N-Methoxycarbonyl-9,12-Dimethoxy-Norchelerythrine: A Novel Antifungal Type-III Benzo[c]phenanthridine from Zanthoxylum simulans Hance Seedlings

Abstract

Zanthoxylum simulans Hance, commonly known as Sichuan pepper, is a well-known medicinal plant recognized for its potential as a source of bioactive specialized metabolites. As part of our interest in natural antifungal compounds, the present study describes the discovery of an unreported N-alcoxycarbonylbenzo[c]phenanthridinium salt, N-methoxycarbonyl-9,12-dimethoxy-norchelerythrine 1 (a type-III benzo[c]phenanthridine), isolated from Z. simulans seedlings, which were propagated under controlled greenhouse conditions. Six-month seedlings were harvested and subjected to cold acid–base extraction. Chromatographic techniques achieved the isolation of 1 from raw alkaloid extract. The structural elucidation of 1 was accomplished through comprehensive spectroscopic analysis, including nuclear magnetic resonance and high-resolution mass spectrometry. Fusarium oxysporum, a fungal pathogen responsible for substantial agricultural losses, was exposed to different concentrations of the novel compound, exhibiting potent antifungal efficacy (IC50 < 3 µM) and fungicide effects. These findings highlight the potential of benzophenanthridines as antifungal leads and underscore the importance of exploring natural products for agricultural applications.