Chemical constituents, antibacterial, antifungal and antioxidant activities from the leaf extracts of <i>Drynaria laurentii</i>

Abstract

The chemical constituents of weighed, air-dried leaf samples of a native Nigerian plant, Drynaria laurentii, were examined. The bioactivity of n-hexane, ethyl acetate and methanol extracts of the plants were tested against ten (10) strains of bacteria and fungi, and their antioxidant activities and antimicrobial properties were studied. Ethyl acetate extract of Drynaria laurentii leaves exhibited 2,2-diphenyl-1-hydrazine (DPPH) radical scavenging property with Inhibition Concentration at 50% (IC50) of 298.912 μg/mL while hexane and methanol extracts of the plant showed no significant antioxidant activity. From the antimicrobial study, the methanol extract of the plant inhibited the growth of all the test organisms at all concentrations while the n-hexane extract specifically inhibited the growth of the test bacteria at 200-25 mg/mL and have low inhibitory effects on all the test fungi. Meanwhile, the ethyl acetate extract inhibited the growth of all the test bacteria from a range of 200–12.5 mg/mL and all the test fungi at the range 200-25 mg/mL. However, some bacteria (6.25 mg/mL) and fungi (12.5-6.25 mg/mL) displayed resistance to the ethyl acetate extract of the plant. The Gas Chromatography-Mass Spectrometry (GC-MS) characterisation of n-hexane leaf extract of D. laurentii afforded nineteen (19) compounds with heptadecanal constituting 15.64% as the most abundant constituent of the extract. Ethyl acetate and methanol extracts of the plant afforded eighteen (18) and seventeen (17) compounds with γ-sitosterol (14.34%) and clionasterol (15.32%) as the abundant constituents in both extracts respectively.