Isochlorogenic Acid Glucosides from the Arabian Medicinal Plant and Their Antimicrobial Activities.

A phytochemical investigation of the stems of the Arabian plant afforded three new isochlorogenic acid derivatives, namely isochlorogenic acid A-3'---glucopyranoside (), isochlorogenic acid A-3'---glucopyranoside methyl ester (), and isochlorogenic acid C-3'---glucopyranoside (), obtained along with thirteen known secondary metabolites belonging to distinct structural classes. The structures of the new metabolites were elucidated by modern spectroscopic techniues based on high-resolution mass spectrometry (HR-ESIMS) and 1D/2D nuclear magnetic resonance (NMR). All isolated compounds were tested for their potential antimicrobial activity against four different bacterial strains (, , , and ), in addition to a fungal strain (), The results were expressed as the diameter of the clear zone (in millimetres) around each well. Compounds and (isochlorogenic acid A-3'---glucopyranoside and isochlorogenic acid C-3'---glucopyranoside, respectively) displayed remarkable antifungal effect and potent antibacterial activities against and , respectively. 3,4-10-trihydroxy-8-acetyloxyguaian-12,6-olide () and angelicoidenol 2---d-glucopyranoside () emerged as interesting dual antibacterial (selective on )/antifungal agents.