Simple and Direct Analysis of Falcarinol and other polyacetylenic Oxylipins in Carrots by Reverse Phase HPLC and Charged Aerosol Detection

Food plants in the Apiaceae (formerly Umbelliferae) family (e.g., carrots, parsley and celery) contain a group of bioactive C17-polyacetylene compounds, sometimes referred to as the polyacetylenic oxylipins. These compounds have been shown to be highly toxic towards bacteria and fungi and to exhibit a diverse range of biological activities in mammals, both beneficial (e.g., their cytotoxicity is proposed to reduce the risk of developing cancer) and detrimental (e.g., occupational allergic contact dermatitis). Three such compounds, falcarinol, falcarindiol and falcarindiol-3-acetate, natural pesticides produced by carrots in response to fungal diseases, have recently garnered a lot of media attention. Although falcarinols have a distinctive UV spectrum, the consequence of conjugated triple bonds, sensitivity tends to be poor due to the actual number of unsaturated bonds present in their structure. Measurement at 205nm offers the best sensitivity; however, sample chromatograms tend to be very complicated due to the presence of many other compounds absorbing at this wavelength. Charged aerosol detection (CAD) is a „universal“, mass-based detector and offers excellent sensitivity, a wide dynamic range, and the advantage that all non-volatile analytes produce similar response, independent of chemical structure. Additionally, unlike UV detection, analytes need not possess a chromophore in order to be determined. We developed a simple reversed-phase HPLC-CAD method to rapidly screen for falcarinol, falcarindiol, and falcarindiol-3-acetate. The method was sensitive (LOQ ˜5ng on column) and reproducible, and the analysis was completed in 15 mins. Data from fresh, baby carrots and Queen Anne's Lace (root, leaf, and flower) are presented.