New Potential Use of Protium spruceanum in Hyperglycemia: α-Glucosidase Inhibition and Protection against Oxidative Stress

The high prevalence of diabetes and obesity encourages research for the development of α-glucosidase inhibitors from natural sources. This study evaluated the activity of fractions obtained from Protium spruceanum branches. Anti-α-glucosidase activity was investigated in vitro using 4-nitrophenyl-α-D-glucopyranoside as the substrate, while free-radical scavenging activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azinobis-3-ethylbenzotiazoline-6-sulfonic acid (ABTS) assays. Furthermore, a model of oxidative stress promoted by H2O2 in fibroblasts was employed, and cell viability was determined by sulforhodamine B. Fractions inhibited α-glucosidase activity effectively, highlighting the hydromethanolic fraction (HMF). Quercitrin, isolated from the HMF, was identified by spectroscopy and quantified by a validated high performance liquid chromatography with diode array detector (HPLC-DAD) method and exhibited free radical scavenging activity comparable to the HMF. However, this flavonoid showed low anti-α-glucosidase effect, suggesting a synergism effect among several components of the HMF. This proposal is also supported by the docking results obtained by PyRx software. The compounds present in the HMF showed a noncompetitive inhibition at the in silico simulation. Finally, the HMF also protected fibroblasts against cell death induced by oxidative stress. This is the first evidence of the capacity of P. spruceanum branches to inhibit α-glucosidase activity and to counteract oxidative stress. These results encourage the use of this Brazilian plant against hyperglycemia-correlated diseases.