Dipeptidyl Peptidase IV Enzyme Research Articles

Untargeted metabolomics, optimization of microwave-assisted extraction using Box-Behnken design and evaluation of antioxidant, and antidiabetic activities of sugarcane bagasse.

The fruit wastes, in particular agricultural wastes, are considered potential and inexpensive sources of bioactive compounds. The current study was aimed at the preparation of an optimized extract of sugarcane bagasse using microwave-assisted extraction (MAE) technology and comparative evaluation of chemical composition, antioxidant, and antidiabetic activities with extract prepared through maceration technique. Box-Behnken Design (BDD) with response surface methodology was applied to observe interactions of three independent variables (ethanol concentrations [%], microwave power [W], and extraction time [min]) on the dependent variables (total phenolic content [TPC] and antioxidant status via 2,2-diphenyl-1-picrylhydrazyl [DPPH] to establish optimal extraction conditions. The ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF-MS) analysis was applied for untargeted metabolite profiling, and in vitro assays were used for evaluation of the antidiabetic and antioxidant potential of the extract. Moreover, an in silico study was used to predict the interaction of five dominant compounds from the UHPLC-Q-TOF-MS profile against the dipeptidyl peptidase-IV (DPP-IV) enzyme. The optimal conditions for the extraction were established at 60% (v/v) ethanol, 500 W microwave power, and 5 min time with TPC 12.83 ± 0.66 mg GAE/g d.w. and DPPH 45.09 ± 0.07%. The UHPLC-Q-TOF-MS analysis revealed the presence of a total of 106 compounds in the extract. Moreover, the extract prepared through MAE technology presented higher TPC and DPPH findings than the extract prepared through maceration. Similarly, the extract was also found with good antidiabetic activity by inhibiting the DPP-IV enzyme which was also rectified theoretically by a molecular docking study. The current study presents a sustainable and an optimized approach for the preparation of sugarcane bagasse extract with functional phytoconstituents and higher antidiabetic and antioxidant activities.

Molecular docking study on procyanidin derivatives as natural dipeptidyl peptidase-IV inhibitors in the treatment of Type 2 diabetes mellitus

Background: Dipeptidyl peptidase IV (DPP-IV) is a multifunctional enzyme responsible for splitting the incretin hormone, which favors the release of insulin from the pancreatic beta cells. DPP-IV inhibitors prevent the degradation of incretins by the DPP-IV enzyme and are useful for the treatment of Type 2 diabetes. Procyanidins obtained from natural sources are polymers of catechin and epicatechin, which act as efficient intestinal DPP-IV inhibitors. Aims and Objectives: The study aimed to perform molecular docking of procyanidin and its derivatives with human DPP-IV to determine its binding efficacy and absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties. Materials and Methods: The three-dimensional structure of human DPP IV was obtained from the RCSB - protein database. A total of 200 ligand derivatives of procyanidin were generated by the software ACD/ChemSketch. Initial quick docking (rough) was done using the software iGEMDOCK v2.0. The ones with the least binding energy were selected, and accurate docking was done in AutoDock 4.0 software. ADMET properties were analyzed using the Swiss ADME online tool. Results: Among the three ligands, 6-azido-2-(3, 4-dihydroxyphenyl)-4-[2-(3, 4-dihydroxyphenyl)-3, 5, 7-trihydroxy-3, 4-dihydro-2H-1-benzopyran-8-y1]-3, 4-dihydro-2H-1-benzopyran-3, 5, 7-triol has excellent binding energy with good ADMET properties. Conclusion: Using the molecular docking method in this study has led to the unveiling of a new natural DPP. IV inhibitor. This compound can be used as an effective drug candidate for treating type 2 diabetes mellitus.

Integration of Deep Learning and Sequential Metabolism to Rapidly Screen Dipeptidyl Peptidase (DPP)-IV Inhibitors from Gardenia jasminoides Ellis.

