Sitagliptin: A Review in Type 2 Diabetes

Sitagliptin Alleviates Obesity in Immature Mice by Inhibiting Oxidative Stress and Inflammation

To investigate the impact of Sitagliptin against obesity and the underlying mechanism. Obese immature mice were treated with 10, 30, and 90 mg/kg Sitagliptin, respectively. The body weights were recorded and the level of serum biochemical indexes were detected. The visceral fat ratio of each mouse was determined. The pathological change in adipose tissues was determined by HE staining, while F4/80 and CD206 levels in adipose tissues were determined by the immunohistochemical analysis. Lipid formation was evaluated by Oil red O staining assay. RAW264.7 cells were stimulated using oxLDL, followed by being incubated with different concentrations of Sitagliptin. The release of ADPN, IL-6, IL-1β, TNF-α, and the activity of SOD, was measured by ELISA assay. Western blotting was applied to determine adipsin, Nrf2, Keap1, and HO-1 protein levels. ROS level was checked using the DCFH-DA assay. RT-PCR assay was utilized to detect the mRNA levels of IL-6, IL-1β, TNF-α, Nrf2, Keap1, and HO-1. The body weight gain, infiltration of multinucleated cells, enlarged size of adipocytes, increased lipid accumulation, elevated visceral fat ratio, declined ADPN level, upregulated adipsin, and disordered serum biochemical indexes in obese immature mice were statistically significantly reversed by Sitagliptin. Excessive release of inflammatory factors and upregulated F4/80 and CD206 were observed in obese immature mice, which were statistically significantly repressed by Sitagliptin. Furthermore, the elevated MDA level, increased SOD activity, and inhibited Nrf2 pathway in obese immature mice were significantly reversed by Sitagliptin. In oxLDL stimulated RAW264.7 cells, increased release of inflammatory factors, ROS, and MDA, elevated SOD activity, and inactivated Nrf2 pathway were observed, which were statistically significantly abolished by the treatment of Sitagliptin. Sitagliptin alleviated obesity in immature mice by inhibiting inflammation and oxidative stress.

Sitagliptin Ameliorates Creb5/lncRNA ENSMUST00000213271-Mediated Vascular Endothelial Dysfunction in Obese Mice

PURPOSE

Obesity is mediated by the changes in dyslipidemia, oxidative stress, and inflammation, leading to vascular endothelial dysfunction. Glucagon-like peptide-1 (GLP-1) analogues and dipeptidyl peptidase-4 inhibitors prevent the development of endothelial dysfunction. However, the underlying mechanism still remains largely unclear. Long non-coding RNAs (lncRNAs), one class of non-coding small RNAs, have been shown to exert a regulatory impact on the endothelial function in obesity. This study aimed to investigate whether the elevation of GLP-1 by a DPP-4 inhibitor sitagliptin improved vascular endothelial function by modulating lncRNAs in obese mice and to clarify the underlying molecular mechanism.

METHODS

Male C57BL/6J mice were fed a high-fat diet for 4 months to induce obesity and some obese mice were treated with sitagliptin for the last 1 month. Levels of total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and glucagon-like peptide-1 (GLP-1) in plasma were detected by ELISA. LncRNA expression profile was analyzed via microarray. Aortic relaxations were examined by myograph. Protein expressions and phosphorylations were determined using western blot. The differentially expressed lncRNAs were validated using qRT-PCR.

RESULTS

Obese mice exhibited increased levels of TC and LDL, decreased concentrations of HDL and GLP-1 in plasma, and impaired aortic endothelium-dependent relaxations; such effects could be reversed by sitagliptin. Moreover, the altered expression profile of lncRNAs in the obese mouse aortae could be modulated by sitagliptin. Consistent with microarray analysis, qRT-PCR also revealed that lncRNA ENSMUST00000213271 was up-regulated in obese mouse aortae and aortic endothelial cells (ECs), which could be down-regulated by sitagliptin. Creb5 silencing reduced lncRNA ENSMUST00000213271 in obese mouse ECs. Knockdown of either Creb5 or lncRNA ENSMUST00000213271 restored the activation of AMPK/eNOS in obese mouse ECs. Furthermore, sitagliptin also suppressed Creb5 and lncRNA ENSMUST00000213271 and increased the phosphorylations of AMPK and eNOS in obese mice.

CONCLUSION

Creb5/lncRNA ENSMUST00000213271 mediated vascular endothelial dysfunction through inhibiting AMPK/eNOS cascade in obesity. Elevation of GLP-1 by sitagliptin possibly improved endothelial function by suppressing Creb5/lncRNA ENSMUST00000213271 and subsequently restoring AMPK/eNOS activation in obese mice. This study will provide new evidence for the benefits of GLP-1 against vasculopathy in obesity.

Adverse cardiac events of hypercholesterolemia are enhanced by sitagliptin in sprague dawley rats

BACKGROUND

Cardiovascular disease (CVD) affects millions worldwide and is the leading cause of death among non-communicable diseases. Western diets typically comprise of meat and dairy products, both of which are rich in cholesterol (Cho) and methionine (Met), two well-known compounds with atherogenic capabilities. Despite their individual effects, literature on a dietary combination of the two in the context of CVD are limited. Therefore, studies on the combined effects of Cho and Met were carried out using male Sprague Dawley rats. An additional interest was to investigate the cardioprotective potential of sitagliptin, an anti-type 2 diabetic drug. We hypothesized that feeding a dietary combination of Cho and Met would result in adverse cardiac effects and would be attenuated upon administration of sitagliptin.

METHODS

Adult male Sprague-Dawley rats were fed either a control (Con), high Met (1.5%), high Cho (2.0%), or high Met (1.5%) + high Cho (2.0%) diet for 35 days. They were orally gavaged with an aqueous preparation of sitagliptin (100 mg/kg/d) or vehicle (water) from day 10 through 35. On day 36, rats were euthanized, and tissues were collected for analysis.

RESULTS

Histopathological evaluation revealed a reduction in myocardial striations and increased collagen deposition in hypercholesterolemia (HChol), responses that became exacerbated upon sitagliptin administration. Cardiac pro-inflammatory and pro-fibrotic responses were adversely impacted in similar fashion. The addition of Met to Cho (MC) attenuated all adverse structural and biochemical responses, with or without sitagliptin.

CONCLUSIONS

Adverse cardiac outcomes in HChol were enhanced by the administration of sitagliptin, and such effects were alleviated by Met. Our findings could be significant for understanding or revisiting the risk-benefit evaluation of sitagliptin in type 2 diabetics, and especially those who are known to consume atherogenic diets.

The Repurposing of FDA-Approved Drugs as FtsZ Inhibitors against Mycobacterium tuberculosis: An In Silico and In Vitro Study

Mycobacterium tuberculosis (Mtb), the causative pathogen of tuberculosis, remains one of the leading causes of death from a single infectious agent. Furthermore, the growing evolution to multi-drug-resistant (MDR) strains requires de novo identification of drug targets for evaluating candidates or repurposing drugs. Hence, targeting FtsZ, an essential cell division protein, is a promising target.

METHODS

Using an in silico pharmacological repositioning strategy, four FDA-based drugs that bind to the catalytic site FtsZ were selected. The Alamar Blue colorimetric assay was used to assess antimicrobial activity and the effect of drugs on Mtb growth through growth curves. Bacterial load was determined with an in vitro infection model using colony-forming units (CFU)/mL, and cytotoxicity on human monocyte-derived macrophages (MDMhs) was assessed by flow cytometry.

RESULTS

Paroxetine and nebivolol exhibited antimycobacterial activity against both reference TB and MDR strains at a concentration of 25 µg/mL. Furthermore, both paroxetine and nebivolol demonstrated a significant reduction (p < 0.05) in viable bacteria compared to the untreated group in the in vitro infection model.

CONCLUSIONS

Collectively, our findings demonstrate that the use of paroxetine and nebivolol is a promising strategy to help in the control of tuberculosis infection.

New advances in drug development for metabolic dysfunction-associated diseases and alcohol-associated liver disease

Metabolic disorders are currently threatening public health worldwide. Discovering new targets and developing promising drugs will reduce the global metabolic-related disease burden. Metabolic disorders primarily consist of lipid and glucose metabolic disorders. Specifically, metabolic dysfunction-associated steatosis liver disease (MASLD) and alcohol-associated liver disease (ALD) are two representative lipid metabolism disorders, while diabetes mellitus is a typical glucose metabolism disorder. In this review, we aimed to summarize the new drug candidates with promising efficacy identified in clinical trials for these diseases. These drug candidates may provide alternatives for patients with metabolic disorders and advance the progress of drug discovery for the large disease burden.

Retagliptin as add-on therapy to metformin in Chinese patients with type 2 diabetes inadequately controlled with metformin: A multicentre, randomized, double-blind, placebo-controlled, phase 3 trial

AIM

To evaluate the efficacy and safety of retagliptin in Chinese patients with type 2 diabetes (T2D) inadequately controlled with metformin.

MATERIALS AND METHODS

This multicentre, phase 3 trial consisted of a 16-week, randomized, double-blind, placebo-controlled period, where patients with HbA1c levels between 7.5% and 11.0% were randomized to receive either once-daily (QD) retagliptin 100 mg (n = 87) or placebo (n = 87), both as an add-on to metformin. The primary endpoint was the change in HbA1c from baseline to week 16.

