Phytochemical screening, in vitro evaluation of the antimicrobial, antioxidant and cytotoxicity potentials of Grewia lasiocarpa E. Mey. ex Harv.

Abstract

The plant Grewia lasiocarpa E. Mey. ex Harv. (Family Malvaceae sensu lato), is relatively understudied. However, plants of this genus are well known for their phyto-medicinal and ethnopharmacological values. This study evaluated the preliminary phytochemistry, Fourier transform infrared (FTIR), Gas chromatography–mass spectroscopy analysis, total phenolic contents, in vitro antibacterial and antioxidant activities of the crude hexane, chloroform and methanol extracts of the leaves and stem bark of G. lasiocarpa. The antimicrobial activity was investigated by agar-well diffusion method against selected clinical strains. The in vitro antioxidant assay of the crude extracts was done using 2, 2՛-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and ferric reducing antioxidant power (FRAP). The phenolic content was measured using Folin–Ciocalteu's assay. The cytotoxicity of the crude extracts was tested using MTT assay on HEK293, HeLa and MCF-7 cell lines. In all the extracts, tannins, flavonoids, phenols and carbohydrates are among the primary and secondary metabolites confirmed to be present, while the FT-IR spectroscopic analysis of all extracts confirmed the presence of alkanes, aromatic and alkyl halides in all extracts of the leaves and stem bark. Among, the major compounds found in all extracts phytol, friedelin, n-hexadecanoic acid were present in the leaves, while in the stem bark, hexadecane, lup-20(29)-en-3-ol, acetate and hexanedioic acid were present. The methanol extracts of the leaves and stem bark had the lowest IC50 value of 0.02 μg/mL and 1.34 exp.−5 μg/mL (DPPH), while for FRAP the methanol extract of the leaves and chloroform extract of the stem had the lowest IC50 value of 9.76 and 12 μg/mL, respectively. The methanol extract of the leaves and stem bark had the highest phenolic content of 132.82 ± 0.22 and 171.12 ± 0.39 mg GAE/g dried extract. Most of the isolates showed varying degree of sensitivity to the extracts, with the hexane extracts of the leaves and stem bark having a remarkable inhibitory effect against Methicillin-resistant Staphylococcus aureus (ACCC 14026). The extracts were relatively not cytotoxic to HEK293. The results are suggestive that G. lasiocarpa leaves and stem bark are rich in bioactive compounds which could be a potential source of natural antioxidants and antibacterial agent for the treatment of diseases relating to the pathogenic bacteria studied.