PHOTOREACTIONS OF 3,3',4',5-TETRACHLOROSALICYLANILIDE WITH PROTEINS

[摘要] The photoreactions of 3,3'',4'',5-tetrachlorosalicylanilide anion (TCSA-) with 2 serum proteins were studied. TCSA- and anions of 2 similar compounds, N-ethyl-3,5-dichlorosalicylamide and salicylanilide, bind noncovalently to human serum albumin (HSA) without irradiation in aqueous pH 7.4 buffered solutions. TCSA- noncovalently bound to HSA yields 3 types of photoproducts when irradiated with UV light (.lambda. [wavelength] > 360 nm). A covalently bonded photoadduct between TCSA- and HSA is formed and histidines in HSA are chemically modified. Two of the 4 TCSA- photoproducts, which form when HSA is absent, are also formed when the TCSA-/HSA complex is irradiated. Apparently, not all proteins in the skin are capable of being the carrier protein in photoallergy to TCSA-; cross reactivity to other halogenated salicylanilides can probably be explained by further photochemical reactions of TCSA- photoproducts.