Dipeptidyl Peptidase-4 Activity Research Articles

The Association Between Circulating Klotho and Dipeptidyl Peptidase-4 Activity and Inflammatory Cytokines in Elderly Patients With Alzheimer Disease.

Introduction:Klotho and Dipeptidyl Peptidase-4 (DPP4) are two proteins that modulate inflammatory pathways. We investigated the association between circulating klotho and DPP4 activity and their relationship with inflammatory cytokines, miR-29a, and miR-195 in Alzheimer Disease (AD).Methods:This study was conducted on 16 AD patients and 16 healthy age-matched controls. Plasma levels of tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β, interleukin-6 (IL-6), klotho, and DPP4 were measured by enzyme-linked immunosorbent assay. Plasma expression of miR-29a and miR-195 were also measured and compared by a real-time polymerase chain reaction.Results:There was a significant increase in TNF-α (p=0.006), IL-1β (p=0.012), and IL-6 (p=0.012) levels in the AD subjects compared with controls. Also, we found a decrease in plasma levels of klotho and an increase in plasma levels of DPP4 in the AD group that was not significant compared with the controls. Lower expression of miR-29a (P=0.009) and higher expression of miR-195 (P=0.003) were observed in the AD group that was significant than controls. Further analysis showed a negative correlation between klotho and plasma levels of IL-6 (r=−0.58, p=0.01). Also, there was a positive correlation between plasma DPP4 activity and TNF-α levels (r=0.50, P=0.04) and IL-1β (r=0.62, P=0.01). Likewise, plasma klotho concentration showed a negative correlation with the age of AD subjects (r=−0.56, P=0.02).Conclusion:TNF-α, IL-1β, and IL-6 are involved in AD pathophysiology, and dysregulation of DPP4 and klotho may be associated with the inflammatory response of AD. Down-regulation of miR-29a and up-regulation of miR-195 indicated the role of miRNAs in the AD process.

INHIBITORY ACTIVITY OF THE ACTIVE COMPOUND OF ETHYL ACETATE FRACTION OF TAMOENJU (Hibiscus surattensis L.) LEAVES AGAINST α-GLUCOSIDASE AND DIPEPTIDYL PEPTIDASE-4 ENZYMES

The ethyl acetate fraction (EAF) of tamoenju (Hibiscus surattensis L.) leaves, used as a traditional antidiabetic agent in Central Sulawesi, has high inhibitory activity against α-glucosidase and dipeptidyl peptidase-4 (DPP-4). The aim of this study was to isolate the active compound of EAF that was carried out by step gradient polarity extraction, then separated and purified by chromatography. The structure was identified and characterized using NMR spectroscopy and LC-MS. α-glucosidase inhibitory activity was evaluated using the in vitro standard α-glucosidase inhibition test, while DPP-4 activity was evaluated by ex vivo DPP-4 inhibitor test using rat blood serum as the enzyme source. IC50 values were determined by nonlinear regression curve and fit using GraphPad Prism 8 and were expressed as mean ± SEM. In this research, we obtained the isolated compound was identified as kaempferol, which was isolated for the first time from this plant. The isolate exhibited potent α-glucosidase and DPP-4 inhibition with IC50 values of 27.78 ± 0.86 and 7.37 ± 0.06 μg/mL, respectively. Acarbose and sitagliptin as positive control had IC50 values of 17.80 ± 0.27 and 25.56 ± 0.43 μg/mL, respectively. The isolate level by LC-MS was estimated to be 182.23 mg/g isolate. Therefore, tamoenju leaves have great potential as functional foods and in the development of antidiabetic drugs. Keywords: α-Glucosidase, Antidiabetic, Dipeptidyl peptidase-4, Kaempferol, Tamoenju, Hibiscus surattensis L

