ENZYME-IMMUNOASSAY FOR 4-HYDROXY-2-(4-METHYLPHENYL)BENZOTHIAZOLE

A specific enzyme immunoassay (EIA) has been developed for 4-hydroxy-2 -(4-methylphenyl)benzothiazole (KB-2714) (1), an active metabolite of 4-acetoxy-2-(4-methylphenyl)benzothiazole (KB-2683) (2) which is a pro mising anti-rheumatic agent. The EIA was based upon antiserum elicited against enylazo)-4-hydroxy-2-(4-methylphenyl)benzothiazole methylphen yl)benzothiazole (3)-bovine serum albumin conjugate and beta-galactosi dase-labelled 5-amino-4-hydroxy-2-(4-methylphenyl)benzothiazole methyl phenyl)benzothiazole (S). The sensitivity of the EIA was significantly improved by the utilization of a bridge heterologous combination syst em. An appropriate dose-response curve of EIA for 4-hydroxy-2-(4-methy lphenyl)benzothiazole was obtained in the range of 10 pg tube-1-20 ng tube-1. The specificity of EIA proved to be satisfactory in terms of c ross-reactivities to 14 benzothiazole-related compounds including gluc uronic acid and sulphuric acid conjugates. The proposed method was eva luated to be useful for the determination of 1 in urine and plasma wit h acceptable recovery and inter- and intra-assay precision.