FTIR characterization, phytochemical, antibacterial, and antioxidant properties of Pterocarpus Osun stembark and leaf extracts

Abstract

Antimicrobial resistance threatens the prevention and treatment of an ever-increasing range of infections caused by microorganisms. It becomes necessary therefore, to determine compounds from natural sources that can be used to develop novel medicines with potent antimicrobial properties. Although, the stem bark of Pterocarpus osun has long been used to treat diarrhea, dysentery, and other gastrointestinal problems, there are no published pharmacological reports to authenticate these uses. The leaf and stem bark of Pterocarpus osun were extracted exhaustively and successively with n-hexane, ethyl acetate and methanol. The antioxidant capacities of the extracts were measured using the 2,2-Diphenyl-1-PicrylHydrazyl (DPPH) scavenging technique and IC50 calculated. The extracts were screened for secondary metabolites and antibacterial activities. The result of the DPPH scavenging activities of the crude fractions compared favorably with that of the ascorbic acid used as standard control. 85.0% activity was recorded at concentration of 62.5µg/mL for the methanol stem bark fraction and, the least activity of 62.7% for ethyl acetate leaf extract at a concentration of 1000µg/mL. Terpenes, saponins, steroids, alkaloids, tannins, and flavonoids were detected in the extracts. Four of the eleven human pathogens used for antimicrobial screening were sensitive, four others were resistant. Zones of inhibition measured ranged between 18 and 29mm. Minimum inhibitory concentration and minimal bacteria/fungicidal concentrations were measured between 1.25 to 5.00mg/mL. The FTIR spectra of the powdered samples and extracts’ fractions reported.