Toxicity profile of honey and ghee, when taken together in equal ratio

Honey and ghee are an essential component of our diet. They play an important role like anti-inflammatory, antioxidative, antimicrobial, etc. It is written in Charak Samhita that an equal mixture of honey and ghee turn into a harmful component for health. This study was designed to explore the mechanism of toxicity through the biochemical and histological parameters in Charles foster rats (24 rats were used). We have divided these rats into four groups (n = 6) - normal, honey (0.7 ml/100 g bw), ghee (0.7 ml/100 g bw), and honey + ghee (1:1) (1.5 ml/100 g bw). Treatment was given orally for 60 days. All rats were sacrificed on 61 days. Biochemical parameters like liver function test, kidney function test, Oxidative stress, Glycemic, and some protein modification parameters were done in blood plasma. We found weight loss, hair loss, red patches on ear, and increased liver function test, oxidative stress, Amadori product formation, advanced glycation end-product formation, dipeptidyl protease (DPP-4) and decreased incretins (glucagon-like peptide-1(GLP-1) and gastric inhibitory polypeptide (GIP)) in honey + ghee group. H&E and immunohistochemistry results showed mild inflammation in liver tissue but no changes in the kidney, intestine and, pancreas. Thus it concluded that the increased formation of Amadori product, DPP-4 activity and low incretins (GLP-1, GIP) activity resulting high postprandial hyperglycemic response could be collectively responsible for oxidative stress-mediated toxicity of honey and ghee in the equal mixture.

Assessing the association between dipeptidyl peptidase-4 inhibitors use and celiac disease through drug adverse event reporting.

Dipeptidyl peptidase 4 (DPP4) enzyme is an endoprotease that removes N-terminal prolines from intestinal peptides.1 These peptides include glucagon-like peptide-1 (GLP-1), which, as one of the main human incretin hormones produced by the gastrointestinal system, enhances insulin secretion in a glucose-dependent manner.2 Inhibition of DPP4 thus raises GLP-1 levels and has a glucose-lowering effect. DPP4 also cleaves other clinically relevant peptides. Celiac disease (CD) is a chronic digestive disorder characterized by an immune response to proteins from wheat and related grains.3 Affected individuals display gluten-derived peptides to the immune system on human leukocyte antigen (HLA) haplotype DR3-DQ2 or DR4-DQ8, but only 2–3% of these haplotype carriers develop CD.4 DPP4 cleaves peptides that are over-represented in the gluten epitopes that bind to HLA haplotype DR3-DQ21; although a direct causal link has yet to be established, the activity of intestinal DPP4 is decreased in the acute and remission phases of CD,5 suggesting a possible association between DPP4 level and CD. DPP4 inhibitors (DPP4i), a common class of glucose-lowering drugs (GLDs), may increase the pool of gluten peptides with N-terminal prolines, potentially increasing the risk of CD. To investigate this potential association, we analyzed the United States Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database, which contains all adverse drug events (ADEs) spontaneously reported to FDA from the first quarter (Q1) of 2004 to Q4 of 2018.6

Effect of cyanopyrrolidine derivatives on the activity of prolylendopeptidase, acute exudative inflammation and visceral pain in mice

Cyanopyrrolidine derivatives benzyloxycarbonyl-methionyl-cyanopyrrolidine (ZMetPrdN), benzyloxycarbonylphenylalanyl- cyanopyrrolidine (ZPhePrdN), tert-butyl-hydroxycarbonyl-glycyl-cyanopyrrolidine (BocGlyPrdN), tert-butyl-hydroxycarbonyl-methionyl-cyanopyrrolidine (BocMetPrdN) are inhibitors of prolylendopeptidase (PREP; EC 3.4.21.26) with an IC50 of 2 nM to 12 nM. ZMetPrdN, ZPhePrdN and BocMetPrdN additionally inhibited dipeptidyl peptidase IV (DPP-4; EC 3.4.14.5) with an IC50 of 1100 nM to 3200 nM. All the compounds have antinociceptive properties in the acetic acid writhing test in mice. But only cyanopyrrolidine derivatives with aromatic substituents decrease exudative inflammation. The cyanopyrrolidine derivatives also increase PREP activity and compensatorily reduce DPP-4 activity in the serum of mice three hours after the induction of inflammation. Thus, cyanopyrrolidine derivatives exhibit antinociceptive and antiexudative properties in part via their effect on PREP.

