Title:Chemistry and Pharmacological Properties of Some Natural and Synthetic Antioxidants for Heavy Metal Toxicity
VOLUME: 20 ISSUE: 36
Author(s):S.J.S. Flora, Rupal Shrivastava and Megha Mittal
Affiliation:Division of Regulatory Toxicology, Defence Research and Development, Establishment, Jhansi Road, Gwalior, M.P. 474 002, India.
Keywords:Antioxidants, chelation therapy, heavy metals, heavy metal toxicity, structure-activity-relationship, oxidative stress.
Abstract:Heavy metals are known to cause oxidative deterioration of bio-molecules by initiating free radical mediated
chain reaction resulting in lipid per-oxidation, protein oxidation and oxidation of nucleic acid like DNA and RNA. The
development of effective dual functioning antioxidants, possessing both metal-chelating and free radical-scavenging properties
should bring into play. Administration of natural and synthetic antioxidants like, quercetin, catechin, taurine, captopril,
gallic acid, melatonin, N-acetyl cysteine, α- lipoic acid and others have been recognized in the disease prevention and
clinical recovery against heavy metal intoxication. These antioxidants affect biological systems not only through direct
quenching of free radicals but also via chelation of toxic metal(s). These antioxidants also, have the capacity to enhance
cellular antioxidant defense mechanism by regenerating endogenous antioxidants, such as glutathione and vitamin C and
E. They also influence cellular signaling and trigger redox sensitive regulatory pathways. The reactivity of antioxidants in
protecting against heavy metal induced oxidative stress depends upon their structural properties, their partitioning abilities
between hydrophilic and lipophilic environment and their hydrogen donation antioxidant properties. Herein, we review
the structural, biochemical and pharmacological properties of selected antioxidants with particular reference to their ability
to (i) chelate heavy metals from its complex (ii) ameliorate free radical (iii) terminate heavy metal induced free radical
chain reaction (iv) regenerate endogenous antioxidants and, (v) excretion of metal without its redistribution.
