Assessment of phytochemical compositions, antibacterial effects and DPPH scavenging activities of ethanolic root extracts of Pterocarpus erinaceus

Abstract

Abstract. Okoli EC, Emaru IJ, Olawale O. 2022. Assessment of phytochemical compositions, antibacterial effects and DPPH scavenging activities of ethanolic root extracts of Pterocarpus erinaceus. Asian J Nat Prod Biochem 20: 56-62. Pterocarpus erinaceus Poir. serve as a medicinal plant to many populations of Nigeria and West Africa. The stem bark, leaves, and roots have been studied for their antioxidant, antimalaria, antiulcerogenic, and antibacterial properties. This study aimed to determine the phytochemical compositions, antibacterial effect and antioxidant activity of the root bark of P. erinaceus. A gas chromatography flame ionization detector (GC?FID) instrument was used for the analysis and quantification of phytochemicals present in the ethanolic root extract of P. erinaceus. The antibacterial test was carried out using the agar well method against standard bacteria: Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa and Escherichia coli while the antioxidant activity was carried out by evaluating the DPPH scavenging activity. Phytochemicals found in the extracts include: flavonoids (44.50%), alkaloids (18.87%), steroids (4.38%), tannins (1.73%), and anti-nutrients (15.12%). The ethanolic root extracts of P. erinaceus exhibited significant antibacterial activity against E. coli and S. aureus but exhibited no growth inhibitory effect on B. subtilis and P. aeruginosa at all tested concentrations (100 µg/mL, 150 µg/mL, and 200 µg/mL). DPPH scavenging activity was significantly high, with 97.53% at a concentration of 1000 µg/mL and 24.26% at 40 µg/mL. This study revealed that the crude ethanolic extract of P. erinaceus root bark contained pharmacologically active compounds and exhibited significant antibacterial activity and DPPH free radical scavenging activity in a concentration-dependent manner.