Dipeptidylpeptidase 4 as a Marker of Activated Fibroblasts and a Potential Target for the Treatment of Fibrosis in Systemic Sclerosis.

Expression of dipeptidylpeptidase 4 (DPP-4) identifies a dermal fibroblast lineage involved in scarring during wound healing. The role of DDP-4 in tissue fibrosis is, however, unknown. The aim of the present study was to evaluate DPP-4 as a potential target for the treatment of fibrosis in patients with systemic sclerosis (SSc). Expression of DPP-4 in skin biopsy samples and dermal fibroblasts was analyzed by real-time polymerase chain reaction, immunofluorescence, and Western blot analyses. The activity of DPP-4 was modulated by overexpression, knockdown, and pharmacologic inhibition of DPP4 using sitagliptin and vildagliptin. The effects of DPP4 inhibition were analyzed in human dermal fibroblasts and in different mouse models of SSc (each n = 6). The expression of DPP-4 and the number of DPP-4-positive fibroblasts were increased in the fibrotic skin of SSc patients, in a transforming growth factor β (TGFβ)-dependent manner. DPP-4-positive fibroblasts expressed higher levels of myofibroblast markers and collagen (each P < 0.001 versus healthy controls). Overexpression of DPP4 promoted fibroblast activation, whereas pharmacologic inhibition or genetic inactivation of DPP4 reduced the proliferation, migration, and expression of contractile proteins and release of collagen (each P < 0.001 versus control mice) by interfering with TGFβ-induced ERK signaling. DPP4-knockout mice were less sensitive to bleomycin-induced dermal and pulmonary fibrosis (P < 0.0001 versus wild-type controls). Treatment with DPP4 inhibitors promoted regression of fibrosis in mice that had received bleomycin challenge and mice with chronic graft-versus-host disease, and ameliorated fibrosis in TSK1 mice (each P < 0.001 versus untreated controls). These antifibrotic effects were associated with a reduction in inflammation. DPP-4 characterizes a population of activated fibroblasts and shows that DPP-4 regulates TGFβ-induced fibroblast activation in the fibrotic skin of SSc patients. Inhibition of DPP4 exerts potent antifibrotic effects when administered in well-tolerated doses. As DPP4 inhibitors are already in clinical use for diabetes, these results may have direct translational implications for the treatment of fibrosis in patients with SSc.

A siRNA mediated hepatic dpp4 knockdown affects lipid, but not glucose metabolism in diabetic mice.

Systemic inhibition of dipeptidyl peptidase 4 (dpp4) represents an effective and established treatment option for type 2 diabetes (T2D). The current study investigated in mice if a liver selective knock-down of dpp4 by therapeutic siRNAs could be a novel, similarly effective treatment option for T2D. Furthermore, the potential effects on hepatic steatosis, inflammation and lipid metabolism were investigated after hepato-selective knock-down of dpp4. The knock-down efficiency and IC50 values of siRNAs targeting dpp4 were analyzed in PC3 cells. In two independent studies, either db/db mice or C57BL/6J mice were injected intravenously with a liposomal formulation of siRNAs targeting either dpp4 or a non-targeting control, followed by metabolically characterization. In comparator groups, additional cohorts of mice were treated with an oral dpp4 inhibitor. In both animal studies, we observed a robust knock-down (~75%) of hepatic dpp4 with a potent siRNA. Hepatic dpp4 knockdown did not significantly affect glucose metabolism or circulating incretin concentrations in both animal studies. However, in obese and diabetic db/db mice hepatic steatosis was reduced and hepatic mRNA expression of acaca, scd1, fasn and pparg was significantly lower after siRNA treatment. Systemic inhibition of the enzymatic dpp4 activity by an oral dpp4 inhibitor significantly improved glucose handling in db/db mice but did not affect hepatic endpoints. These data demonstrate that a targeted reduction of dpp4 expression in the liver may not be sufficient to improve whole-body glucose metabolism in obese and diabetic mice but may improve hepatic lipid metabolism.