RESULTS

At week 16, the least squares mean change in HbA1c from baseline, compared with placebo, was -0.82% (95% CI, -1.05% to -0.58%) for the retagliptin 100 mg QD group (P < .0001) per treatment policy estimand. Significantly higher proportions of patients in the retagliptin 100 mg QD group achieved HbA1c levels of less than 6.5% (11.5%) and less than 7.0% (26.4%) compared with those receiving placebo (0% and 4.6%; P = .0016 and P < .0001, respectively) at week 16. Retagliptin 100 mg QD also lowered fasting plasma glucose and 2-hour postprandial plasma glucose levels. The incidence of adverse events (AEs) during the treatment period was similar between the two groups. However, slightly higher proportions of increased lipase and increased amylase in the retagliptin 100 mg QD group were observed. No patients discontinued treatment permanently because of AEs, and no episodes of severe hypoglycaemia were reported.

CONCLUSIONS

Retagliptin 100 mg QD as an add-on therapy to metformin offers a new therapeutic option for treating Chinese patients with T2D inadequately controlled by metformin alone, and is generally well tolerated.

Synthesis and clinical application of representative small-molecule dipeptidyl Peptidase-4 (DPP-4) inhibitors for the treatment of type 2 diabetes mellitus (T2DM)

Diabetes mellitus is a chronic metabolic disorder characterized by high blood glucose levels, which can cause many diseases, including osteoporosis, fractures, arthritis, and foot complications. The inhibitors of dipeptidyl peptidase-4 (DPP-4), an enzyme involved in glucose metabolism regulation, are essential for managing Type 2 Diabetes Mellitus (T2DM). The inhibition of DPP-4 has become a promising treatment approach for T2DM because it can increase levels of active glucagon-like peptide-1 (GLP-1), leading to improved insulin secretion in response to glucose and reduced release of glucagon. The review commences by elucidating the role of DPP-4 in glucose homeostasis and its significance in T2DM pathophysiology. Furthermore, it presents the mechanism of action, preclinical pharmacodynamics, clinical efficacy, and toxicity profiles of small-molecule DPP-4 inhibitors across various clinical stages. This comprehensive review provides valuable insights into the synthesis and clinical application of DPP-4 inhibitors, serving as an invaluable resource for researchers, clinicians, and pharmaceutical professionals interested in diabetes therapeutics and drug development.

Identification of levomenthol derivatives as potential dipeptidyl peptidase-4 inhibitors: a comparative study with gliptins

Dipeptidyl peptidase-4 (DPP4) inhibitors are a potent therapeutic treatment for type 2 diabetes mellitus (T2DM). There is a family of compounds used as DPP4 inhibitors (DPP4Is) called gliptins. They bind tightly to DPP4 to form an inactive protein-ligand complex. However, there remains a need to identify novel DPP4Is that are more efficacious and safer due to the increasing prevalence of T2DM and the undesirable side effects of gliptins. To identify potential DPP4Is, we screened over 1800 novel compounds in a comparative study with gliptins. We performed dual-factor molecular docking to assess the binding affinity of the compounds to DPP4 and found four compounds with a higher binding affinity to DPP4 than currently used gliptins. The newly identified compounds interacted with the dyad glutamate (GLU205 and GLU206) and tyrosine (TYR662 and TYR666) residues in DPP4's active site. We performed molecular dynamics simulations to determine the stability of the protein-ligand complexes formed by the compounds and DPP4. Furthermore, we examined the toxicity and pharmacological profile of the compounds. The compounds are drug-like, easy to synthesize, and relatively less toxic than gliptins. Collectively, our results suggest that the novel compounds are potential DPP4Is and should be considered for further studies to develop novel antidiabetics.Communicated by Ramaswamy H. Sarma.

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.

Overview of Ethnobotanical-Pharmacological Studies Carried Out on Medicinal Plants from the Serra da Estrela Natural Park: Focus on Their Antidiabetic Potential

The Serra da Estrela Natural Park (NPSE) in Portugal stands out as a well-preserved region abundant in medicinal plants, particularly known for their pharmaceutical applications in diabetes prevention and treatment. This comprehensive review explores these plants' botanical diversity, traditional uses, pharmacological applications, and chemical composition. The NPSE boast a rich diversity with 138 medicinal plants across 55 families identified as traditionally and pharmacologically used against diabetes globally. Notably, the Asteraceae and Lamiaceae families are prevalent in antidiabetic applications. In vitro studies have revealed their significant inhibition of carbohydrate-metabolizing enzymes, and certain plant co-products regulate genes involved in carbohydrate metabolism and insulin secretion. In vivo trials have demonstrated antidiabetic effects, including glycaemia regulation, insulin secretion, antioxidant activity, and lipid profile modulation. Medicinal plants in NPSE exhibit various activities beyond antidiabetic, such as antioxidant, anti-inflammatory, antibacterial, anti-cancer, and more. Chemical analyses have identified over fifty compounds like phenolic acids, flavonoids, terpenoids, and polysaccharides responsible for their efficacy against diabetes. These findings underscore the potential of NPSE medicinal plants as antidiabetic candidates, urging further research to develop effective plant-based antidiabetic drugs, beverages, and supplements.

Adverse Cardiac Events of Hypercholesterolemia Are Enhanced by Sitagliptin Administration in Sprague Dawley Rats

Background

Cardiovascular disease (CVD) affects millions worldwide and is the leading cause of death among non-communicable diseases. Western diets typically comprise of meat and dairy products, both of which are rich in cholesterol (Cho) and methionine (Met), two well-known compounds with atherogenic capabilities. Despite their individual effects, literature on a dietary combination of the two in the context of CVD are limited. An additional interest was to investigate the cardioprotective potential of sitagliptin, an anti-type 2 diabetic drug. Thus, we hypothesized that atherogenic feeding would result in adverse cardiac effects and would attenuate upon sitagliptin administration.

Methods

Six-week-old adult male Sprague-Dawley rats were fed either a control (Con), high Met (1.5%), high Cho (2.0%), or high Met (1.5%) + high Cho (2.0%) diet for 35 days. They were orally gavaged with vehicle (water) or sitagliptin (100 mg/kg/d) from day 10 through 35. On day 36, rats were euthanized, and tissues were collected for analysis.

Results

Histopathological evaluation revealed a reduction in myocardial striations and increased collagen deposition in hypercholesterolemia (HChol), responses that became exacerbated upon sitagliptin administration. Cardiac pro-inflammatory and pro-fibrotic responses were adversely impacted in similar fashion. The addition of Met to Cho (MC) attenuated all adverse structural and biochemical responses, with or without sitagliptin.

Conclusion

Adverse cardiac outcomes in HChol were enhanced with sitagliptin administration and such effects were alleviated by Met. Our findings could be significant for understanding the risk-benefit of sitagliptin in type 2 diabetics who are known to consume atherogenic diets.

Network Proteins of Human Sortilin1, Its Expression and Targetability Using Lycopene

BACKGROUND

Sortilin1 (SORT1) is a ubiquitously expressed transporter involved in sorting or clearing proteins and is pathologically linked to tissue fibrosis and calcification. Targeting SORT1 may have potential clinical efficacy in controlling or reversing cardiovascular fibrosis and/or calcification. Hence, this study assessed the protein-protein network of human SORT1 and its targetability using known nutra-/pharmaceuticals.

MATERIAL AND METHODS

Network proteins of human SORT1 were identified using the String database, and the affinity of the protein-protein interaction of this network was analysed using Chimera software (Chimera-1.17.3-mac64). The tissue-specific expression profile of SORT1 was evaluated and assessed for enrichment in different cell types, including immune cells. A library of in-house small molecules and currently used therapeutics for cardiovascular diseases were screened using AutoDock Vina to assess the targetability of human SORT1. The concentration affinity (CA) ratio of the small molecules was estimated to assess the clinical feasibility of targeting SORT1.

RESULTS

IGF2R, NTRK2, GRN and GGA1 were identified as high-affinity interaction networks of SORT1. Of these high-affinity interactions, IGF2R and GRN can be considered relevant networks in regulating tissue fibrosis or the microcalcification process due to their influence on T-cell activation, inflammation, wound repair, and the tissue remodelling process. The tissue cell-type enrichment indicated major expression of SORT1 in adipocytes, specialised epithelial cells, monocytes, cardiomyocytes, and thyroid glandular cells. The binding pocket analysis of human SORT1 showed twelve potential drug interaction sites with varying binding scores (0.86 to 5.83) and probability of interaction (0.004 to 0.304). Five of the drug interaction sites were observed to be targetable at the therapeutically feasible concentration of the small molecules evaluated. Empagliflozin, sitagliptin and lycopene showed a superior affinity and CA ratio compared to established inhibitors of SORT1.

CONCLUSION

IGF2R and GRN are relevant networks of SORT1, regulating tissue fibrosis or the microcalcification process. SORT1 can be targeted using currently approved small-molecule therapeutics (empagliflozin and sitagliptin) or widely used nutraceuticals (lycopene), which should be evaluated in a randomised clinical trial to assess their efficacy in reducing the cardiac/vascular microcalcification process.

Anti-inflammatory and antinociceptive effects of sitagliptin in animal models and possible mechanisms involved in the antinociceptive activity

Background

Sitagliptin is an antidiabetic drug that inhibits dipeptidyl peptidase-4 enzyme. This study aimed to investigate the antinociceptive and anti-inflammatory effects of sitagliptin in formalin and carrageenan tests and determine the possible mechanism(s) of its antinociceptive activity.

Methods

Male Swiss mice (25-30 g) and male Wistar rats (180-220 g) were used for formalin and carrageenan tests, respectively. In the formalin test, paw licking time and in the carrageenan test, paw thickness were considered as indexes of pain behavior and inflammation respectively. Three doses of sitagliptin (2.5, 5, and 10 mg/kg) were used in these tests. Also, several antagonists and enzyme inhibitors were used to evaluate the role of adrenergic, serotonergic, dopaminergic, and opioid receptors as well as the NO/cGMP/KATP pathway in the antinociceptive effect of sitagliptin (5 mg/kg).

