Evaluation of the antioxidant and antibacterial activity of aqueous and ethanoic extracts of two medicinal plants used to treat diarrhea in Côte d’Ivoire

Abstract

This study was initiated to evaluate the antioxidant and antibacterial activities of aqueous and ethanoic extracts of Anthocleista djalonensis and Uvaria chamae, two plants of the African pharmacopoeia used by the peoples of the northern Côte d’Ivoire to treat severe cases of diarrhea. A series of extraction by maceration was carried out. The extracts obtained were assayed by the colorimetric method and their antioxidant activity determined by spectrophotometer using the free radical scavenging (DPPH) and iron reduction (FRAP) methods. Dilution and agar diffusion methods on Mueller Hinton medium were used to determine MICs and inhibition diameters. The assay of the extracts determined the polyphenol content ranging from 6.8 to 21.1 mg. The total phenol content of the ethanol extract of Uvaria chamae was the highest. Evaluation of the free radical scavenging activity and the reducing power of ferric ions to ferrous ions of the extracts of both plants indicated variable IC50 values ranging from 4 to 14 (μg/mL). The lowest value (4 μg/mL) close to that of vitamin C (reference molecule) (3.5 μg/mL) was obtained with the aqueous and ethanoic extracts of Anthocleista djalomensis and Uvaria chamae respectively. Furthermore, all germs were found to be sensitive to the action of the extracts with inhibition diameters greater than 10 mm and MICs greater than 3.12 mg/mL. This sensitivity could be due to the presence of phytochemicals such as total phenols, flavonoids, tannins, alkaloids, saponins whose antimicrobial activities have already been shown. These investigations justify the traditional use of these plants in the treatment of diarrhea and dysentery.