Cleaving Ergot Alkaloids by Hydrazinolysis—A Promising Approach for a Sum Parameter Screening Method

Abstract

Ergot alkaloids are mycotoxins formed by fungi of the Claviceps genus, which are some of the most common contaminants of food and feed worldwide. These toxins are a structurally heterogeneous group of compounds, sharing an ergoline backbone. Six structures and their corresponding stereoisomers are typically quantified by either HPLC-FLD or HPLC-MS/MS and the values subsequently summed up to determine the total ergot alkaloid content. For the development of a screening method targeting all ergot alkaloids simultaneously, the alkaloids need to be transferred to one homogeneous structure: a lysergic acid derivative. In this study, two promising cleaving methods—acidic esterification and hydrazinolysis—are compared, using dihydroergocristine as a model compound. While the acidic esterification proved to be unsuitable, due to long reaction times and oxidation sensitivity, hydrazinolysis reached a quantitative yield in 40‒60 min. Parallel workup of several samples is possible. An increasing effect on the reaction rate by the addition of ammonium iodide was demonstrated. Application of hydrazinolysis to a major ergot alkaloid mix solution showed that all ergopeptines were cleaved, but ergometrine/-inine was barely affected. Still, hydrazinolysis is a suitable tool for the development of a sum parameter screening method for ergot alkaloids in food and feed.

Quantification of Ergot Alkaloids via Lysergic Acid Hydrazide—Development and Comparison of a Sum Parameter Screening Method

“…The heterogeneity issue of the ergot alkaloids can be overcome by derivatization to a lysergic acid derivative as one uniform structure shared by all major ergot alkaloids. Previously, we reported a study examining and optimizing different cleaving methods regarding the suitability for a routine analysis SPM [27]. Hydrazinolysis of the ergot alkaloids to lysergic acid hydrazide (Figure 1c) turned out to be the most promising method in terms of handling, parallel sample work-up, and reaction time.…”

“…Based on our pre-study comparing different cleaving methods, hydrazinolysis proved to be the best method for a routine analysis method [27]. However, most tests and optimizations in the previous publication were performed on the structurally similar dihydroergocristine (DHEC) as a model compound, differing just by saturation of one double bond (C9-C10 of the ergoline structure).…”

Introduction to This Special Issue of Toxins: Application of Novel Methods for Mycotoxin Analysis

“…Indeed, this new regulation also calls for methods that can be implemented for quick compliance testing. An interesting approach for EA screening was proposed by Kuner et al [ 3 ], whose proposed method is based on EA cleavage by hydrazinolysis to convert them in a lysergic acid derivative, allowing their total content (sum of 12 EA) in food and feed to be quantified.…”

ERGOT Claviceps purpurea (Fries) Tulasne ALKALOID DIVERSITY AND VIRULENCE: EVOLUTION, GENETIC DIVERSIFICATION, AND METABOLIC ENGINEERING (review)

“…Методы отбора проб, выделения, очистки, обнаружения, количественной оценки алкалоидов спорыньи в продуктах питания, кормах, растительных материалах и тканях животных очень подробно описаны, стандартизированы и валидированы (92)(93)(94). Для количественного определения используют жидкостную хроматографию с флуоресцентным (LC-FLD) или масс-пектрометрическим (LC-МС/МС) детектированием (92,94). Реже применяется жидкостная хроматография с УФ-детекцией (LC-UV) (92) и иммуноферментный анализ (ELISA) (92,94,95).…”

“…Для количественного определения используют жидкостную хроматографию с флуоресцентным (LC-FLD) или масс-пектрометрическим (LC-МС/МС) детектированием (92,94). Реже применяется жидкостная хроматография с УФ-детекцией (LC-UV) (92) и иммуноферментный анализ (ELISA) (92,94,95). Также применяются экспрессметоды -количественный анализ с реактивом Ван Урка (van Urk reagent, колориметрическое неселективное определение суммы индольных алкалоидов) (40,94) и тонкослойная хроматография (40).…”