Traditional Chinese medicine (TCM) possesses unique advantages in the management of blood glucose and lipids. However, there is still a significant gap in the exploration of its pharmacologically active components. Integrated strategies encompassing deep-learning prediction models and active validation based on absorbable ingredients can greatly improve the identification rate and screening efficiency in TCM. In this study, the affinity prediction of 11,549 compounds from the traditional Chinese medicine system's pharmacology database (TCMSP) with dipeptidyl peptidase-IV (DPP-IV) based on a deep-learning model was firstly conducted. With the results, Gardenia jasminoides Ellis (GJE), a food medicine with homologous properties, was selected as a model drug. The absorbed components of GJE were subsequently identified through in vivo intestinal perfusion and oral administration. As a result, a total of 38 prototypical absorbed components of GJE were identified. These components were analyzed to determine their absorption patterns after intestinal, hepatic, and systemic metabolism. Virtual docking and DPP-IV enzyme activity experiments were further conducted to validate the inhibitory effects and potential binding sites of the common constituents of deep learning and sequential metabolism. The results showed a significant DPP-IV inhibitory activity (IC50 53 ± 0.63 μg/mL) of the iridoid glycosides' potent fractions, which is a novel finding. Genipin 1-gentiobioside was screened as a promising new DPP-IV inhibitor in GJE. These findings highlight the potential of this innovative approach for the rapid screening of active ingredients in TCM and provide insights into the molecular mechanisms underlying the anti-diabetic activity of GJE.

Two novel dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides identified from truffle (Tuber sinense) by peptidomics, in silico, and molecular docking analysis

The aim of present study is to explore the endogenous dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides from the edible truffle species Tuber sinense. The 4038 endogenous peptides from fresh ascocarps were identified using a peptidomics analysis based on the ultra-performance liquid chromatography-quadrupole-Orbitrap-tandem mass spectrometry (UPLC-Q-Orbitrap-MS2). Afterward, ten DPP-IV inhibitory peptides were screened through Peptide Ranker software and BIOPEP database. According to the absorption, distribution, metabolism, excretion, toxicities (ADMET) analysis and molecular docking analysis, two peptides (APIKIPVGPGTL and IEDPDAPPPPPPREVIKN) were finally confirmed. The affinity values of APIKIPVGPGTL and IEDPDAPPPPPPREVIKN were − 8.8 and − 8.4 Kcal/mol, respectively. Two peptides had hydrogen bonds and hydrophobic interaction with amino acid residue in the S1 and S2 pockets of DPP-IV enzyme. Furthermore, the half-maximal inhibitory concentrations of two peptides were 643.14 ± 1.79 µM and 668.29 ± 1.31 µM, respectively. The oral glucose tolerance test (OGTT) of two peptides showed excellent hypoglycemic effect at 30 min after gavage. Our work may have important theoretical significance and practical value for further exploring the endogenous peptides of truffle species.

Molecular Docking and in vitro Enzyme Assay of Bioactive Compound Isolated from Rhus tripartite Collected from Hail Region of Saudi Arabia as Potential Anti-Diabetic Agent

Abstract: Aim: In the present investigation, we have studied the inhibitory potential of a bioactive compound isolated from Rhus tripartite on Glucokinase (GK), Dipeptidyl Peptidase-IV (DPP-IV), alpha-glucosidase, and alpha-amylase enzymes. Materials and Methods: The plant leaves were subjected to Soxhlet extraction followed by qualitative phytochemical screening and the separation of active constituents by applying column chromatography. The obtained fraction was subjected to spectral analysis to identify the compound. Molecular docking followed by in vitro enzyme assays were used to study the inhibitory effect of the isolated compound. Results: The plant leaves were used for the extraction, and the identified compound was S-benzo[d]oxazol-2-yl 2-(piperazine-1-yl)ethanethioate, confirmed by spectral analysis. From in-silico ADMET analysis, the isolated compound displayed most drug-likeness features, and in molecular docking studies, it has developed many crucial hydrogen bonding and hydrophobic interactions with enzymes (PDB IDs: 1V4S, 2P8S, 3BAX, and 3WY2). An in vitro enzyme assay validated the virtual screening results of isolated compounds. Isolated compound at 250 μgm/ mL displayed 96.29±2.56, 89.23±2.1, 72.72±0.75, and 69.76±0.85% activity against GK, DPP-IV, alpha-amylase, and alpha-glucosidase enzymes, respectively. Conclusion: Our study concluded that DM could be treated using an isolated compound after further in-vivo and in-vitro studies. Keywords: DPP-IV, in-vitro, Rhus tripartite, Isolation, Characterization.

Insulin secretory actions of ethanolic extract of Acacia arabica bark in high fat-fed diet-induced obese Type 2 diabetic rats.

