Analysis of Patents Issued in China for Antihyperglycemic Therapies for Type 2 Diabetes Mellitus

Natural Inhibitors of Mammalian α-Amylases as Promising Drugs for the Treatment of Metabolic Diseases

α-Amylase is a generally acknowledged molecular target of a distinct class of antidiabetic drugs named α-glucosidase inhibitors. This class of medications is scarce and rather underutilized, and treatment with current commercial drugs is accompanied by unpleasant adverse effects. However, mammalian α-amylase inhibitors are abundant in nature and form an extensive pool of high-affinity ligands that are available for drug discovery. Individual compounds and natural extracts and preparations are promising therapeutic agents for conditions associated with impaired starch metabolism, e.g., diabetes mellitus, obesity, and other metabolic disorders. This review focuses on the structural diversity and action mechanisms of active natural products with inhibitory activity toward mammalian α-amylases, and emphasizes proteinaceous inhibitors as more effective compounds with significant potential for clinical use.

Cellulose filter paper immobilized α-glucosidase and its application to screening inhibitors from traditional Chinese medicine

In this study, α-glucosidase was successfully immobilized on cellulose filter paper and further applied to screening inhibitors from traditional Chinese medicines combined with CE analysis. For α-glucosidase immobilization, cellulose filter paper was used as the carrier and grafted with amino groups by coating chitosan, then α-glucosidase was covalently bonded on the amino-modified carrier via epoxy ring-opening reaction using polyethylene glycol diglycidyl ether as the crosslinker. Several parameters influencing the enzyme immobilization were optimized and the optimal values were enzyme concentration of 4 U mL^-1 , polyethylene glycol diglycidyl ether concentration of 1.25%, chitosan concentration of 7.5 mg mL^-1 , immobilization pH 7.0, crosslinking time of 4 h and immobilization time of 2 h. The immobilized α-glucosidase exhibited good batch-to-batch reproducibility (RSD = 2.1%, n = 5), excellent storage stability (73.5% of its initial activity after being stored at 4°C for 15 days) and reusability (75% of its initial activity after 10 repeated cycles). The Michaelis constant of immobilized α-glucosidase and half-maximal inhibitory concentration of acarbose were calculated to be 1.12 mM and 0.38 μM, respectively. Finally, the immobilized α-glucosidase was used for screening inhibitors from 14 kinds of Traditional Chinese Medicine extracts, and Sanguisorbae Radix showed the strongest inhibitory effect on α-glucosidase. This article is protected by copyright. All rights reserved.

Hypolipidemic effect of Alisma orientale (Sam.) Juzep on gut microecology and liver transcriptome in diabetic rats

Alisma orientale (Sam.) Juzep (A. orientale) is a traditional herb that is often used to treat disease including edema and hyperlipidemia. However, the molecular mechanism by which Alisma orientale (Sam.) Juzep exerts its hypolipidemic effects remains unclear. In this study, a diabetic rat model was established by feeding a high-fat and high-sugar diet combined with a low-dose streptozotocin injection (HFS). Then the rats were treated with an A. orientale water extract (AOW), an A. orientale ethanolic extract (AOE) or metform (MET). The gut microflora and liver transcriptome were analyzed by high-throughput next-generation sequencing. Ultra-performance liquid chromatography-triple quadrupole-mass spectrometry was employed to analyze the major compounds in the AOE. The results showed that the serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels in rats of the AOE group (2.10 g/kg/day, 14 days) were significantly lower than those in the HFS group (p<0.01). Moreover, AOE treatment altered the gut microecology, particularly modulating the relative abundance of gut microflora involved in lipid metabolism compared with the HFS group. Furthermore, compared with the HFS group, the mRNA expression levels of Fam13a, Mapk7, Mpp7, Chac1, Insig1, Mcpt10, Noct, Greb1l, Fabp12 and Hba-a3 were upregulated after the administration of AOE. In contrast, the mRNA expression levels of Lox, Mybl1, Arrdc3, Cyp4a2, Krt20, Vxn, Ggt1, Nr1d1 and S100a9 were downregulated. Moreover, AOE treatment for two weeks markedly promoted the relative abundance of Lachnospiraceae (p = 0.0013). The triterpenoids contents in AOE were alisol A, alisol A 24-acetate, alisol B, alisol B 23-acetate, alisol C 23-acetate, alisol F, alisol F 24-acetate, and alisol G. Our findings above illustrated that the hypolipidemic effect of the triterpenoids of A. orientale is mediated mainly through alteration of the gut microecology and the regulation of genes involved in cholesterol metabolism, especially Insig1.

In vitro α-glucosidase inhibition by honeybush (Cyclopia genistoides) food ingredient extract—potential for dose reduction of acarbose through synergism

Synergistic in vitro inhibition of intestinal α-glucosidase by acarbose and xanthones indicates potential for reducing the effective dose of acarbose.

The Effect of Chilgoza Pine Nut (Pinus gerardiana Wall.) on Blood Glucose and Oxidative Stress in Diabetic Rats

PURPOSE

Diabetes can increase oxidative stress in various tissues of the body, and the progress of this process is associated with intensification of the complications of diabetes. The current study purposed to evaluate the protective effect of Pinus gerardiana (PG) seed on oxidative stress induced by diabetes in the liver and serum of streptozotocin (STZ)-induced diabetic rats.

MATERIALS AND METHODS

This interventional study was performed on 36 male Wistar rats. The rats were randomly divided into 6 groups (healthy controls, healthy treated with 3% and 6% (PG), diabetic control, diabetic treated with 3% and 6% (PG) doses). After 6 weeks of intervention, weight, glucose, and oxidative stress parameters in serum and liver including total antioxidant capacity, malondialdehyde, total thiol and superoxide dismutase activity were measured. Data analysis was done by statistical software version 16 and Tukey's one-way ANOVA tests.

RESULTS

Diabetic rats showed significantly higher malondialdehyde and fasting glucose levels (12±1.2 mmol/L) and significant reductions in fasting insulin serum, weight (-37%), and activity of superoxide dismutase enzymes, total thiol groups, and total antioxidant capacity of serum and liver (about +49% in liver and +16% in serum) (p < 0.001) compared with the healthy groups. Oral administration of PG nuts to diabetic rats caused a significant reduction in malondialdehyde and fasting glucose levels (-43%) and weight loss (+15%), and a significant increase in activity of superoxide dismutase enzymes, total thiol groups, and total antioxidant capacity of serum and liver (p < 0.001).

CONCLUSION

The present study concluded that PG can decrease fasting blood glucose, improve insulin resistance, reduce weight loss, and improve oxidative stress indices in the serum and liver of STZ-induced diabetic rats. It is a potential therapeutic food supplement for the treatment and prevention of hyperglycemia and high oxidative stress of diabetes.