The C-8-S-isomers of ergot alkaloids — a review of biological and analytical aspects

Abstract

Ergot alkaloids are secondary metabolites that are produced by fungi and contaminate cereal crops and grasses. The ergot alkaloids produced by Claviceps purpurea are the most abundant worldwide. The metabolites exist in two configurations, the C-8-R-isomer (R-epimer) and the C-8-S-isomer (S-epimer). These two configurations can interconvert to one another. Ergot alkaloids cause toxic effects after consumption of ergot-contaminated food and feed at various concentrations. For bioactivity reasons, the C-8-R-isomers have been studied to a greater extent than the C-8-S-isomer since the C-8-S-isomers were considered biologically inactive. However, recent studies suggest the contrary. Analytical assessment of ergot alkaloids now includes the C-8-S-isomers and high concentrations of specific C-8-S-isomers have been identified. The inclusion of the C-8-S-isomer in regulatory standards is reviewed. This review has identified that further research into the C-8-S-isomers of ergot alkaloids is warranted. In addition, the inclusion of the C-8-S-isomers into regulatory recommendations worldwide for food and feed should be implemented. The objectives of this review are to provide an overview of historic and current studies that have assessed the C-8-S-isomers. Specifically, this review will compare the C-8-R-isomers to the C-8-S-isomers with an emphasis on the biological activity and analytical assessment.

Determination of Ergot Alkaloids: Comparison of extraction efficiencies in several cereal production chains by UPLC-MS/MS

“…Determining EAs is of great importance and for this reason, a stable, e cient, and sensitive analytical method, able to determine and quantify them, should be developed (Chung 2021;Silva 2023;Cherewyk 2024). Considering the medium-high polarity of these compounds, according to the literature, the SLE (solid-liquid extraction) has mainly been used with non-polar organic solvents (like dichloromethane/ethylacetate/methanol/25% aqueous ammonia) under alkaline conditions (Muller 2009;Bryła 2015) or with polar solvents (like methanol and acetonitrile) under acidic conditions (Mulder 2015; Rubert 2012; Versilovskis 2020).…”

“…A maximum level of 500 µg/kg was established, but from the 1st July 2024, a reduction for some categories of foods should guarantee an higher level of safety. To safeguard humans' health, EFSA reported a total daily intake (TDI) for ergot alkaloids of 0.6 µg/kg body weight per day, and an acute reference dose of 1 µg/kg body weight (EFSA 2012).Determining EAs is of great importance and for this reason, a stable, e cient, and sensitive analytical method, able to determine and quantify them, should be developed (Chung 2021;Silva 2023;Cherewyk 2024). Considering the medium-high polarity of these compounds, according to the literature, the SLE (solid-liquid extraction) has mainly been used with non-polar organic solvents (like dichloromethane/ethylacetate/methanol/25% aqueous ammonia) under alkaline conditions (Muller 2009;Bryła 2015) or with polar solvents (like methanol and acetonitrile) under acidic conditions (Mulder 2015; Rubert 2012; Versilovskis 2020).…”