Glycosylated Phenols and an Unprecedented Diacid from the Saudi Plant Cissus rotundifolia

Bioassay-guided investigation of the Saudi medicinal and edible plant Cissus rotundifolia yielded seven metabolites, including the new sucrose diester cissuxinoside (1) and the unprecedented cissoic acid (2), belonging to unusual classes of secondary metabolites. Their chemical structures were elucidated through a combination of HR-MS and NMR data. The absolute configuration of cissoic acid was assigned by comparison of experimental and TDDFT-calculated electronic circular dichroism (ECD) spectra. In addition, three rare C-glycosyl flavones (3-5) were fully characterized and for 3 and 4 NMR data are reported here for the first time. This study identified 1-O-(4-coumaroyl)-β-D-glucopyranose (7) as the main compound responsible for the glucose uptake stimulation effect exerted by the extract.