Machine Learning and In Vitro Chemical Screening of Potential α-Amylase and α-Glucosidase Inhibitors from Thai Indigenous Plants.

Diabetes mellitus is a major predisposing factor for cardiovascular disease and mortality. α-Amylase and α-glucosidase enzymes are the rate-limiting steps for carbohydrate digestion. The inhibition of these two enzymes is clinically used for the treatment of diabetes mellitus. Here, in vitro study and machine learning models were employed for the chemical screening of inhibiting the activity of 31 plant samples on α-amylase and α-glucosidase enzymes. The results showed that the ethanolic twig extract of Pinus kesiya had the highest inhibitory activity against the α-amylase enzyme. The respective ethanolic extract of Croton oblongifolius stem, Parinari anamense twig, and Polyalthia evecta leaf showed high inhibitory activity against the α-glucosidase enzyme. The classification analysis revealed that the α-glucosidase inhibitory activity of Thai indigenous plants was more predictive based on phytochemical constituents, compared with the α-amylase inhibitory activity (1.00 versus 0.97 accuracy score). The correlation loading plot revealed that flavonoids and alkaloids contributed to the α-amylase inhibitory activity, while flavonoids, tannins, and reducing sugars contributed to the α-glucosidase inhibitory activity. In conclusion, the ethanolic extracts of P. kesiya, C. oblongifolius, P. anamense, and P. evecta have the potential for further chemical characterization and the development of anti-diabetic recipes.

Hypoglycemic peptide-enriched hydrolysates of Corbicula fluminea and Chlorella sorokiniana possess synergistic hypoglycemic activity through inhibiting α-glucosidase and dipeptidyl peptidase-4 activity.

BACKGROUND: The prevalence of diabetes mellitus worldwide has increased in recent decades. Maintaining the level of blood glucose is the most basic and important issue for diabetics. This study aimed to investigate the hypoglycemic activity of a combination of hypoglycemic peptide-enriched hydrolysates of Corbicula fluminea (ACH) and Chlorella sorokiniana (PCH). RESULTS: Combined supplementation of ACH and PCH synergistically inhibited α-glucosidase and DPP4 activities in vitro. After 4 weeks of treatment with ACH and/or PCH, the plasma glucose concentration and insulin, homeostasis model assessment-estimated insulin resistance (HOMA-IR), total cholesterol (TC) and triglyceride (TG) levels significantly decreased. The hypoglycemic peptides in ACH and PCH were purified and assayed for α-glucosidase and DPP4 activity. The hypoglycemic peptides in ACH and PCH effectively decreased α-glucosidase and DPP4 activities. In silico assays showed that these two peptide types have different docking poses, which determined their inhibitory effect against α-glucosidase and DPP4 activity. CONCLUSION: Combined treatment with hypoglycemic peptide-enriched ACH and PCH could modulate blood glucose by synergistically inhibiting α-glucosidase and DPP4 activities. © 2021 Society of Chemical Industry.

In Silico Approaches to Identify Polyphenol Compounds as α-Glucosidase and α-Amylase Inhibitors against Type-II Diabetes.

Type-II diabetes mellitus (T2DM) results from a combination of genetic and lifestyle factors, and the prevalence of T2DM is increasing worldwide. Clinically, both α-glucosidase and α-amylase enzymes inhibitors can suppress peaks of postprandial glucose with surplus adverse effects, leading to efforts devoted to urgently seeking new anti-diabetes drugs from natural sources for delayed starch digestion. This review attempts to explore 10 families e.g., Bignoniaceae, Ericaceae, Dryopteridaceae, Campanulaceae, Geraniaceae, Euphorbiaceae, Rubiaceae, Acanthaceae, Rutaceae, and Moraceae as medicinal plants, and folk and herb medicines for lowering blood glucose level, or alternative anti-diabetic natural products. Many natural products have been studied in silico, in vitro, and in vivo assays to restrain hyperglycemia. In addition, natural products, and particularly polyphenols, possess diverse structures for exploring them as inhibitors of α-glucosidase and α-amylase. Interestingly, an in silico discovery approach using natural compounds via virtual screening could directly target α-glucosidase and α-amylase enzymes through Monte Carto molecular modeling. Autodock, MOE-Dock, Biovia Discovery Studio, PyMOL, and Accelrys have been used to discover new candidates as inhibitors or activators. While docking score, binding energy (Kcal/mol), the number of hydrogen bonds, or interactions with critical amino acid residues have been taken into concerning the reliability of software for validation of enzymatic analysis, in vitro cell assay and in vivo animal tests are required to obtain leads, hits, and candidates in drug discovery and development.

