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.

糖尿病与肥胖症的高患病率推动了从天然资源中开发α-葡萄糖苷酶抑制剂（α-glucosidase inhibitor）的相关研究。本研究针对斯普鲁斯裂榄（Protium spruceanum）枝条提取物的分级组分活性展开评估：以4-硝基苯基-α-D-吡喃葡萄糖苷（4-nitrophenyl-α-D-glucopyranoside）为底物，通过体外实验探究各组分的抗α-葡萄糖苷酶活性；同时采用2,2-二苯基-1-苦基肼基（DPPH）与2,2'-联氮-双-3-乙基苯并噻唑啉-6-磺酸（ABTS）法检测其自由基清除活性。此外，本研究构建了过氧化氢（H₂O₂）诱导的成纤维细胞氧化应激模型，并采用磺酰罗丹明B（sulforhodamine B）法检测细胞活力。各组分均能有效抑制α-葡萄糖苷酶活性，其中水甲醇分级组分（hydromethanolic fraction, HMF）表现最为突出。从HMF中分离得到的槲皮苷（quercitrin）经光谱法鉴定，并通过经验证的高效液相色谱-二极管阵列检测器（HPLC-DAD）法完成定量分析，其自由基清除活性与HMF相当。但该黄酮类化合物的抗α-葡萄糖苷酶活性较弱，提示HMF中的多种组分可能存在协同作用，该推论亦得到PyRx软件模拟分子对接结果的佐证。计算机模拟（in silico）结果显示，HMF中的化合物均表现出非竞争性抑制作用。最后，HMF还可保护成纤维细胞免受氧化应激诱导的细胞死亡。本研究首次证实了斯普鲁斯裂榄（P. spruceanum）枝条具有抑制α-葡萄糖苷酶活性与对抗氧化应激的能力，上述结果为利用该巴西植物治疗高血糖相关疾病提供了科学依据。