Acacia arabica commonly known as 'babul' has been widely used for the treatment of numerous diseases, including diabetes due to their potential pharmacological actions. The aim of the present study was to investigate the insulinotropic and antidiabetic properties of ethanol extract of Acacia arabica (EEAA) bark through in vitro and in vivo studies in high fat-fed (HFF) rats. EEAA at 40-5000 µg/ml significantly increased (P<0.05-0.001) insulin secretion with 5.6 and 16.7 mM glucose, respectively, from clonal pancreatic BRIN BD11 β-cells. Similarly, EEAA at 10-40 µg/ml demonstrated a substantial (P<0.05-0.001) insulin secretory effect with 16.7 mM glucose from isolated mouse islets, with a magnitude comparable to 1 µM glucagon-like peptide-1 (GLP-1). Diazoxide, verapamil, and calcium-free conditions decreased insulin secretion by 25-26%. The insulin secretory effect was further potentiated (P<0.05-0.01) with 200 µM isobutylmethylxanthine (IBMX; 1.5-fold), 200 µM tolbutamide (1.4-fold), and 30 mM KCl (1.4-fold). EEAA at 40 µg/ml, induced membrane depolarization and elevated intracellular Ca2+ as well as increased (P<0.05-0.001) glucose uptake in 3T3L1 cells and inhibited starch digestion, glucose diffusion, dipeptidyl peptidase-IV (DPP-IV) enzyme activity, and protein glycation by 15-38%, 11-29%, 15-64%, and 21-38% (P<0.05, 0.001), respectively. In HFF rats, EEAA (250 mg/5 ml/kg) improved glucose tolerance, plasma insulin, and GLP-1 levels, and lowered DPP-IV enzyme activity. Phytochemical screening of EEAA revealed the presence of flavonoids, tannins and anthraquinone. These naturally occurring phytoconstituents may contribute to the potential antidiabetic actions of EEAA. Thus, our finding suggests that EEAA, as a good source of antidiabetic constituents, would be beneficial for Type 2 diabetes patients.

Encapsulation and Assessment of Antidiabetic Potential of α-Lactalbumin-Derived Hydrolysates.

Dipeptidyl peptidase-IV (DPP-IV) is an exopeptidase mainly present in epithelial tissues of the liver, kidney, and intestine. It is involved in the cleavage of a variety of substrates including the incretin hormones like glucagon-like peptide-1 (GLP-1). GLP-1 binds to the GLP-1 receptors of pancreatic β-cells and leads to β-cell proliferation and increases insulin secretion through associated gene expression. In diabetes, a constant increase in the glucose level leads to glucotoxicity, which destroys pancreatic β-cells, decreases the insulin level, and further increases the blood glucose level. Inhibition of DPP-IV is one of the strategies for the treatment of type 2 diabetes. In recent years, peptides derived from a variety of dietary proteins have been reported to exhibit inhibitory activity against the DPP-IV enzyme. Such peptides should also be protected from the action of digestive enzymes to keep their bioactivity intact. Therefore, the present investigation was aimed to evaluate the in vitro DPP-IV inhibition potential and in vivo antidiabetic potential of α-lactalbumin in non-encapsulated hydrolysate (NEH), freeze-dried encapsulated hydrolysate (FDEH), and emulsified encapsulated hydrolysate (EEH) forms. Percent DPP-IV inhibition by the NEH, FDEH, and EEH after simulated gastrointestinal digestion was 36 ± 2.28, 54 ± 2.02, and 64 ± 2.02, respectively. The oral administration of the NEH, FDEH, and EEH at a dose of 300 mg/kg body weight was evaluated in nicotinamide-streptozotocin-induced type 2 diabetic experimental rats in a study of 30 days. Rats in the diabetic control group showed an increase in the blood glucose level and liver function enzymes and a decrease in GLP-1, insulin, and antioxidative enzymes. Administration of hydrolysates reversed the parameters by lowering the blood glucose level and increasing GLP-1 and insulin levels in plasma. The blood lipid profile, liver enzyme (ALT, AST, and AP) levels, and catalase and superoxide dismutase activity were also found to be normalized and better managed in experimental diabetic rats.

Coumarin-Based Sulfonamide Derivatives as Potential DPP-IV Inhibitors: Pre-ADME Analysis, Toxicity Profile, Computational Analysis, and In Vitro Enzyme Assay.