DPP8 is a novel therapeutic target for multiple myeloma

Dipeptidyl peptidases (DPPs) are proteolytic enzymes that are ideal therapeutic targets in human diseases. Indeed, DPP4 inhibitors are widely used in clinical practice as anti-diabetic agents. In this paper, we show that DPP4 inhibitors also induced cell death in multiple human myeloma cells. Among five DPP4 inhibitors, only two of them, vildagliptin and saxagliptin, exhibited apparent cytotoxic effects on myeloma cell lines, without any difference in suppression of DPP4 activity. As these two DPP4 inhibitors are known to have off-target effects against DPP8/9, we employed the specific DPP8/9 inhibitor 1G244. 1G244 demonstrated anti-myeloma effects on several cell lines and CD138+ cells from patients as well as in murine xenograft model. Through siRNA silencing approach, we further confirmed that DPP8 but not DPP9 is a key molecule in inducing cell death induced by DPP8/9 inhibition. In fact, the expression of DPP8 in CD38+ cells from myeloma patients was higher than that of healthy volunteers. DPP8/9 inhibition induced apoptosis, as evidenced by activated form of PARP, caspases-3 and was suppressed by the pan-caspase inhibitor Z-VAD-FMK. Taken together, these results indicate that DPP8 is a novel therapeutic target for myeloma treatment.

Synthesis and discovery of triazolo-pyridazine-6-yl-substituted piperazines as effective anti-diabetic drugs; evaluated over dipeptidyl peptidase-4 inhibition mechanism and insulinotropic activities

A family of 12 triazolo-pyridazine-6-yl-substituted piperazines (5a-l) was synthesized and evaluated for their Dipeptidyl peptidase-4 (DPP-4) inhibition potentials in order to develop them as anti-diabetic medications. In the two-step synthesis process, 6-chloro-3-(m-tolyl)-[1,2,4]triazolo[4,3-b]pyridazine was synthesized with one-pot mode using pyridine, 3,6-dichloropyridazine 5-(3-methyl-phenyl)tetrazole in toluene. Conjugating corresponding 2° amines with 6-chloro-3-(m-tolyl)-[1,2,4]triazolo[4,3-b]pyridazine afforded the target triazolo-pyridazine-6-yl-substituted piperazines (5a-l). DPP-4 inhibition potential of these compounds was testified in silico and in nitro along with their insulinotropic activities in 832/13 INS-1 cells. H2O2 radical scavenging assay and MTT assay were conducted to assess the antioxidant and cytotoxicity of these compounds respectively. Molecular docking and ELISA based enzyme inhibition assay results revealed the strong inhibition potential of the target compounds. MTT assay results indicated a maximum dose of 2.5 nM (IC50 1.25 nM) could be used and above this level vital for the cells. Compounds 5a, 5c, 5g and 5i were found with excellent antioxidant and insulinotropic activity up to 99%.

Increased Plasma Dipeptidyl Peptidase-4 Activities Predict Mild Cognitive Impairment in Elderly Type 2 Diabetic Patients: Findings from the GDMD Cohort Study in China