FTZ attenuates liver steatosis and fibrosis in the minipigs with type 2 diabetes by regulating the AMPK signaling pathway.

Fufang Zhenzhu Tiaozhi formula (FTZ), a preparation of Chinese herbal medicine, has various pharmacological properties, such as hypoglycemic, hypolipidemic, anticoagulant, and anti-inflammatory activities. Hepatocyte apoptosis is a marker of nonalcoholic steatohepatitis (NASH) and contributes to liver injury, fibrosis, and inflammation. Given the multiple effects of FTZ, we investigated whether FTZ can be a therapeutic agent for NASH and its mechanism. In the present study, we observed that FTZ treatment had an obviously favorable influence on hepatic steatosis and fibrosis in the histopathologic features of type 2 diabetes mellitus (T2DM) and coronary heart disease (CHD) with NASH minipigs. In addition, immunohistochemical analysis showed increased expression of the fibrotic marker α-smooth muscle actin (α-SMA), and a TUNEL assay revealed increased apoptotic positive hepatic cells in the liver tissues of the model group. Furthermore, FTZ administration reduced the increased expression of α-SMA, and FTZ inhibited apoptosis by affecting Bcl-2/Bax and cleaved caspase-3 expression. Mechanistically, our data suggested that FTZ treatment attenuated hepatic steatosis and fibrosis via the adenosine monophosphate-activated protein kinase (AMPK) pathway. In vitro studies showed that FTZ also attenuated intracellular lipid accumulation in HepG2 cells exposed to palmitic acid (PA) and oleic acid (OA). FTZ upregulated the expression levels of P-AMPK and BCL-2 and downregulated BAX. The changes induced by FTZ were reversed by Compound C, an inhibitor of AMPK. In conclusion, FTZ attenuated NASH by ameliorating steatosis and hepatocyte apoptosis, which is attributable to the regulation of the AMPK pathway.

Assessing the In Vitro Inhibitory Effects on Key Enzymes Linked to Type-2 Diabetes and Obesity and Protein Glycation by Phenolic Compounds of Lauraceae Plant Species Endemic to the Laurisilva Forest.

Methanolic leaf extracts of four Lauraceae species endemic to Laurisilva forest (Apollonias barbujana, Laurus novocanariensis, Ocotea foetens and Persea indica) were investigated for the first time for their potential to inhibit key enzymes linked to type-2 diabetes (α-amylase, α-glucosidase, aldose reductase) and obesity (pancreatic lipase), and protein glycation. Lauraceae extracts revealed significant inhibitory activities in all assays, altough with different ability between species. In general, P. indica showed the most promissing results. In the protein glycation assay, all analysed extracts displayed a stronger effect than a reference compound: aminoguanidine (AMG). The in vitro anti-diabetic, anti-obesity and anti-glycation activities of analysed extracts showed correlation with their flavonols and flavan-3-ols (in particular, proanthocyanins) contents. These Lauraceae species have the capacity to assist in adjuvant therapy of type-2 diabetes and associated complications, through modulation of the activity of key metabolic enzymes and prevention of advanced glycation end-products (AGEs) formation.

Role of CaMKII in the regulation of fatty acids and lipid metabolism.

