Equisarmine, a new steroidal glycoalkaloid, from sterile stems of Equisetum arvense
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Atsumi Shimada
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Hiroshi Ueno
Abstract
Glutaminase is an important target that is often over expressed in neurodegenerative and lifestyle related diseases but few effective inhibitors of this enzyme have yet reached clinical trials. To select plants with high glutaminase inhibitory activities, this study was to compare glutaminase inhibitory activities of 20 plant extracts and investigate the isolation, structural elucidation and the inhibitory activity of an active compound from the selected extract of Equisetum arvense L. (horsetail). Equisarmine (1), a new steroidal glycoalkaloid, was elucidated by analyzing its nuclear magnetic resonance (NMR) and electrospray ionization mass spectrometry (ESI-MS) spectral data. The half maximal inhibitory concentration (IC50) values of 1 and 6-diazo-5-oxo-L-norleucine (DON) as control were 0.72 mM and 0.27 mM, respectively. The results suggest that the extract from horsetail shows the strongest biological activity among 20 tested plant extracts, and that 1 may serve as a lead compound for the prevention and treatment of neurodegenerative and lifestyle-related diseases by targeting glutaminase. This is the first report on the structure and glutaminase inhibitory activity of 1.
Funding source: JSPS KAKENHI
Award Identifier / Grant number: JP22K05484
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Research ethics: The local Institutional Review Board deemed the study exempt from review.
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Informed consent: Not applicable.
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Author contributions: The authors have accepted responsibility for the entire content of this manuscript and approved its submission.
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Use of Large Language Models, AI and Machine Learning Tools: None declared.
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Conflict of interest: The authors state no conflict of interest.
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Research funding: This work was supported by JSPS KAKENHI Grant Number JP22K05484 to A.Shimada.
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Data availability: The raw data can be obtained on request from the corresponding author.
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Supplementary Material
This article contains supplementary material (https://doi.org/10.1515/znc-2025-0126).
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