Inibição de α-glicosidase por preparações ricas em verbascosídeo de Lippia dulcis Trevir. (Verbenaceae)

Abstract

Lippia dulcis Trevir. (Verbenaceae) is a medicinal plant used by Amazonian communities in the control of diabetes and as a tranquilizer. Recent studies by our group have indicated the potential of L. dulcis preparations to inhibit α-glycosidase (GL). The present study originated an article that aimed to confirm the inhibitory activity of GL, as well as to quantify the verbascoside (VEB) and to perform studies of molecular anchoring of VEB with GL of Bacillus stearothermophilus. The same ethanolic extract (EE) and the fractions tested by Germano (2019) were reassessed. However, the present in vitro inhibition test of GL was optimized in terms of substrate concentration; the presence of GHS; and a strict control of the working temperature. In addition, the tests were performed in the presence and absence of a simulated gastric fluid. The EE and the fractions L. dulcis present inhibitory activity of Bacillus stearothermophilus GL. The fractions FAD2 and FAD3, in the assay without gastric fluid, were the ones that most inhibited GL, with inhibitions of 63.67% and 61.74% and UIG values of 675.00 and 654.57 μmol.min-1 .g -1 of sample, respectively. HPLC-DAD analysis confirmed the predominant presence of VEB in the samples. Theoretical studies of molecular docking of VEB with the enzyme GL from Bacillus stearothermophilus were consistent with the inhibitory activity of this enzyme in the experimental tests. Therefore, we can confirm that the preparations of L. dulcis present inhibitory activity of the enzyme GL from Bacillus stearothermophilus.