Preparation of CIT-protein conjugates using a novel citrinin derivative as hapten

Abstract

In this paper, a novel citrinin (CIT) derivative, 8-MeO-CIT, was synthesized by the method of methylation, with the protection of hydroxyl in CIT using methoxyl for the first time. The overall yield of 8-methoxyl-citrinin (8-MeO-CIT) was about 49.8%. 8-MeO-CIT was then purified by two-dimensional TLC, and its characteristics were analyzed by HPLC and ESI–MS. 8-MeO-CIT-BSA and CIT-BSA were prepared using the NHS-ester method and the Mannich-type method, respectively. Characteristics of both CIT-protein conjugates were determined by UV–Vis and FT-IR spectroscopy. Results showed that the conjugate molar ratio and utilized ratio of CIT in 8-MeO-CIT-BSA increased by 4.1 and 18.4% compared to CIT-BSA. It suggested that NHS-ester method using novel 8-MeO-CIT as hapten might prefer to traditional Mannich-type method for preparing CIT-protein conjugates.