Phytochemical Screening and Comparative Evaluation of Antioxidant Activity of Different Parts of Anonidium mannii (Oliv) Engl. et Diels.

Aims: This study aimed at identifying the phytochemical constituents, to evaluate and compare the in vitro antioxidant potential of the methanolic extracts of the leaves, trunk (wood and bark) and roots (wood and bark) of Anonidium mannii (Oliv) Engl. and Diels which is used in Cameroon for the treatment of rheumatism.  
Place and Duration of Study: The work was conducted at the Pharmacochemistry and Natural Substances Laboratories of the Faculty of Medicine and Pharmaceutical Sciences, University of Douala. All the experiments were carried out from the 15th October 2019 to the 31th July 2020. 
Methodology: Phytochemical screening was based on conventional techniques focusing on color reactions and precipitation. The evaluation of the antioxidant power was carried out by the method of scavenging the free radical DPPH of the extracts and by reading the absorbance for each concentration at 517 nm. 
Results: The phytochemical screening of the extracts revealed the presence of alkaloïds, flavonoïds, anthraquinones, coumarins, terpenes, steroïds, saponins, phenols and anthocyanins. All extracts tested showed antioxidant activity, particularly root wood with an IC50 = 1.85 µg/ml identical to the standard (BHT: Butylhydroxytoluène). 
Conclusion: Due to evidence that reactive oxygen species play a causal role in auto-immune diseases, such as rheumatoid arthritis, these results justify the use of the leaves or the stem bark of A. mannii in the traditional pharmacopeia for the treatment of rheumatism. However, the wood of the roots having presented the best activity (IC50 = 1.85 µg/ml). It would be beneficial to suggest this plant part to the local populations for the management of that pathology. This study is the first comparative biological study conducted on the different parts of A. mannii.