Results

Sitagliptin showed significant antinociceptive and anti-inflammatory effects in the formalin and carrageenan tests respectively. In the carrageenan test, all three doses of sitagliptin significantly (P < 0.001) reduced paw thickness. Pretreatment with yohimbine, prazosin, propranolol, naloxone, and cyproheptadine could not reverse the antinociceptive effect of sitagliptin (5 mg/Kg), which indicates that adrenergic, opioid, and serotonin receptors (5HT2) are not involved in the antinociceptive effects. L-NAME, methylene blue, glibenclamide, ondansetron, and sulpiride were able to reverse this effect.

Conclusions

NO/cGMP/KATP, 5HT3 and D2 pathways play an important role in the antinociceptive effect of sitagliptin. Additionally significant anti-inflammatory effects observed in the carrageenan test might contribute in reduction of pain response in the second phase of the formalin test.

Electrochemical Assays for the Determination of Antidiabetic Drugs-A Review

This article presents the current state of knowledge regarding electrochemical methods for determining the active substances within drugs that are used in the treatment of type 1 and type 2 diabetes. Electrochemical methods of analysis, due to their sensitivity and easiness, are a great alternative to other, usually more expensive analytical assays. The determination of active substances mentioned in this review is based on oxidation or reduction processes on the surface of the working electrode. A wide variety of working electrodes, often modified with materials such as nanoparticles or conducting polymers, have been used for the highly sensitive analysis of antidiabetic drugs. The presented assays allow us to determine the compounds of interest in various samples, such as pharmaceutical products or different human bodily fluids.

Sitagliptin Induces Tolerogenic Human Dendritic Cells

Sitagliptin, an anti-diabetic drug, is a dipeptidyl peptidase (DPP)-4/CD26 inhibitor with additional anti-inflammatory and immunomodulatory properties. In this study, we investigated for the first time the effect of sitagliptin on the differentiation and functions of human dendritic cells generated from monocytes (MoDCs) for 4 days using the standard GM-CSF/IL-4 procedure. LPS/IFN-γ treatment for an additional 24 h was used for maturation induction of MoDCs. Sitagliptin was added at the highest non-cytotoxic concentration (500 µg/mL) either at the beginning (sita 0d protocol) or after MoDC differentiation (sita 4d protocol). Sitagliptin impaired differentiation and maturation of MoDCs as judged with the lower expression of CD40, CD83, CD86, NLRP3, and HLA-DR, retention of CD14 expression, and inhibited production of IL-β, IL-12p70, IL-23, and IL-27. In contrast, the expression of CD26, tolerogenic DC markers (ILT4 and IDO1), and production of immunoregulatory cytokines (IL-10 and TGF-β) were increased. Generally, the sita 0d protocol was more efficient. Sitagliptin-treated MoDCs were poorer allostimulators of T-cells in MoDC/T-cell co-culture and inhibited Th1 and Th17 but augmented Th2 and Treg responses. Tolerogenic properties of sitagliptin-treated MoDCs were additionally confirmed by an increased frequency of CD4+CD25+CD127- FoxP3+ Tregs and Tr1 cells (CD4+IL-10+FoxP3-) in MoDC/T-cell co-culture. The differentiation of IL-10+ and TGF-β+ Tregs depended on the sitagliptin protocol used. A Western blot analysis showed that sitagliptin inhibited p65 expression of NF-kB and p38MAPK during the maturation of MoDCs. In conclusion, sitagliptin induces differentiation of tolerogenic DCs, and the effect is important when considering sitagliptin for treating autoimmune diseases and allotransplant rejection.

Can Antidiabetic Medications Affect Telomere Length in Patients with Type 2 Diabetes? A Mini-Review

The fight against aging is an eternal pursuit of humankind. The aging rate of patients with type 2 diabetes mellitus (T2DM) is higher than that of healthy individuals. Reducing the aging rate of patients with T2DM and extending their life expectancy are challenges that endocrinologists are eager to overcome. Many studies have shown that antidiabetic medications have potent anti-aging potential. Telomeres are repetitive DNA sequences located at the ends of chromosomes, and telomere shortening is a hallmark of aging. This review summarizes clinical trials that have explored the association between antidiabetic medications and telomere length (TL) in patients with T2DM and explore the mystery of delaying aging in patients with T2DM from the perspective of telomeres. Various antidiabetic medications may have different effects on TL in patients with T2DM. Metformin and sitagliptin may protect telomeres in patients with T2DM, while exogenous insulin may promote telomere shortening in patients with T2DM. The effect of acarbose and glyburide on TL in patients with T2DM is still uncertain due to the absence of evidence from longitudinal studies.

Bee Venom and Its Two Main Components-Melittin and Phospholipase A2-As Promising Antiviral Drug Candidates

Viruses are known to infect most types of organisms. In humans, they can cause several diseases that range from mild to severe. Although many antiviral therapies have been developed, viral infections continue to be a leading cause of morbidity and mortality worldwide. Therefore, the discovery of new and effective antiviral agents is desperately needed. Animal venoms are a rich source of bioactive molecules found in natural goods that have been used since ancient times in alternative medicine to treat a variety of human diseases. Recently, and with the onset of the COVID-19 pandemic, scientists have regained their interest in the possible use of natural products, such as bee venom (BV), as a potential antiviral agent to treat viral infections. BV is known to exert many therapeutic activities such as anti-proliferative, anti-bacterial, and anti-inflammatory effects. However, there is limited discussion of the antiviral activity of BV in the literature. Therefore, this review aims to highlight the antiviral properties of BV and its two primary constituents, melittin (MEL) and phospholipase A2 (PLA2), against a variety of enveloped and non-enveloped viruses. Finally, the innovative strategies used to reduce the toxicity of BV and its two compounds for the development of new antiviral treatments are also considered.

Effect of sitagliptin combined with Yiqi yangyin huoxue decoction on clinical efficacy and hemorheology in early diabetic nephropathy

BACKGROUND

Early diabetic nephropathy (DN) is a complication of diabetes mellitus. It mainly affects kidney microvessels and glomerular function, and its timely and effective treatment is critical for early DN. However, the effects of treatments comprising simple Western medicine are not optimal. With the promotion and implementation of integrated Chinese and western medicine treatments, remarkable results have been achieved for many diseases. To this end, we explored the clinical efficacy of integrated traditional Chinese and western medicines for the treatment of early DN.

AIM

To investigate the effect of sitagliptin tablets combined with Yiqi yangyin huoxue decoction on clinical efficacy and hemorheology in patients with early DN.

METHODS

Through a retrospective analysis, 123 patients with early DN were admitted to the endocrinology clinic of the Changzhou NO. 7 People's Hospital from January 2021 to October 2022 and were selected as study subjects. After rigorous screening, 100 patients with early DN were enrolled. The control group (CG, n = 50) and the observation group (OG, n = 50) were divided according to the treatment method. The CG were treated with sitagliptin, and the OG were treated with sitagliptin plus the Yiqi yangyin huoxue decoction. Both groups were treated for 3 mo. For both groups, the baseline data and clinical efficacy were compared, and changes in blood glucose levels, lipid levels, renal function, and hematological indicators before (T0) and after (T1) treatment were assessed.

RESULTS

The total effective rate for the OG was 94.00% and that of the CG was 80.00% (P < 0.05). After treatment (T1), the levels of fasting blood glucose, 2 h postprandial glucose, total cholesterol, triacylglycerol, and low-density lipoprotein cholesterol in OG patients were obviously lower than those in the CG (P < 0.05), and cystatin C, homocysteine, urinary microalbumin, and blood creatinine values in OG patients were also obviously lower than those in the CG (P < 0.05); erythrocyte deposition, plasma viscosity, whole blood high shear viscosity, and whole blood low shear viscosity were markedly lower in OG patients than in the CG (P < 0.05).

CONCLUSION

Sitagliptin combined with Yiqi yangyin huoxue decoction has a remarkable effect when used to treat patients with early DN. Further, it is helpful in improving hemorheological indices and controlling disease progression.

Tutorial review for peptide assays: An ounce of pre-analytics is worth a pound of cure

The recent increase in peptidomimetic-based medications and the growing interest in peptide hormones has brought new attention to the quantification of peptides for diagnostic purposes. Indeed, the circulating concentrations of peptide hormones in the blood provide a snapshot of the state of the body and could eventually lead to detecting a particular health condition. Although extremely useful, the quantification of such molecules, preferably by liquid chromatography coupled to mass spectrometry, might be quite tricky. First, peptides are subjected to hydrolysis, oxidation, and other post-translational modifications, and, most importantly, they are substrates of specific and nonspecific proteases in biological matrixes. All these events might continue after sampling, changing the peptide hormone concentrations. Second, because they include positively and negatively charged groups and hydrophilic and hydrophobic residues, they interact with their environment; these interactions might lead to a local change in the measured concentrations. A phenomenon such as nonspecific adsorption to lab glassware or materials has often a tremendous effect on the concentration and needs to be controlled with particular care. Finally, the circulating levels of peptides might be low (pico- or femtomolar range), increasing the impact of the aforementioned effects and inducing the need for highly sensitive instruments and well-optimized methods. Thus, despite the extreme diversity of these peptides and their matrixes, there is a common challenge for all the assays: the need to keep concentrations unchanged from sampling to analysis. While significant efforts are often placed on optimizing the analysis, few studies consider in depth the impact of pre-analytical steps on the results. By working through practical examples, this solution-oriented tutorial review addresses typical pre-analytical challenges encountered during the development of a peptide assay from the standpoint of a clinical laboratory. We provide tips and tricks to avoid pitfalls as well as strategies to guide all new developments. Our ultimate goal is to increase pre-analytical awareness to ensure that newly developed peptide assays produce robust and accurate results.

