Synthesis of furaltadone metabolite, 3-amino-5-morpholinomethyl-2-oxazolidone (AMOZ) and novel haptens for the development of a sensitive enzyme-linked immunosorbent assay (ELISA)
A sensitive and specific monoclonal enzyme-linked immunosorbent assay (ELISA) for the determination of tissue-bound metabolite 3-amino-5-morpholinomethyl-2-oxazolidone (AMOZ) was developed. Three different haptens of AMOZ were synthesized. The haptens (I, III) were derived from 4-carboxybenzaldehyde and ethyl 4-bromobutyrate, respectively. Hapten II was based on hapten I but a CN bond in the parent structure was reduced. Corresponding immunogens and coating antigens were prepared to improve the assay sensitivity. The hybridomas 4 × 108 secreting antibodies against CPAMOZ were obtained from immunogens I-BSA by monoclonal antibody (mAb) technology. The antibody indicated that: (1) the small molecular AMOZ cannot induce the specific response against AMOZ; (2) the weakened conjugation effect improved the recognition of AMOZ. Assessment of twelve coating antigen/antibody combinations consequently resulted in the development of an indirect competitive enzyme-linked immunosorbent assay (icELISA). The results showed that the sensitivity was highly improved about fifteen-fold for the novel heterologous coating antigen at low hapten density. The IC50 value of the ELISA for CPAMOZ was 0.13 ng mL−1. The cross reactivity values of the assay with NPAMOZ, AMOZ and FTD were 118%, 2.3% and 16.3%. Recoveries from AMOZ fortified animal tissues were in a range of 82.6–108.4% and the CV values were less than 12.5%. The immunoassay was further validated by a LC-MS/MS method and the two methods showed good correlation (r2 = 0.9908). The proposed icELISA could be used for an accurate monitoring of AMOZ in animal tissues.