Phytochemical profiling and pharmacological activities of ethanol and n-hexane extracts of Daniellia oliveri

This study compared the medicinal properties of polar and non-polar extracts of Daniellia oliveri. D. oliveri was extracted by cold extraction, using ethanol and n-hexane. The phytochemicals were analyzed using standard methods. The chemical constituents of the extracts were determined with Gas chromatography mass spectroscopy (GC-MS). The antioxidant properties were determined using 2,2-diphenyl-1-picryl-hydrazyl (DPPH) and Lipid peroxidation (LPO) assays. The antidiabetic activities were evaluated with alpha-glucosidase and alpha-amylase assays. Lipoxygenase and membrane stability assays were used to estimate the anti-inflammatory properties. Antimicrobial activities of extracts of D. oliveri against three strains each of bacteria and fungi were evaluated by the Agar well diffusion method. The screening of the ethanol and n-hexane extract of D. oliveri revealed the presence of sterols, coumarins, glycosides, quinones, xanthoproteins, flavonoids, phenol, tannin, alkaloids, saponins, steroids, terpenes, proanthocyanin, and flavanols, but vitamin C was found only in the ethanol extract. The results of the GC-MS analysis of D. oliveri showed eugenol as the major constituent for the ethanol extract and 3,4-dihydroxyphenylglycol as the major constituent for the n-hexane extract. The result of 2,2-diphenyl-1-picryl-hydrazyl (DPPH) inhibition by the ethanol and n-hexane extract of D. oliveri showed that n-hexane extract (nHE) possessed a stronger antioxidant property than the ethanol extract (EE), with IC50 535.20 µg/mL and 662.13 µg/mL, respectively. lipid peroxidation of the ethanol extract and the n-hexane extract of D. oliveri showed that the EE has stronger antioxidant activity than the nHE (IC50 of 646.304 µg/mL and 719.26 µg/mL, respectively). The EE exhibited higher antidiabetic activities compared to the nHE and the values obtained are significantly different. For the lipoxygenase assay, the EE showed a lower value of IC50 81.67 µg/mL than that of the nHE (313.28 µg/mL), but for the membrane stability assay, the activities of both extracts were significantly different, with the nHE having a higher inhibitory activity than the EE. The nHE and EE of D. oliveri showed activities against all strains of bacteria and fungi at all graded concentrations, but were less effective against C. parapsilosis for both extracts. For the test against three strains of bacteria, the EE and nHE showed the lowest MIC values against K. pneumoniae (12.5 mg/ mL and 10.5 mg/ mL, respectively). This study has shown that D. oliveri has medicinal potential; for most of the results, the ethanol extract showed better activities in lipid peroxidation, lipoxygenases, α-amylase, α-glucosidase, antifungal, and antibacterial assays than the n-hexane extract except for DPPH and membrane stability.