DPPIV inhibition: promising therapy for the treatment of type 2 diabetes

CMD-05, a novel promising clinical anti-diabetic drug candidate, in vivo and vitro studies

Dipeptidyl peptidase IV (DPP-IV) inhibitor has been expected to be a new class of anti-diabetic agent. The present study was designed to characterize the pharmacological profiles of CMD-05, a novel DPP-IV inhibitor discovered in our laboratory, in vitro and in vivo. The IC₅₀ of CMD-05 on DPP-IV inhibitory activity was approximately 12 nM while vildagliptin was 3.5 nM in vitro. In diabetes rat model established by high fat diet/low dose streptozotocin, CMD-05 inhibited DPP-IV activity, significantly improved glucose tolerance, increased GLP-1 and insulin levels in plasma. Long-term administration of CMD-05 decreased HbA1c and TG levels and improved the islet function without significantly effect on body weight. Furthermore, CMD-05 reduced INS-1 cell apoptosis and increased GLP-1 secretion in NCI-H716. After oral administration, CMD-05 reached peak concentration at 30 min with half-life of 288 minutes and the inhibitory rate of DPP-IV greater than 50% lasted for 15 h. In fasted normal rats, CMD-05 didn't cause significant hypoglycemia. CMD-05 had a lower cytotoxicity than vildagliptin in vitro and its maximum tolerance dose in mice is beyond 2000 mg/kg. These results indicated that CMD-05 has similar activity with vildagliptin in vivo and has a much longer half-life and lower cytotoxicity than vildagliptin.

Novel DPP-4 inhibitors against diabetes

DPP-4 specifically degrades the incretin hormone GLP-1 and GIP, both of which are vital modulators of blood glucose homeostasis. Attributed to its potential biological function, DPP-4 inhibition has presently represented an attractive therapeutic strategy for treating diabetes and aroused a significant interest in the pharmaceutical industry. Chemical stability, selectivity and pharmacokinetic properties have been continuously emphasized during the long journey of R&D centered on DPP-4 inhibitors. The current landscape of the development of DPP-4 inhibitors is outlined in this review, with a focus on rational drug design and structural optimization to pursue chemical stability, selectivity and favorable pharmacokinetic properties. In addition, the structure-activity relationships, based on reported DPP-4 inhibitors, will be discussed.

Icatibant , the bradykinin B2 receptor antagonist with target to the interconnected kinin systems

INTRODUCTION

HOE-140/ Icatibant is a selective, competitive antagonist to bradykinin (BK) against its binding to the kinin B2 receptor. Substitution of five non-proteogeneic amino acid analogues makes icatibant resistant to degradation by metalloproteases of kinin catabolism. Icatibant has clinical applications in inflammatory and vascular leakage conditions caused by an acute (non-controlled) production of kinins and their accumulation at the endothelium B2 receptor. The clinical manifestation of vascular leakage, called angioedema (AE), is characterized by edematous attacks of subcutaneous and submucosal tissues, which can cause painful intestinal consequences, and life-threatening complications if affecting the larynx. Icatibant is registered for the treatment of acute attacks of the hereditary BK-mediated AE, i.e., AE due to C1 inhibitor deficiency.

AREAS COVERED

This review discusses emerging knowledge on the kinin system: kinin pharmacological properties, biochemical characteristics of the contact phase and kinin catabolism proteases. It underlines the responsibility of the kinins in AE initiation and the potency of icatibant to inhibit AE formation by kinin-receptor interactions.

EXPERT OPINION

Icatibant antagonist properties protect BK-mediated AE patients against severe attacks, and could be developed for use in inflammatory conditions. More studies are required to confirm whether or not prolonged and frequent applications of icatibant could result in the impairment of the cardioprotective effect of BK.