BACKGROUND & AIMS: Previous studies have reported the beneficial roles of the activation of calmodulin-dependent protein kinase (CaMK)II to many cellular functions associated with human health. This review aims at discussing its activation by exercise as well as its roles in the regulation of unsaturated, saturated, omega 3 fatty acids, and lipid metabolism. METHODS: A wide literature search was conducted using online database such as 'PubMed', 'Google Scholar', 'Researcher', 'Scopus' and the website of World Health Organization (WHO) as well as Control Disease and Prevention (CDC). The criteria for the search were mainly lipid and fatty acid metabolism, diabetes, and metabolic syndrome (MetS). A total of ninety-seven articles were included in the review. RESULTS: Calmodulin-dependent protein kinase activation by exercise is helpful in controlling membrane lipids related with type 2 diabetes and obesity. CaMKII regulates many health beneficial cellular functions in individuals who exercise compared with those who do not exercise. Regulation of lipid metabolism and fatty acids are crucial in the improvement of metabolic syndrome. CONCLUSIONS: Approaches that involve CaMKII could be a new avenue for designing novel and effective therapeutic modalities in the treatment or better management of metabolic diseases such as type 2 diabetes and obesity.

Inhibition of enzymes associated with metabolic and neurological disorder by dried pomegranate sheets as a function of pomegranate cultivar and fruit puree.

BACKGROUND: Obesity and type 2 diabetes mellitus are the most extended current chronic diseases and also Alzheimer pathology which is a progressive degenerative neurological disorder. Therefore, finding effective enzyme inhibitors responsible for the development of these diseases are essential. Therefore, the aim of this study was to investigate the impact of fruit purée (Cydonia oblonga, Ziziphus jujube and Malus domestica) and pomegranate juice cultivar ('Mollar de Elche' and 'Wonderful') of dried pomegranate sheets (DS) on the inhibition of enzymes associated with metabolic (α-amylase, α-glucosidase, and pancreatic lipase activity), and neurological disorder (acetylcholinesterase and butyrylcholinesterase activity). Quality properties (colour coordinates, texture properties and sensory characteristics) of DS were also studied. In addition, it was researched the effect of storage conditions (4 months at 4 and 20 °C) on phenolic content. RESULTS: DS from jujube had the highest antioxidant capacity and were characterized by the highest storage stability with respect to phenolic compounds. The α-amylase and α-glucosidase half maximal inhibitory concentration (IC50 , in mg mL-1 ) inhibition of DS ranged from 107 to 216 and from 55.2 to values indicating no effect, respectively. The inhibition toward pancreatic lipase (IC50 < 5 mg mL-1 ), acetylcholinesterase (ranged 9.15-22.2%) and butyrylcholinesterase (ranged 20.6-48.6%) was increased with the presence of total flavonoids and hydroxycinnamic acids content (identifying mainly in DS from quinces). It is noteworthy that none of the samples presented off-flavour notes, supporting the high quality of the products. CONCLUSION: DS can be an innovative supplement to a diet as a snack used in the prevention of neurological changes and disorders of carbohydrate and lipid metabolism. © 2020 Society of Chemical Industry.

A novel hypoglycemic agent: polysaccharides from laver (Porphyra spp.).

Type-II diabetes mellitus (T2DM) has become one of the most prevalent diseases on Earth and some treatments have been developed to manage it. One intestinal enzyme α-amylase can break down starch to glucose. Inhibiting its activity will control blood glucose and provide an essential approach for the management of T2DM. Alpha-amylase inhibitor (α-AI) specifically inhibits the activity of α-amylase, and reduces the blood glucose level efficiently. To develop a novel α-AI, the red seaweed laver (Porphyra spp.) was exploited in this work, whose extracts contain polysaccharides showing an inhibitory effect against α-amylase. The crude polysaccharides were extracted using hot water (85 °C) and degraded to low-molecular-weight polysaccharides with 7% of H2O2. One polysaccharide PD-1 exhibiting a competitive binding mode with an IC50 of 12.72 mg mL-1 was separated from these degraded polysaccharides, showing approximately 98.78% of α-amylase inhibition activity. In vivo, PD-1 could efficiently suppress postprandial blood glucose levels in normal and diabetic rats. The polysaccharide inhibitor from red seaweed laver could be regarded as a novel functional food ingredient in T2DM management.

