Evaluation in vitro du potentiel de certaines plantes médicinales camerounaise contre les maladies neurodégénératives : Cas de la maladie de Parkinson

Abstract

Neurodegenerative diseases, such as Parkinson's disease, are characterized by a progressive loss of the structure and function of neurons. The weak therapeutic response and the progressive nature of these diseases, as well as, a wide range of side effects (such as nausea, vomiting, hallucinations, constipation, dizziness and hepatotoxic effects) caused by modern therapeutic approaches, necessitated a complementary or alternative drug treatment that is relatively safe, particularly from medicinal plants. Traditional Cameroonian herbal medicine used against some neurological disorders (such as epilepsy, depression, anxiety, migraine, seizures and schizophrenia), represent therapeutic benefits for the treatment of neurodegenerative diseases. To promote this medicine, an ethnobotanical survey was carried out in the Noun Division. The crude extracts were prepared using the mixture of CH2Cl2 and MeOH (1:1, v/v). Their antioxidant and anti-acetylcholinesterase effects were determined in vitro. The anti-inflammatory properties of the crude extracts of plants were determined in vitro by evaluating their inhibitory effect on the production of nitric oxide (NO) by the RAW 264.7 macrophages stimulated by lipopolysaccharrides and inhibitor of 15-lipoxygenase (15-LOX). The protective effect of the active extracts on human glioblastoma / U373MG astrocytoma cells against aminochrome induced toxicity was also evaluated in vitro. Out of thirty identified and studied medicinal plants, the Asteraceae family was the most represented with six species, and its leaves were the most used parts. Most of the crude extracts showed a better antioxidant potential compared to vitamin C or trolox. More precisely, the extract of Dacryodes edulis exhibited the highest antioxidant capacity (385.15 mg AAE / g of extract), Alchornea laxiflora extract showed better inhibition of lipid peroxidation (3.20 µg / mL), Cola acuminata extract showed higher reducing power (0.620) and Annona senegalensis extract showed better anti-free radical activity (7.40 µg / mL). Crinum purpurascens extract exhibited better acetylcholinesterase inhibitory activity with an IC50 value of 99.40 μg / mL, which is significantly higher than that of the reference compound galanthamine. The extract of C. purpurascens exhibited the best inhibitory activity of NO with an IC50 of 12.08 ± 1.68 µg / mL comparable to that of quercetin (6.59 ± 0.87 µg / mL). Annona muricata seed extract exhibited the highest 15-LOX inhibitory activity with an IC50 value of 30.43 μg / mL. The extracts of A. senegalensis, A. laxiflora, D. edulis, C. acuminata, C. purpurascens and A. muricata which have presented the best activities mentioned above were selected for the rest of our study. The extracts of A. Laxiflora, D. edulis, A. muricata and A. senegalensis significantly (p<0.05) decreased aminochrome-induced toxicity on U373MGsiGST6 cells. No significant difference was observed between these plant extracts and the reference compound, nicotine. However, only extracts from A. laxiflora and A. muricata significantly (p<0.05) increased mitochondrial membrane potential in U373MGsiGST6 cells. It emerges from this study that several plants used by the traditional health practitioners of the Noun Division are effective against some neurological disorders.