Molecular Mechanistic Insights into Dipeptidyl Peptidase-IV Inhibitory Peptides to Decipher the Structural Basis of Activity.

Dipeptidyl peptidase-IV (DPP-IV) inhibiting peptides have attracted increased attention because of their possible beneficial effects on glycemic homeostasis. However, the structural basis underpinning their activities has not been well understood. This study combined computational and in vitro investigations to explore the structural basis of DPP-IV inhibitory peptides. We first superimposed the Xaa-Pro-type peptide-like structures from several crystal structures of DPP-IV ligand-protein complexes to analyze the recognition interactions of DPP-IV to peptides. Thereafter, a small set of Xaa-Pro-type peptides was designed to explore the effect of key interactions on inhibitory activity. The intramolecular interaction of Xaa-Pro-type peptides at the first and third positions from the N-terminus was pivotal to their inhibitory activities. Residue interactions between DPP-IV and residues of the peptides at the fourth and fifth positions of the N-terminus contributed significantly to the inhibitory effect of Xaa-Pro-type tetrapeptides and pentapeptides. Based on the interaction descriptors, quantitative structure-activity relationship (QSAR) studies with the DPP-IV inhibitory peptides resulted in valid models with high R2 values (0.90 for tripeptides; 0.91 for tetrapeptides and pentapeptides) and Q2 values (0.33 for tripeptides; 0.68 for tetrapeptides and pentapeptides). Taken together, the structural information on DPP-IV and peptides in this study facilitated the development of novel DPP-IV inhibitory peptides.

Contribution of amino acids in the active site of dipeptidyl peptidase 4 to the catalytic action of the enzyme.

Dipeptidyl peptidase 4 (DP4)/CD26 regulates the biological function of various peptide hormones by releasing dipeptides from their N-terminus. The enzyme is a prominent target for the treatment of type-2 diabetes and various DP4 inhibitors have been developed in recent years, but their efficacy and side effects are still an issue. Many available crystal structures of the enzyme give a static picture about enzyme-ligand interactions, but the influence of amino acids in the active centre on binding and single catalysis steps can only be judged by mutagenesis studies. In order to elucidate their contribution to inhibitor binding and substrate catalysis, especially in discriminating the P1 amino acid of substrates, the amino acids R125, N710, E205 and E206 were investigated by mutagenesis studies. Our studies demonstrated, that N710 is essential for the catalysis of dipeptide substrates. We found that R125 is not important for dipeptide binding but interacts in the P1`position of the peptide backbone. In contrast to dipeptide substrates both amino acids play an essential role in the binding and arrangement of long natural substrates, particularly if lacking proline in the P1 position. Thus, it can be assumed that the amino acids R125 and N710 are important in the DP4 catalysed substrate hydrolysis by interacting with the peptide backbone of substrates up- and downstream of the cleavage site. Furthermore, we confirmed the important role of the amino acids E205 and E206. However, NP Y, displaying proline in P1 position, is still processed without the participation of E205 or E206.

Protein Hydrolysis as a Way to Valorise Squid-Processing Byproducts: Obtaining and Identification of ACE, DPP-IV and PEP Inhibitory Peptides.

The industrial processing of Argentine shortfin squid to obtain rings generates a significant amount of protein-rich waste, including the skin, which is rich in collagen and attached myofibrillar proteins. This waste is generally discarded. In this study, skin was used as a source of proteins that were hydrolysed using Trypsin, Esperase® or Alcalase®, which released peptides with antioxidant potential and, in particular, antihypertensive (ACE inhibition), hypoglycemic (DPP-IV inhibition) and/or nootropic (PEP inhibition) potential. Among the three enzymes tested, Esperase® and Alcalase produced hydrolysates with potent ACE-, DPP-IV- and PEP-inhibiting properties. These hydrolysates underwent chromatography fractionation, and the composition of the most bioactive fractions was analysed using HPLC-MS-MS. The fractions with the highest bioactivity exhibited very low IC50 values (16 and 66 µg/mL for ACE inhibition, 97 µg/mL for DPP-IV inhibition and 55 µg/mL for PEP inhibition) and were mainly derived from the hydrolysate obtained using Esperase®. The presence of Leu at the C-terminal appeared to be crucial for the ACE inhibitory activity of these fractions. The DPP-IV inhibitory activity of peptides seemed to be determined by the presence of Pro or Ala in the second position from the N-terminus, and Gly and/or Pro in the last C-terminal positions. Similarly, the presence of Pro in the peptides present in the best PEP inhibitory fraction seemed to be important in the inhibitory effect. These results demonstrate that the skin of the Argentine shortfin squid is a valuable source of bioactive peptides, suitable for incorporation into human nutrition as nutraceuticals and food supplements.

