Comparison of electrospray ionization and atmospheric pressure photoionization liquid chromatography mass spectrometry methods for analysis of ergot alkaloids from endophyte-infected sleepygrass (Achnatherum robustum)

Abstract

Ergot alkaloids are mycotoxins with an array of biological effects. With this study, we investigated for the first time the application of atmospheric pressure photoionization (APPI) as an ionization method for LC-MS analysis of ergot alkaloids, and compared its performance to that of the more established technique of electrospray ionization (ESI). Samples of the grass Achnatherum robustum infected with the ergot producing Epichloë fungus were extracted using cold methanol and subjected to reserved-phase HPLC-ESI-MS and HPLC-APPI-MS analysis. The ergot alkaloids ergonovine and lysergic acid amide were detected in these samples, and quantified via external calibration. Validation parameters were recorded in accordance with ICH guidelines. A triple quadrupole MS operated in multiple reaction monitoring yielded the lowest detection limits. The performance of APPI and ESI methods was comparable. Both methods were subject to very little matrix interference, with percent recoveries ranging from 82% to 100%. As determined with HPLC-APPI-MS quantification, lysergic acid amide and ergonovine were extracted from an A. robustum sample infected with the Epichloë fungus at concentrations of 1.143±0.051 ppm and 0.2822±0.0071 ppm, respectively. There was no statistically significant difference between these concentrations and those determined using ESI for the same samples.

Interspecific and intraspecific hybridEpichloëspecies symbiotic with the North American native grassPoa alsodes

“…For comparison, this method was applied to the analysis of endophyte-infected Elymus canadensis (strain NFe746) and the alkaloids NANL, chanoclavine I, and peramine were all detected, consistent with previous literature (Clay and Schardl 2002;Charlton et al 2012;Schardl et al 2013bSchardl et al , 2013c. In addition, a sample of endophyte-infected sleepygrass (Achnatherum robustum) previously shown to contain chanoclavine (Shymanovich et al 2015;Jarmusch et al 2016) was also analyzed, and this compound was detected in the control sample, as expected. A synthetic standard of NANL was included as a positive control and for the purpose of estimating NANL concentration in plant samples.…”

Selection and characterization of botanical natural products for research studies: a NaPDI center recommended approach

“…One technique is to conduct a "spike recovery" study, in which a standard is spiked into the botanical matrix at known concentrations, and the concentration is backcalculated to evaluate accuracy. 95,[196][197][198] Quantitative NMR and pre-or post-column derivatization 199 also can be used to quantify metabolites without known standards. 200 We end this section with a word of caution, which is that it is easy to become so focused on method validation that one is distracted from the overall research question (which typically relates to safety and/or efficacy of a botanical).…”

Chemical composition, insecticidal and biochemical effects of Melaleuca alternifolia essential oil on the Helicoverpa armigera

“…Many plants contain various bioactive secondary metabolites, such as terpenes , flavonoids (Sharififar et al, 2016) and alkaloids (Jarmusch et al, 2016), which are natural pesticides source. To cope with bioactive secondary metabolites, the insects can This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.…”