An overview on the role of bioactive α-glucosidase inhibitors in ameliorating diabetic complications.

Recently the use of bioactive α-glucosidase inhibitors for the treatment of diabetes have been proven to be the most efficient remedy for controlling postprandial hyperglycemia and its detrimental physiological complications, especially in type 2 diabetes. The carbohydrate hydrolysing enzyme, α-glucosidase, is generally competitively inhibited by the α-glucosidase inhibitors and results in the delayed glucose absorption in small intestine, ultimately controlling the postprandial hyperglycemia. Here we have reviewed the most recent updates in the bioactive α-glucosidase inhibitors category. This review provides an overview of the α-glucosidase inhibitory potentials and efficiency of controlling postprandial hyperglycemia of various bioactive compounds such as flavonoids, phenolic compound, polysaccharide, betulinic acid, tannins, anthocyanins, steroids, polyol, polyphenols, galangin, procyanidins, hydroxyl-α-sanshool, hydroxyl-ß-sanshool, erythritol, ganomycin, caffeoylquinic acid, resin glycosides, saponins, avicularin, oleanolic acids, urasolic acid, ethanolic extracts etc., from various dietary and non-dietary naturally occurring sources.

Effects of hot­water extracts from 26 herbs on α­glucosidase activity.

α­glucosidase is a key enzyme that plays a role in glucose absorption in the gastrointestinal tract, and the inhibition of its activity induces the prevention of postprandial hyperglycemia. Several α­glucosidase inhibitors have been used as medicines for type 2 diabetes, but a similar effect is observed in natural resources, including traditional herbs and their phytochemicals. To identify the presence of the α­glucosidase inhibitory activity in herbs, in which various functional effects have been known to occur, the present study investigated the effects of hot­water extracts of 26 types of herbs on α­glucosidase activity in an in vitro assay. The results indicated significant increases in the inhibition of α­glucosidase activity in 1,000 µg/ml olive (P<0.01), white willow (P<0.01) and red rooibos hot­water extracts. Furthermore, ≥50% inhibition of α­glucosidase activity was determined to be significant in 1,000 µg/ml coltsfoot, green tea and bearberry hot­water extracts. In addition, the effects of bearberry, green tea and coltsfoot hot­water extracts on α­glucosidase activity in vivo were evaluated according to the blood glucose levels (BGLs) in maltose and glucose load model rats. It was indicated that the administration of these three herb extracts significantly reduced the increasing BGLs after maltose loading until 0.5 h compared with the control group. However, only coltsfoot extract significantly reduced the increasing BGLs after glucose loading until 0.5 h compared with the control group. Thus, the present results may facilitate the understanding of a novel functionality in traditional herbs, which could be useful for the prevention of disease onset and progression, such as in hyperglycemia and type 2 diabetes.

Clinacanthus nutans Leaves Extract Reverts Endothelial Dysfunction in Type 2 Diabetes Rats by Improving Protein Expression of eNOS.

Diabetes mellitus is associated with endothelial dysfunction; it causes progressive vascular damage resulting from an impaired endothelium-dependent vasorelaxation. In the diabetes state, presence of hyperglycemia and insulin resistance predisposes to endothelial dysfunction. Clinacanthus nutans, widely used as a traditional medicine for diabetes is reported to have hypoglycemic, hypolipidemic, antioxidant, and anti-inflammatory properties. However, the possibility of C. nutans affecting the vascular endothelial function in diabetes remains unclear. This study was aimed at evaluating the effects of C. nutans methanolic leaves extract (CNME) on endothelial function in a type 2 diabetes (T2DM) rat model. Sixty male Sprague-Dawley rats were divided into five groups (n = 12 per group): nondiabetic control, nondiabetic treated with four weeks of CNME (500 mg/kg/daily), untreated diabetic rats, diabetic treated with metformin (300 mg/kg/daily), and diabetic treated with CNME (500 mg/kg/daily). T2DM was induced by a single intraperitoneal injection of low-dose streptozotocin (STZ) to rats fed with high-fat diet (HFD). Endothelial-dependent and endothelial-independent relaxations and contractions of the thoracic aorta were determined using the organ bath. Aortic endothelial nitric oxide synthase (eNOS) expression was determined using Western blotting. Endothelial-dependent relaxation was reduced in diabetic rats. Both diabetic groups treated with CNME or metformin significantly improved the impairment in endothelium-dependent vasorelaxation; this was associated with increased expression of aortic eNOS protein. CNME- and metformin-treated groups also reduced aortic endothelium-dependent and aortic endothelium-independent contractions in diabetics. Both of these diabetic-treated groups also reduced blood glucose levels and increased body weight compared to the untreated diabetic group. In conclusion, C. nutans improves endothelial-dependent vasodilatation and reduces endothelial-dependent contraction, thus ameliorating endothelial dysfunction in diabetic rats. This may occur due to its effect on increasing eNOS protein expression.