DPP-4 inhibitors and type 2 diabetes mellitus in Parkinson's disease: a mutual relationship

Parkinson's disease (PD) usually occurs due to the degeneration of dopaminergic neurons in the substantia nigra (SN). Management of PD is restricted to symptomatic improvement. Consequently, a novel treatment for managing motor and non-motor symptoms in PD is necessary. Abundant findings support the protection of dipeptidyl peptidase 4 (DPP-4) inhibitors in PD. Consequently, this study aims to reveal the mechanism of DPP-4 inhibitors in managing PD. DPP-4 inhibitors are oral anti-diabetic agents approved for managing type 2 diabetes mellitus (T2DM). T2DM is linked with an increased chance of the occurrence of PD. Extended usage of DPP-4 inhibitors in T2DM patients may attenuate the development of PD by inhibiting inflammatory and apoptotic pathways. Thus, DPP-4 inhibitors like sitagliptin could be a promising treatment against PD neuropathology via anti-inflammatory, antioxidant, and anti-apoptotic impacts. DPP-4 inhibitors, by increasing endogenous GLP-1, can also reduce memory impairment in PD. In conclusion, the direct effects of DPP-4 inhibitors or indirect effects through increasing circulating GLP-1 levels could be an effective therapeutic strategy in treating PD patients through modulation of neuroinflammation, oxidative stress, mitochondrial dysfunction, and neurogenesis.

Effects of Sitagliptin on Metabolic Indices and Hormone Levels in Polycystic Ovary Syndrome: a Meta-analysis of Randomized Controlled Trials

To evaluate the effects of sitagliptin on the metabolic indices and hormone levels in patients with polycystic ovary syndrome (PCOS). PubMed, EMBASE, Web of Science, Cochrane Library, WanFang Data, and China National Knowledge Infrastructure (CNKI) were searched for randomized controlled trials (RCTs) published up to March 2022. Eligible studies were identified based on the inclusion criteria. The primary outcomes included the homeostasis model assessment of insulin resistance (HOMA-IR), body mass index (BMI), and total testosterone level (TT). Other outcomes included levels of sex hormones, glucose, and lipid metabolism. Forty-five studies were initially identified, and 6 RCTs with 394 patients were finally included in this study. The meta-analysis results suggest that sitagliptin improved HOMA-IR (WMD =  - 0.35; 95% CI (- 0.62, - 0.08); P = 0.01), BMI (WMD =  - 1.27; 95% CI (- 1.76, - 0.77); P < 0.00001), TT (SMD =  - 0.66; 95% CI (- 1.25, - 0.07); P = 0.03), and HDL-C (SMD = 0.11; 95% CI (0.03, 0.18); P = 0.005). No significant differences were observed between the sitagliptin and control groups in other outcomes and in terms of adverse events. Evidence from meta-analyses suggests that sitagliptin was superior in improving insulin sensitivity, total serum testosterone, high-density lipoprotein, and body mass index. However, due to the limitations of published studies, it is difficult to draw a definite conclusion. Larger, higher-quality studies are needed to evaluate the efficacy of sitagliptin in women with PCOS.

HYPOGLYCEMIC EFFECT OF SITAGLIPTIN AND AMINOGUANIDINE COMBINATION IN EXPERIMENTAL DIABETES MELLITUS

The aim of the work was to determine the antidiabetic effect of a sitagliptin and aminoguanidine combination in rats with experimental diabetes mellitus.

Materials and methods. The study was carried out on male Wistar rats and C57BL/KsJ-db/db mice. According to the models used, it was divided into 4 series, in which alloxan, steroid-induced (dexamethasone) and streptozotocin-nicotinamide-induced diabetes mellitus (DM) were formed, respectively, in rats, and in the 4 series, obese C57BL/KsJ-db/db mice were used. In the 1 and 2 series, the treatment was started prophylactically – 3 h after the alloxan administration and simultaneously with the dexamethasone administration, in the 3rd and 4th series, the treatment was carried out after the pathology had developed – 7 days after the streptozotocin with nicotinamide administration, and in the obese mice – immediately after their distribution according to the groups. The treatment was carried out with sitagliptin (10 mg/kg), aminoguanidine (25 mg/kg), or a combination thereof. The treatment was continued till the end of the experiment, which was completed with an oral glucose tolerance test (OGTT) after 4 h of fasting. The obtained data were subjected to statistical processing.

Results. In the course of the experiments, it was found out that the prophylactic administration of a sitagliptin and aminoguanidine combination, unlike each of the components, prevented the development of alloxan DM. More effectively than the administration of sitagliptin alone, it reduced the severity of steroid-induced DM, which was expressed in a significantly lower level of fasting glycemia (after 4 h of fasting) and postprandial glycemia (during OGTT). Under the conditions of streptozotocin-nicotinamide-induced DM, the studied combination slowed down the progression of the pathology, and in the obese mice, the course therapeutic administration of sitagliptin and its combination reduced the severity of carbohydrate metabolism disorders (fasting glycemia) and increased the rate of glucose utilization.

Conclusion. As an iNOS blocker, aminoguanidine enhances the antidiabetic effect of sitagliptin, preventing the development of alloxan diabetes and reducing the severity of steroid-induced DM when administered prophylactically. When administered therapeutically, it reduces the severity of streptozotocin-nicotinamide-induced DM in rats and type 2 DM in mice with a predisposition to obesity.

 

Drug-associated acquired hemophilia A: an analysis based on 185 cases from the WHO pharmacovigilance database

INTRODUCTION

Acquired hemophilia A (AHA) is a rare autoimmune hemorrhagic disease occurring in several underlying conditions. Drug-associated AHA (D-AHA) is poorly addressed nowadays.

AIM

This work aims to identify and characterize which drugs are associated with AHA using the WHO global database of reported potential effects of medicinal products (VigiBase).

METHODS

First, we realized a disproportionality analysis using the information component (IC) to identify D-AHA in VigiBase. IC compares observed- and expected-values in order to find associations between drugs and adverse drug reactions (ADRs) using disproportionate Bayesian reporting. IC₀₂₅ is the lower end of a 95% credibility interval for the IC. Then, we collected cases of drugs significantly associated with AHA from July 2004 to November 2021.

RESULTS

14 drugs with IC₀₂₅ > 0 were identified representing a total of 185 cases. D-AHA occurred more frequently in men (59%) than women (41%). The median (min-max) age at onset was 75 years (8-98). The median [Q1-Q3] time to onset of D-AHA from the start of the suspected drug was 30 days [9.5-73.75] and 10% of cases resulted in a fatality. The drugs associated with the highest IC₀₂₅ (IC₀₂₅ > 2) were Clopidogrel, Alemtuzumab, Omalizumab. This study retrieved for the first time three usually used drugs (3/14) that exhibit a significant pharmacovigilance signal for D-AHA.

CONCLUSION

This worldwide pharmaco-epidemiologic study updates the list of the drugs associated with AHA. The clinician should be aware of these possible severe ADR, which might require larger epidemiological and pathophysiologic studies.

Combined therapy of GABA and sitagliptin prevents high-fat diet impairment of beta-cell function

We recently demonstrated that combined therapy of GABA and sitagliptin promoted beta-cell proliferation, and decreased beta-cell apoptosis in a multiple low-dose streptozotocin (STZ)-induced beta-cell injury mouse model. In this study, we examined whether this combined therapy is effective in ameliorating the impairment of beta-cell function caused by high-fat diet (HFD) feeding in mice. Male C57BL/6J mice were fed normal chow diet, HFD, or HFD combined with GABA, sitagliptin, or both drugs. Oral drug daily administration was initiated one week before HFD and maintained for two weeks. After two weeks of intervention, we found that GABA or sitagliptin administration ameliorated the impairment of glucose tolerance induced by HFD. This was associated with improved insulin secretion in vivo. Notably, combined administration of GABA and sitagliptin significantly enhanced these effects as compared to each of the monotherapies. Combined GABA and sitagliptin was superior at increasing beta-cell mass, and associated Ki67⁺ and PDX-1⁺ beta-cell counts. In addition, we found that HFD-induced compensatory beta-cell proliferation was associated with increased activation of unfolded protein response (UPR), as indicated by BiP expression. This could be an important mechanism of compensatory beta-cell proliferation, and beta cells treated with GABA and sitagliptin showed greater UPR activation. Our results suggest that the combined use of these agents produces superior therapeutic outcomes.

Development and Validation for Quantification of 7-Nitroso Impurity in Sitagliptin by Ultraperformance Liquid Chromatography with Triple Quadrupole Mass Spectrometry

The purpose of this research study was to develop an analytical method for the quantification of 7-nitroso-3-(trifluoromethyl)-5,6,7,8-tetrahydro-[1,2,4] triazolo [4,3-a] pyrazine (7-nitroso impurity), which is a potential genotoxic impurity. Since sitagliptin is an anti-diabetic medication used to treat type 2 diabetes and the duration of the treatment is long-term, the content of nitroso impurity must be controlled by using suitable techniques. To quantify this impurity, a highly sensitive and reproducible ultraperformance liquid chromatography with triple quadrupole mass spectrometry (UHPLC-MS/MS) method was developed. The analysis was performed on a Kromasil-100, with a C18 column (100 mm × 4.6 mm with a particle size of 3.5 µm) at an oven temperature of approximately 40 °C. The mobile phase was composed of 0.12% formic acid in water, with methanol as mobile phases A and B, and the flow rate was set to 0.6 mL/min. The method was validated according to the current International Council for Harmonisation (ICH) guidelines with respect to acceptable limits, specificity, reproducibility, accuracy, linearity, precision, ruggedness and robustness. This method is useful for the detection of the impurity at the lowest limit of detection (LOD), which was 0.002 ppm, and the lowest limit of quantification (LOQ), which was 0.005 ppm. This method was linear in the range of 0.005 to 0.06 ppm and the square of the correlation coefficient (R2) was determined to be > 0.99. This method could help to determine the impurity in the regular analysis of sitagliptin drug substances and drug products.

