Phytochemical Study of Eryngium cymosum F. Delaroche and the Inhibitory Capacity of Its Main Compounds on Two Glucose-Producing Pathway Enzymes

One undescribed acylated flavonol glucoside and five known compounds were isolated from the aerial parts of Eryngium cymosum F. Delaroche, a plant that is used in traditional Mexican medicine to treat type 2 diabetes. The chemical structures of the isolated compounds were elucidated using a variety of spectroscopic techniques, including 1D and 2D nuclear magnetic resonance (NMR) and mass spectrometry (MS). Chlorogenic acid (1), rosmarinic acid (2), caffeic acid (3), protocatechuic acid (4), kaempferol-3-O-(2,6-di-O-trans-ρ-coumaryl)-β-d-glucopyranoside (5), and the new acylated flavonol glucoside quercetin-3-O-(2,6-di-O-trans-ρ-coumaryl)-β-d-glucopyranoside (6) were isolated. This is the first report on the natural occurrence of quercetin-3-O-(2,6-di-O-trans-ρ-coumaryl)-β-D-glucopyranoside (6). In addition, according to the HPLC profile obtained for the water extract (WE), chlorogenic acid (1) and rosmarinic acid (2) were identified as the main compounds, while kaempferol-3-O-(2,6-di-O-trans-ρ-coumaryl)-β-d-glucopyranoside (5) were the main compound in the butanolic extract. We demonstrate the important role of compound 5 over the inhibition of G6Pase and FBPase. The isolated compounds may play an important role in the hypoglycemic effect of the extract and may act in a synergic way, but more experiments are needed to corroborate these findings.