A monoclonal antibody (mAb) specific to ochratoxin A (OTA) was produced from a stable hybridoma cell line, 9C9H9, generated by the fusion of P3/NS1/1-AG4-1 myeloma cells with spleen cells isolated from a BALB/c mouse immunized with OTA-keyhole limpet hemocyanin. The 9C9H9 mAb belongs to the immunoglobulin G1 (kappa chain) isotype. A competitive direct enzyme-linked immunosorbent assay (cdELISA) and a competitive indirect ELISA were established for antibody characterization. The concentrations causing 50% inhibition of binding of OTA-horseradish peroxidase to the antibody by OTA, OTB, and OTC were found to be 0.32, 0.17, and 0.28 ng/mL, respectively, in the cdELISA. A sensitive and rapid mAb-based gold nanoparticle immunochromatographic strip was also developed using this mAb. This strip has a detection limit of 5 ng/mL for OTA and can be completed in 10 min. Analysis of OTA in coffee samples revealed that data obtained from immunochromatographic strip were in a good agreement with those obtained from cdELISA. The mAb-based cdELISA and immunochromatographic strip assay established in this study were sensitive and accurate for rapid screening of OTA in coffee samples.

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Monascus purpureus and its fermentation products have been used in food coloring and meat preservation in Asia for centuries and have also been recently used as dietary supplements because of their cholesterol-lowering ability. However, the presence of the mycotoxin citrinin (CTN), a secondary metabolite of Monascus species, in fermentation products is a potential threat to public health. In the present study, HPLC was used to analyze CTN levels in lipid and aqueous extracts of commercialized Monascus products. CTN was detected in lipid extracts of all examined samples at concentrations varying between 0.28 and 6.29 microg/g, but was not found in aqueous extracts. When human embryonic kidney cells (HEK293) were incubated for 72 h with Monascus extracts, the concentrations causing 50% cell death by all lipid extracts were in the range of 1.8-4.7 mg/mL, whereas aqueous extracts showed a lower cytotoxicity. Incubation of HEK293 cells with 60 microM pure CTN for 72 h caused cell viability to fall to 50% of control levels. In addition, coadministration of pure CTN and lipid extracts from Monascus samples significantly enhanced CTN cytotoxicity for HEK293 cells using the MTT assay. These results provide the first information about the cytotoxic effects of various Monascus samples and CTN-Monascus mixtures on a human cell line.