Phytochemical Investigation of Juncus hybridus: Truxinic Acid Sucrose Diesters and α-Glucosidase Inhibitory Activity

Background/Objectives: Truxinic acid derivatives, particularly their glycosylated forms, are rare natural products with a limited distribution in the plant kingdom. As part of our ongoing phytochemical investigations of Juncaceae species, the secondary metabolites of Juncus hybridus were investigated. Methods: Chromatographic separation of the methanolic extract resulted in the isolation of fifteen compounds, including truxinic acid derivatives, phenanthrenes, flavonoids, other phenolic compounds, and megastigmanes. Their structures were elucidated by extensive spectroscopic analyses, including 1D and 2D NMR spectroscopy and high-resolution mass spectrometry (HR-MS). Results: Two compounds, junhybridins A and B, were identified as new truxinic acid sucrose diesters. This study provides a comprehensive report of the phytochemical composition of J. hybridus. The identification of two new truxinic acid derivatives further expands the known chemical diversity of the Juncaceae family. Seven selected compounds were evaluated for their α-glucosidase inhibitory activity. Among them, luteolin displayed the strongest inhibition, with an IC50 value of 5.91 μM, while juncusol also exhibited considerable activity. Conclusions: These findings expand the chemotaxonomic knowledge of the Juncaceae family and identify J. hybridus as an unexpected source of rare glycosylated truxinic acid derivatives.