Effects of the butylated hydroxyanisole and butylated hydroxytoluene on the DNA adduct formation and arylamines N-acetyltransferase activity in humancolon tumor cells

The effects of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) on N-acetyltransferase (NAT) activity were examined using a human col on tumor cell line (colo 205). BHA or BHT were added to the cytosols or to the medium of human colon rumor cells: The NAT activity was measured by hig h performance liquid chromatography, assaying the amounts of acetylated 2-a minofluorene (AAF), p aminobenzoic acid (N-Ac-PABA), nonacetylated 2 amino- fluorene (AF) and p-aminobenzoic acid (PABA). The NAT activity in the human colon tumor cells and cytosols was suppressed by BHA or BHT in a close-dep endent manner. The apparent values of Km and Vmax of NAT of human colon tum or cells were also decreased by BHA or BHT in cytosols and in intact cells. BHA ol BHT may act as a noncompetitive mhibitor. After the incubation of h uman colon tumor cells with AF in the presence of BHA or BHT, the cells wer e recovered and DNA was prepared and hydrolysed to nucleotides. Adducted nu cleotides were extracted into butanol and AF-DNA adducts were analysed by H PLC. The results also demonstrated that when BHA or BHT was added to the me dia, a decrease in AF-DNA adduct formation was seen in the human colon tumo r cells. The finding of AF-DNA adduct formation in cultured human colon tum or cells suggest the possibility of using cultured cells for assessing aryl amine-induced DNA damage.