Ergochromes: Heretofore Neglected Side of Ergot Toxicity.

Miroslav Flieger,Petr Novák,Eva Stodůlková,Marek Kuzma,Miroslav Kolařík,Valéria Grobárová,Kirk D Broders,Kamila Píchová,Stephen A Wyka,Petr Man,Jan Černý,Ladislav Cvak

doi:10.3390/toxins11080439

Abstract

Ergot, fungal genus Claviceps, are worldwide distributed grass pathogens known for their production of toxic ergot alkaloids (EAs) and the great agricultural impact they have on both cereal crop and farm animal production. EAs are traditionally considered as the only factor responsible for ergot toxicity. Using broad sampling covering 13 ergot species infecting wild or agricultural grasses (including cereals) across Europe, USA, New Zealand, and South Africa we showed that the content of ergochrome pigments were comparable to the content of EAs in sclerotia. While secalonic acids A–C (SAs), the main ergot ergochromes (ECs), are well known toxins, our study is the first to address the question about their contribution to overall ergot toxicity. Based on our and published data, the importance of SAs in acute intoxication seems to be negligible, but the effect of chronic exposure needs to be evaluated. Nevertheless, they have biological activities at doses corresponding to quantities found in natural conditions. Our study highlights the need for a re-evaluation of ergot toxicity mechanisms and further studies of SAs’ impact on livestock production and food safety.

Highlights

Ergot, the genus Claviceps (Ascomycota: Hypocreales) includes obligate plant parasitic fungi that develop in the ovary of grasses, sedges, and rushes and form sclerotia containing toxins
While many researchers continue to focus on compounds that possess the tetracyclic ergoline ring of ergot alkaloids, we showed that so far neglected secalonic acids A–C (SAs) are abundant as alkaloids and have similar toxicity to cell cultures
Despite the fact that ergochromes do not play a significant role in acute toxicity of ergot, the complexity of the secondary metabolites produced by Claviceps species including secalonic acids points to a more complex fungus-grazing animal interaction

Summary

Introduction

The genus Claviceps (Ascomycota: Hypocreales) includes obligate plant parasitic fungi that develop in the ovary of grasses (including cereals), sedges, and rushes and form sclerotia containing toxins. The famous rye ergot, Claviceps purpurea, is a member of the section Claviceps which is specified by the production of highly toxic ergopeptines [1]. It has been shown, that C. purpurea sensu lato L.) is a complex of four cryptic species with different host grass spectra. S.) and C. humidiphila, cereal crops seem to be infected by just C. purpurea s. Toxins 2019, 11, 439 important from an agricultural point of view [2,3]. Recent findings suggest further cryptic diversification among North American C. purpurea s. l. specimens and their impacts on agricultural remains uncertain [4]

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