Background: Dipeptidyl peptidase-4(DPP4) is a newly identified adipokine that has been proved to promote hyperglycemia, insulin resistance, oxidative stress and inflammation, all of which have been involved in the pathogenesis of mild cognitive impairment (MCI). Hence, we examined whether increased DPP4 activity was associated with prospective risk of MCI and determined whether this association was mediated by these four risk factors in elderly type 2 diabetic patients. Methods: Baseline plasma DPP4 activity, HOMA of insulin resistance (HOMA-IR), oxidative stress parameters, inflammatory markers and long-term glycemic control were ascertained in a cohort of elderly type 2 diabetic patients aged>60 years (n = 2,066), along with questionnaire findings, biochemical measurements and MCI diagnoses. Prospective associations of baseline DPP4 activity and MCI events and its possible mediators were determined by Cox regression and mediation analyses. Findings: Over a median follow-up of 4.8 years, 367 patients (17.8 %) were diagnosed with MCI. Higher baseline DPP4 activity, IL-6, CRP, nitrotyrosine and 8-iso-PGF2a were independent predictors of MCI after adjustment (P<0.001). Furthermore, IL-6, CRP, nitrotyrosine and 8-iso-PGF2a all had statistically significant mediating effects on DPP4 activity-associated MCI incidence (P<0.05). We did not find a positive association between baseline HOMA-IR, average HbA1c and MCI incidence. Interpretation: Our results suggest that increased plasma DPP4 activity is an independent risk factor for incident MCI, and this association appears to be partially mediated by oxidative stress and inflammation, not insulin resistance or long-term glycemic control, both of which might not be able to predict MCI as well. Trial Registration: Registered on the Chinese clinical trial registry (ChiCTR-EPC-14005273). Funding Statement: This study was supported by grants from National Natural Science Foundation of China (Grant NO. 81770829 and NO. 81560144), Scientific Research and Technology Development Projects of Science and Technology Department of Guangxi province (Grant NO.1598012-13), Natural Science Foundation of Guangxi Province (Grant NO. 2015GXNSFBA139119) and High-Level Medical Talents Training Program of Guangxi Province (G201903002). Declaration of Interests: The authors declare no competing interests. Ethics Approval Statement: The GDMD Study was approved by the institutional medical ethical committee at Affiliated Hospital of Guilin Medical University. All participants gave written informed consent before data collection.

Nitrothiadiazolo[3,2-a]pyrimidines as promising antiglycating agents

Managing the advanced glycation end-products (AGEs) concentration is a reliable approach to achieve control over the pathogenesis of diabetic vascular complications. Inhibition of dipeptidyl peptidase-4 (DPP-4) is also an attractive way to tackle type 2 diabetes mellitus (T2DM). We showed previously that azoloazine heterocycles have the potential to prevent the formation of AGEs and in this work, we conducted docking studies with DPP-4 of 5-alkylamino-6-nitro-1,3,4-thiadiazolo[3,2-a]pyrimidines. Consequently, we have developed a synthetic approach to these structures by chlorodeoxygenation and amination reactions. Antidiabetic properties of obtained compounds were studied by evaluating DPP-4 (ex vivo/in vitro) and AGEs formation inhibition (in vitro). It was shown that the nitrothiadiazolopyrimidines exhibit a higher antiglycation activity than reference compound aminoguanidine, but only moderate inhibition of DPP-4. The most active DPP-4 inhibitor 1l had IC50 of 55.87 μM and showed the ability to inhibit serum DPP-4 activity in rats after 10 mg/kg oral administration but with the less and shorter effect than vildagliptin. At the same time, 1l was the most active antiglycating compound in the series (IC50 134.4 μM). Copper chelation properties of synthesized compounds were also investigated since the formation of AGEs is catalyzed by the transition metal cations. A noticeable correlation between antiglycation activity and metal chelation was revealed. Both activities (antiglycation and copper chelation) correlated with quantum-chemical properties (calculated with ab initio) of the tested compounds. These findings will allow us to predict both activities in the future, without the need to model multiple steps of glycation reaction.

Optimization of the benzamide fragment targeting the S2′ site leads to potent dipeptidyl peptidase-IV inhibitors

Our recently successful identification of benzoic acid-based DPP-4 inhibitors spurs the further quest for in-depth structure-activity relationships (SAR) study in S2' site DPP-4. Thus novel benzamide fragments were designed to target the S2' site to compromise lipophilicity and improve oral activity. Exploring SAR by introduction of a variety of amide and halogen on benzene ring led to identification of several compounds, exerting moderated to excellent DPP-4 activities, in which 4'-chlorine substituted methyl amide 17g showed most potent DPP-4 activity with the IC50 value of 1.6 nM. Its activity was superior to reference alogliptin. Docking study ideally verified and interpreted the obtained SAR of designed compounds. As a continuation, DPP-8/9 assays revealed the designed compounds exhibited good selectivity over DPP-8 and DPP-9. Subsequent cell-based test indicated compound 17g displayed low toxicity toward the LO2 cell line up to 100 μM. In vivo evaluation showed compound 17g robustly improved the glucose tolerance in normal mice. Importantly, 17g exhibited reasonable pharmacokinetic (PK) profiles for oral delivery. Overall, compound 17g has the potential to a safe and efficacious DPP-4 inhibitor for T2DM treatment.

