Strong-cation-exchange, solid-phase extraction of pyrrolizidine alkaloids and their N-oxides from honey samples was followed by reduction of the N-oxides and subsequent analysis of total pyrrolizidine alkaloids using high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. A limited survey of 63 preprocessing samples of honey, purposefully biased toward honeys attributed to floral sources known to produce pyrrolizidine alkaloids, demonstrated levels of pyrrolizidine alkaloids up to approximately 2000 parts per billion (ppb) in a sample attributed to Echium plantagineum. Up to 800 ppb pyrrolizidine alkaloids was detected in some honeys not attributed by the collector to any pyrrolizidine alkaloid-producing floral source. No pyrrolizidine alkaloids were detected in approximately 30% of the samples in this limited study, while some honeys showed the copresence of pyrrolizidine alkaloids from multiple floral sources such as E. plantagineum and Heliotropium europaeum. In addition, retail samples of blended honeys (with no labeling to suggest that pyrrolizidine alkaloid-producing floral sources were used in the blends) have been shown to contain up to approximately 250 ppb pyrrolizidine alkaloids.
The pyrrolizidine alkaloids of 68 Australian honey samples as well as extracts of Australian and New Zealand pollen samples collected from anthers, and pollen baskets harvested from honeybees, were identified and quantified using HPLC-atmospheric pressure chemical ionization (APCI)-MS. HPLC-electrospray ionization (ESI)-MS was applied for simultaneous quantitation of the alkaloids and their N-oxides. The highest level of pyrrolizidine alkaloid content, in excess of 2500 µg equivalents of echimidine per kg of honey (ppb), was observed with an Echium plantagineum-derived sample. Honeys attributed to E. plantagineum, Heliotropium europaeum and H. amplexicaule were determined by the presence of echimidine, heliotrine and indicine respectively as the major alkaloid observed, as identified by HPLC-APCI-MS. Use of the silica-based SCX SPE columns on the honey and pollen samples tentatively identified a new suite of alkaloids/N-oxides characteristic of E. vulgare. The highest level determined was approximately 5000 ppb. Four samples returned levels of between 1200 and 2850 ppb and four were between 550 and 950 ppb. The level of pyrrolizidine alkaloids/N-oxides in the pure pollen was considerably higher compared to the honey at about 11 000 ± 3000 ppm (mg/kg) whereas levels in the pollen baskets from honeybees returned lower levels of alkaloids, with a range of 925 to 4000 ppm and a mean (from 4 samples) of 2125 ppm. The combination of silica-based SCX SPE and HPLC-ESI-MS analysis has confirmed the natural predominance of N-oxides over the parent, tertiary-base pyrrolizidine alkaloids in the honey and pollen samples.
This report describes the advantages and disadvantages associated with the application of gas chromatography/mass spectrometry and liquid chromatography/electrospray and atmospheric pressure chemical ionization mass spectrometry to trace analysis of pyrrolizidine alkaloids and PA N-oxides.
Nematode seed galls from Festuca nigrescens obtained from New Zealand and USA were examined using an ELISA for the presence of an antigen derived from the corynetoxin (CT)-producing bacterium, Rathayibacter toxicus. Since the galls from New Zealand were only weakly positive, and those from USA were negative, for the presence of the R. toxicus antigen, it was determined whether CT-like material was present. Tunicaminyluracil-glycolipids, similar to CTs produced by R. toxicus were identified in old nematode seed galls from F. nigrescens from USA and New Zealand. The estimates of CT-like levels in galls by ELISA, HPLC and in vitro enzyme inhibition were consistent.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.