Tebrophen--an old polyphenol drug with anticancer potential

In vitro high-throughput screening was carried out in order to detect new activities for old drugs and to select compounds for the drug development process comprising new indications. Tebrophen, a known antiviral drug, was found to inhibit activities on inflammation and cancer related targets. In primary screening this semisynthetic halogenated polyphenol was identified to inhibit the activities of kinases ZAP-70 and Lck (IC₅₀ 0.34 µM and 16 µM, respectively), as well as hydrolase DPPIV (at 80 µM 41% inhibition). Next, it showed no cytotoxic effects on standard cell lines within 24 h. However, tebrophen slowed propagation of breast cancer (MDA-MB-231), osteosarcoma (U2OS) and cervical carcinoma (HeLa), through at least 35 population doublings in a dose-dependent manner. It completely stopped the division of the prostate cancer (PC3) cell line at 50 µM concentration and the cells entered massive cell death in less than 20 days. On the other hand, tebrophen did not influence the growth of normal fibroblasts. According to the measured oxidative burst and estimated in silico parameters its direct antioxidative ability is limited. The obtained results indicate that tebrophen can be considered a promising lead molecule for generating more soluble derivatives with specific anticancer efficacy.

Pharmacology of dipeptidyl peptidase-4 inhibitors: similarities and differences

The dipeptidyl peptidase (DPP)-4 inhibitors, which enhance glucose-dependent insulin secretion from pancreatic β cells by preventing DPP-4-mediated degradation of endogenously released incretin hormones, represent a new therapeutic approach to the management of type 2 diabetes mellitus. The 'first-in-class' DPP-4 inhibitor, sitagliptin, was approved in 2006; it was followed by vildagliptin (available in the EU and many other countries since 2007, although approval in the US is still pending), saxagliptin (in 2009), alogliptin (in 2010, presently only in Japan) and linagliptin, which was approved in the US in May 2011 and is undergoing regulatory review in Japan and the EU. As the number of DPP-4 inhibitors on the market increases, potential differences among the different members of the class become important when deciding which agent is best suited for an individual patient. The aim of this review is to provide a comprehensive and updated comparison of the pharmacodynamic and pharmacokinetic properties of DPP-4 inhibitors, and to pinpoint pharmacological differences of potential interest for their use in therapy. Despite their common mechanism of action, these agents show significant structural heterogeneity that could translate into different pharmacological properties. At the pharmacokinetic level, DPP-4 inhibitors have important differences, including half-life, systemic exposure, bioavailability, protein binding, metabolism, presence of active metabolites and excretion routes. These differences could be relevant, especially in patients with renal or hepatic impairment, and when considering combination therapy. At the pharmacodynamic level, the data available so far indicate a similar glucose-lowering efficacy of DPP-4 inhibitors, either as monotherapy or in combination with other hypoglycaemic drugs, a similar weight-neutral effect, and a comparable safety and tolerability profile. Data on nonglycaemic parameters are scant at present and do not allow a comparison among DPP-4 inhibitors. Several phase III trials of DPP-4 inhibitors are currently ongoing; these trials, along with post-marketing surveillance data, will hopefully increase our knowledge about the long-term efficacy and safety of DPP-4 inhibitor therapy, the effect on pancreatic cell function and peripheral glucose metabolism, and the effect on cardiovascular outcomes in patients with type 2 diabetes.

Discovery of potent, selective, and orally bioavailable quinoline-based dipeptidyl peptidase IV inhibitors targeting Lys554

Dipeptidyl peptidase IV (DPP-4) inhibition is a validated therapeutic option for type 2 diabetes, exhibiting multiple antidiabetic effects with little or no risk of hypoglycemia. In our studies involving non-covalent DPP-4 inhibitors, a novel series of quinoline-based inhibitors were designed based on the co-crystal structure of isoquinolone 2 in complex with DPP-4 to target the side chain of Lys554. Synthesis and evaluation of designed compounds revealed 1-[3-(aminomethyl)-4-(4-methylphenyl)-2-(2-methylpropyl)quinolin-6-yl]piperazine-2,5-dione (1) as a potent, selective, and orally active DPP-4 inhibitor (IC₅₀=1.3 nM) with long-lasting ex vivo activity in dogs and excellent antihyperglycemic effects in rats. A docking study of compound 1 revealed a hydrogen-bonding interaction with the side chain of Lys554, suggesting this residue as a potential target site useful for enhancing DPP-4 inhibition.