Phytochemical screening, total polyphenols and flavonoids content and antiradical activity of methanolic extract of Lannea welwitschii (Hiern) Engl. (Anacardiaceae) from Gabon

The present study was carried out to identify chemical groups, measure polyphenols and total flavonoids, and evaluate the anti-free radical activity of the methanolic extract of the trunk bark of Lannea welwitschii who is a plant currently used to treat various diseases in the gabonese pharmacopoeia so as respiratory tract infections. The phytochemical screening was carried out on the methanolic (maceration) extract using standard laboratory methods. Total polyphenols and total flavonoids were measured by spectrophotometric assay while anti-free radical activity was assessed by ABTS method. The Phytochemical screening revealed the presence of polyphenols, tannin, flavonoids, alkaloids, reducing compounds, terpenes and coumarins. The determination of the total polyphenols of the methanolic extract from gallic acid showed a content of 598.18 ± 6.69 mg EAG/100 g of dry matter and the total flavonoids from quercetin showed a content of 91.71 ± 2.43 mg EQ/100 g of dry matter. Finally, the evaluation of the anti-free radical activity showed that the methanolic extract of the trunk bark of Lannea welwitschii has a weak free radical activity compared to that of gallic acid: IC50 are respectively 76.57 μg/ml and 0.47 μg/ml.