Phytochemical Analysis, Antioxidant and Antimicrobial Properties of Vitex doniana Sweet Leaves and Fruits Extracts

Abstract

Vitex doniana belong to Verbernaceae family, has medicinal importance in West Africa. Based on its folkloric medicinal use in Benin, this study aimed to search for phytochemical constituents and evaluated antimicrobial and antioxydant activity of V. doniana plant extracts. Disc diffusion method was used to evaluate the antibacterial activity using 10 references strains and 9 meat isolated Staphylococcus. The antifungal activity was evaluate with 03 fungal strains (Penicillium citrinum, Aspergillus tamarii and Fusarium verticilloides) and the antioxidant activity was determined by both DPPH and ABTS methods. 31% of the secondary metabolites sought were found in the leaves compared to 30% in the fruits. Besides, polyphenols are more concentrated in the fruits ethanol extract (356.12 ±28.10 μgEAG/g) than those of leaves (86.76±19.93 μgEAG/g). For antibacterial activity, the inhibition zones diameters of the active extracts vary depending on the strains (p = 0.001) for the fruits ethanol extracts (p = 0.01) and leaves ethanol extracts (p < 0.05) respectively. The fruits ethanolic extract inhibited 80% of the reference strains while the leaves ethanolic extract inhibited 60% of the strains. The inhibition diameters of the fruits ethanolic extract vary from 12.75±0.35 mm (M. luteus) after 24 hours to 4.00±0.00 mm obtained with the E. coli strain after 48 hours. Furthermore, the inhibition diameters of the leaves ethanolic extract vary from 12.5±0.00 mm (S. epidermidis) after 24 hours to 6.5±0.00 mm obtained with the E. coli strain after 24 hours. The lowest MIC (0.312 mg/mL) was obtained with the leaves ethyl acetate extract with the S. equorum strain while the highest MIC (20 mg/mL) was obtained with the fruits ethanolic extracts (S. xylosus and S. saprophyticcus), fruits ethyl acetate (S. aureus). The leaves ethyl acetate extract also showed the lowest MBC of 0.625 mg/mL on the S. equorum strain with a bactericidal effect. The bactericidal effect was also observed with the S. lentus and S. haemolyticcus strains. The comparative effect of the susceptibility of the fungal strains to the extracts shows that F. verticilliodes strain is the most sensitive while A. tamarii is the most resistant. Furthermore, the two extracts of V. doniana fruits showed weak antioxidant activities with IC50 ranging from 3375.00±189.93 μg/μL (fruits ethyl acetate extract) to 3800.0±70.71 μg/μL (fruits ethanol extract). The leaves and fruits extracts displays the good antibacterial, antifungal and antioxidant activities. These results partialy justify the traditional use of V. doniana extracts.