Identification of sitagliptin binding proteins by affinity purification mass spectrometry

Type 2 diabetes mellitus (T2DM) is recognized as a serious public health concern with increasing incidence. The dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin has been used for the treatment of T2DM worldwide. Although sitagliptin has excellent therapeutic outcome, adverse effects are observed. In addition, previous studies have suggested that sitagliptin may have pleiotropic effects other than treating T2DM. These pieces of evidence point to the importance of further investigation of the molecular mechanisms of sitagliptin, starting from the identification of sitagliptin-binding proteins. In this study, by combining affinity purification mass spectrometry (AP-MS) and stable isotope labeling by amino acids in cell culture (SILAC), we discover seven high-confidence targets that can interact with sitagliptin. Surface plasmon resonance (SPR) assay confirms the binding of sitagliptin to three proteins, i. e., LYPLAL1, TCP1, and CCAR2, with binding affinities (K _D) ranging from 50.1 μM to 1490 μM. Molecular docking followed by molecular dynamic (MD) simulation reveals hydrogen binding between sitagliptin and the catalytic triad of LYPLAL1, and also between sitagliptin and the P-loop of ATP-binding pocket of TCP1. Molecular mechanics Poisson-Boltzmann Surface Area (MMPBSA) analysis indicates that sitagliptin can stably bind to LYPLAL1 and TCP1 in active sites, which may have an impact on the functions of these proteins. SPR analysis validates the binding affinity of sitagliptin to TCP1 mutant D88A is ~10 times lower than that to the wild-type TCP1. Our findings provide insights into the sitagliptin-targets interplay and demonstrate the potential of sitagliptin in regulating gluconeogenesis and in anti-tumor drug development.

Dipeptidylpeptidase (DPP)-4 inhibitor therapy increases circulating levels of anti-inflammatory soluble frizzle receptor protein (sFRP)-5 which is decreased in severe COVID-19 disease

Obesity and type 2 diabetes (T2D) show an increased risk for a severe COVID-19 disease. Treatment with DPP4 inhibitor (DPP4i) results in reduced mortality and better clinical outcome. Here, we aimed to identify potential mechanisms for the observed DPP4i effect in COVID-19. Comparing T2D subjects with and without DPP4i treatment, we identified a significant increase of the anti-inflammatory adipokine sFRP5 in relation to DPP4 inhibition. sFRP5 is a specific antagonist to Wnt5a, a glycopeptide secreted by adipose tissue macrophages acting pro-inflammatory in various diseases. We therefore examined sFRP5 levels in patients hospitalised for severe COVID-19 and found significant lower levels compared to healthy controls. Since sFRP5 might consequently be a molecular link for the beneficial effects of DPP4i in COVID-19, we further aimed to identify the exact source of sFRP5 in adipose tissue on cellular level. We therefore isolated pre-adipocytes, mature adipocytes and macrophages from adipose tissue biopsies and performed western-blotting. Results showed a sFRP5 expression specifically in mature adipocytes of subcutaneous and omental adipose tissue. In summary, our data suggest that DPP4i increase serum levels of anti-inflammatory sFRP5 which might be beneficial in COVID-19, reflecting a state of sFRP5 deficiency.

Sitagliptin mitigates hypoxia/reoxygenation (H/R)-induced injury in cardiomyocytes by mediating sirtuin 3 (SIRT3) and autophagy

Potential ischemia/reperfusion (I/R) injuries are commonly induced during treatment of cardiovascular diseases, such as acute myocardial infarction (AMI). It is reported that oxidative stress and over-autophagy in cardiomyocytes are involved in the pathogenesis of I/R injury. Sitagliptin is an effective inhibitor of dipeptidyl peptidase 4 (DPP-4) for the treatment of diabetes, which is recently reported to regulate oxidative stress and autophagy. The present study is designed to explore the function of Sitagliptin on I/R injury. Hypoxia/reoxygenation (H/R) condition was used to simulate the I/R injury on cardiomyocytes. We found that the declined cell viability and elevated expression level of creatine kinase myocardial band (CK-MB) were observed in the H/R group, accompanied by the increased mitochondrial reactive oxygen species (ROS), elevated cellular malondialdehyde (MDA) level, and mitochondrial dysfunction. After Sitagliptin treatment, the damages in H9c2 cardiomyocytes, oxidative stress, and mitochondrial dysfunction were significantly alleviated. In addition, the overactivated autophagy and mitophagy in H/R-challenged cardiomyocytes were dramatically mitigated by Sitagliptin, accompanied by the upregulation of SIRT3. Lastly, the protective effect of Sitagliptin on H/R-induced mitophagy, autophagy, and damages in cardiomyocytes was dramatically abolished by the knockdown of SIRT3. Taken together, our data reveal that Sitagliptin ameliorated the H/R-induced injury in cardiomyocytes by mediating sirtuin 3 (SIRT3) and autophagy.

Role of Dipeptidyl Peptidase 4 Inhibitors in Antidiabetic Treatment

In recent years, important changes have occurred in the field of diabetes treatment. The focus of the treatment of diabetic patients has shifted from the control of blood glucose itself to the overall management of risk factors, while adjusting blood glucose goals according to individualization. In addition, regulators need to approve new antidiabetic drugs which have been tested for cardiovascular safety. Thus, the newest class of drugs has been shown to reduce major adverse cardiovascular events, including sodium-glucose transporter 2 (SGLT2) and some glucagon like peptide 1 receptor (GLP1) analog. As such, they have a prominent place in the hyperglycemia treatment algorithms. In recent years, the role of DPP4 inhibitors (DPP4i) has been modified. DPP4i have a favorable safety profile and anti-inflammatory profile, do not cause hypoglycemia or weight gain, and do not require dose escalation. In addition, it can also be applied to some types of chronic kidney disease patients and elderly patients with diabetes. Overall, DPP4i, as a class of safe oral hypoglycemic agents, have a role in the management of diabetic patients, and there is extensive experience in their use.

Effects of sitagliptin on serum lipid levels in patients with type 2 diabetes: a systematic review and meta-analysis

AIM

Lipid abnormalities often occur in patients with diabetes mellitus and the coexistence of diabetes mellitus and dyslipidaemia will increase the risk of cardiovascular diseases. However, the specific effects of sitagliptin on lipid control remain elusive in diabetic patients. The aim of this meta-analysis is to investigate the effects of sitagliptin alone or with other antidiabetic agents on serum lipid control.

METHODS

PubMed, Cochrane Library, Embase and the ClinicalTrials.gov website were systematically searched from 2006 (the first year that sitagliptin entered market) to 16 January 2021. Eligible studies were randomized clinical trials (RCTs) of sitagliptin including outcomes of serum total cholesterol (TC), triglycerides, high-density lipoprotein cholesterol (HDL-C) or low-density lipoprotein cholesterol (LDL-C).

RESULTS

A total of 14 RCTs with 2654 patients were identified. Treatment with sitagliptin alone or in combination with other antidiabetic agents significantly reduced serum TC [mean difference (MD) = -5.52 95% confidence interval (95% CI), -7.88 to -3.15; P < 0.00001] and LDL-C (MD = -0.07; 95% CI, -0.14 to 0.00; P < 0.00001) in patients with type 2 diabetes. No statistical significances were found in serum triglycerides (MD = 1.53; 95% CI, -8.22 to 11.28; P = 0.76) or HDL-C (MD = 0.65; 95% CI, -1.59 to 0.29; P = 0.18). Subgroup analyses suggest that sitagliptin can significantly decrease serum LDL-C, TC and triglyceride levels compared with placebo alone, and no statistical significance was found in comparison with the serum HDLC levels.

CONCLUSION

Sitagliptin alone or in combination with other antidiabetic agents significantly reduces serum TC and LDL-C in patients with type 2 diabetes mellitus, while no significant difference was observed in serum triglycerides or HDL-C.

Comparative Evaluation of Chiglitazar and Sitagliptin on the Levels of Retinol-Binding Protein 4 and Its Correlation With Insulin Resistance in Patients With Type 2 Diabetes

Aims

We evaluated the efficacy and significant changes in the levels of retinol-binding protein 4 (RBP-4) and insulin resistance in patients with type 2 diabetes mellitus (T2DM) treated with chiglitazar versus sitagliptin.

Methods

Eighty-one T2DM patients with haemoglobin A1c (HbA1c) level of 7.5%-10.0% were selected. Based on the study criteria, patients were randomly assigned to receive chiglitazar (32 mg), chiglitazar (48 mg), or sitagliptin (100 mg) orally for 24 weeks. Sociodemographic and anthropometric characteristics, lipid profiles, glucose profiles, and serum RBP-4 levels were determined at baseline and at the end of the therapy.