Anti-diabetic properties of brewer's spent yeast peptides. In vitro, in silico and ex vivo study after simulated gastrointestinal digestion.

Brewer's spent yeast (BSY) hydrolysates are a source of antidiabetic peptides. Nevertheless, the impact of in vitro gastrointestinal digestion of BSY derived peptides on diabetes has not been assessed. In this study, two BSY hydrolysates were obtained (H1 and H2) using ß-glucanase and alkaline protease, with either 1 h or 2 h hydrolysis time for H1 and H2, respectively. These hydrolysates were then subjected to simulated gastrointestinal digestion (SGID), obtaining dialysates D1 and D2, respectively. BSY hydrolysates inhibited the activity of α-glucosidase and dipeptidyl peptidase IV (DPP-IV) enzymes. Moreover, although D2 was inactive against these enzymes, D1 IC50 value was lower than those found for the hydrolysates. Interestingly, after electrophoretic separation, D1 mannose-linked peptides showed the highest α-glucosidase inhibitory activity, while non-glycosylated peptides had the highest DPP-IV inhibitory activity. Kinetic analyses showed a non-competitive mechanism in both cases. After peptide identification, GILFVGSGVSGGEEGAR and IINEPTAAAIAYGLDK showed the highest in silico anti-diabetic activities among mannose-linked and non-glycosylated peptides, respectively (AntiDMPpred score: 0.70 and 0.77). Molecular docking also indicated that these peptides act as non-competitive inhibitors. Finally, an ex vivo model of mouse jejunum organoids was used to study the effect of D1 on the expression of intestinal epithelial genes related to diabetes. The reduction of the expression of genes that codify lactase, sucrase-isomaltase and glucose transporter 2 was observed, as well as an increase in the expression of Gip (glucose-dependent insulinotropic peptide) and Glp1 (glucagon-like peptide 1). This is the first report to evaluate the anti-diabetic effect of BSY peptides in mouse jejunum organoids.

Identification, rapid screening, docking mechanism and in vitro digestion stability of novel DPP-4 inhibitory peptides from wheat gluten with ginger protease.

To better understand the hypoglycemic potential of wheat gluten (WG), we screened dipeptidyl peptidase IV (DPP-4) inhibitory active peptides from WG hydrolysates. WG hydrolysates prepared by ginger protease were found to have the highest DPP-4 inhibitory activity among the five enzymatic hydrolysates, from which a 1-3 kDa fraction was isolated by ultrafiltration. Further characterization of the fraction with nano-HPLC-MS/MS revealed 1133 peptides. Among them, peptides with P'2 (the second position of the N-terminal) and P2 (the second position of the C-terminal) as proline residues (Pro) accounted for 12.44% and 43.69%, respectively. The peptides including Pro-Pro-Phe-Ser (PPFS), Ala-Pro-Phe-Gly-Leu (APFGL), and Pro-Pro-Phe-Trp (PPFW) exhibited the most potent DPP-4 inhibitory activity with IC50 values of 56.63, 79.45, and 199.82 µM, respectively. The high inhibitory activity of PPFS, APFGL, and PPFW could be mainly attributed to their interaction with the S2 pocket (Glu205 and Glu206) and the catalytic triad (Ser630 and His740) of DPP-4, which adopted competitive, mixed, and mixed inhibitory modes, respectively. After comparative analysis of PPFS, PPFW, and PPF, Ser was found to be more conducive to enhancing the DPP-4 inhibitory activity. Interestingly, peptides with P2 as Pro also exhibited good DPP-4 inhibitory activity. Meanwhile, DPP-4 inhibitory peptides from WG showed excellent stability, suggesting a potential application in type 2 diabetes (T2DM) therapy or in the food industry as functional components.

