Phytochemical Characterization and Anti-Biofilm Activity of L. Roots.

In this study, three new undescribed triterpene saponins named primulasaponin III-V (-) were isolated from the roots of L. of Bulgarian origin together with the known primulasaponin I. Their structures were elucidated via 1D and 2D NMR spectroscopy and HR-ESI-MS. In addition, 17 known phenolic compounds (six flavones, three acetophenones, four bisbibenzyls, and four phenolic glycosides) were identified in the chloroform and methanol extracts. Among them, flavone, 2'-methoxyflavone, 3'-methoxyflavone, 3'-hydroxy-4',5'-dimethoxyflavone, 2',5'-dimethoxyflavone, 3'-methoxy-4',5'-methylendioxyflavone, paeonol, 2-primeverosyl-5-methoxy-acetophenone, and paeonolide were detected for the first time in the roots of The minimum inhibitory and minimum bactericidal concentrations of the chloroform and methanol extracts of roots and the saponin-enriched fraction were determined, with MIC values ranging between 0.5 and 1 mg/mL. Additionally, the tested samples were evaluated for their ability to inhibit biofilm formation in the presence of sub-MICs. All tested samples showed better biofilm inhibition of Gram-negative strains compared to Gram-positive strains. The strongest effect was observed for the chloroform extract against the biofilm formation of , while the saponin-enriched fraction showed the highest percentage of biofilm inhibition of , , and . At the same time, chloroform extract showed lower cytotoxicity against human keranocyte cell line HaCaT, as compared with methanol extract and the saponin-enriched fraction.