Formation of 8-hydroxydeoxyguanosine in calf thymus DNA treated with tert-butylhydroquinone, a major metabolite of butylated hydroxyanisole

Oxidative DNA damage caused by butylated hydroxyanisole (BHA), 2- tert-butyl(1,4)hydroquinone (TBHQ, a metabolite of BHA) and 2,5-di- tert-butyl(1,4)hydroquinone (DTBHQ), as well as 2,6-di- tert-butyl(1,4)benzoquinone (BHTQ, a metabolite of butylated hydroxytoluene), was evaluated by measuring the formation of 8-hydroxy-deoxyguanosine (80HdG) in calf thymus DNA. 80HdG formation was greatly increased by TBHQ in a concentration-dependent manner. This effect was strongly enhanced by CuCl 2 and suppressed by EDTA, bathocuproinedisulfonic acid disodium salt, methionine, glutathione reduced form or catalase, but was not affected by mannitol, sodium benzoate or sodium azide. Thus, TBHQ-induced 80HdG formation may be mediated by copper. DTBHQ also induced the formation of 80HdG, though to a much lesser extent than TBHQ, and its effect was stimulated by CuCl 2. BHA had a small enhancing effect at high concentration, only in the presence of CuCl 2, whereas in the case of BHTQ, it occurred both in the presence of CuCl 2 and FeCl 2.