ORIGINAL PAPER In vitro studies on calf thymus DNA interaction and 2-tert-butyl-4-methylphenol food additive Soheila Kashanian • Jafar Ezzati Nazhad Dolatabadi Received: 26 August 2009 / Revised: 14 January 2010 / Accepted: 18 January 2010 / Published online: 10 February 2010 Ó Springer-Verlag 2010 Abstract The interaction of native calf thymus DNA (CT- DNA) with 2-tert-butyl-4-methylphenol (TBMP) at physi- ological pH has been investigated by spectrofluorometric and viscosimetric techniques. TBMP molecules were found to intercalate between base pairs of DNA, demonstrated by an increase in the specific viscosity of DNA and decrease in the fluorescence of TBMP solutions in the presence of increasing amounts of DNA and the calculated binding constants (K f ) at different temperatures. Furthermore, the enthalpy and entropy of the reaction between TBMP and CT-DNA showed that the reaction is exothermic and enthalpy favored (DH =-19.18 kJ mol -1 ; DS = -26.98 J mol -1 K -1 ) which are other evidences to indi- cate that TBMP is able to be intercalated in the DNA base pairs. Keywords CT-DNA  tert-Butyl-4-methylphenol  Intercalation Introduction The synthetic phenolic antioxidants are frequently used to prevent food, pharmaceutical, and other commercial products from oxidative rancidity. Various studies have shown that they could enter human body through the intake of foods, pharmaceutics, etc. Therefore, the use of these additives is subject to regulations which define the per- mitted compounds and their concentration limits in animal and human food [1]. 2-tert-Butyl-4-methylphenol (TBMP) is one of the synthetic phenols which are used as intermediates for the preparation of antioxidants and UV stabilizers added in rubbers, plastics, foods, and oils to inhibit or slow oxidative process. It has been considered that the antioxidant action of phenols depends on the hydrogen-donating capacity of a hydroxyl group in each molecule [2]. The synthetic antioxidants have been very thoroughly tested for their toxicological capacity, but some of them are coming after a long period of use or under heavy pressure as new toxicological data accumulate, which impose some cautions in their use [3]. When radicals oxidize phenolic antioxidants during the induction time, reactive interme- diates such as quinone methides, quinones, and dimer can be formed which suggested that toxicological capacity of phenols may be dependent on radical reactions [4]. P-tert-butylphenol (PTBP) and 2-tert-butyl-4-methylphe- nol induced pronounced hyperplasia and papillomas in the hamster forestomach [5]. These findings indicate that PTBP and TBMP may cause carcinogenic effects for hamster forestomach after long-term administration. Moreover, both 1-hydroxy and tert-butyl substituents may have an active role at inducing hamster forestomach tumors [4]. In the present investigation in vitro interaction of TBMP with native calf thymus DNA in 10 mM Tris–HCl aqueous solutions at neutral pH 7.4 was examined in more details, utilizing spectrofluorometeric and viscosimetric procedures. S. Kashanian (&) Faculty of Chemistry, Nanoscience and Nanotechnology Research Center (NNRC), Razi University, Kermanshah, I.R. Iran e-mail: kashanian_s@yahoo.com J. Ezzati Nazhad Dolatabadi Department of Biology, Faculty of Science, Razi University, Kermanshah, I.R. Iran 123 Eur Food Res Technol (2010) 230:821–825 DOI 10.1007/s00217-010-1226-6