Dietary 5,6,7-Trihydroxy-flavonoid Aglycones and 1-Deoxynojirimycin Synergistically Inhibit the Recombinant Maltase-Glucoamylase Subunit of α-Glucosidase and Lower Postprandial Blood Glucose.

1-Deoxynojirimycin (1-DNJ) is the major effective component of mulberry leaves, exhibiting inhibitory activity against α-glucosidase. However, due to the low content of 1-DNJ in mulberry products, its level cannot meet the lowest dose to exhibit its activity. In this study, a combination of dietary 5,6,7-trihydroxy-flavonoid aglycones with 1-DNJ showed synergistic inhibitory activity against maltase of mice α-glucosidase and recombinant C- and N-termini of maltase-glucoamylase (MGAM) and baicalein with 1-DNJ exhibited the strongest synergistic effect. The synergistic effect of the combination was also confirmed by the maltose tolerance test in vivo. Enzyme kinetics, molecular docking, fluorescence spectrum, and circular dichroism spectrometry studies indicated that the major mechanism of the synergism is that baicalein was a positive allosteric inhibitor and bound to the noncompetitive site of MGAM, causing an increase of the binding affinity of 1-DNJ to MGAM. Our results might provide a theoretical basis for the design of dietary supplements containing mulberry products.

Type 2 diabetes risk gene Dusp8 regulates hypothalamic Jnk signaling and insulin sensitivity.

Recent genome-wide association studies (GWAS) identified DUSP8, encoding a dual-specificity phosphatase targeting mitogen-activated protein kinases, as a type 2 diabetes (T2D) risk gene. Here, we reveal that Dusp8 is a gatekeeper in the hypothalamic control of glucose homeostasis in mice and humans. Male, but not female, Dusp8 loss-of-function mice, either with global or corticotropin-releasing hormone neuron-specific deletion, had impaired systemic glucose tolerance and insulin sensitivity when exposed to high-fat diet (HFD). Mechanistically, we found impaired hypothalamic-pituitary-adrenal axis feedback, blunted sympathetic responsiveness, and chronically elevated corticosterone levels driven by hypothalamic hyperactivation of Jnk signaling. Accordingly, global Jnk1 ablation, AAV-mediated Dusp8 overexpression in the mediobasal hypothalamus, or metyrapone-induced chemical adrenalectomy rescued the impaired glucose homeostasis of obese male Dusp8-KO mice, respectively. The sex-specific role of murine Dusp8 in governing hypothalamic Jnk signaling, insulin sensitivity, and systemic glucose tolerance was consistent with functional MRI data in human volunteers that revealed an association of the DUSP8 rs2334499 risk variant with hypothalamic insulin resistance in men. Further, expression of DUSP8 was increased in the infundibular nucleus of T2D humans. In summary, our findings suggest the GWAS-identified gene Dusp8 as a novel hypothalamic factor that plays a functional role in the etiology of T2D.

The effects of aspirin and N-3 fatty acids on telomerase activity in adults with diabetes mellitus.

