Cytogenotoxicity of the aqueous extract of Parquetina nigrescens leaf using Allium cepa assay.

Parquetina nigrescens has been used for decades in ethnomedicine for its antioxidant, antimicrobial, anti-inflammatory, analgesic, and aphrodisiac properties. In this study, the cytotoxic and genotoxic effect of aqueous crude leaf extracts of P. nigrescens on the root meristematic cells of Allium cepa was examined. Volatile organic compounds (VOCs) present in the plant extract were also identified using gas chromatography-mass spectrometry (GC-MS). The extract was prepared with tap water as is locally practised by many Nigerians. Onion bulbs were exposed to 1, 5, 10, 20, and 50% concentrations of the extract for the analysis of root growth inhibition and chromosomal aberration. Lead nitrate (10 ppm) and tap water were used as the positive and negative controls, respectively. The result showed cytotoxicity which was observed as statistically significant (p <p0.05), concentration-dependent inhibition of root growth from 5 to 50% concentrations of the plant extract compared with the negative control. At 10 and 20% concentrations, the extract showed statistically significant (p < 0.05) genotoxicity by inducing different chromosomal aberrations such as fragments, disturbed spindle, delayed, and sticky chromosomes. The GC-MS analysis identified 14 VOCs of which 1, 2-benzenediol, 4H-pyran-4-one, 2, 3-dihydro-3,5-dihydroxy-6-methyl, and 5-hydroxymethylfurfural were believed to be responsible for the observed cytogenotoxicity. These results show that the aqueous crude leaf extracts of P. nigrescens at high concentrations are cytogenotoxic and therefore should be consumed with caution.