Ethnotherapy study, phytochemical screening and antioxidant activity of Antrocaryon klaineanum Pierre and Anthocleista nobilis G. Don. Medicinal plants from Gabon

Medicinal plants, used by more than 80% of the population in Africa, have a significant role in the systems of public health. They constitute a complement or even an alternative to conventional drugs. In this work, we were interested in the validation of the use of some medicinal plants in traditional pharmacopeia. The detection and the identification of the natural compounds being of therapeutic interest were carried out. Six extracts (water, water-ethanol and water-acetone) from Antrocaryon klaineanum; Anthocleista nobilis, were evaluated for ethnotherapy study, phytochemical and antioxidant activities. The powdered plants samples were analyzed for the phytochemical screening using standard laboratory methods. The total phenols, flavonoids, proanthocyanidins and antioxidant activities were evaluated with methods Folin-Ciocalteu, Aluminium chloride, HCl-butanol hydrolysis and Antioxidant Activity Index (AAI) assay, respectively. From the results, polyphenols, flavonoids, tannins gallic and triterpenoids were revealed to be present in the two plants. The phytochemical analysis highlights the presence of total polyphenols, flavonoids and proanthocyanidins in the extracts of Antrocaryon klaineanum compared to the extracts of Anthocleista nobilis. Water, water-ethanol and water-acetone extracts of A klaineanum showed a strong antioxidant activity (AAIWE=3.26; AAIWEE = 7.86; AAIWAE = 4.13). The extracts of A. nobilis present weak antioxidant activity compared to the extracts of Vitamin C and BHA (AAI values of 7.02 and 7.58, respectively). The use of these plants in traditional medicine is justified and they constitute a source for other traditional investigations.