Pyrrolizidine Alkaloids – Natural Toxins Risk in Queensland Honey

Abstract

Pyrrolizidine alkaloids are widely distributed natural toxins and their consumption has been connected with acute and chronic liver damage, and even death, in wildlife, livestock and humans. There are more than 600 pyrrolizidine alkaloids, with the 1,2-unsaturated pyrrolizidine alkaloids being potent carcinogens. Their presence in food is concerning to food regulators, and Food Standards Australia New Zealand (FSANZ) have established a provisional tolerable daily intake for these alkaloids of 1 μg/kg BW/day.
Pyrrolizidine alkaloids occur in approximately 3% of flowering plants. Internationally it has been reported that such toxins can be found in honey due to transfer by bees of pollen/nectar from certain flowers, particularly Heliotropium, Crotalaria, Echium and Senecio species. Concern has been raised as to the extent of this contamination in Australian honey, but their presence in Queensland honey has not previously been examined.
Greater than 200 honey samples, sourced from markets and shops in Queensland, were analysed by UHPLC-MS/MS for 20 common pyrrolizidine alkaloids. Correlations between the occurrence of pyrrolizidine alkaloids and the botanical/ geographical origin of the honey are essential as pyrrolizidine alkaloid contamination at up to 4000 μg/kg has been detected. In this study, the predominant alkaloids detected were isomers lycopsamine, indicine and intermedine, displaying identical MS/MS spectra. Separation of these isomers by UHPLC has enabled comparisons of the relative amounts present in honey to those amounts in east coast pyrrolizidine alkaloid containing plants. Notably, only low levels of alkaloids from Echium plantagineum (Paterson’s curse) and Senecio species were detected in honey. Plant pyrrolizidine alkaloid profiles will be compared to those found in honey samples.