Recent research on dipeptidyl peptidase-IV (DPP-IV) inhibitors has made it feasible to treat type 2 diabetes mellitus (T2DM) with minimal side effects. Therefore, in the present investigation, we aimed to discover and develop some coumarin-based sulphonamides as potential DPP-IV inhibitors in light of the fact that molecular hybridization of many bioactive pharmacophores frequently results in synergistic activity. Each of the proposed derivatives was subjected to an in silico virtual screening, and those that met all of the criteria and had a higher binding affinity with the DPP-IV enzyme were then subjected to wet lab synthesis, followed by an in vitro biological evaluation. The results of the pre-ADME and pre-tox predictions indicated that compounds 6e, 6f, 6h, and 6m to 6q were inferior and violated the most drug-like criteria. It was observed that 6a, 6b, 6c, 6d, 6i, 6j, 6r, 6s, and 6t displayed less binding free energy (PDB ID: 5Y7H) than the reference inhibitor and demonstrated drug-likeness properties, hence being selected for wet lab synthesis and the structures being confirmed by spectral analysis. In the in vitro enzyme assay, the standard drug Sitagliptin had an IC50 of 0.018 µM in the experiment which is the most potent. All the tested compounds also displayed significant inhibition of the DPP-IV enzyme, but 6i and 6j demonstrated 10.98 and 10.14 µM IC50 values, respectively, i.e., the most potent among the synthesized compounds. Based on our findings, we concluded that coumarin-based sulphonamide derivatives have significant DPP-IV binding ability and exhibit optimal enzyme inhibition in an in vitro enzyme assay.

Chemical composition of the dietary supplement Coccinia grandis (L.) Voigt, and its effect on antioxidant status and inflammatory markers in patients with type 2 diabetes mellitus

Herbal dietary supplements are widely used throughout the world with reports of their use among patients with type 2 diabetes mellitus (T2DM). The present work aimed to provide a comprehensive depiction of the dietary supplement Coccinia grandis (L.) Voigt (in the form of aqueous extract of freeze-dried powder), and to determine its antioxidant and anti-inflammatory effects in patients with T2DM. The antioxidant and anti-inflammatory effects of the dietary supplement were evaluated through a three-month long, randomised, double-blind, placebo-controlled clinical trial involving 158 newly diagnosed patients with T2DM. The dietary supplement consisted of phytoconstituents including loliolide, neophytadiene, palmitic acid methyl ester, among others. The absence of microorganisms was observed for a month at 40°C. In vitro antidiabetic assays revealed the inhibition of α-amylase, α-glucosidase, and dipeptidyl peptidase-IV enzymes, and also the enhancement of glucose uptake in cells. Administration of C. grandis dietary supplement (500 mg/day) for three months was able to change variables from the baseline to the end of the intervention, in the test and placebo groups, as -3.25 ± 3.93 and 1.42 ± 4.84 U/L for glutathione reductase (p &lt; 0.001), 12.75 ± 33.35 and -1.45 ± 41.93 nmol/dL for malonaldehyde (p = 0.025), and 5.89 ± 11.49 and 0.46 ± 13.11 pg/mL for interleukin-6 (p = 0.002), respectively. The standardised dietary supplement showed antidiabetic activity in vitro. The clinical study revealed its promising commercial application as a dietary supplement, by improving antioxidant status and reducing inflammation in newly diagnosed patients with T2DM.

Therapeutic Potential of Silybum marianum and Pergularia tomentosa Extracts from Jordanian Origin in Diabetes Mellitus

Background: Jordan is a country well-known for its diversity in wild plants, and for many decades, folk medicines have represented part of its cultural heritage. In the present study, investigations have been focused on the therapeutic potential of Silybum marianum and Pergularia tomentosa on type 2 diabetes mellitus. In type 2 diabetes, which is considered a global health problem, the body cannot respond to or produce insulin hormonem, which raises the blood glucose level, resulting in mortality, morbidity, healthcare expenses, and reduced life quality. Dipeptidyl peptidase-IV (DPP-IV) enzyme, a serine protease, is responsible for deactivating incretin hormones that promote insulin secretion. Accordingly, the DPP-IV inhibitory activity of these plant extracts that prolong the hypoglycemic effect of incretins was evaluated. Method: The aerial parts of S. marianum and P. tomentosa were dried, ground, and extracted with ethanol. The ethanol extract was dried under reduced pressure and was partitioned by methanol, butanol, and hexane according to a systematic procedure. The inhibition of the DPP-IV enzyme by the different extracts was studied (at 10.0 mg/mL concentration). Sitagliptin was used as the positive control. Results: Fortunately, most of the plant extracts have noticeable inhibitory activity against the DPPIV enzyme. It was found that the tested methanol extract of S. marianum has an inhibitory activity of 75.6% and the butanol extract of P. tomentosa has an inhibitory activity of 73.6%, which are analogous to DPP-IV inhibition of sitagliptin (78.5%), the used positive inhibitor. A superior inhibition of 98.1% was displayed for the butanol extract of S. marianum at 10.0 mg/ mL concentration. Conclusion: The revealed DPP-IV inhibitory activity of tested extracts advocates that their active constituents, particularly flavonoids, are capable of binding to the enzyme’s active cleft.