Association of DPP-4 Concentrations with the Occurrence of Gestational Diabetes Mellitus and Excessive Gestational Weight Gain.

Gestational diabetes mellitus (GDM) is considered one of the most common diseases that occur during pregnancy. In addition to increasing the risk of numerous complications throughout gestation, it is also believed to have a long-term potential to impact the risk of developing type 2 diabetes mellitus (T2DM) and cardiovascular disease for the mother and her offspring. While there are clear guidelines for healthy weight gain in pregnancy depending on pre-pregnancy BMI, as well as dietary and training recommendations to achieve this, an increasing number of women are experiencing excessive gestational weight gain (EGWG). Such patients have a higher risk of developing GDM and gestational hypertension, as well as requiring caesarian delivery. Dipeptidyl peptidase-4 (DPP-4) is a glycoprotein that seems to play an important role in glucose metabolism, and inhibition of its activity positively affects glucose regulation. The aim of our study was to compare DPP-4 concentrations in patients with GDM and EGWG with healthy women. DPP-4 levels were assessed in serum and urine samples collected on the day of delivery. The bioelectrical impedance analysis (BIA) method was also used to analyze the body composition of patients on the second day of the postpartum period. DPP-4 serum concentrations were significantly higher in patients in the GDM and EGWG groups compared to healthy women. Urinary DPP-4 concentrations were significantly higher in the control and GDM groups than in the EGWG group. Serum DPP-4 levels were positively correlated with BMI measured before pregnancy, on the delivery day, and in the early postpartum period, among other factors. According to our knowledge, this is the first study to determine DPP-4 levels in EGWG patients. DPP-4 may be related to the occurrence of GDM and EGWG; however, this requires further research.

An Update on Dipeptidyl Peptidase-IV Inhibiting Peptides.

Diabetes is a chronic metabolic disorder. According to the International Diabetes Federation, about 537 million people are living with diabetes. The two types of diabetes are type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM), among which the population affected by T2DM is relatively higher. A major reason for T2DM is that insulin stimulation is hampered due to the inactivation of incretin hormones. Dipeptidyl peptidase-IV (DPP-IV) is a serine protease that is directly involved in the inactivation of incretin hormones, e.g., glucagon-like peptide-1 (GLP-1). Therefore, the inhibition of DPP-IV can be a promising method for managing T2DM, in addition to other enzyme inhibition strategies, such as inhibition of α-amylase and α -glucosidase. Currently, about 12 different gliptin drugs are available in the market that inhibit DPP-IV in a dose-dependent manner. Instead of gliptins, 'peptides' can also be employed as an alternative and promising way to inhibit DPP-IV. Peptide inhibitors of DPP-IV have been identified from various plants and animals. Chemically synthesized peptides have also been experimented for inhibiting DPP-IV. Most peptides have been analysed by biochemical assays, whereas some in vitro assays have also been reported. Molecular docking analysis has been applied to comprehend the mechanism of inhibition. In this review, certain aspects of natural as well as synthetic peptides are described that have been proven to inhibit DPP-IV.

Identification, characterization, and insights into the mechanism of novel dipeptidyl peptidase-IV inhibitory peptides from yak hemoglobin by in silico exploration, molecular docking, and in vitro assessment.