Results

After treatment for 24 weeks, significant changes in fasting blood glucose (FBG), fasting insulin (Fins), 2 h-blood glucose (2h-BG), the score values of insulin resistance/insulin secretion/β cell function (HOMA-IR, HOMA-IS, and HOMA-β), triglyceride (TG), free fatty acid (FFA), high-density lipoprotein cholesterol (HDL-C), and RBP-4 levels were detected in patients with chiglitazar administration and sitagliptin administration. Changes in RBP-4 levels were positively correlated with changes in HOMA-IR and 2 h-BG in linear regression.

Conclusions

Chiglitazar showed a greater improvement in parameters of diabetes than sitagliptin, and changes in serum RBP-4 levels were associated with changes in insulin-sensitizing parameters.

Clinical Trial Registration

ClinicalTrials.gov, CT.gov identifier: NCT02173457.

The Potential Role of Cyclopeptides from Pseudostellaria heterophylla, Linum usitatissimum and Drymaria diandra, and Peptides Derived from Heterophyllin B as Dipeptidyl Peptidase IV Inhibitors for the Treatment of Type 2 Diabetes: An In Silico Study

Dipeptidyl peptidase 4 (DPP4) inhibitors can treat type 2 diabetes by slowing GLP-1 degradation to increase insulin secretion. Studies have reported that Pseudostellaria heterophylla, Linum usita-tissimum (flaxseed), and Drymaria diandra, plants rich in Caryophyllaceae-type cyclopeptides and commonly used as herbal or dietary supplements, are effective in controlling blood sugar. The active site of DPP4 is in a cavity large enough to accommodate their cyclopeptides. Molecular modeling by AutoDock Vina reveals that certain cyclopeptides in these plants have the potential for DPP4 inhibition. In particular, “Heterophyllin B” from P. heterophylla, “Cyclolinopeptide C” from flaxseed, and “Diandrine C” from D. diandra, with binding affinities of −10.4, −10.0, and −10.7 kcal/mol, are promising. Docking suggests that DPP4 inhibition may be one of the reasons why these three plants are beneficial for lowering blood sugar. Because many protein hydrolysates have shown the effect of DPP4 inhibition, a series of peptides derived from Heterophyllin B precursor “IFGGLPPP” were included in the study. It was observed that IFWPPP (−10.5 kcal/mol), IFGGWPPP (−11.4 kcal/mol), and IFGWPPP (−12.0 kcal/mol) showed good binding affinity and interaction for DPP4. Various IFGGLPPP derivatives have the potential to serve as scaffolds for the design of novel DPP4 inhibitors.

Stability of extemporaneously prepared sitagliptin phosphate solution

Sitagliptin is a dipeptidyl peptidase-4 (DPP-4) inhibitor that is used orally in conjunction with diet and exercise to control sugar levels in type 2 Diabetes Mellitus patients. This study aimed to extemporaneously prepare SiP solution (1% w/v) using pure Sitagliptin phosphate (SiP) powder and assess its stability according to pharmaceutical regulatory guidelines. Four SiP solutions, coded T1, T2, T3, and T4, were extemporaneously prepared using pure SiP powder as a source of API. The most suitable one, in terms of general organoleptic properties, was selected for further investigations, including stability studies. For this last purpose, samples of the T4 solution were kept under two storage conditions, room temperature (25˚C and 60% Relative Humidity) and accelerated stability conditions (40˚C and 75% Relative Humidity). Assay, pH, organoleptic properties, related substances, and microbial contamination were evaluated for 4 consecutive weeks. A High-Performance Liquid Chromatography (HPLC) analytical method was developed and validated to be used for the analysis and quantification of SiP in selected solution formulation. The adopted formula had a pH on the average of 3 to 4. During the stability tests, all pH values remained constant. Furthermore, after 4 weeks of storage under both conditions, the SiP concentration was close to 100%. A stable SiP extemporaneous solution was successfully prepared using pure SiP powder. Patients with swallowing problems who use feeding tubes and are unable to take oral solid dosage forms may benefit from this research. Community pharmacists can prepare the solution using sitagliptin powder as the source of the active ingredient.

Shenqi compound ameliorates type-2 diabetes mellitus by modulating the gut microbiota and metabolites

The gut microbiota (GM) and metabolites are important factors in mediating the development of type-2 diabetes mellitus (T2DM). An imbalance in the gut microbiota and metabolites can disrupt the function of the intestinal barrier, cause changes in the permeability of the intestinal mucosa and promote the immune inflammatory response, thereby aggravating the fluctuation of blood glucose level and promoting the occurrence and development of the chronic complications of DM. Manipulating the GM and metabolites is a promising therapeutic intervention and is being studied extensively. Shenqi compound (SQC) is a traditional Chinese medicine formulation, which has been widely used to improve T2DM. Studies have demonstrated that SQC can reduce glycemic variability, alleviate the inflammatory response, etc. However, its underlying mechanism remains unknown. Therefore, in this experiment, We administered SQC to Goto-Kakizaki (GK) rats and evaluated its effect on blood glucose homeostasis and the intestinal mucosal barrier. We identified the profiles of the GM and metabolites with the aid of 16S rDNA gene sequencing and non-target metabolomics analysis. It showed that SQC intervention could reduce glycemic variability, regulate serum levels of glucagon and insulin, and improve injury to the intestinal mucosal barrier of GK rats. In the gut, the ratio of bacteria of the phyla Bacteroidetes/Firmicutes could be improved after SQC intervention. SQC also regulated the relative abundance of Prevotellaceae, Butyricimonas, Bacteroides, Blautia, Roseburia, Lactobacillus, and Rothia. We found out that expression of 40 metabolites was significantly improved after SQC intervention. Further analyses of metabolic pathways indicated that the therapeutic effect of SQC might be related predominantly to its ability to improve gluconeogenesis/glycolysis, amino acid metabolism, lipid metabolism, citrate cycle, and butanoate metabolism. These results suggest that SQC may exert a beneficial role in T2DM by modulating the GM and metabolites in different pathways.

Genome-Wide Transcriptome Analysis in Type 2 Diabetes Patients Treated by Sitagliptin

OBJECTIVE

In this study, transcriptome sequencing was performed on patients with type 2 diabetes mellitus treated with different prognosis to explore the differential level genes of different hypoglycemic effects of sitagliptin.

METHODS

Patients with newly diagnosed T2DM (within six months of diagnosis) were selected as the study subjects. Patients were given sitagliptin 100 mg once a day orally. After 12 weeks of regular drug therapy, the reduction in glycated hemoglobin was compared before and after drug administration. The patients were then divided into two groups: the significantly effective group (M) and the less effective group (N). High-throughput sequencing of the transcriptome was conducted to detect the differential expression levels of genes in peripheral blood mononuclear cells. Expanded sample size validation of the candidate differential genes was conducted using reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

After 12 weeks of treatment with sitagliptin, high-throughput sequencing of the transcriptome found that expression of the following genes was different when comparing the significantly effective group (M) and the less effective group (N): ghrelin (GHRL), insulin-like growth factor-1 receptor (IGF1R), mitogen-activated protein kinase-3 (MAPK3), phosphatidylinositol-4,5-bisphosphonate 3-kinase, catalytic subunit delta (PIK3CD), and the suppressor of cytokine signaling-3 (SOCS3). The validation results of RT-PCR showed that, in the significantly effective group (M), the expression of IGF1R was significantly increased (P = 0.034), the expression of MAPK3 was significantly reduced (P = 0.002), and the expression of SOCS3 was also significantly reduced (P < 0.001).

CONCLUSION

There was a significant difference in gene level between patients with significant hypoglycemic effect and patients with poor hypoglycemic effect, and the expression of IGF1R increased and the expression of MAPK3 and SOCS3 decreased.

Sitagliptin protects renal glomerular endothelial cells against high glucose-induced dysfunction and injury

Sitagliptin is a well-established anti-diabetic drug that also exerts protective effects on diabetic complications. Previous work reveals that sitagliptin has a protective effect on diabetic nephropathy (DN). Vascular impairment frequently occurs in diabetic renal complications. Here, we evaluated the protective function of sitagliptin in human renal glomerular endothelial cells (HrGECs) under high glucose (HG) conditions. Expressions of the pro-inflammatory cytokines interleukin-1β (IL-1β) and interleukin-8 (IL-8) were assessed using real-time PCR and ELISA. Endothelial cells permeability was assayed using the fluorescein isothiocyanate dextran (FITC-dextran) and trans-endothelial electrical resistance (TEER) assay. The results show that sitagliptin mitigated HG-induced oxidative stress in HrGECs with decreased levels of mitochondrial reactive oxygen species (ROS), Malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG). Sitagliptin inhibited HG-induced production of pro-inflammatory cytokines interleukin-1β (IL-1β) and interleukin-8 (IL-8) in HrGECs. It also ameliorated HG-induced aggravation of HrGECs permeability and reduction of the tight junction component claudin-5. Moreover, kruppel Like Factor 6 (KLF6) mediated the protective effects of sitagliptin on endothelial monolayer permeability against HG. Collectively, sitagliptin reversed the HG-induced oxidative stress, inflammation, and increased permeability in HrGECs via regulating KLF6. This study suggests that sitagliptin might be implicated as an effective strategy for preventing diabetic renal injuries in the future.