Chemical composition of pumpkin (Cucurbita maxima) seeds and its supplemental effect on Indian women with metabolic syndrome

This study aimed to investigate the effect of pumpkin ( Cucurbita maxima ) seed supplementation on the anthropometric measurements, biochemical parameters, and blood pressure (BP) of Indian women with metabolic syndrome (MetS). Initially, in vitro antioxidant activities of pumpkin seeds extract were assessed using standard methods. In vitro alpha-amylase, alpha-glucosidase, and dipeptidyl peptidase IV (DPP-IV) inhibition effects, along with glucose uptake assay using 3T3-L1 cell lines were performed to determine the antidiabetic effects of the seeds extract. Fatty acids and phytoconstituents were identified using gas chromatography-mass spectrometry (GC–MS). Indian women aged 30–50 years, having MetS were assigned either to intervention (n = 21) or control (n = 21) group on a random basis. Participants in the intervention group received 5 g of pumpkin seeds for 60 days. Participants in both intervention and control were advised to follow certain dietary guidelines throughout the study. Pumpkin seeds extract exhibited not only strong reducing power but also scavenged DPPH and ABTS ●+ free radicals with low IC 50 values. Pumpkin seeds inhibited alpha-amylase, alpha-glucosidase, and DPP-IV enzymes at varying concentrations with IC 50 values of 138, 22, and 246 µg/mL, respectively. Furthermore, glucose uptake was enhanced by 213% at 300 ng/mL on the 3T3-L1 cell line. GC–MS analysis showed the presence of propyl piperidine, flavone, oleic acid, and methyl esters of fatty acids in the seed extract. On comparing the changes in mean reduction/ increment in the anthropometric measurements as well as biochemical parameters and BP between the groups, significant difference ( P = 0.012) was observed only for fasting plasma glucose. Findings of the present study highlight the role of pumpkin seeds as a cost-effective adjunct in treating MetS.

Antidiabetic and antihyperlipidemic effects of crude fractions and isolated compound from Striga orobanchioides Benth on streptozotocin induced diabetic rats

BackgroundStriga orobanchioides Benth is a traditionally used Ayurvedic medicinal plant for the treatment of diabetes. Scientific validation of the claim is studied in this research. The significant bioactivity of the plant components is obligatory for its use in medicine. ObjectiveThe present work is to extract bioactive fractions and chemicals, biological activity of the chemicals and to identify potentially bioactive compound(s) from ethanolic extract of the plant. Materials and methodsEthanolic extract of the authenticated plant was fractionated and subjected to in vitro and in vivo antidiabetic and antihyperlipidemic activity. In vitro α-amylase and α-glucosidase enzyme activity was carried out on digestive enzyme. Streptozotocin (STZ) induced diabetes mellitus in rats model was preferred for in vivo activity where antidiabetic parameters body weight, urine volume, blood glucose level, glycosylated hemoglobin, serum insulin, liver glycogen and lipid profile as an antihypertensive parameters were assessed. Isolation of bioactive compounds was carried out by chromatographic techniques and identification of the compound was done by FTIR, Mass spectrometry and NMR spectroscopy. The molecular docking study with α-amylase, α-glucosidase, dipeptidyl peptidase-IV (DPP-IV), glucokinase (GK) as diabetic markers and on 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) and Niemann-Pick C1-Like 1 (NPC1L1) was carried out. ResultsEthyl acetate-methanol fraction of the ethanol extract showed presence of pentacyclic triterpenoids (81.5% w/w) in GC-HRMS study. Spectroscopic analysis of the isolated compound revealed presence betulin. In vitro antidiabetic activity pointed out robust inhibition of the digestive enzymes by the fractions known as bioactive fraction and betulin. Betulin at a dose of 40 mg/kg treated group showed significant improvement of diabetic conditions. The gene expression studies revealed that betulin in 40 mg/kg dose has positive effects for carbohydrate metabolism in liver, lowers the hepatic inflammation and increases insulin secretion. The plant compound demonstrated significant inhibitory potential on α-amylase, α-glucosidase, DPP-IV and GK enzymes in silico. ConclusionThe biological study reveals that betulin could dominate the succession of diabetes in dose dependent manner. The plant and specifically Betulin exerts a significant antidiabetic and antihyperlipidemic effects that are more possibly through stimulation of insulin secretion, increase in PPAR-α level with an increase in GRIA2 mRNA expression.

