Potential of the Hydroethanolic Extract of Lannea microcarpa’s Fruit on Oxidative Stress Induced Alzheimer’s Disease

Background: Alzheimer’s disease (AD) is the commonest neurodegenerative disease affecting about 33 million of people worldwide, with no efficient cure so far. Many studies have reported oxidative stress (OS) as an important factor involved in AD physiopathology. The imbalance between the production of prooxidants and antioxidant defense mechanisms, favours an overproduction of reactive oxygen species (ROS) which bring about brain cell impairment and nerve impulse transmission disruption, leading to memory loss. This work was aimed at evaluating the neuroprotective activity of Lannea microcarpa’s fruit on oxidative stress induced Alzheimer’s disease rat model.

Method: Total phenolic, flavonoid and tannins contents, and antioxidant activity using DPPH scavenging and FRAP tests; were determined in the fruit extract. 28 female rats of 6 months were used. AlCl3 at 10 mg/kg was administered four times per week by intraperitoneal injection during 7 weeks. Morris water maze and eight arms radial maze tests were performed to assess animal behaviour. Total proteins, catalase activity, malondialdehyde, nitrite, reduced glutathione, and acetylcholinesterase activity were determined. Brain histopathological analysis was also performed.

Results: The quantitative analysis of secondary metabolites revealed the presence of phenols (40.961 ± 0.003 mg GAE/g extract), flavonoids (22.381 ± 0.003 mg CE/g extract), and tannins (10.64 ± 0.16 mg TAE/g extract) in the extract. Antioxidant activity was determined by the capacity to scavenge DPPH radical (94.739 ± 0.207 %), and to reduce ferric ion (0.894 ± 0.036 mmol Fe2+/ g extract). The administration of Lannea microcarpa’s fruit extract to rats decreased the escape latency in the Morris water maze, and the time to visit the maze’s arms in the eight arms radial maze (EARM). It also increased catalase activity; but lowered malondialdehyde, nitrite and acetylcholinesterase activity, and prevented lesions in the brain.

Conclusion: The fruit’s extract showed a significant effect on oxidative stress biomarkers and acetylcholinesterase actitivity. Lannea microcarpa’s fruit could therefore be targeted as neuroprotective regarding its anti-acetylcholinesterase property.