A number of anti diabetic drugs

A number of anti-diabetic drugs are available that inhibit α-glucosidase activity, including acarbose, voglibose and miglitol [6,7]. These inhibitors, however, also exhibit undesirable side effects, such as adverse gastrointestinal symptoms and liver toxicity [8,9]. For diabetics, it would therefore be beneficial to identify α-glucosidase inhibitors that had fewer adverse side-effects. Moreover, for the general population it would be useful to find food-grade α-glucosidase inhibitors that could be incorporated into foods to reduce the rate of starch digestion, and thereby preventing diabetes from arising in the first place. Certain polyphenolic compounds isolated from plants are known to inhibit the activity of α-glucosidase and are suitable for incorporation into functional foods and supplements [[10], [11], [12]]. Proanthocyanidins are the most abundant polyphenolic compounds after lignin. These substances are oligomers and polymers of flavan-3-ol monomer units such as catechin, epicatechin, afzelechin, epiafzelechin, gallocatechin, and epigallocatechin. The monomers may be joined together by A-type linkages (containing an ether bond in addition to the CC bond) or a B-type PF-04620110 australia (CC bond between monomers) [13,14]. Previously, the α-glucosidase inhibitory capacities of proanthocyanidins from Manilkara zapota [15], Choerospondias axillaris peels [8], elderberry [16], and Annona muricata Linn. leaf [17] have been demonstrated. Some studies suggest that the α-glucosidase inhibitory activity of proanthocyanidins increases as their mean degree of polymerization increases [8,16]. Conversely, others studies have shown that oligomers have a stronger inhibitory activity than polymers [4,18]. These contrasting findings may be due to a variety of factors: the extracts used were complex mixtures containing many different proanthocyanidins; the proanthocyanidins had different linking types; there were other types of bioactive compounds in the proanthocyanidin extracts. Therefore, it is important to use pure well-characterized proanthocyanidins and α-glucosidase to obtain more information about the precise nature of their interactions. Procyanidins are the most common form of edible proanthocyanidins, which are found in many fruits, vegetables, legumes, grains and nuts [19]. The α-glucosidase inhibitory activity of the procyanidin dimer (IC50 = 9.0 ± 0.9 μM) has previously been shown to be much stronger than acarbose (IC50 = 131.2 ± 19 μM), a widely used anti-diabetic drug [16]. However, the nature of the interaction between procyanidin dimers and α-glucosidase has not been investigated before. In this research, therefore, a B-type procyanidin dimer (epicatechin unit, Fig. 1A) was selected to investigate the interaction with α-glucosidase. A range of spectroscopic methods, including fluorescence, circular dichroism, and ultraviolet spectroscopy, were used in combination with molecular simulation to characterize the interactions. This research provides new insights into the mechanism by which BPD inhibits α-glucosidase activity, which may lead to the development of more effective functional foods and supplements to tackle type 2 diabetes.
Materials and methods
Results and discussion
Conclusion This work was supported by National Natural Science Foundation of China [Grant No. 31460394 and 31760441]; The Jiangxi Province Postgraduate Innovation Fund [Grant No. YC2017-B012] and the Support Program for Outstanding Youth Talents in Jiangxi Province [Grant No. 20171BCB23026].
Introduction Fasting and postprandial glycemic levels are two indexes for diagnosis of the chronic hyperglycemia in type 2 diabetes mellitus. Researches have shown that postprandial high glycemic level is a major factor of leading to the onset and development of type 2 diabetes (Dong, Li, Zhu, Liu, & Huang, 2012). Besides, the increase of glycemic level could lead to the acceleration of non-enzymatic glycation which would produce the advanced glycation end products (AGEs). The previous study found that AGEs were associated with diabetic complications, such as neuropathy, cataracts, retinopathy and chronic kidney disease (Hwang, Wang, & Lim, 2017). Thus, glycemic control is an effective and long–term therapy to reduce the risk of type 2 diabetes as well as cardiovascular and neurological complications (Yilmazer-Musa, Griffith, Michels, Schneider, & Frei, 2012). The postprandial hyperglycemia is primarily due to the fast uptake of glucose in the intestine, in which α-glucosidase plays a crucial role in the hydrolysis of dietary carbohydrates. α-Glucosidase, located at the brush-border of small intestine cells, is a key glucoside hydrolase catalyzing disaccharides and oligosaccharides to absorbable monosaccharides in the final step of carbohydrates digestive process (Xu et al., 2015). Therefore, α-glucosidase inhibitors suppress the activity of α-glucosidase to delay the release of glucose reducing the postprandial hyperglycemia from the source, which is an important approach to the treatment of type 2 diabetes in clinic. Moreover, inhibiting non-enzymatic glycation to reduce the formation of AGEs is important for the prevention and treatment of diabetic complications.