L.O. Iniaghe

Parkinson’s disease (PD) is a progressive neurodegenerative disorder characterized by the gradual loss of dopaminergic neurons within the substantia nigra pars compacta, leading to dopamine depletion, oxidative stress, and motor dysfunction. Despite advances in neuropharmacology, current treatment options remain largely symptomatic and fail to halt disease progression. This has intensified the search for novel neuroprotective agents, particularly from natural sources. Afzelia africana, a medicinal plant traditionally used across West Africa for the management of inflammatory and oxidative stress-related conditions, contains phytochemicals such as flavonoids, tannins, and terpenoids that may possess neuroprotective properties. This study investigated the neuroprotective and histopathological effects of the ethanolic stem bark extract of Afzelia africana in a rotenone-induced Parkinsonism model using male Wistar rats. The plant material was extracted by cold maceration in ethanol and subjected to qualitative phytochemical screening. Acute toxicity was evaluated using a modified Lorke’s method. The animals used for this study were randomly distributed in 5 different treatment groups, namely: control (no treatment), vehicle alone, rotenone and vehicle, rotenone and 250 mg/kg Afzelia africana extract and rotenone and 500 mg/kg Afzelia africana extract. Animals in all groups received the different drug treatments daily while those in the last three groups received 1 mg/kg of rotenone on days 1,4,7 and 10. Neurobehavioural performance was assessed using the wire hanging and elevated plus maze tests on days 0, 5 and 10. On the 11th day, animals were sacrificed via ketamine injection, organs were harvested, weighed and preserved in formalin and used for histopathological studies. The phytochemical screening revealed the presence of saponins, glycosides, terpenoids, alkaloids, tannins, and phenolic compounds; the LD50 was estimated to be than 5000 mg/kg. Rotenone administration caused marked impairment in motor coordination and increased anxiety-like behaviour; however, treatment with A. africana extract significantly improved (p<0.05) motor strength, prolonged latency to fall in the wire hanging test, and enhanced open-arm exploration in the elevated plus maze. Histopathological examination of the striatum showed that A. africana attenuated neuronal atrophy and pyknosis, while also ameliorating hepatic and renal alterations induced by rotenone exposure. The findings demonstrate that the ethanolic stem bark extract of Afzelia africana possesses neuroprotective and anxiolytic activities suggesting its potential as a promising natural therapeutic candidate drug discovery.