Neuroprotective effect of genistein on cognitive impairment in vascular dementia experimental mice model

The present study aims to determine the neuroprotective efficacy of genistein on vascular dementia in experimental model mice and explore the underlying mechanisms. To induce vascular dementia, chronic bilateral common carotid artery occlusion was performed on female mice brain by occluding both common carotid arteries for 30 min followed by 24 h reperfusion to induce neuronal injury. After surgery, the mice were treated daily by oral administration of genistein (5.0, and 10.0 mg/kg, i.p., o.d.) for one months. The cognition function of treated mice, were evaluated by Morris Water Maze (MWM) test, neurological functions measured as short-term memory and motor performance. In addition, cerebral infarct size, oxidative damage, mitochondrial activity in terms of neuronal apoptosis and cellular viability, Nissl and TUNEL staining were chosen to assess neuronal damage within the hippocampal CA1 area. In present study, there was an increase in cognitive impairment and neuronal damages within CA1 hippocampal subregion caused by chronic cerebral hypoperfusion. Genistein administration significantly counteracted cognitive impairment and re-established motor performance in vascular dementia in mice. Genistein was able to prevent cognitive deficits, and reversed CCH-induced hippocampal neuronal loss and apoptosis. Genistein treatment significantly reduced neuronal apoptosis and increased cellular viability, almost completely suppressed the circulating dipeptidyl peptidase-4 activity, and enhanced glucagon-like peptide-1 concentration in vascular dementia in experimental model mice. This study suggests that genistein has potent neuroprotective activity against chronic cerebral hypoperfusion and may be considered as a potential treatment for cognitive deficits and neuronal injury in the hippocampal CA1 area.

Oleuropein-enriched chocolate by extra virgin olive oil blunts hyperglycaemia in diabetic patients: Results from a one-time 2-hour post-prandial cross over study.

Oleuropein, a component of extra virgin olive oil (EVOO), reduces post-prandial glycemia with a mechanism counteracting oxidative stress-mediated incretin down-regulation. In this study we evaluated if the intake of an oleuropein-enriched chocolate could have positive effects on glycaemia and insulin levels in patients with type 2 diabetes mellitus (T2DM) and healthy subjects (HS). Twenty-five consecutive T2DM patients and 20 HS were recruited. Participants were randomized to receive 40g oleuropein-enriched chocolate by EVOO or 40g control chocolate spread in a cross-over design. Serum glucose, insulin, glucagon-like peptide-1 (GLP1), and dipeptidyl-peptidase-4 (DPP4) were measured before and 2h after chocolate intake. In T2DM, the pairwise comparisons showed that intake of oleuropein-enriched chocolate was associated with a significantly less increase of blood glucose compared to control; GLM analysis showed a significant difference for treatments with respect to glucose (p=0.04), GLP1 (p<0.001) and DPP-4 activity (p=0.01). In HS, the pairwise comparisons showed that, after oleuropein-enriched chocolate intake, blood glucose concentration and DPP4 activity did not change; conversely a significant increase was observed for insulin and GLP1. After control chocolate intake, a significant increase for blood glucose, insulin levels and DPP4 activity were observed while GLP1 did not change. The study shows that using EVOO as source of oleuropein administration of 40g oleuropein-enriched chocolate is associated with a modest increase or no change of glycemia in T2DM and HS respectively, via an incretin-mediated mechanism.

