Enzyme Immunoassay for Ursodeoxycholic Acid 7-N-Acetylglucosaminides in Human Urine

A specific enzyme immunoassay (EIA) for ursodeoxycholic acid 7-N acetylglucosaminides (UDCA-7-NAGs), novel metabolites of ursodeoxycholic acid, has been developed. The EIA was based upon antisera elicited against the glycine conjugated UDCA-7-NAG-bovine serum albumin conjugate and horseradish peroxidase-labeled-UDCA-7-NAG. The sensitivity was significantly improved by the utilization of the bridge heterologous combination system. An appropriate dose response curve of EIA for glycine conjugated UDCA-7-NAG was obtained in the range of 0.3-6ng/tube. The specificity of ETA proved to be satisfactory in terms of cross-reactivities to related bile acids. The proposed method is useful for the determination of UDCA-7-NAGs in human urine with acceptable reliability.