Type 2 Diabetes mellitus is associated with aging and shortened telomere length. Telomerase replaces lost telomeric repeats at the ends of chromosomes and is necessary for the replicative immortality of cells. Aspirin and the n3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are commonly used therapies in people with type 2 diabetes for reducing cardiovascular disease events, though their relation to telomerase activity is not well studied. We explored the effects of aspirin, EPA + DHA, and the combined effects of aspirin and EPA + DHA treatment on telomerase activity in 30 adults with diabetes mellitus. EPA and DHA ingestion alone increased telomerase activity then a decrease occurred with the addition of aspirin consumption. Crude (F-stat = 2.09, p = 0.13) and adjusted (F-stat = 2.20, p = 0.14) analyses of this decrease showed signs of a trend. These results suggest that aspirin has an adverse effect on aging in diabetics who have relatively high EPA and DHA ingestion.

Adding value to polyvinylpolypyrrolidone winery residue: A resource of polyphenols with neuroprotective effects and ability to modulate type 2 diabetes-relevant enzymes.

A polyphenols-rich extract was obtained from polyvinylpolypyrrolidone (PVPP) winery residue, and its neuroprotective effects and ability to modulate the kinetics of type 2 diabetes-relevant enzymes were characterized. The PVPP-white wine extract is a mixture of polyphenols (840.08 ± 161.25 µg/mg, dry weight) dominated by proanthocyanidins and hydroxycinnamic acids, affording strong antioxidant activity, as detected by the protection of membrane lipids against oxidation and superoxide radical anion scavenging activity. Regarding type 2 diabetes framework, the extract inhibits α-glucosidase (Ki = 166.9 µg/mL) and aldose reductase (Ki = 127.5 µg/mL) through non-competitive mechanisms. Despite the modest ability to inhibit rat brain acetylcholinesterase, it protects neuronal SH-SY5Y cells against oxidative damage promoted by glutamate, decreasing reactive oxygen species generation and preserving cell redox state. Thus, PVPP-white wine extract has potential to support the development of functional foods and/or nutraceuticals aiming neuroprotection and glucose homeostasis regulation, with high relevance in Alzheimers disease and type 2 diabetes interlink.

Portulaca oleracea L. extract reduces hyperglycemia via PI3k/Akt and AMPK pathways in the skeletal muscles of C57BL/Ksj-db/db mice.

HEADINGS ETHNOPHARMACOLOGICAL RELEVANCE: Portulaca oleracea L. is a succulent annual herb, which has various pharmacological effects including antidiabetic property. However, in vivo the reducing effect of P. oleracea on hyperglycemia and its mechanism of action have not been clarified in a mouse model of type 2 diabetes. AIM OF THE STUDY: The effects of Portulaca oleracea L. extract (POE) on hyperglycemia were investigated in an animal model of type 2 diabetes. MATERIALS AND METHODS: C57BL/Ksj-db/db mice were randomly divided into three groups: db/db-control group was fed a standard semi-synthetic diet (AIN-93 G), db/db-RG group was fed AIN-93 G supplemented with rosiglitazone (RG) (0.005%, w/w), and db/db-POE group was fed AIN-93 G supplemented with POE (0.4%, w/w) for 6 weeks. Diabetes-related physical and biochemical indicators and the phosphorylation of components of PI3k/Akt and AMPK pathways were measured. RESULTS: The blood glucose and the glycosylated hemoglobin levels (HbA1c) in db/db-POE group were significantly lower than those in db/db-control group. In db/db-POE group, The homeostatic index of insulin resistance (HOMA-IR) decreased significantly, whereas the quantitative insulin sensitivity check index (QUICKI) was higher than those in db/db-control group. POE significantly elicited the phosphorylation of IRS-1Tyr612, AktSer473, and AS160Thr642, and the activation of PI3K in the skeletal muscle of mice. Additionally, POE significantly stimulated the phosphorylation of AMPKThr172, TBC1D1Ser231, and ACCSer79 and elevated the expression of plasma membrane-glucose transporter type 4 (GLUT4). CONCLUSIONS: These results indicate that POE reduces hyperglycemia by improving insulin resistance through the PI3k/Akt and AMPK pathways in the skeletal muscle of C57BL/Ksj-db/db mice.

