Quinoa (Chenopodium quinoa Willd.) protein hydrolysates with in vitro dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant properties

The potential of quinoa to act as a source of dipeptidyl peptidase IV (DPP-IV) inhibitory and antioxidant peptides was studied. A quinoa protein isolate (QPI) with a purity of 40.73 ± 0.90% was prepared. The QPI was hydrolysed at 50 °C for 3 h with two enzyme preparations: papain (P) and a microbial papain-like enzyme (PL) to yield quinoa protein hydrolysates (QPHs). The hydrolysates were evaluated for their DPP-IV inhibitory and oxygen radical absorbance capacity (ORAC) activities. Protein hydrolysis was observed in the QPI control, possibly due to the activity of quinoa endogenous proteinases. The QPI control had significantly higher DPP-IV half maximal inhibitory concentrations (IC₅₀) and lower ORAC values than QPH-P and QPH-PL (P < 0.05). Both QPH-P and QPH-PL had similar DPP-IV IC₅₀ and ORAC values. QPH-P had a DPP-IV IC₅₀ value of 0.88 ± 0.05 mg mL⁻¹ and an ORAC activity of 501.60 ± 77.34 μmol Trolox equivalent (T.E.) g⁻¹. To our understanding, this is the first study demonstrating the in vitro DPP-IV inhibitory properties of quinoa protein hydrolysates. QPHs may have potential as functional ingredients with serum glucose lowering properties.     

猴头菌子实体醇提物的生物活性

通过对猴头菌(Hericium erinaceus)子实体的乙醇提取物进行萃取,得到了石油醚、氯仿、乙酸乙酯、正丁醇和剩余水分部共5个分部,通过定性鉴定分析了其中次生代谢物质的成分,并以保护PC12细胞损伤和抑制DPP-IV酶的活性为实验模型,寻找具有抗衰老、降血糖等生物活性组分。结果表明,猴头菌子实体的醇提取物中可能含有生物碱、酚类(或鞣质)、甾类(或萜类)、蒽醌等物质。5个分部对NaN3诱导所致的PC12细胞损伤均具有一定恢复作用,与对照(69.5%)比,剩余水分部活性最强(84.6%)。石油醚分部和剩余分部在浓度为1.0mg/mL时对DPP-IV酶的抑制率超过了阳性对照药(25.25%),而氯仿萃取分部在浓度为0.4mg/mL时活性已超过阳性对照药,说明氯仿分部具有较强的降血糖潜力。     

Study on the Mechanism of the Blood-Glucose-Lowering Effect of Collagen Peptides from Sturgeon By-Products

In a previous study, we found that the collagen peptides prepared from the by-products of Bester sturgeon had an inhibitory effect on elevated blood glucose levels in a glucose tolerance test with ICR mice. In the present study, we examine the mechanism of the effect of sturgeon collagen peptides (SCPs) in detail. When glucose was orally administered to mice along with the SCPs, it was found that the glucose remained in the stomach for a longer time. In the above tests, the amount of glucose excreted in the feces of mice also increased. On the contrary, it was revealed that the SCPs have a dipeptidyl-peptidase-IV (DPP-IV) inhibitory ability in an in vitro test. In subsequent oral and intravenous glucose administration tests, glucagon-like peptide-1 (GLP-1) and insulin levels in the blood of mice were maintained at high levels. These results suggested the following three mechanisms: SCPs slow the rate of transportation of glucose from the stomach into the small intestine, resulting in delayed glucose absorption; SCPs suppress the absorption of glucose in the small intestine and excrete it from the body; SCPs inhibit DPP-IV in the blood and maintain a high GLP-1 level in blood, which in turn stimulates insulin secretion.     

海洋生物源DPP-Ⅳ抑制肽的制备和构效关系的研究进展

糖尿病是一种血糖水平慢性增高的代谢性疾病,对人类的生命健康产生严重影响。长期的高血糖症会导致肥胖、高血压等并发症的发生。目前临床用于治疗糖尿病的药物如西格列汀、利格列汀等存在毒副作用较大等问题,开发高效、安全的天然降血糖活性物质成为了当前的研究热点。二肽基肽酶-IV（dipeptidyl peptidase-IV,DPP-IV）抑制肽是一类通过抑制DPP-IV活性从而达到降血糖作用的生物活性肽。天然食物来源的DPP-IV抑制肽具有安全性高、毒副作用小、可长期服用等优点,可应用于降血糖功能性食品。海洋生物资源丰富,是制备DPP-Ⅳ抑制肽的重要来源。本文对国内外海洋生物蛋白源DPP-IV抑制肽的来源、分离纯化、结构鉴定和功能活性评价进行了综述,并对下一步研发应用提出建议,旨在为开发DPP-IV抑制肽功能性食品提供参考。