Abstract

EVALUATION OF THE ANTI-AMNESIC AND NEUROPROTECTIVE ACTIVITIES OF A MIXED PREPARATION OF EXTRACTS FROM: GINKGO BILOBA AND ENANTIA CHLORANTHA ON ALZHEIMER’S

Simone Veronique Fannang*, Jean Emmanuel Mbosso Teinkela, Moïse Henri Julien NKO’O, Marie Ange Belva Bilounga Nsengue, Bertin Sone Enone, Gisele Etame Loe, François Eya’ane Meva, Jacques Yinyang, Nnanga Nga

ABSTRACT

Introduction: Alzheimer's disease represents the second cause of neurodegenerative dementia after vascular dementias in the world, constituting a real public health problem. Indeed, according to the WHO in 2023, nearly 10 million new cases will be recorded per year, particularly in middle income countries. Many molecules have been developed however, they remain less accessible, with numerous undesirable effects, hence the need for perpetual research into active biomolecules. The objective of this work was to evaluate the antiamnesic properties and neuroprotective of mixed and separate preparations of extracts of Ginkgo biloba and Annickia chlorantha on a model of Alzheimer's disease induced by scopolamine in rats. Methodology: After carrying out qualitative and quantitative phytochemical screenings, an acute toxicity test was carried out following the protocol defined by OECD guideline 423. Subsequently, the pharmacological study was carried out on 30 male rats divided into 6 groups of 5 animals each and treated for 21 days: a normal control (NaCl 0.9% + ED, 10 ml/kg), the other groups received in addition to the scopolamine solution (1 mg/kg ip), donepezil (5 mg/kg) for the positive control, the extracts of Ginkgo biloba (100 mg/kg), Annickia chlorantha (100 mg/kg), and the preparation mixed (100 mg/kg) respectively for the three test batches. At the end of this phase, a neurobehavioral study was carried out, followed by sacrifice and removal of the hippocampus and cerebral cortex for biochemical and histological analyses. Results: Phytochemistry revealed the presence of numerous classes of secondary metabolites, including phenolic compounds, flavonoids and alkaloids. Concerning the acute toxicity test, no deaths or alterations in organic functions were recorded, suggesting that LD50 is greater than 5000 mg/kg. Scopolamine induced in the negative control, an increase (p ˂ 0.001) in the recognition indices of the object and the preferred arm in the different tests, in the activity of cerebral acetylcholinesterase (p ˂ 0.001) as well as the installation of oxidative stress and neuronal neurodegeneration characteristic of Alzheimer's disease. Treatment with donepezil and the different extracts reversed the trend of evolution of these parameters, and protected the treated group from the alterations observed in the negative control. Conclusion: the antiamnesic, neuroprotective and antioxidant properties would be linked to the synergistic action of the bioactive molecules contained in the two extracts.

Keywords: Alzheimer's disease, Gingko biloba, Annickia chlorantha, Oxidative stress, acetylcholinesterase, neurodegeneration.