The effects of DPP4 inhibitors on the levels of plasma catecholamines and their metabolites in patients with type 2 diabetes

AimsDipeptidyl peptidase 4 inhibitors (DPP4Is) can increase sympathetic activity. We aimed to evaluate the direct association between serum DPP4 activity and sympathetic activity in humans. MethodsFasting serum DPP4 activity and plasma levels of catecholamines and their metabolites were measured in 211 patients with type 2 diabetes mellitus (T2DM) treated with DPP4I (n = 146) or non-DPP4I therapy (n = 65) and in healthy control subjects (n = 30). ResultsAlthough there were no differences in plasma levels of catecholamines and their metabolites between the DPP4I and non-DPP4I groups, the levels in both of these groups were lower than those in the healthy control group. In DPP4I-treated patients, serum DPP4 activity showed an inverse correlation with plasma levels of norepinephrine (NE) (r = −0.339, p < 0.01), metanephrine (MET) (r = −0.251, p < 0.01) and normetanephrine (r = −0.312, p < 0.001). In addition, plasma MET level showed a weak inverse correlation with serum DPP4 activity in the combined T2DM group. In DPP4I-treated patients, the inverse correlation between DPP4 activity and plasma NE remained significant even after multiple adjustments. ConclusionsOur results suggest that although sympathetic activity is lower in patients with T2DM, the greater the suppression of DPP4 activity by DPP4I therapy, the greater the increase in sympathetic activity is, which may have clinical implications in high risk T2DM patients.

Dipeptidyl peptidase-4 inhibitors can inhibit angiotensin converting enzyme

Angiotensin-1 converting enzyme inhibitors (ACEIs) improve insulin sensitivity. Inhibitors of dipeptidyl peptidase-4 (DPP-4) are anti-diabetic drugs with several cardio-renal effects. Both ACE and DPP-4 share common features. Thus, we tested if they could be inhibited by one inhibitor. First, in silico screening was used to investigate the ability of different DPP-4 inhibitors or ACEIs to interact with DPP-4 and ACE. The results of screening were then extrapolated into animal study. Fifty Sprague Dawley rats were randomly assigned into 5 groups treated with vehicle, captopril, enalapril, linagliptin or sitagliptin. Both low and high doses of each drug were tested. Baseline blood samples and samples at days 1, 8, 10, 14 were used to measure plasma DPP-4 and ACE activities and angiotensin II levels. Active glucagon-like peptide-1 (GLP-1) levels were measured after oral glucose challenge. All tested DPP-4 inhibitors could interact with ACE at a relatively reasonable binding energy while most of the ACEIs only interacted with DPP-4 at a predicted high inhibition constant. In rats, high dose of sitagliptin was able to inhibit ACE activity and reduce angiotensin II levels while linagliptin had only a mild effect. ACEIs did not significantly affect DPP-4 activity or prevent GLP-1 degradation. It seems that some DPP-4 inhibitors could inhibit ACE and this could partially explain the cardio-renal effects of these drugs. Further studies are required to determine if such inhibition could take place in clinical settings.

Association of circulating klotho and dipeptidyl peptidase-4 activity with inflammatory cytokines in elderly patients with Alzheimer's disease

Association of circulating klotho and dipeptidyl peptidase-4 activity with inflammatory cytokines in elderly patients with Alzheimer's disease

30-days effects of vildagliptin on vascular function, plasma viscosity, inflammation, oxidative stress, and intestinal peptides on drug-na\xefve women with diabetes and obesity: a randomized head-to-head metformin-controlled study

