R. Sumathi et al., EFFECT OF DL-ALPHA-LIPOIC ACID ON TISSUE REDOX STATE IN ACUTE CADMIUM-CHALLENGED TISSUES, Journal of nutritional biochemistry, 7(2), 1996, pp. 85-92
Cadmium as an environmental pollutant has aroused great concern due to
its toxic effects on various body tissues. Supplementation of thiol c
ompounds has been suggested to protect against the toxic effects of re
duced oxygen species by contributing to the thiol pool of the cell. Th
e present study was designed to determine whether dietary supplementat
ion of DL alpha-lipoic acid (15 and 30 mg/kg), a ''meta-vitamin,'' to
cadmium-intoxicated vats (3 mg/kg) affords protection against the oxid
ative stress caused by the metal. The fiver and kidney of the metal-ad
ministered rats showed elevated levels of hydroxyl radicals and malond
ialdehyde (basal and induced), a decreased level of antioxidants-reduc
ed glutathione, total thiols protein thiols, nonprotein thiols, ascorb
ate, alpha-tocopherol and retinol and antioxidizing enzymes-superoxide
dismutase, catalase, tau-glutamyl transpeptidase, glutathione peroxid
ase, glucose-6-phosphate dehydrogenase, glutathione reductase, and glu
tathione-S-transferase. Lipoate supplementation changed the tissue red
ox state directly by scavenging the free radicals and indirectly by bo
lstering the antioxidants and antioxidizing enzyme defenses. In vitro
studies revealed that, among the mono and dithiols (glutathione, cyste
ine, dithiothreitol, and lipoic acid), lipoic acid was the most potent
scavenger of free radicals produced during cadmium-induced hepatotoxi
city. The drug contributes its thiol groups to detoxify the divalent m
etal and subsequently ameliorates the cell membrane integrity.