Sitagliptin ameliorates hypoxia-induced damages in endometrial stromal cells: an implication in endometriosis

Hypoxia-induced damage in endometrial stromal cells (ESCs) is an important event in the pathological progression of Endometriosis. It is reported that significant inflammation is induced by hypoxia in ESCs, mediated by serval inflammatory progressions, pathways, or factors. Sitagliptin, an important member of the dipeptidyl peptidase-4 (DPP-4) inhibitors family and has been widely used for the management of type 2 diabetes. It has been recently reported to exert significant anti-inflammatory effects. Here, we aim to assess whether Sitagliptin possesses a protective effect against hypoxia-induced damages in ESCs. Our findings indicate that exposure to hypoxia significantly increased oxidative stress in ESCs by increasing the production of reactive oxygen species (ROS) and decreasing the levels of reduced glutathione (GSH), which was ameliorated by Sitagliptin. Additionally, the excessively produced inflammatory mediators, including tumor necrosis factor (TNF)-α, interleukin (IL)-6, monocyte chemoattractant protein-1 (MCP-1), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE₂), and high mobility group box (HMGB)-1, in hypoxia-treated HESCs were pronouncedly repressed by Sitagliptin. The activated p38 mitogen-activated protein kinases (MAPK) pathway was observed in hypoxia-stimulated HESCs, then greatly inhibited by the introduction of Sitagliptin. Lastly, hypoxia-induced phosphorylation and degradation of IκBα, as well as the upregulation of nuclear factor kappa-B (NF-κB) p65 and increased transcriptional activity of NF-κB, were dramatically abolished by Sitagliptin. Collectively, Sitagliptin ameliorated hypoxia-induced damages in ESCs by suppressing the inflammation.

Simultaneous determination of rivaroxaban and sitagliptin in rat plasma by LC–MS/MS and its application to pharmacokinetic drug-drug interaction study

A sensitive and accurate LC-MS/MS method was developed and validated for the simultaneous quantification of rivaroxaban (RIV) and sitagliptin (SIT) in rat plasma using apixaban as internal standard (IS). An Agilent Eclipse plus C18 column (2.1 × 100 mm, 3.5 µm, Agilent) was used for chromatographic separation with isocratic elution. Multiple reaction monitoring (MRM) using positive-ion ESI mode to monitor ion transitions of m/z 436.8→144.9 for RIV, m/z 407.7→173.8 for SIT, m/z 459.8→442.8 for IS. The procedure of method validation included selectivity, linearity, precision, accuracy, matrix effect, extraction recovery and stability were conducted according to the guidelines of EMA and FDA. The results indicated that no obvious drug-drug interactions occurred might be owing to their differences in metabolic pathways.

Comparison of New Glucose-Lowering Drugs on Risk of Pancreatitis in Type 2 Diabetes: A Network Meta-Analysis

BACKGROUND & AIMS

Whether new glucose-lowering drugs increases the risk of pancreatitis in individuals with type 2 diabetes remains controversial. This present network meta-analysis aims to investigate the risk of pancreatitis associated with the use of glucagon-like peptide (GLP)-1 agonists and dipeptidyl peptidase (DPP)-4 inhibitors in the treatment of type 2 diabetes mellitus.

METHODS

PubMed, Web of Science, EMBASE and the Cochrane Library were searched. The literature was published from the date of their inception to July 21, 2021, including placebo-controlled or head-to-head trials of 2 new glucose-lowering drugs. Relative ratio (RR) and 95% confidence interval (CI) were used to assess the risk of GLP-1 agonists and DPP-4 inhibitors for pancreatitis or pancreatic cancer among patients with type 2 diabetes.

RESULTS

Seventeen studies were identified, covered 102257 participants. The pooled results showed a neutral relationship between GLP-1 agonists and pancreatitis (Overall RR, 0.96; 95% CI, 0.31-3.00) or pancreatic cancer (Overall RR, 1.10; 95% CI, 0.31-4.10) compared to placebo. Meanwhile, DPP-4 inhibitors were not be associated with the increased risk of pancreatitis (Overall RR, 1.60; 95% CI, 0.25-11.00) or pancreatic cancer (Overall RR, 0.79; 95% CI, 0.26-2.40). Among them, lixisenatide and saxagliptin may be the safest drug compared to other drugs according to the ranking of probability. Sensitivity and subgroup analysis confirmed the stability of the core results.

CONCLUSION

The most obvious finding to emerge from this study is that GLP-1 agonists and DPP-4 inhibitors are safe with respect to pancreatitis and pancreatic cancer risk compared to placebo. This conclusion may provide useful evidence for correlated clinical researches.

Pharmacokinetics and Bioequivalence of Sitagliptin Phosphate/Metformin Hydrochloride Tablets in Healthy Chinese Subjects: A Randomized, Open-Label, Crossover Study

OBJECTIVE

Our objective was to evaluate the pharmacokinetics and bioequivalence of test and reference (JANUMET^®) formulations of sitagliptin phosphate/metformin hydrochloride tablets at a single dose of 50 mg/850 mg.

METHODS

The study was a randomized, open-label, two-period, double-crossover trial. Volunteers under fasting (n = 24) and fed (n = 24) conditions were given a single oral dose of test or reference formulations of sitagliptin phosphate/metformin hydrochloride tablets 50 mg/850 mg. We used the liquid chromatography tandem mass spectrometry method to determine the concentrations of sitagliptin and metformin in the plasma of subjects. Pharmacokinetic metrics were calculated using the WinNonlin 7.0 program, and bioequivalence was evaluated using SAS 9.4.

RESULTS

Under the fasting condition, the 90% confidence intervals (CIs) of geometric mean ratio for maximum plasma drug concentration (C_max), area under the plasma concentration-time curve from time zero to time t (AUC_0-t), and AUC from time zero to infinity (AUC_0-∞) of sitagliptin between the test and reference groups were 101.70-120.62%, 99.81-105.61%, and 100.27-106.12%, respectively; for metformin, they were 90.39-111.48%, 94.76-109.12%, and 95.76-110.38%, respectively. Under the fed condition, they were 102.12-117.31%, 100.80-107.81%, and 100.82-107.78%, respectively, for sitagliptin and 95.53-105.22%, 92.76-103.07%, and 93.40-104.14%, respectively, for metformin. Both were generally well-tolerated.

CONCLUSION

The two formulations of sitagliptin phosphate/metformin hydrochloride tablets were bioequivalent under fasting and fed conditions in healthy Chinese subjects.

Protective effect of quercetin against the metabolic dysfunction of glucose and lipids and its associated learning and memory impairments in NAFLD rats

BACKGROUND

Quercetin (QUE) is a flavonol reported with anti-inflammatory and antioxidant activities, and previous results from the group of this study have demonstrated its neuroprotective effect against lipopolysaccharide-induced neuropsychiatric injuries. However, little is known about its potential effect on neuropsychiatric injuries induced or accompanied by metabolic dysfunction of glucose and lipids.

METHODS

A nonalcoholic fatty liver disease (NAFLD) rat model was induced via a high-fat diet (HFD), and glucolipid parameters and liver function were measured. Behavioral performance was observed via the open field test (OFT) and the Morris water maze (MWM). The plasma levels of triggering receptor expressed on myeloid cells-1 (TREM1) and TREM2 were measured via enzyme-linked immunosorbent assay (ELISA). The protein expression levels of Synapsin-1 (Syn-1), Synaptatogmin-1 (Syt-1), TREM1 and TREM2 in the hippocampus were detected using western blotting. Morphological changes in the liver and hippocampus were detected by HE and Oil red or silver staining.

RESULTS

Compared with the control rats, HFD-induced NAFLD model rats presented significant metabolic dysfunction, hepatocyte steatosis, and impaired learning and memory ability, as indicated by the increased plasma concentrations of total cholesterol (TC) and triglyceride (TG), the impaired glucose tolerance, the accumulated fat droplets and balloon-like changes in the liver, and the increased escaping latency but decreased duration in the target quadrant in the Morris water maze. All these changes were reversed in QUE-treated rats. Moreover, apart from improving the morphological injuries in the hippocampus, treatment with QUE could increase the decreased plasma concentration and hippocampal protein expression of TREM1 in NAFLD rats and increase the decreased expression of Syn-1 and Syt-1 in the hippocampus.

CONCLUSIONS

These results suggested the therapeutic potential of QUE against NAFLD-associated impairment of learning and memory, and the mechanism might involve regulating the metabolic dysfunction of glucose and lipids and balancing the protein expression of synaptic plasticity markers and TREM1/2 in the hippocampus.

High-throughput bioanalysis of sitagliptin in plasma using direct analysis in real time mass spectrometry and its application in the pharmacokinetic study thereof

Sitagliptin is a dipeptidyl peptidase-IV inhibitor for the treatment of type 2 diabetes mellitus. In the present study, a sensitive and high-throughput quantitative method based on the direct analysis in real time tandem mass spectrometry has been developed and validated for the bioanalysis of sitagliptin in rat plasma without chromatographic separation. Sitagliptin and its internal standard retagliptin were detected in positive ion mode by multiple reaction monitoring transitions at m/z 408.2→235.0 and 465.2→260.1, respectively. The method includes a simple solid-phase extraction sample preparation procedure, through which appropriate and reproducible analytical results within the linear concentration range of 20-2000 ng/mL have been achieved. The intra- and interday precisions were <10.6% and the accuracies were ranging from -8.17 to 2.60%. This method has been successfully applied to the pharmacokinetic study of sitagliptin after single intravenous administration in rats. This approach shows considerable promise of direct analysis in real time tandem mass spectrometry method in the high-throughput bioanalysis.

Branched chain amino acids-friend or foe in the control of energy substrate turnover and insulin sensitivity?

