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United States Department of Agriculture

Agricultural Research Service

Research Project: DEVELOPMENT AND EVALUATION OF IMPROVED MATERIALS FOR MYCOTOXIN ANALYSIS

Location: Bacterial Foodborne Pathogens & Mycology Research Unit

Title: Photolysis of Cyclopiazonic Acid to Fluorescent Products

Author
item Maragos, Chris

Submitted to: World Mycotoxin Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 9, 2008
Publication Date: December 22, 2008
Citation: Maragos, C.M. 2008. Photolysis of Cyclopiazonic Acid to Fluorescent Products. World Mycotoxin Journal. 2(1):77-84.

Interpretive Summary: Cyclopiazonic acid (CPA) is a mycotoxin produced by some of the same species of fungi that produce the more widely known aflatoxins. As a consequence it has been found previously that CPA and the aflatoxins may co-occur in commodities under certain conditions. CPA is not fluorescent, so most methods for detecting this toxin rely upon its absorbance in the ultraviolet (UV) region. We have determined that, upon exposure to strong UV light, CPA reacts to form fluorescent products. Because fluorescence is generally a less widespread phenomenon than absorbance, this effect may be used to impart an additional level of selectivity upon analyses for this toxin. The ability to photolyze CPA and detect this toxin by fluorescence may open up new avenues for determination of this mycotoxin alone or together with the aflatoxins.

Technical Abstract: Cyclopiazonic acid (CPA) is a mycotoxin produced by some of the same species of fungi that produce the more widely known aflatoxins. As a consequence it has been found previously that CPA and the aflatoxins may co-occur in commodities under certain conditions. CPA, which is a substituted indole, has a chromophore with absorptions in the ultraviolet (UV) region (223 nm, 278 nm). Quantification of CPA is commonly accomplished by liquid chromatographic separation followed by detection of one of the UV absorbances. CPA has not previously been described as fluorescent, and it likely is not. However, herein we report that, following exposure to high intensity UV light in a photochemical reactor, fluorescent products of CPA are produced. In methanol or aqueous acetonitrile these products have an excitation maximum of 372 nm and an emission maximum of 462 nm. Upon exposure to UV light for extended periods a decrease in the absorbance of CPA at 223 nm and 278 nm and a concomitant increase in fluorescence was observed. CPA and aflatoxin B1 were separated by reverse-phase liquid chromatography and the eluant was subjected to post-column photolysis, which allowed the fluorescence detection of both toxins. The ability to photolyze CPA and detect this toxin by fluorescence may open up new avenues for determination of this mycotoxin alone or together with the aflatoxins.

Last Modified: 7/31/2014
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