fe2+-induced lipid peroxidation in rat brain homogenate, scavenge DPPH and OH radicals, as well as chelate Fe2+ were determined. Results GC characterization revealed the presence of augustamine and undulatine as the predominant alkaloids in the extracts. There was no significant (P > 0.05) difference in the inhibitory effects of the extracts on ChE activities. However, KA extract exhibited significantly higher (P < 0.05) MAO inhibitory effect than KN. Also, KA extract inhibited Fe2+- induced malondialdehyde (MDA) production in rat brain homogenate more significantly than KN, while there was no significant difference in DPPH and OH radicals scavenging, as well as Fe2+-chelating abilities of the extracts. Conclusions Our findings revealed that KN and KA alkaloid extracts exhibited significant effect in vitro on biological pathways that may contribute to neuroprotection for the management of neurodegenerative diseases.
Keywords: neurodegenerative diseases; neuropharmacotherapy; nutraceuticals.