Vol.5 : Number 7
A Review on oxidative burst: Biochemical implications of metal toxicity

Author(s): Darshan Malik, Sunita Singh, Jayita Thakur, Amarjeet Kaur, S Nijhawan

The bioaccumulation and biomagnification of metals is a source of great concern for the living systems. A wide range of

heavy metals which are the essential micronutrients for plants and animals exhibit toxic effects at higher levels via

metabolic interference and mutagenesis. The metals are reported to enter the bio geo chemical cycle via atmosphere, soil

erosion and through high anthropogenic activities and cause toxicity in plants, fishes and animals. Heavy metals like Lead

(Pb), Cadmium (Cd), Chromium (Cr), Arsenic (As) and Nickel (Ni) cause enhanced production of Reactive Oxygen Species

(ROS) such as .O2 , H2O2, and .OH radicals. The increased generation of ROS cause "oxidative burst" in the system. Cells

under oxidative stress display various dysfunctions due to lesions caused by ROS to lipids, proteins and DNA.

Accumulation of heavy metals in the system result in abiotic stress leading to the induction of the antioxidant defenserelated

secondary metabolites viz. phytochelatin (PC), ascorbate, glutathione (GSH), anthocyanin and carotenoids. Various

steps can be employed to counteract the stress induced by increased levels of heavy metals. Chelation therapy has emerged

as an effective treatment against reducing metal toxicity in animals by using chelating agents like Calcium Disodium

Ethylene Diamine Tetra Acetic Acid (CaNa2EDTA), British Anti Lewisite (BAL) and Mono methyl Meso 2, 3-

Dimercaptosuccinic Acid (MmDMSA). Metal toxicity in the environment can be managed by using hyper accumulating

plant species belonging to the family of Brassicaceae, Solanaceae and Crassulaceae for phytoremediation and phytomining.

This review is a comparative analysis of the effects of heavy metal toxicity on various physiological and biochemical

processes of both plants and animals as well as methods to counteract them.

Key Words: Apoptosis, Cellular toxicity, Chelation therapy, Fenton reaction, Glutathione, Heavy metals,

Oxidative burst, Phytoremediation, Phytomining, Reactive oxygen species, Signal transduction

Country: India