Identification of two novel dipeptidyl peptidase-IV inhibitory peptides from sheep whey protein and inhibition mechanism revealed by molecular docking

In this study, the peptides with dipeptidyl peptidase-IV (DPP-IV) inhibitory activities were obtained by trypsin hydrolysis from sheep whey protein. The results showed that the highest DPP-IV inhibitory activity of the hydrolysate (77.80% ± 1.87%) was obtained by trypsin enzymolysis for 4.0 h with 24.50% ± 0.05% of the degree of hydrolysis (DH). Peptides with inhibitory activity against DPP-IV were purified using anion-exchange (DEAE-52) and size-exclusion (G15 dextran gel) chromatography. A total of 86 peptides were identified using LC-MS/MS. The binding energies of RLYLHENK(RL8) and MQEHFTCCR(MQ9) to DPP-IV were determined to be -11.29 kcal/mol and -10.79 kcal/mol with molecular docking in silico, respectively. RL8 and MQ9 could bind to DPP-IV mainly through hydrogen bonds and hydrophobic interactions, and inhibit the DPP-IV enzyme by occupying the S2 pocket. The IC50 values of RL8 and MQ9 in vitro were 166.4 μmol/L and 214.8 μmol/L, respectively. The inhibitory activities in situ modes of the two peptides were evaluated using Caco-2 cells. The IC50 values of RL8 and MQ9 in situ were 158.3 μmol/L and 251.6 μmol/L, respectively. The RL8 and MQ9 derived from sheep whey protein can be considered as a potential source of natural DPP-IV inhibitor.

In-silico Exploration of Phytoconstituents of Gymnema sylvestre as Potential Glucokinase Activators and DPP-IV Inhibitors for the Future Synthesis of Silver Nanoparticles for the Treatment of Type 2 Diabetes Mellitus

Background: Diabetes has a large death toll worldwide, particularly as it falls into the ten leading causes of death. Type 2 diabetes mellitus (T2DM) occurs as the body becomes resistant to insulin and sugar accumulates in the blood. It has been observed that dipeptidyl peptidase-IV (DPP-IV) inhibitors and glucokinase activators are known therapeutic agents to treat T2DM. Among the possible medicinal plants, Gymnema sylvestre (GyS) belongs to the Apocynaceae family and is traditionally used for the treatment of different diseases. This plant is also known as “Gurmur” because it has a sugarreducing ability. GyS is known to be one of the main botanicals for the treatment of diabetes. Objective: Considering the studies described above, we have tried to investigate the natural DPP-IV inhibitors and potent glucokinase activators from the phytoconstituents of GyS. New drug candidates from the medicinal plant GyS have been reported as potent DPP-IV inhibitors and glucokinase activators. Methods: As a preliminary investigation, we have studied the effectiveness of phytoconstituents of GyS in T2DM through molecular docking as a proof of concept of synthesizing silver nanoparticles (for the treatment of T2DM) using an extract of this plant. Results: The present investigative research shows that the recognized compounds included in the present analysis have important values in the treatment of diabetes mellitus. The nine compounds selected are evaluated on the basis of DPP-IV and glucokinase enzyme binding energy values and their drug properties. Except for quercitol, all the selected compounds have exhibited much more potent glucokinase activation potential than their native ligands. Gymnemasin A, lupeol, gymnemoside A, gymnemasaponin V, and gymnemic acid I have shown excellent DPP-IV inhibitory potential. Conclusion: We aimed to synthesize the silver nanoparticles from the leaf extract of GyS for the treatment of T2DM. As a preliminary investigation, we have studied the effectiveness of phytoconstituents of GyS in T2DM through molecular docking as proof of synthesizing silver nanoparticles (for the treatment of T2DM) using an extract of this plant. As a result of the present investigation, it has been concluded that these compounds can be used to treat T2DM, and hence, in the future, we can synthesize the silver nanoparticles from the GyS extract for the treatment of T2DM.

