Cytogenotoxic and biological evaluation of the aqueous extracts of Grewia lasiocarpa: An Allium cepa assay

Abstract

The widespread use of medicinal herbs has raised serious concerns over its quality, safety, and efficacy. Therefore, precise scientific assessment has become a precondition for acceptance of herbal health claims. In this study the aqueous extracts of the leaves and stem bark of G. lasiocarpa were evaluated for their cytogenotoxic potentials using Allium cepa (L.) assay, preliminary phytochemistry tests using Fourier transform infrared (FTIR) spectroscopy, total phenolic content and in vitro antioxidant activity using 1 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity and Ferric reducing antioxidant power (FRAP) assay. The total phenolic content of the extracts was also determined using Folin–Ciocalteu reagent assay. Distilled water and hydrogen peroxide (300 mM) were used as a negative and positive control, respectively. Four different concentrations (200, 600, 800 and 1000 μg/mL) were used for the root growth inhibition assay. The effective concentration (EC50) values of the leaves and stem bark were determined as 446.59 and 325.59 μg/mL respectively. The concentrations used for the cytogenotoxic effects induced a dose-dependent root growth inhibitory, mitotic index (MI) and mitodepressive (MD) effects at 24, 48 and 72 h. The extracts used induced a relatively low % of chromosomal aberrations in the A. cepa root tip cells with C-mitosis and bi-nucleic being the highest scored abnormalities. The aqueous extract of the stem bark had a higher level of phenol (92.54 ± 2.20 mg GAE/g) when compared to the leaves extract. However, both exhibited higher antioxidant activity than the standard drugs used. The suitability of A. cepa assay as a tool for monitoring the genotoxic effects of medicinal plants is affirmed and the aqueous extracts at the ½EC50, EC50 and 2EC50 concentrations were found to be non-toxic. The results from the antioxidant assays reveal that these extracts have good antioxidant potentials.