Dipeptidyl peptidase IV (DPP-IV) inhibitory peptides were screened and identified from yak hemoglobin for the first time by in silico analysis, molecular docking, and in vitro evaluation. Results showed that yak hemoglobin had a high potential to produce DPP-IV inhibitory peptides based on the sequence alignment and bioactive potential evaluation. Furthermore, "pancreatic elastase + stem bromelain" was the optimal combined-enzymatic strategy by simulated proteolysis. Additionally, 25 novel peptides were found from its simulated hydrolysate, among which 10 peptides had high binding affinities with DPP-IV by molecular docking. Most of these peptides were also in silico characterized with favorable physicochemical properties and biological potentials, including relatively low molecular weight, high hydrophobicity, several net charges, good water solubility, nontoxicity, acceptable sensory quality, and good human intestinal absorption. Finally, six novel DPP-IV inhibitory peptides were identified via in vitro assessment, among which EEKA (IC50 = 235.26 µM), DEV (IC50 = 339.45 µM), and HCDKL (IC50 = 632.93 µM) showed the strongest capacities. The hydrogen bonds and electrostatic attractions formed with core residues within the S2 pocket of DPP-IV could be mainly responsible for their inhibition performances. This work provided a time-saving method and broadened application for yak by-products development as sources of functional foods.

Screening of novel DPP-IV inhibitory peptides derived from bovine milk proteins using a peptide array platform.

Dipeptidyl peptidase IV (DPP-IV) has become an important target in the prevention and treatment of diabetes. Although many DPP-IV inhibitory peptides have been identified by a general approach involving the repeated fractionation of food protein hydrolysates, the obtained results have been dependent on the content of each peptide and fractionation conditions. In the present study, a peptide array that provides comprehensive assays of peptide sequences was used to identify novel DPP-IV inhibitory peptides derived from bovine milk proteins; these peptides were then compared with those identified using the general approach. While the general approach identified only known peptides that were abundant in the hydrolysate, the peptide array-based approach identified 10 novel DPP-IV inhibitory peptides, all of which had proline at the second residue from the N-terminus. The proper or combined use of these two approaches, which have different advantages, will enable the efficient development of novel bioactive foods and drugs.

iDPPIV-SI: identifying dipeptidyl peptidase IV inhibitory peptides by using multiple sequence information.

Currently, diabetes has become a great threaten for people's health in the world. Recent study shows that dipeptidyl peptidase IV (DPP-IV) inhibitory peptides may be a potential pharmaceutical agent to treat diabetes. Thus, there is a need to discriminate DPP-IV inhibitory peptides from non-DPP-IV inhibitory peptides. To address this issue, a novel computational model called iDPPIV-SI was developed in this study. In the first, 50 different types of physicochemical (PC) properties were employed to denote the peptide sequences. Three different feature descriptors including the 1-order, 2-order correlation methods and discrete wavelet transform were applied to collect useful information from the PC matrix. Furthermore, the least absolute shrinkage and selection operator (LASSO) algorithm was employed to select these most discriminative features. All of these chosen features were fed into support vector machine (SVM) for identifying DPP-IV inhibitory peptides. The iDPPIV-SI achieved 91.26% and 98.12% classification accuracies on the training and independent dataset, respectively. There is a significantly improvement in the classification performance by the proposed method, as compared with the state-of-the-art predictors. The datasets and MATLAB codes (based on MATLAB2015b) used in current study are available at https://figshare.com/articles/online_resource/iDPPIV-SI/20085878.Communicated by Ramaswamy H. Sarma.

Preparation, identification, and inhibitory mechanism of dipeptidyl peptidase IV inhibitory peptides from goat milk whey protein.

This study explores potential hypoglycemic mechanisms by preparing and identifying novel dipeptidyl peptidase IV (DPP-IV) inhibitory peptides from goat milk (GM) whey protein. Papain was used to hydrolyze the GM whey protein. After purification by ultrafiltration, the Sephadex column, and preparative RP-HPLC, the peptide inhibited DPP-IV, α-glucosidase, and α-amylase with IC50 of 0.34, 0.37, and 0.72 mg/mL, respectively. To further explore the inhibitory mechanism of peptides on DPP-IV, SPPEFLR, LDADGSY, YPVEPFT, and FNPTY were identified and synthesized for the first time, with IC50 values of 56.22, 52.16, 175.7, and 62.32 µM, respectively. Molecular docking and dynamics results show that SPPEFLR, LDADGSY, and FNPTY bind more tightly to the active pocket of DPP-IV, which was consistent with the in vitro activity. Furthermore, the first three N-terminals of SPPEFLR and FNPTY peptides exhibit proline characteristics and competitively inhibit DPP-IV. Notably, the first N-terminal leucine of LDADGSY may play a key role in inhibiting DPP-IV.

