Chrysoeriol and other polyphenols from Tecoma stans with lipase inhibitory activity

Tecoma stans is traditionally used by several ethnical groups in Mexico and Central America to treat diabetes. This species is mentioned in the majority of the ethnopharmacological studies compiled in Mexico focused in medicinal plants used as anti-diabetic treatment.

Recently, this plant was found to display a high level of pancreatic lipase inhibitory activity, in addition to the several action mechanisms already described. Here we show the phytochemical and in vitro pharmacological characterization of some of the compounds responsible for the antilipase activity.

Starting with a hydroalcoholic extract, fractions were obtained by liquid-liquid separation and successive processes of column chromatography purifications. Lipase inhibitory activity was measured employing a spectrophotometric analysis. For structural elucidation (1)H and (13)C NMR experiments were used. HPLC was used to quantify and confirm the identity of the bioactive compounds.

Bio-guided chemical purification of the hydroalcoholic extract produced an organic fraction (ethyl acetate, TsEA), flavone fractions (TsC1F13), (TsC1F15), (TsC1F16) and isolated compounds (chrysoeriol, apigenin, luteolin, and verbascoside) with the capability to inhibit the activity of pancreatic lipase. The most active fraction (TsC2F6B) was constituted by a mixture of Chrysoeriol (5,7-dihydroxy-2-[4-hydroxy-3-methoxyphenyl]chromen-4-one, 96% ) and Apigenin (4%). This flavone mixture displayed a percentage of inhibition of 85% when it was eavaluated at 0.25mg/mL. Luteolin and chrysoeriol produced a noncompetitive and mixed inhibition with values of IC50=63 and 158µM respectively. The content of chrysoeriol was also quantified in the hydroalcoholic extract (TsHAE) and organic fraction (TsEA) as 1% and 7% respectively. All of this confirms that high proportion of both flavones produce an increase of the biological activity due to they show the highest inhibition of lipase enzyme in a concentration dependant way.

These results evidence that the medicinal use of T. stans could be in part because of its lipase inhibitory activity allowing to adapt the administration of this plant before meals. Also this data could help to develop a novel phytopharmaceutical drug (standardized in luteolin, chrysoeriol, and apigenin) auxiliary for the Type 2 Diabetes mellitus.