Photoreaction of indole-containing mycotoxins to fluorescent products

Development and Evaluation of Monoclonal Antibodies for Paxilline

Paxilline (PAX) is a tremorgenic mycotoxin that has been found in perennial ryegrass infected with Acremonium lolii. To facilitate screening for this toxin, four murine monoclonal antibodies (mAbs) were developed. In competitive indirect enzyme-linked immunosorbent assays (CI-ELISAs) the concentrations of PAX required to inhibit signal development by 50% (IC50s) ranged from 1.2 to 2.5 ng/mL. One mAb (2-9) was applied to the detection of PAX in maize silage. The assay was sensitive to the effects of solvents, with 5% acetonitrile or 20% methanol causing a two-fold or greater increase in IC50. For analysis of silage samples, extracts were cleaned up by adsorbing potential matrix interferences onto a solid phase extraction column. The non-retained extract was then diluted with buffer to reduce solvent content prior to assay. Using this method, the limit of detection for PAX in dried silage was 15 µg/kg and the limit of quantification was 90 µg/kg. Recovery from samples spiked over the range of 100 to 1000 µg/kg averaged 106% ± 18%. The assay was applied to 86 maize silage samples, with many having detectable, but none having quantifiable, levels of PAX. The results suggest the CI-ELISA can be applied as a sensitive technique for the screening of PAX in maize silage.

HPLC method for simultaneous detection of aflatoxins and cyclopiazonic acid

Aspergillus species in section Flavi are among the most relevant mycotoxigenic fungi. The organisms are well-known producers of the highly carcinogenic aflatoxins and of other mycotoxins, such as cyclopiazonic acid. Aflatoxins and cyclopiazonic acid analyses can be routinely used for identification purposes within the section. Two separate chromatographic runs with distinct columns and detectors for each toxin were required in previous reports. A straightforward high performance liquid chromatography (HPLC) procedure for the simultaneous detection of these compounds in fungal cultures was developed in the present work using a methanol/water mobile phase, postcolumn photochemical derivatisation and fluorescence detection. The proposed method was tested with standards and fungal extracts of 24 Aspergillus section Flavi strains and compared to the common individual detection of these mycotoxins by HPLC analyses.