Chemical Constituents of Bai Ethnomedicinal Plant Pararuellia delavayana and Their Antimicrobial Activity

Chemical constituents from the Bai ethnomedicinal plant Pararuellia delavayana and their antimicrobial activity were investigated. The isolation and purification were performed using various column chromatography techniques, including silica gel, RP-18, D101 macroporous resin, Sephadex LH-20, and HPLC. The structures of the isolated compounds were elucidated based on comprehensive analysis of their physicochemical properties, 1D, 2D-NMR spectra, and mass spectrometry data. The antimicrobial activities of all isolates were evaluated using the microbroth dilution method. Eleven compounds were isolated from the ethyl acetate fraction of a 70% acetone extract of the dried whole plant, and determined as benzyl-(5-O-syringoyl-β-D-apiofuranosyl)-(1→2)-β-D-glucopyranoside (1), (6R, 9R)-3-oxo-α-ionol-9-O-β-D-glucopyranoside (2), byzantionoside B (3), linarionoside B (4), (-)-syringaresinol-4-O-β-D-glucopyranoside (5), (-)-syringaresinol-4-O-β-D-apiofuranosyl-(1→2)-β-D-glucopyranoside (6), (+)-lyonirenisol-3a-O-β-D-glucopyranoside (7), luteolin (8), apigenin (9), tilianin (10), and β-sitosterol (11). Compound 1 was a new benzyl alcohol glycoside, named pararuellioside A. All compounds were reported from P. delavayana for the first time. According to in vitro antimicrobial assay, compound 8 exhibited significant activity against Staphylococcus epidermidis with a minimum inhibitory concentration (MIC) value of 50 μg/mL.