Identification of Novel Dipeptidyl Peptidase-IV Inhibitory Peptides in Chickpea Protein Hydrolysates.

Dipeptidyl peptidase-IV (DPP-IV) is one of the main targets for blood sugar control. Some food protein-derived peptides are thought to have DPP-IV inhibitory (DPP-IVi) activity. In this study, chickpea protein hydrolysates (CPHs) obtained through Neutrase hydrolysis for 60 min (CPHs-Pro-60) exhibited the highest DPP-IVi activity. DPP-IVi activity after simulated in vitro gastrointestinal digestion was maintained at >60%. Peptide libraries are established after the identification of peptide sequences. Molecular docking verified that the four screened peptides (AAWPGHPEF, LAFP, IAIPPGIPYW, and PPGIPYW) could bind to the active center of DPP-IV. Notably, IAIPPGIPYW exhibited the most potent DPP-IVi activity (half maximal inhibitory concentration (IC50): 12.43 µM). Both IAIPPGIPYW and PPGIPYW exhibited excellent DPP-IVi activity in Caco-2 cells. These results indicated that chickpea could be used as a source of natural hypoglycemic peptides for food and nutritional applications.

Discovery of anthraquinones as DPP-IV inhibitors: Structure-activity relationships and inhibitory mechanism.

Dipeptidyl peptidase IV (DPP-IV) is an integrated type II transmembrane protein that reduces endogenous insulin contents and increases plasma glucose levels by hydrolyzing glucagon-like peptide-1 (GLP-1). Inhibition of DPP-IV regulates and maintains glucose homeostasis, making it an attractive drug target for the treatment of diabetes II. Natural compounds have tremendous potential to regulate glucose metabolism. In this study, we examined the DPP-IV inhibitory activity of a series of natural anthraquinones and synthetic structural analogues on DPP-IV using fluorescence-based biochemical assays. The inhibitory efficiency differed among anthraquinone compounds with different structures. Alizarin (7), aloe emodin (11), emodin (13) emerged the outstanding inhibitory potential for DPP-IV with IC50 values lower than 5 µM. To clarifying the inhibitory mechanism, inhibitory kinetics were performed, which showed that alizarin red S (8) and 13 were effective non-competitive inhibitors of DPP-IV, while alizarin complexone (9), rhein (12), and anthraquinone-2-carboxylic acid (23) were mixed inhibitors. Emodin was determined as inhibitor with the strongest DPP-IV-binding affinity determined via molecular docking. Structure-activity relationship (SAR) demonstrated that hydroxyl group at C-1 and C-8 sites and hydroxyl, hydroxymethyl or carboxyl group at the C-2 or C-3 site were very essential for DPP-IV inhibition, replacement of hydroxyl group with amino group at C-1 could led to an increase of the inhibitory potential. Further fluorescence imaging showed that both compounds 7 and 13 significantly inhibited DPP-IV activity in RTPEC cells. Overall, the results indicated that anthraquinones would be a natural functional ingredient for inhibiting DPP-IV and provided new ideas for searching and developing potential antidiabetic compounds.

Identification and molecular docking study of sugarcane leaf-derived compounds as potent dipeptidyl peptidase IV, α-glucosidase, and α-amylase inhibitors.

