Activités de l’extrait aqueux des feuilles de moringa oleifera (moringaceae) sur les performances physiques et profil de toxicité chez les rats

Abstract

In order to optimize their performance, athletes are often obliged to repeat high intensity training sessions with little recovery. This situation leads to neuromuscular tiredness and overtraining which can be prejudicial for them. Moreover, food deficiency could have major effects on their health, drive and performance. To solve this problem, many athletes consume banned doping substances. However, the consumption of these substances presents many health risks. The objective of this work was to study the activities of the aqueous extract of the leaves of M. oleifera on physical performance and to evaluate the toxicity profile related to oral administration of this extract in Wistar albino rats (Rattus norvegicus). The work was divided into four major parts comprising phytochemical and nutritional studies, anti-fatigue, anti-oxidant and anti-stress effects and the evaluation of the toxicological profile of the extract. The phytochemical screening and nutritional value evaluation of the aqueous extracts of Moringa oleifera was carried out by colorimetric method. The anti-fatigue effects were evaluated from two models of physical activity in rats (acute and chronic). In order to elucidate the mechanism responsible for those effects, glycemia, lactamia, uremia, triglyceridemia, hepatic and muscle glycogen, oxidative stress parameters (SOD, CAT, GPx and MDA) and hematological parameters were measured by colorimetric method. The anti-stress activity was also evaluated using two models of induction of stress in the rats (force swimming test and immersion and immobilization). For that purpose, the behavior scored (latency, crossing, grooming and rearing), the ulceration and gastric mucosa, oxidative stress parameters (SOD, CAT, GPx and MDA) and serum biochemical parameters (glycemia, uremia and triglyceridemia) were measured. Finally, we evaluated the toxicity profile of the leaf aqueous extract of M. oleifera. Acute administration consisted on oral administration of a single dose of extract (2000 mg/kg). Sub-chronic study consisted of oral repeated administration during 42 consecutive days of three dose levels (400, 800 and 1600 mg/kg). The behavioral, hematological and serum biochemical parameters were measured. Histological sections of liver, kidneys and lungs were realized. Phytochemical analysis of the aqueous extracts of M. oleifera revealed the presence of numerous classes of major compounds (tannins, phenols, flavonoids and glycosides). Nutritional analysis showed that the extract is rich in metabolisable energy (2810.98 kcal/kg of extract) and minerals (sodium (272.70±28.04 g/kg of DM), potassium (120.70±14.18 g/kg of DM), calcium (28.368±0.94 g/kg of DM), iron (26.44±3.51 g/kg of DM), zinc (21.06±0.29 g/kg of DM), magnesium (11.57±0.59 g/kg of DM) and copper (3.52±0.17 g/kg of DM)). M. oleifera extract increased (p˂0.05) maximum swimming time (56.55% to 67.71%), blood hemoglobin (12.46%), read blood (25.09%) and white (41.19%) cells, blood glucose (36.70%), hepatic (76.18%) and muscle (145.15%) glycogen reserves of rats subjected to acute or chronic physical activities (p<0.05- p˂0.001). The extract also increased significantly (p<0.05-p˂0.001) the activity of antioxidant enzymes and decreased the blood concentrations of MDA. Furthermore, it decreased significantly (p<0.05-p˂0.001) blood concentrations of lactate (53.83%), triglycerides (66.95%), urea (62.08%), hematocrit (7.31%), percentage of granulocyte (37.90%), rate of lymphocytes (25.31%) and granulocytes (48.33%) as compared to control group. The 200 mg/kg dose was most effective. The results of the anti-stress activity of this extract showed a modification (p<0.05-p˂0.001) of the behavior scored (latency, crossing, grooming, and rearing), ulceration (53.06%) and gastric mucosa (10.43%), oxidative stress parameters (SOD, CAT, GPx and MDA) and serum biochemical parameters (glycemia (39.86%), uremia (56.37%) and triglyceridemia (59.56%). After acute administration, M. oleifera extract appeared slightly toxic, with LD50 greater than 2000 mg/kg. Sub-chronic study of the extract at doses of 800 and 1600mg/kg showed areas of vascular congestion and inflammation foci effects which were reversible after discontinuation of extract administration. The leaves aqueous extract of M. oleifera possesses simultaneously, anti-fatigue and anti-stress effects. These effects could be due to the presence in the plant of secondary metabolites which may neutralize or delay toxins related to fatigue and stress, to promote adaptations and to increase fat utilization and skeletal muscle metabolic regulators. Toxicological studies also showed that the administration of the aqueous extract of M. oleifera could be without risk to the organism at the therapeutic doses (100, 200 and 400mg/kg).