The combined effect of vitamins restored normal testicular function in Cd-exposed rats (Sen Gupta et al., 2004). The effect of dietary vitamin E intake on lipid peroxidation as measured by the production of thiobarbituric acid reactive substances (TBARS) was assessed. It appears that reduction in the increase in TBARS due to Cd-induced

toxicity may be an important factor in the action of vitamin E (Beytut et al., 2003). The protective role of melatonin, an effective antioxidant and free radical scavenger, against cadmium was also studied (Karbownik et al., 2001). Melatonin slightly reduced lipid peroxidation in the testes induced by cadmium. The most common oxidation numbers of arsenic are +5, +3, and −3, in which the element is able to form both inorganic and organic compounds in the environment and within the human body (Hei and Filipic, 2004). In combination ABT199 with other elements such as oxygen, sulphur RG7422 mw and chlorine the element is referred to as inorganic arsenic and as combined with hydrogen and carbon as organic arsenic. Since most arsenic compounds are colourless and/or do not smell, the presence of arsenic in food,

water or air, is a serious human health risk. Inorganic arsenic includes arsenite (As(III)) and arsenate (As(V)) and can be either methylated to form monomethylarsonic acid (MMA) or dimethylated as in dimethylarsinic acid (DMA) (Arnold et al., 2006 and Wang and Rossman, 1996). The metabolism of inorganic arsenic involves a two-electron reduction of pentavalent arsenic, mediated by GSH, followed by oxidative methylation to form pentavalent organic arsenic. Arsenic trioxide (As2O3) is the most prevalent inorganic arsenical found in air, while a variety of inorganic arsenates (AsO43−) or arsenites (AsO2−) occur in water, soil, or food (Ding et al., 2005). Gallium arsenide (GaAs) is used in electronics industry and has also negative impact on human health. Although gallium arsenide is poorly soluble, it undergoes slow dissolution and oxidation to form gallium trioxide and arsenite (Webb et al., 1986). The toxic effects of GaAs consist of liberated Oxymatrine arsenic enhanced

by the other effects of the gallium. Arsenic is toxic to the majority of organ systems; inorganic arsenic being more toxic than methylated organic arsenic (Mandal and Suzuki, 2002). The trivalent forms are the most toxic and react with thiol groups of proteins. The pentavalent forms possess less toxicity, however uncouple oxidative phosphorylation. Trivalent arsenic inhibits various cellular enzymes, including for example pyruvate dehydrogenase, resulting in a reduced conversion of pyruvate to acetyl coenzyme A (CoA) (Wang and Rossman, 1996). Enzyme inhibition occurs through binding to sulphydryl groups. Arsenic also inhibits the uptake of glucose into cells, gluconeogenesis, fatty acid oxidation, and further production of acetyl CoA.