BACKGROUND: Dipeptidyl peptidase-IV (DPP-IV), α-glucosidase, and α-amylase play a prominent role in regulating postprandial blood sugar levels, which are regarded as key targets for the treatment of type 2 diabetes mellitus (T2DM). The present study aimed to characterize bioactive compounds as potent crucial sugar metabolism enzyme inhibitors from sugarcane leaves by virtual screening. In total, 41 sugarcane leaf-derived compounds were used for the screening of multiple targets. Subsequently, the molecular mechanism and activity validation in vitro of the interaction between enzymes and compound were carried out. RESULTS: Flavonoid compound schaftoside was identified by molecular simulation and showed significant DPP-IV (0.1050 ± 1.22 mmol L-1 ), α-glucosidase (0.078 ± 0.06 mmol L-1 ), and α-amylase (0.3067 ± 0.35 mmol L-1 ) inhibitory effects. The residues ARG125 and TYR662 of DPP-IV may play crucial roles in inhibiting the activity of DPP-IV. Multiple hydrogen bonds and electrostatic interactions were exhibited between schaftoside and α-glucosidase. Molecular modeling revealed that schaftoside displays strong binding with the catalytic triad (ASP197, ASP300, and GLU233) of α-amylase. CONCLUSION: Our findings demonstrate that schaftoside from sugarcane leaves might be an edible for T2DM treatment." © 2023 Society of Chemical Industry.

Mining and Validation of Novel Hemp Seed-Derived DPP-IV-Inhibiting Peptides Using a Combination of Multi-omics and Molecular Docking.

Hemp seed-derived inhibitors of dipeptidyl peptidase IV (DPP-IV) demonstrate potential as novel therapeutics for diabetes; however, their proteome and genome remain uncharacterized. We used multi-omics technology to mine peptides capable of inhibiting DPP-IV. First, 1261 and 1184 proteins were identified in fresh and dry hemp seeds, respectively. Simulated protease cleavage of dry seed proteins yielded 185,446 peptides for virtual screening to select the potential DPP-IV-inhibiting peptides. Sixteen novel peptides were selected according to their DPP-IV-binding affinity determined via molecular docking. In vitro DPP-IV inhibition assays identified the peptides LPQNIPPL, YPYY, YPW, LPYPY, WWW, YPY, YPF, and WS with half-maximal inhibitory concentration (IC50) values lower than 0.5 mM, which were 0.08 ± 0.01, 0.18 ± 0.03, 0.18 ± 0.01, 0.20 ± 0.03, 0.22 ± 0.03, 0.29 ± 0.02, 0.42 ± 0.03, and 0.44 ± 0.09 mM, respectively. The dissociation constants (KD) of the 16 peptides ranged from 1.50 × 10-4 to 1.82 × 10-7 M. Furthermore, Caco2 and INS-1 cell assays showed that all 16 peptides could efficiently inhibit DPP-IV activity and increase insulin and glucagon-like peptide-1 concentrations. These results demonstrate a well-established and efficient method to isolate food-derived therapeutic DPP-IV-inhibiting peptides.

Synergistic modification of collagen structure using ionic liquid and ultrasound to promote the production of DPP-IV inhibitory peptides.

BACKGROUND: Dual modification of collagen was performed using ionic liquid (IL) and ultrasound (US) to modulate the activity of collagen hydrolyzed peptides and reveal the production mechanism of cowhide-derived dipeptidyl peptidase (DPP-IV) inhibitory peptides. RESULTS: The results revealed that dual modification (IL + US) significantly improved the hydrolytic degree of collagen (P < 0.05). Meanwhile, IL and US tended to promote the break of hydrogen bonds, but inhibit the crosslinking between collagens. The double modification reduced the thermal stability and accelerated the exposure of tyrosine and phenylalanine of collagen, and improved the proportion of small molecular (< 1 kDa) peptides in collagen hydrolysates. Interestingly, the hydrophobic amino acid residues and DPP-IV inhibitory activity of collagen peptides with small molecular weight (< 1 kDa) was increased further under the combination of IL and US. CONCLUSION: Enhanced hypoglycemic activity of collagen peptides can be attained through the dual modification of IL and US. © 2023 Society of Chemical Industry.

Multivalent dipeptidyl peptidase IV fragment-nanogold complex inhibits cancer metastasis by blocking pericellular fibronectin.

