Up to now the research about
Up to now, the research about the effect of PAs on inhibiting carbohydrase activity in vitro or reducing blood sugar level in vivo was mainly reported in PAs from grape seeds, Lepisanthes alata (Malay cherry) leaves, sorghum, pomegranate, cranberry and persimmon (Banerji and Banerjee, 2016, Barrett et al., 2013, Cai et al., 2015, Li et al., 2018, Zhang et al., 2016). Compared with other polyphenols, these PAs showed a stronger affinity with carbohydrase attributed to their numerous hydroxyl groups and complicated structure. However, the overwhelming majority PAs are in the class of procyanidins. BLPs, as a source of prodelphinidins (EGCG as construction unit), whose special structure may make it a different bioactivity and functional mechanism.
Materials and methods
Results and discussion
Conclusions The present study demonstrated that Chinese bayberry (Myrica rubra Sieb. et Zucc.) leaves proanthocyanidins (BLPs) exhibited a remarkable α-glucosidase inhibitory potential through a non-competitive allosteric inhibition mechanism. BLPs was found to be interacted with α-glucosidase using multi-spectroscopic methods in combination with molecular docking techniques. The fluorescence quenching of α-glucosidase indicated the formation of BLPs-α-glucosidase complex mainly driven by hydrophobic interaction and hydrogen bonding. And this interaction induced a hydrophobic environment of Regorafenib hydrochloride residues around α-glucosidase and conformational changes of α-glucosidase molecule through fluorescence spectra, CD and FT-IR analyses, which could be attributed to the decrease of α-glucosidase activity. Molecular docking study further provided a visual simulation about the binding of BLPs to α-glucosidase. In conclusion, BLPs showed potential as a natural alternative of α-glucosidase inhibitor. A new insight into the inhibition mechanism of PAs especially prodelphinidins on α-glucosidase was investigated via particular structure of BLPs (more than 90% is B-type linked EGCG polymer). And the related inhibition potential and inhibition mode of BLPs were first provided, which could give the basis of application in food systems and medical treatment. Some further in-depth studies are also needed, such as the study of structure-activity relationship about PAs on α-glucosidase inhibition, and effects of BLPs in real food matrix and in vivo.
Introduction α-Glucosidase (EC 184.108.40.206; alias, lysosomal α-glucosidase) is an enzyme that hydrolyzes carbohydrates (i.e. starches and disaccharides) to produce more metabolically available sugars (i.e. glucose) in the course of catabolic metabolism . Although both can functionally hydrolyze carbohydrates, α-glucosidase is distinct from β-glucosidase, which also cleaves glycosidic bonds . It is generally well recognized that α-glucosidase is directly associated with type II diabetes mellitus (DM) due to the fact that high activity of this enzyme increases plasma glucose levels, which in turn affects glucose absorption in these patients. Thus, various studies regarding α-glucosidase inhibition and the development of its inhibitors have been conducted and reported due to interest in the treatment of type II DM via downregulation of α-glucosidase activity. Especially, some α-glucosidase inhibitors, such as voglibose, acarbose, and miglitol, have been highlighted and mostly addressed in the clinical setting [, , ]. In addition, α-glucosidase is thought to be involved in many biological functions associated with various diseases: i) it participates in tumor metastasis through cellular interaction with collagen type I and IV ; ii) α-glucosidase inhibition effectively reduces the risk of cerebrovascular events  and colorectal cancer  in DM patients; and an autosomal recessive disorder affecting α-glucosidase causes Pompe disease . Thus, the investigation of α-glucosidase has a wide range of potential impacts, including aiding in the development of an inhibitor of α-glucosidase for treating type II DM.