Discovery and functional mechanism of novel dipeptidyl peptidase Ⅳ inhibitory peptides from Chinese traditional fermented fish (Chouguiyu)

Dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides from fermented foods exhibit great potential to alleviate type 2 diabetes mellitus (T2DM). In this study, the DPP-IV inhibition activity of peptide extract from Chouguiyu was obviously enhanced after 4–8 d fermentation. A total of 125 DPP-IV inhibitory peptides in Chouguiyu were identified by peptidomics and were obtained from 46 precursor proteins, mainly including nebulin, titin, muscle-type creatine kinase, hemoglobin, and actin. After molecular docking with DPP-IV, four novel DPP-IV inhibitory peptides possessing the lowest docking energy were selected, including EPAEAVGDWR (D37), IPHESVDVIK (D22), PDLSKHNNHM (D35), and PFGNTHNNFK (D1). The DPP-IV inhibition activity of D37, D22, D35, and D1 were further verified after synthesis with the IC50 of 0.10 mM, 2.69 mM, 3.88 mM, and 8.51 mM, respectively, in accordance with their docking energies. Energy interaction showed that the structures of EP-, IPH-, -NHM, and PF- in these peptides were easy to connect with DPP-IV enzyme through hydrogen bond, salt bridge, and alkyl. The surface force including the H-bond interaction, hydrophobicity, aromatic interaction, and SAS, played a major role in the interaction between DPP-IV enzyme and peptides. The peptides that possess high hydrophobicity and can form strong hydrogen bond and salt bridge are potential DPP-IV inhibitory peptides using for T2DM remission.

Purification, identification and in silico studies of antioxidant, antidiabetogenic and antibacterial peptides obtained from sorghum spent grain hydrolysate

The identification of antioxidant, antidiabetogenic and antimicrobial peptides obtained from sorghum spent grain (SSG) protein hydrolysate was performed. Antioxidant activity (AOA) was evaluated by ABTS+ radical cation scavenging, antidiabetogenic activity (ADA) by dipeptidyl peptidase IV (DPP-IV) inhibition, and antimicrobial activity (AMA) through the minimum inhibitory concentration (MIC) method against 2 Gram-negative and 3 Gram-positive bacteria. SSG peptides were fractionated using a Sephadex G-25 molecular exclusion column, and fractions collected (F1–F6) were evaluated through AOA, ADA and AMA assays. The chromatographic process allowed increasing 20% the AOA and 35% the ADA in F2, and 90% the AMA in fractions F5 and F6. The most active fractions (F2, F5 and F6) were evaluated using LC-ESI-Q-TOF tandem mass spectrometry, which allowed identifying six new peptides with high bioactivity. Moreover, the docking refinement protocol showed that identified peptides could interact with the DPP-IV enzyme, two of them in a competitive inhibition mode. Sorghum spent grain (SSG) could be an important source of bioactive peptides. Additionally, this is the first report indicating the presence of antibacterial peptides encrypted in sorghum proteins.

In vitro and in cellulo anti-diabetic activity of AuI- and AuIII-isothiourea complexes

About 100 million people worldwide have type II diabetes (T2D), making it one of the most common metabolic diseases. DPP-IV (dipeptidyl peptidase-IV) inhibitors are new class of anti-diabetic drugs. Gold complexes are known for diverse biological activities. Considering these precedents, and growing interest in developing metal-based enzyme inhibitors, we report here the DPP-IV inhibitory potential of cationic, and neutral chiral gold (I), and gold (III) isothiourea complexes. Colorimetric assay with recombinant DPP-IV enzyme was employed for initial screening. Kinetic based mechanistic studies were also performed on most active complexes. Efficiency of identified inhibitors in biological environment was assessed in in cellulo assay, using Caco-2 cell line. These complexes showed a good to moderate inhibition of DPP-IV with IC50 values in the range of 22.0-99.0 µM, as compared to standard inhibitor, sitagliptin (IC50 = 0.033 ± 0.04 µM). It was observed that steric, and electronic properties of the isothiourea ligands have profound effect on the DPP-IV inhibitory activity of these complexes. To the best of our knowledge this study reports for the first time isothiourea-based gold complexes as inhibitors of DPP-IV enzyme. These results thus provide an approach for exploring new insights into the development of effective agents against diabetes using incretin-based therapy.