Inhibition of cancer metastasis is a fundamental challenge in cancer treatment. We have previously shown that metastasis of cancer cells in the lung is critically promoted by the interaction between the superficial dipeptidyl peptidase IV (DPP IV) expressed on lung endothelial cells and the pericellular polymeric fibronectin (polyFN) of circulating cancer cells. In the present study, we aimed to search for DPP IV fragments with high avidity to polyFN and develop FN-targeted gold nanoparticles (AuNPs) conjugated with DPP IV fragments for treating cancer metastasis. We first identified a DPP IV fragment encompassing amino acids 29-130 of DPP IV, designated DP4A, which contained FN-binding sites and could specifically bind to FN immobilized on gelatin agarose beads. Furthermore, we conjugated maltose binding protein (MBP)-fused DP4A proteins to AuNPs for fabricating a DP4A-AuNP complex and evaluated its FN-targeted activity in vitro and anti-metastatic efficacy in vivo. Our results show that DP4A-AuNP exhibited higher binding avidity to polyFN than DP4A by 9 folds. Furthermore, DP4A-AuNP was more potent than DP4A in inhibiting DPP IV binding to polyFN. In terms of polyFN-targeted effect, DP4A-AuNP interacted with FN-overexpressing cancer cells and was endocytosed into cells 10 to 100 times more efficiently than untargeted MBP-AuNP or PEG-AuNP with no noticeable cytotoxicity. Furthermore, DP4A-AuNP was superior to DP4A in competitive inhibition of cancer cell adhesion to DPP IV. Confocal microscopy analysis revealed that binding of DP4A-AuNP to pericellular FN induced FN clustering without altering its surface expression on cancer cells. Notably, intravenous treatment with DP4A-AuNP significantly reduced metastatic lung tumor nodules and prolonged the survival in the experimental metastatic 4T1 tumor model. Collectively, our findings suggest that the DP4A-AuNP complex with potent FN-targeted effects may have therapeutic potential for prevention and treatment of tumor metastasis to the lung.

In vitro antidiabetic and antihypercholesterolemic activities of camel milk protein hydrolysates derived upon simulated gastrointestinal digestion of milk from different camel breeds.

Milk protein hydrolysates derived from 4 camel breeds (Pakistani, Saheli, Hozami, and Omani) were evaluated for in vitro inhibition of antidiabetic enzymatic markers (dipeptidyl peptidase IV and α-amylase) and antihypercholesterolemic enzymatic markers (pancreatic lipase and cholesterol esterase). Milk samples were subjected to in vitro simulated gastric (SGD) and gastrointestinal digestion (SGID) conditions. In comparison with intact milk proteins, the SGD-derived milk protein hydrolysates showed enhanced inhibition of α-amylase, dipeptidyl peptidase IV, pancreatic lipase, and cholesterol esterase as reflected by lower half-maximal inhibitory concentration values. Overall, milk protein hydrolysates derived from the milk of Hozami and Omani camel breeds displayed higher inhibition of different enzymatic markers compared with milk protein hydrolysates from Pakistani and Saheli breeds. In vitro SGD and SGID processes significantly increased the bioactive properties of milk from all camel breeds. Milk protein hydrolysates from different camel breeds showed significant variations for inhibition of antidiabetic and antihypercholesterolemic enzymatic markers, suggesting the importance of breed selection for production of bioactive peptides. However, further studies on identifying the peptides generated upon SGD and SGID of milk from different camel breeds are needed.

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.

The Mycobacterium tuberculosis prolyl dipeptidyl peptidase cleaves the N-terminal peptide of the immunoprotein CXCL-10.

Dipeptidyl peptidases constitute a class of non-classical serine proteases that regulate an array of biological functions, making them pharmacologically attractive enzymes. With this work, we identified and characterized a dipeptidyl peptidase from Mycobacterium tuberculosis (MtDPP) displaying a strong preference for proline residues at the P1 substrate position and an unexpectedly high thermal stability. MtDPP was also characterized with alanine replacements of residues of its active site that yielded, for the most part, loss of catalysis. We show that MtDPP catalytic activity is inhibited by well-known human DPP4 inhibitors. Using MALDI-TOF mass spectrometry we also describe that in vitro, MtDPP mediates the truncation of the C-X-C motif chemokine ligand 10, indicating a plausible role in immune modulation for this mycobacterial enzyme.