Chemical constituents and hypoglycemic activity of Phlomis tuberosa / 中草药

ABSTRACT

Objective: To study the chemical constituents and hypoglycemic activity of Phlomis tuberosa. Methods: The db/db diabetic mice was used to screen the hypoglycemic active site of P. tuberosa. The chemical constituents were isolated and purified by various separation and analysis techniques. The structures of these compounds were identified by spectroscopic analysis (1H-, 13C-NMR and MS). The hypoglycemic activities of these compounds were verified by the DPP-4 inhibitory activity in vitro. Results: Ethyl acetate extract of P. tuberosa showed significant hypoglycemic effect. Twenty-five compounds were isolated from the active site, containing β-stiosterol (1), stigmasterol (2), daucosterol (3), clerosterol-stigmast-4-ene-3,6-dione (4), 22-dehydro- stigmast-4-ene-3,6-dione (5), ellagic acid (6), ethyl gallate (7), gllagic acid (8), 4-hydroxybenzoic acid (9), 3,4-diohydroxybenzoic acid (10), cinnamic acid (11), p-hydroxy-cinnamic acid (12), caffeic acid (13), 5-hydromethylfuraldehyde (14), quinic acid (15), chlorogenic acid (16), ferulic (17), 2,3-dimethoxy-5-methyl-6-(3,7,11,15,19-pentamethyl-2,6,10,14,18-eicosapentaen-1- yl)-2,5-cyclohexadiene-1,4-dione (18), 1-O-caffeoyl- quinic acid (19), 3,5-dimethoxy-4-hydroxy-benzene carbonic-1-O-β-D-glucoside (20), 2-O-butyl-α-D-fructofuranoside (21), n-octadecanoic acid (22), stearic acid (23), methyl-5-(hydroxymethyl) furan-2-carboxylate (24) and 4-hydroxy-3-methoxy-benzaldehyde(25). Nine compounds were obtained from the genus Phlomis for the first time, in which ellagic acid (6), quinic acid (15), and 1-O- caffeoylquinic acid (19) showed strong DPP-4 inhibitory activity with IC50 of 72.3, 89.2, and 103.4 μmol/L, respectively. The IC50 of the positive drug diprotin A was 50 μmol/L. Conclusion: Compounds (3-7 and 18-21) are obtained from the genus Phlomis for the first time. Compound 6, 15, and 19 show DPP-4 inhibitory activities.