Abstract

Oxidant stress is implied in numerous illnesses as a triggering factor or partner to their complications. The present work aimed to determine the antioxidant activity of total flavonoids extracts from A. lobata and to identify the molecules that are supposed to be responsible for this activity. The crude extracts, obtained by maceration in 70% (v/v) aqueous methanol, have been extracted successively by hexane, chloroform, ethyl acetate and n-butanol. The crude (S₁, S₂), ethyl acetate (S₁^III, S₂^III) and n-butanol (S₁^IV, S₂^IV) extracts underwent a phytochemical screening in order to test the radical scavenging activity against 1, 1’ - diphenyl-2-picrylhydrazyl (DPPH). Qualitative analysis by thin layer chromatography permitted the study to put in evidence the flavonoids content of the different extracts. Contents in phenolic compounds were relatively high in the stems (3604 ± 511, 11 µg GAE/g) in relation to the leaves of A. lobata (3240 ± 711, 05 µg GAE/g). EC₅₀ of 6, 422.5, 430 and 357.5 μg/ml were graphically determined for vitamine C, S₁^III, S₂^III, S₁^IV and S₂^IVrespectively; fractions S₁, S₂ and S₂^IV showed an EC₅₀ greater than 500 μg/ml.

Key words: Adenia lobata, flavonoids, antioxidant activity, DPPH, Ivorian pharmacopeia.