Branched chain amino acids (BCAA) and their derivatives are bioactive molecules with pleiotropic functions in the human body. Elevated fasting blood BCAA concentrations are considered as a metabolic hallmark of obesity, insulin resistance, dyslipidaemia, nonalcoholic fatty liver disease, type 2 diabetes and cardiovascular disease. However, since increased BCAA amount is observed both in metabolically healthy and obese subjects, a question whether BCAA are mechanistic drivers of insulin resistance and its morbidities or only markers of metabolic dysregulation, still remains open. The beneficial effects of BCAA on body weight and composition, aerobic capacity, insulin secretion and sensitivity demand high catabolic potential toward amino acids and/or adequate BCAA intake. On the opposite, BCAA-related inhibition of lipogenesis and lipolysis enhancement may preclude impairment in insulin sensitivity. Thereby, the following review addresses various strategies pertaining to the modulation of BCAA catabolism and the possible roles of BCAA in energy homeostasis. We also aim to elucidate mechanisms behind the heterogeneity of ramifications associated with BCAA modulation.

Anti-fibrotic activity of sitagliptin against concanavalin A-induced hepatic fibrosis. Role of Nrf2 activation/NF-κB inhibition

Sitagliptin is known for its anti-diabetic activity though it has other pleiotropic pharmacological actions. Its effect against concanavalin A (Con A)-induced hepatic fibrosis has not been investigated yet. Our target was to test whether sitagliptin can suppress the development of Con A-induced hepatic fibrosis and if so, what are the mechanisms involved? Con A (6 mg/kg) was injected once weekly to male Swiss albino mice for four weeks. Sitagliptin was daily administered concurrently with Con A. Results have shown the potent hepatoprotective activity of sitagliptin against Con A-induced hepatitis and fibrosis. That was evident through the amelioration of hepatotoxicity serum parameters (ALT, AST, ALP, and LDH) and the increase in the level of serum albumin in sitagliptin treated mice. Simultaneously, there was amendment of the Con A-induced hepatic lesions and repression of fibrosis in sitagliptin-treated animals. Hydroxyproline, collagen content and the immuno-expression of the fibrotic markers, TGF-β and α-SMA were depressed upon sitagliptin treatment. Sitagliptin suppressed Con A-induced oxidative stress and increased antioxidants. RT-PCR analysis showed enhancement of mRNA expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and its target genes (GCLc, GCLm, NQO-1, HO-1) by sitagliptin. Furthermore, sitagliptin ameliorated the level and immuno-expression of nuclear factor kappa-B (NF-κB) alongside the immuno-expression of the inflammatory cytokine, TNF-α. Taken together, this study demonstrates the hepatoprotective activity of sitagliptin which may be in part related to enhancement of Nrf2 signaling pathway and inhibition of NF-κB which interact inflammatory response in liver. Sitagliptin might be a new candidate to suppress hepatitis-associated fibrosis.

Effects of Sitagliptin as Monotherapy and Add-On to Metformin on Weight Loss among Overweight and Obese Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis

BACKGROUND

Sitagliptin is known as an antidiabetic agent inhibiting the dipeptidyl peptidase-4. Although sitagliptin may influence weight, controversial results have been reported, and there is no general agreement on this issue. Therefore, this study assessed the effect of sitagliptin as monotherapy and add-on therapy to metformin on weight reduction in overweight or obese cases with type 2 diabetes.

METHODS

We reviewed the following databases to identify all relevant papers published until 1st April 2021: Web of Science, MEDLINE, Embase, Scopus, Cochrane Central Register of Controlled Trials Cochrane Library, and Google Scholar. The research included all clinical trials investigating the effect of sitagliptin in obese or overweight adult patients with type 2 diabetes without any language restriction.

RESULTS

In total, eighteen randomized controlled trials with 2009 participants were included in our meta-analysis. Results showed supplementation of sitagliptin has led to weight loss for sitagliptin treated (MD  -0.99; 95% CI; (-1.87, -0.12); p=0.026)) and sitagliptin+metformin treated groups (MD  -1.09; 95% CI; (-1.69, -0.49); p<0.001)). Also, the intervention has influenced body mass index in sitagliptin treated (MD  -0.23; 95% CI; (-0.45, 0.02); p=0.033)) and sitagliptin+metformin treated groups (MD -0.52; 95% CI; (-0.96, 0.08); p=0.020)) comparing to placebo.

CONCLUSION

Our results demonstrated that sitagliptin administration with or without metformin might reduce the body weight and body mass index if these drugs are taken for more than 6 months.

LncRNA ENSMUST00000155383 is Involved in the Improvement of DPP-4 Inhibitor MK-626 on Vascular Endothelial Function by Modulating Cacna1c-Mediated Ca2+ Influx in Hypertensive Mice

Objective: This study investigated the protective effects of dipeptidyl peptidase-4 inhibitor MK-626 on vascular endothelial function by regulating lncRNAs in hypertensive vasculature.

Methods: Angiotensin Ⅱ (Ang Ⅱ)-loaded osmotic pumps were implanted in mice with or without MK-626 administration. GLP-1 levels in plasma were measured by ELISA. Aortic rings were suspended in myograph for tension measurement. Microarray was performed to analyze lncRNA and mRNA expression profiles. Protein expression and phosphorylation were examined by Western blot. The differentially expressed (DE)-genes were validated by qRT-PCR. The intracellular Ca²⁺ concentration was detected by laser confocal system.

Results: MK-626 elevated plasma GLP-1 level, increased eNOS phosphorylation, improved endothelium-dependent relaxations, and reduced systolic blood pressure in Ang Ⅱ-induced hypertensive mice. Microarray revealed the dysregulations of 723 lncRNAs and 742 mRNAs were reversed by MK-626 in hypertensive mouse aortae. qRT-PCR validation showed that 13 DE-lncRNAs and eight dysregulated mRNAs in both hypertensive mouse aortae and mouse aortic endothelial cells (MAECs) were rescued by MK-626. Among them, four mRNAs (Cacna1C, Itgav, Itga8, and Npnt) were co-expressed with lncRNA ENSMUST00000155383. Cacna1C protein expression was reduced in the ECs but was elevated in smooth muscle cells from Ang Ⅱ-infused mice, which were both reversed by MK-626. Knockdown of lncRNA ENSMUST00000155383 suppressed the increased Cacna1c protein and mRNA expression, elevated Ca²⁺ level, and enhanced eNOS phosphorylation induced by MK-626 in the hypertensive mouse ECs.

Conclusion: The dysregulations of lncRNA ENSMUST00000155383-associated genes might play crucial roles in hypertension-induced endothelial dysfunction through affecting calcium pathway. MK-626 might ameliorate endothelial dysfunction by upregulating lncRNA ENSMUST00000155383, enhancing Ca²⁺ concentration, and subsequently restoring eNOS activity in hypertension.

Sitagliptin Modulates Oxidative, Nitrative and Halogenative Stress and Inflammatory Response in Rat Model of Hepatic Ischemia-Reperfusion

A possibility of repurposing sitagliptin, a well-established antidiabetic drug, for alleviating injury caused by ischemia-reperfusion (IR) is being researched. The aim of this study was to shed some light on the molecular background of the protective activity of sitagliptin during hepatic IR. The expression and/or concentration of inflammation and oxidative stress-involved factors have been determined in rat liver homogenates using quantitative RT-PCR and Luminex^® xMAP^® technology and markers of nitrative and halogenative stress were quantified using targeted metabolomics (LC-MS/MS). Animals (n = 36) divided into four groups were treated with sitagliptin (5 mg/kg) (S and SIR) or saline solution (C and IR), and the livers from IR and SIR were subjected to ischemia (60 min) and reperfusion (24 h). The midkine expression (by 2.2-fold) and the free 3-nitrotyrosine (by 2.5-fold) and IL-10 (by 2-fold) concentration were significantly higher and the Nox4 expression was lower (by 9.4-fold) in the IR than the C animals. As compared to IR, the SIR animals had a lower expression of interleukin-6 (by 4.2-fold) and midkine (by 2-fold), a lower concentration of 3-nitrotyrosine (by 2.5-fold) and a higher Nox4 (by 2.9-fold) and 3-bromotyrosine (by 1.4-fold). In conclusion, IR disturbs the oxidative, nitrative and halogenative balance and aggravates the inflammatory response in the liver, which can be attenuated by low doses of sitagliptin.

Is Sitagliptin Effective for Modulating Metabolic Disturbances Associated With Olanzapine in Schizophrenia Patients? A Double-blind Placebo-controlled Clinical Trial

PURPOSE/BACKGROUND

The mortality rate of patients with schizophrenia due to metabolic disturbances is high. Our aim is to survey the effects of sitagliptin on metabolic disturbances associated with olanzapine in patients with schizophrenia.

METHODS/PROCEDURES

In this 12-week double-blind placebo-controlled clinical trial, 71 patients taking olanzapine (10 to 30 mg) for at least 1 month were randomly allocated to enter 1 of the 2 treatment groups (olanzapine plus placebo or olanzapine plus sitagliptin). Sitagliptin was added to patients 'current medications with the dose of 100 mg/d. Physical examinations and measurement of anthropometric (body mass index and waist circumference) and laboratory parameters (fasting blood sugar, glycated hemoglobin, total cholesterol, low-density lipoprotein, high-density lipoprotein, and triglyceride) were measured at baseline, week 4, and week 12. The patients were assessed for any side effects of the medications in each visit.

FINDINGS/RESULTS

Sixty-one patients (30 in the sitagliptin and 31 in the placebo group) completed the trial. The anthropometric measurements at the end of the study did not differ between the 2 groups. glycated hemoglobin and total cholesterol were significantly lower in the sitagliptin group after 12 weeks. Other metabolic profile revealed either no change or minimal magnitude changes. No major side effect was reported.

IMPLICATIONS/CONCLUSIONS

Metabolic disturbances associated with olanzapine treatment in patients with schizophrenia can be modulated by sitagliptin.