Appraisal of phytotoxic, cytotoxic and genotoxic potential of essential oil of a medicinal plant Vitex negundo

Abstract

The excessive use of synthetic herbicides in agriculture has steered the development of resistance in weeds along with the production of toxic effects on the environment. Essential oils (EOs) are emerging as an alternative to the synthetic herbicides or agrochemicals because of their effectiveness and easy degradability. A study was, therefore, planned to investigate the phytotoxic, cytotoxic and genotoxic potential of EO extracted from Vitex negundo L., a medicinally important plant. Chemical characterization using GC–MS revealed that V. negundo EO is rich in sesquiterpenes with β-Caryophyllene (27.80 %) as the major compound. The phytotoxic effect of the EO (0.10–2.50 mg/mL) was investigated against two agricultural weeds: Avena fatua L. and Echinochloa crus-galli (L.) P. Beauv. Germination percentage and early seedling growth (coleoptile and root length) decreased significantly with an increase in EO concentration in both the test weeds. The cytotoxic potential of the oil was explored in Allium cepa L. by accessing mitotic index (MI) and chromosomal aberration percentage, whereas the effect on DNA integrity was evaluated as a percentage of head DNA (HDNA) and tail DNA (TDNA), tail moment (TM) and olive tail moment (OTM). EO treatment altered the cell cycle as evinced by a significant decrease in MI and an increase in aberration percentage at concentrations ≥ 0.05 and ≥ 0.025 mg/mL, respectively. In response to 0.10 mg/mL EO treatment, HDNA decreased by 9.37 %, whereas an increase of ∼1.67, 4.70 and 1.80 fold was observed in TDNA, TM and OTM, respectively. The study concludes that V. negundo EO induced cytotoxic and genotoxic effects might be accountable for the phytotoxicity of EO against weeds, and thus holds a good potential for use under sustainable agricultural systems.