Chemical characterization and biological activitie of Newbouldia laevis and Pterocarpus Santalinoides leaves

Abstract

This study was aimed at phytochemical screening, antibacterial and antiradical activities of aqueous and hydro- ethanolic extracts of two medicinal plants leaves, Newbouldia laevis and Pterocarpus santalinoides, collected in southern Benin. Phytochemical analysis of these plants revealed the presence of coumarins, polyphenols (flavonoids and tannins) and mucilage in both samples. But only Pterocarpus santalinoides leaves showed the presence of saponins and leucoanthocyanins. The quantitative analysis of phenolic compounds in both samples showed that the extracts (aqueous and hydro-ethanolic) of Newbouldia laevis leaves had the highest levels of total polyphenols (22.18 ± 0,02 et 22. 63 ± 0,07 ?g GAE/ mg of extract) but lower levels of condensed tannins and flavonoids. While the aqueous-ethanolic extract of Pterocarpus santalinoides leaves has the highest tannins content (22.90 ± 0.01 µg CE / mg of extract) and flavonoid content (3.88 ± 0.01 µg QE / mg of extract).For antibacterial test Newbouldia laevis hydro-ethanolic extract was more effective on Klebsiella pneumoniae than the aqueous extract, while the aqueous extract of Pterocarpus santalinoides has been active on the same strain. Escherichia coli, Salmonella typhi and Shigella sp were inhibited by higher CMI (1.23 mg / mL) of the four extracts. The antiradical activity was determined on the basis of their scavenging activity of the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical, the best IC50 were: 65 µg / mL and 125µg / mL respectively for Newbouldia laevis and Pterocarpus santalinoides leaves aqueous extracts.