In vitro antioxidant and inhibitory activities of polyphenolic-rich extracts of Syzygium cumini (Linn) Skeels leaf on two important enzymes relevant to type II diabetes mellitus.

In this study, the effect of free and bound polyphenolic-rich extract of Syzygium cumini (Linn) Skeels leaf on antioxidant as well as α-amylase and α-glucosidase activities were determined using in vitro model. Polyphenolic-rich extract of Syzygium cumini (Linn) Skeels leaf was prepared accordingly and the capability of the extract to inhibit antioxidants as typified by ferric reducing power (FRAP) and 1,1-diphenyl-2-picryl-hydrazil (DPPH) among other free radicals scavenging abilities were quantified spectrophotometrically, added to this, the activities of (α-amylase and α-glucosidase were also assessed. The bound phenolic extract exhibited more in vitro antioxidant properties as represented by their high radicals scavenging ability in all the free radicals evaluated. Also, the polyphenolic-rich extracts inhibited α-amylase and α-glucosidase, with bound phenolics showing significant (p<0.05) increase in a dose-dependent manner than free phenolics. Therefore, this study suggests the use of Syzygium cumini leaf as a nutraceutical in the management/ control of type II diabetes mellitus patients.

Identification of Phenolic Compounds from Nettle as New Candidate Inhibitors of Main Enzymes Responsible on Type-II Diabetes.

BACKGROUND: In medicinal chemistry, the discovery of small organic molecules that can be optimized and lead to a future drug capable of effectively modulating the biological activity of a therapeutic target remains a major challenge. Because of the harmful secondary effects of synthesized therapeutic molecules, the development of research has been oriented towards phytomedicines. Phenolic compounds from medicinal plants are constantly explored for new therapeutic use. METHODS: In this paper, we studied interactions between main enzymes responsible for causing type 2 diabetes mellitus (T2DM) and phenolic compounds from nettle (Urtica dioica L.) using molecular Docking with Molecular Operating Environment Software (MOE). RESULTS: Docking results show a common molecule (secoisolariciresinol), which may form stable complexes with depeptidyl peptidase 4 (DPP-4), alpha-amylase and beta-glucosidase with binding energy of -7.04732084 kcal/mol, -3.82946181 kcal/mol and -4.16077089 kcal/mol respectively. Besides secoisolariciresinol, other phenolic compounds give better docking score than the original co-crystallized ligand for alpha-amylase (PDB ID 5U3A) and beta-glucosidase (PDB ID 1OGS). CONCLUSION: The obtained results are promising for the discovery of new alpha-amylase and betaglucosidase inhibitors. This study also confirms the folk use of nettle as antidiabetic agent.

Flavonoids extracted from mulberry (Morus alba L.) leaf improve skeletal muscle mitochondrial function by activating AMPK in type 2 diabetes.