BackgroundObesity is the main risk factor for diabetes and excessive visceral fat triggers low-grade inflammatory process, mediated by activation and release of cytokines and high flow of free fatty acids that contribute to insulin resistance, increased oxidative stress, and impaired endothelial function. Metformin and vildagliptin have known vasculoprotective actions, but the value of these drugs on drug-naïve diabetic patients during 30 days use warrants investigation. Our purpose was to observe their effects on endothelial function, oxidative stress, inflammatory biomarkers, and plasma viscosity.Methods38 women with obesity and type 2 diabetes drug-naïve, aged between 19 and 50 years, BMI ≥ 30 kg/m2, were recruited and subjected to measurements of endothelial function, nutritive skin microvascular reactivity, plasma viscosity, inflammatory and oxidative stress biomarkers at baseline and randomized 1:1 to ingest metformin (850 mg twice/day) or vildagliptin (50 mg twice/day) during 30 days, and then, re-evaluated.ResultsNo differences between groups were noticed at baseline. After treatment, vildagliptin promoted an improvement on endothelial-dependent and -independent vasodilatations, at arteriole level, while metformin resulted in improved nutritive microvascular reactivity, at the capillary level. Intragroup analysis showed that vildagliptin reduced insulin, C-peptide and oxidized LDL, and increased adiponectin and glucagon-like peptide-1 while metformin reduced weight, plasma glucose, total cholesterol, HDL-c, LDL-c, and dipeptidyl peptidase-4 activity, with an unexpected increase on tumor necrosis factor-α. No significant difference in plasma viscosity was noted.ConclusionsIn the vascular beds investigated, both drugs used for only 30 days improved endothelial function, through distinct, and possibly, complementary mechanisms on drug-naïve diabetic women.Trial Registration ClinicalTrials.gov: NCT01827280

Late gestational testosterone exposure causes glucose deregulation and elevated cardiac VCAM-1 and DPP-4 activity in rats

Context Increased vascular cell adhesion molecule-1 (VCAM-1) has been reported to be a critical link between obesity and atherosclerotic cardiovascular diseases while dipeptidyl peptidase-4 (DPP-4) has been implicated in the development of disrupted glucose regulation and inflammation. Objective This study aimed to investigate the effect of gestational testosterone exposure on glucose metabolism, atherogenic dyslipidemia, as well as circulating and cardiac VCAM-1, oxidative stress biomarkers and DPP-4 activity in pregnant rats. Methods Pregnant Wistar rats received either vehicle or testosterone (0.5 mg/kg; sc) between gestational days 14 and 19. Results Gestational testosterone exposure caused impaired glucose homeostasis that was accompanied with atherogenic dyslipidemia, elevated circulating and cardiac levels of VCAM-1, uric acid, malondialdehyde as well as increased DPP-4 activity. However, nitric oxide levels were decreased. Conclusion This study shows that gestational testosterone exposure causes glucose deregulation and atherogenic dyslipidemia that is accompanied by increased circulating and cardiac VCAM-1 and DPP-4 activity.

Identification of a Novel Scaffold for Inhibition of Dipeptidyl Peptidase-4.

Dipeptidyl peptidase-4 (DPP-4) is considered a major drug target for type 2 diabetes mellitus (T2DM). In addition to T2DM, a regulatory role of DPP-4 was also found in cardiovascular diseases. Existing DPP-4 inhibitors have been reported to have several adverse effects. In this study, a computer-aided drug design approach and its use to detect a novel class of inhibitor for DPP-4 are reported. Through structure and pharmacophore-based screening, we identified 13 hit compounds from an ∼4-million-compound library. Physical interactions of these hits with DPP-4 were studied using docking and explicit solvent molecular dynamics (MD) simulations. Later, MMPBSA binding energy was calculated for the ligand/protein simulation trajectories to determine the stability of compounds in the binding cavity. These compounds have a novel scaffold and exhibited a stable binding mode. "Best-in-screen" compounds (or their closest available analogs) were resourced and their inhibition of DPP-4 activity was experimentally validated using an in vitro enzyme activity assay in the presence of 100 and 10 μM compounds. These assays identified a compound with a spirochromanone center with 53% inhibition activity at a 100 μM concentration. A further five spirochromanone compounds were synthesized and examined in silico and in vitro; again, one compound showed 53% inhibitory activity action at 100 μM. Overall, this study identified two novel "spirochromanone" compounds that lowered DPP-4 activity by more than ∼50% at 100 μM. This study also showed the impact of fast in silico drug design techniques utilizing virtual screening and MD to identify novel scaffolds to bind and inhibit DPP-4. Spirochromanone motif identified here may be used to design molecules to achieve drug-like inhibitory action against DPP-4.