Structure\u2013function engineering of novel fish gelatin-derived multifunctional peptides using high-resolution peptidomics and bioinformatics

The multifunctional properties of fish gelatin hydrolysates have not been completely elucidated. Here, the biological characterization of these peptides was performed to engineer multifunctional peptides. Bioactive peptides were produced from mackerel byproducts via successive enzymatic hydrolysis reactions using subtilisin A and actinidin as microbial and herbal proteases. The antibacterial activity against both gram-negative and -positive food-borne pathogens, including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Klebsiella pneumoniae, as well as the inhibitory potential of angiotensin-converting enzyme (ACE) and dipeptidyl peptidase IV (DPP-IV), was accessed in vitro. The synthesized peptides demonstrated multifunctional properties, which were further confirmed by in silico protocols. The ACE and DPP-IV inhibitory (IC50) values of P1, P2, and P3 were 0.92 and 0.87, 0.51 and 0.93, 0.78 and 1.16 mg mL−1, respectively. Moreover, the binding energy was sufficient for all three peptides to inhibit both ACE and DPP-IV enzymes with excellent three-dimensional conformation (RMSD = 0.000) for all six docking mechanisms.

Influence of fish protein hydrolysate-pistachio green hull extract interactions on antioxidant activity and inhibition of α-glucosidase, α-amylase, and DPP-IV enzymes

This study investigated the effects of protease type (Alcalase, papain and pepsin), fractionation (2 and 10 kDa nominal molecular weight cutoff) and pistachio green hull (PGH) extract addition on antioxidant activity (DPPH radical scavenging and metal chelating activity), α-glucosidase, α-amylase, and dipeptidyl peptidase IV (DPP-IV) inhibitory activity of Sind sardine hydrolysates. Papain led to the highest degree of hydrolysis and antioxidant activity and the addition of PGH enhanced the bioactivity. Hydrolysates and fractions had stronger inhibition of α-amylase than α-glucosidase, and hydrolysates from papain and Alcalase were more active than those from pepsin against α-amylase. Interaction of PGH and the hydrolysates/peptidic fractions resulted in a decrease in α-glucosidase and α-amylase inhibition. The kinetics of α-amylase inhibition with papain hydrolysates and papain-PGH showed competitive inhibition. Hydrolysates and fractions also significantly inhibited DPP-IV, but PGH did not inhibit the enzyme or change the inhibitory effect of the hydrolysates and fractions (P ≥ 0.05). Furthermore, the highest surface hydrophobicity was observed for the >10 kDa fractions and the values increased by the addition of PGH to the hydrolysates. Therefore, PGH–hydrolysate interaction improved only the antioxidant capacity of the protein hydrolysates with nil or negative effects on the enzyme inhibition.

Effects of 22 traditional anti-diabetic medicinal plants on DPP-IV enzyme activity and glucose homeostasis in high-fat fed obese diabetic rats

The present study investigated the effects of hot water extracts of 22 medicinal plants used traditionally to treat diabetes on Dipeptidyl peptidase-IV (DPP-IV) activity both in vitro and in vivo in high-fat fed (HFF) obese-diabetic rats. Fluorometric assay was employed to determine the DPP-IV activity. For in vivo studies, HFF obese-diabetic rats were fasted for 6 h and blood was sampled at different times before and after the oral administration of the glucose alone (18 mmol/kg body weight) or with either of the four most active plant extracts (250 mg/5 ml/kg, body weight) or established DPP-IV inhibitors (10 μmol/5 ml/kg). DPP-IV inhibitors: sitagliptin, vildagliptin and diprotin A, decreased enzyme activity by a maximum of 95–99% (P<0.001). Among the 22 natural anti-diabetic plants tested, Anogeissus Latifolia exhibited the most significant (P<0.001) inhibitory activity (96 ± 1%) with IC50 and IC25 values of 754 and 590 μg/ml. Maximum inhibitory effects of other extracts: Aegle marmelos, Mangifera indica, Chloropsis cochinchinensis, Trigonella foenum-graecum and Azadirachta indica were (44 ±7%; 38 ± 4%; 31±1%; 28±2%; 27±2%, respectively). A maximum of 45% inhibition was observed with >25 μM concentrations of selected phytochemicals (rutin). A. latifolia, A. marmelos, T. foenum-graecum and M. indica extracts improved glucose tolerance, insulin release, reduced DPP-IV activity and increased circulating active GLP-1 in HFF obese-diabetic rats (P<0.05–0.001). These results suggest that ingestion of selected natural anti-diabetic plants, in particular A. latifolia, A. marmelos, T. foenum-graecum and M. indica can substantially inhibit DPP-IV and improve glucose homeostasis, thereby providing a useful therapeutic approach for the treatment of T2DM.