ETHNOPHARMACOLOGICAL RELEVANCE: Mulberry (Morus alba L.) leaves have been widely applied to controlling blood glucose as a efficacious traditional Chinese medicine or salutary medical supplement. The extracts of mulberry leaf suppress inflammatory mediators and oxidative stress, protect the pancreatic ß-cells and modulate glucose metabolism in diabetic rats. Our previous studies and others have shown that mulberry leaf extract has excellent therapeutic effects on type 2 diabetes mellitus (T2DM), however, the underlying mechanism remains to be studied. AIM OF THE STUDY: Skeletal muscle insulin resistance (IR) plays an important role in the pathogenesis of T2DM. The aim of this study was to investigate the effects and mechanisms of Mulberry leaf flavonoids (MLF) in L6 skeletal muscle cells and db/db mice. MATERIALS AND METHODS: L6 skeletal muscle cells were cultured and treated with/without MLF for in vitro studies. For in vivo studies, the db/db mice with/without MLF therapy were used. Coomassie brilliant blue staining and α-SMA immunofluorescence staining were used to identify the differentiated L6 cells. Glucose level and ATP level of L6 myotubes were performed by optical density detection and cell viability was performed by MTT method. Mitochondrial membrane potential of L6 myotubes was detected by JC-1 fluorescent staining. ROS level of L6 myotubes was detected by DCFH-DA fluorescent staining. The body weight, food intake, and blood glucose of the mice were measured in different treatment days. Oral glucose tolerance test (OGTT), starch glucose tolerance test (STT) and insulin tolerance test (ITT) were performed in mice. Glycated hemoglobin, glycated serum protein, insulin, liver and muscle glycogen, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-c) and low-density lipoprotein cholesterol (LDL-c) of the mice were detected by corresponding kit. The pathologic change of pancreas and skeletal muscle of mice were performed by H & E staining. Immunohistochemistry staining was used to detect the GLUT4 and p-AMPK expressions in skeletal muscle in mice. GLUT4, CPT-1, NRF1, COXIV, PGC-1α, and p-AMPK expression levels in L6 cells and mice were detected by western bolt assay. RESULTS: MLF and metformin significantly ameliorated muscle glucose uptake and mitochondrial function in L6 muscle cells. MLF also increased the phosphorylation of AMPK and the expression of PGC-1α, and up-regulated the protein levels of m-GLUT4 and T-GLUT4. These effects were reversed by the AMPK inhibitor compound C. In db/db mice, MLF improve diabetes symptoms and insulin resistance. Moreover, MLF elevated the levels of p-AMPK and PGC-1α, raised m-GLUT4 and T-GLUT4 protein expression, and ameliorated mitochondrial function in skeletal muscle of db/db mice. CONCLUSIONS: MLF significantly improved skeletal muscle insulin resistance and mitochondrial function in db/db mice and L6 myocytes through AMPK-PGC-1α signaling pathway, and our findings support the therapeutic effects of MLF on type 2 diabetes.

Standardized Emblica officinalis fruit extract inhibited the activities of α-amylase, α-glucosidase, and dipeptidyl peptidase-4 and displayed antioxidant potential.

BACKGROUND: Emblica officinalis, known as amla in Ayurveda, has been used as a folk medicine to treat numerous pathological conditions, including diabetes. However, the novel extract of E. officinalis fruit extract (amla fruit extract, AFE, Saberry®) containing 100 g kg-1 ß-glucogallin along with hydrolyzable tannins has not yet been extensively studied for its antidiabetic potential. OBJECTIVE: The aim of this study was to investigate the antidiabetic and antioxidant activities of AFE and its stability during gastric stress as well as its thermostability. METHODS: The effect of AFE on the inhibition of pancreatic α-amylase and salivary α-amylase enzymes was studied using starch and yeast α-glucosidase enzyme using 4-nitrophenyl α-d-glucopyranoside as substrate. Further, 2,2-diphenyl-1-picrylhydrazyl radical scavenging and reactive oxygen species inhibition assay was performed against AFE. RESULTS: AFE potently inhibited the activities of α-amylase and α-glucosidase in a concentration-dependent manner with half maximal inhibitory concentration (IC50 ) values of 135.70 µg mL-1 and 106.70 µg mL-1 respectively. Furthermore, it also showed inhibition of α-glucosidase (IC50 562.9 µg mL-1 ) and dipeptidyl peptidase-4 (DPP-4; IC50 3770 µg mL-1 ) enzyme activities. AFE is a potent antioxidant showing a free radical scavenging activity (IC50 2.37 µg mL-1 ) and protecting against cellular reactive oxygen species (IC50 1.77 µg mL-1 ), and the effects elicited could be attributed to its phytoconstituents. CONCLUSION: AFE showed significant gastric acid resistance and was also found to be thermostable against wet heat. Excellent α-amylase, α-glucosidase, and DPP-4 inhibitory activities of AFE, as well as antioxidant activities, strongly recommend its use for the management of type 2 diabetes mellitus. © 2019 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.