Effect of refinery waste effluent on tocopherol,carotenoid,phenolics and other antioxidants content in Allium cepa

Abstract

Pollution in water used for irrigation is a major cause of stress generation in plant system. Under these stress conditions, reactive oxygen species derived from molecular oxygen can accumulate in plant, resulting in the oxidation of nucleic acids, lipids, chlorophyll and so on. This study was conducted in Allium cepa to analyze the alteration in the levels of nonenzymatic antioxidants as a consequence of Mathura refinery waste water (MRWW) exposure. The studied antioxidants were glutathione (GSH) and ascorbic acid (ASC). Their determination was carried out in A. cepa bulbs exposed to different concentrations of MRWW that is 0.25×, 0.5×, 0.75× and 1.0×. A significant increase in the levels of these nonenzymatic antioxidants in onion bulbs upon treatment with MRWW suggested that these can serve as suitable biomarkers of toxicity. The toxicity of waste water was also tested on the level of tocopherol (Toc) and carotenoid (CAR) in onion bulbs, and in both the cases a high level of these metabolites was noticed. Phenolic content of A. cepa after the waste water insult was found to be increased, again a manifestation of adaptation against heavy metal and oxidative stress. It is clear from our findings that GSH, ASC, Toc and CAR in A. cepa system could serve as potential biomarkers for the presence of toxicants like heavy metals and its hazards in MRWW. The test waste water demonstrated profound effects on these parameters which is suggestive of the warrior strategies adopted by the plant system against the pollution-induced stress.