Synergistic Effect of Plant-Derived Deglucoruscin in Combination with Conventional Antimicrobials Against Staphylococcus aureus and Candida albicans

A detailed phytochemical investigation of rhizomes and roots of Ruscus aculeatus led to the isolation of fifteen pure compounds, belonging to the furostanol and spirostanol glycoside classes. Among them, one novel furostanol saponin (1) was identified, alongside twelve known furostanol (2–8) and spirostanol (11–15) saponins and two sulphated glycosides (9–10). Structural elucidation of all isolated compounds was accomplished through comprehensive 1D and 2D NMR spectroscopic analyses, complemented by mass spectrometry. The CHCl3 extract of Ruscus aculeatus and its major metabolite, the spirostanol derivative (12), exhibited a weak antimicrobial activity. Of particular interest, compound 12 when co-administered with voriconazole (VRC) showed a significant inhibitory effect against the azole-resistant Candida albicans ATCC 10231 strain, demonstrating a synergistic effect that underscores its potential to restore antifungal efficacy and combat resistance mechanisms. These findings highlight compound 12 as a promising adjuvant candidate in antifungal therapy, particularly against resistant Candida strains.