Department of Chemistry, School of Natural Sciences and Mathematics, Chinhoyi University of Technology, Chinhoyi, Zimbabwe.
Department of Chemistry, School of Natural Sciences and Mathematics, Chinhoyi University of Technology, Chinhoyi, Zimbabwe; Department of Chemical Sciences, Faculty of Science and Technology Midlands State University, Private Bag 9055 Senga Road, Gweru, 263, Zimbabwe.
J Ethnopharmacol. 2023 Aug 10;312:116501. doi: 10.1016/j.jep.2023.116501. Epub 2023 Apr 24.
Herbal traditional medicine is used by millions of people in Africa for treatment of ailments such as diabetes mellitus, stomach disorders and respiratory diseases. Xeroderris stuhlmannii (Taub.) Mendonca & E.P. Sousa (X. stuhlmannii (Taub.)) is a medicinal plant used traditionally in Zimbabwe to treat type 2 diabetes mellitus (T2DM) and its complications. However, there is no scientific evidence to support its inhibitory effect against digestive enzymes (α-glucosidases) that are linked to high blood sugar in humans.
This work aims to investigate whether bioactive phytochemicals of crude X. stuhlmannii (Taub.) can scavenge free radicals and inhibit α-glucosidases in order to reduce blood sugar in humans.
Here we examined the free radical scavenging potential of crude aqueous, ethyl acetate and methanolic extracts of X. stuhlmannii (Taub.) using the diphenyl-2-picrylhydrazyl assay in vitro. Furthermore, we carried out in vitro inhibition of α-glucosidases (α-amylase and α-glucosidase) by the crude extracts using chromogenic 3,5-dinitrosalicylic acid and p-nitrophenyl-α-D-glucopyranoside substrates. We also used molecular docking approaches (Autodock Vina) to screen for bioactive phytochemical compounds targeting the digestive enzymes.
Our results showed that phytochemicals in X. stuhlmannii (Taub.) aqueous, ethyl acetate and methanolic extracts scavenged free radicals with IC values ranging from 0.002 to 0.013 μg/mL. Furthermore, crude aqueous, ethyl acetate and methanolic extracts significantly inhibited α-amylase and α-glucosidase with IC values of 10.5-29.5 μg/mL (versus 54.1 ± 0.7 μg/mL for acarbose) and 8.8-49.5 μg/mL (versus 161.4 ± 1.8 μg/mL for acarbose), respectively. In silico molecular docking findings and pharmacokinetic predictions showed that myricetin is likely a novel plant-derived α-glucosidase inhibitor.
Collectively, our findings suggest pharmacological targeting of digestive enzymes by X. stuhlmannii (Taub.) crude extracts may reduce blood sugar in humans with T2DM via inhibition of α-glucosidases.
在非洲，数以百万计的人使用草药传统医学来治疗糖尿病、胃病和呼吸道疾病等疾病。 Xeroderris stuhlmannii（Taub.）Mendonca 和 E.P. Sousa（X. stuhlmannii（Taub.））是津巴布韦传统上用于治疗 2 型糖尿病（T2DM）及其并发症的药用植物。然而，没有科学证据支持其对与人类高血糖相关的消化酶（α-葡萄糖苷酶）的抑制作用。
本工作旨在研究粗提 Xeroderris stuhlmannii（Taub.）的生物活性植物化学物质是否能清除自由基并抑制α-葡萄糖苷酶，从而降低人类的血糖。
在此，我们使用二苯基-2-苦基肼法（DPPH 法）体外检测 Xeroderris stuhlmannii（Taub.）的粗提物的水提物、乙酸乙酯提取物和甲醇提取物的自由基清除能力。此外，我们使用显色 3,5-二硝基水杨酸和对硝基苯-α-D-吡喃葡萄糖苷底物，对粗提物的α-葡萄糖苷酶（α-淀粉酶和α-葡萄糖苷酶）进行体外抑制作用。我们还使用分子对接方法（Autodock Vina）筛选针对消化酶的生物活性植物化学化合物。
我们的结果表明，Xeroderris stuhlmannii（Taub.）水提物、乙酸乙酯提取物和甲醇提取物中的植物化学物质可清除自由基，IC 值范围为 0.002 至 0.013μg/mL。此外，粗提物的水提物、乙酸乙酯提取物和甲醇提取物对α-淀粉酶和α-葡萄糖苷酶的抑制作用显著，IC 值分别为 10.5-29.5μg/mL（阿卡波糖为 54.1±0.7μg/mL）和 8.8-49.5μg/mL（阿卡波糖为 161.4±1.8μg/mL）。基于分子对接的体内药理学研究和药代动力学预测结果表明，杨梅素可能是一种新型的植物来源的α-葡萄糖苷酶抑制剂。
综上所述，Xeroderris stuhlmannii（Taub.）粗提取物通过靶向消化酶可能会降低 2 型糖尿病患者的血糖，这提示我们可以通过抑制α-葡萄糖苷酶来降低血糖。
