New enantioselective liquid chromatography method development and validation of dipeptidyl peptidase IV inhibitors using a macrocyclic glycopeptide (vancomycin) chiral stationary phase under polar ionic mode condition

The direct separation of dipeptidyl peptidase IV (DPP-4) inhibitors such as Sitagliptin (STG), Linagliptin (LIG), and Saxagliptin (SAG) enantiomers in normal phase conditions have been achieved on immobilized polysaccharide-based chiral stationary phases (CSPs), as well as on the macrocyclic glycopeptide vancomycin chiral stationary phase (Chirobiotic V2) under polar ionic mode. The enantiomers of these targets could be separated completely (resolution factor Rs > 2) using the Chirobiotic V2 column in polar ionic mode with the mobile phase (MeOH/AcOH/TEA 100/0.3/0.1 v/v/v) in an isocratic elution at 1.0 ml min^-1 . The effect of the mobile phase composition on separation, including buffer salts, acid-base modifiers, and analyte structures, was evaluated. The developed technique was validated in the polar ionic mode according to the International Conference on Harmonization (ICH) Q2R1 guidelines in terms of accuracy, precision, selectivity, linearity, limit of detection (LOD), and limit of quantification (LOQ). The calibration curve was linear in a concentration range from LOQ to 3.75 μg/ml. The LOD and LOQ of STG, LIG, and SAG were 0.15 and 0.45, 0.15 and 0.50, 0.16 and 0.50, respectively. The proposed method is said to be selective, accurate, and precise. Finally, the validated method was used successfully for the quantitative determination of DPP-4 enantiomers in pharmaceutical analytes.

Sitagliptin ameliorates advanced glycation end-product (AGE)-induced degradation of extracellular matrix in human primary chondrocytes

Accumulation of advanced glycation end-products (AGEs) increases inflammation and triggers processes involved in the pathogenesis of osteoarthritis (OA). As a major debilitating age-related disease, it is imperative that novel therapies for OA be sought. In the present study, we investigated the effects of the selective dipeptidyl peptidase IV (DPP-4) inhibitor sitagliptin in human primary chondrocytes exposed to insult by AGEs to elucidate the potential role of sitagliptin in the treatment of OA. Our findings show that inhibition of DPP-4 by sitagliptin could reduce oxidative stress, increase cell viability and prevent degradation of type II collagen and aggrecan by matrix metalloproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) induced by AGEs in human primary chondrocytes. Mechanistically, we found that sitagliptin inhibited AGEs-induced nuclear translocation of p65 protein and drastically decreased the luciferase activity of NF-κB. These findings indicate that sitagliptin may have potential as a novel therapeutic option for the treatment and prevention of OA.

Discovery of Novel Tricyclic Heterocycles as Potent and Selective DPP-4 Inhibitors for the Treatment of Type 2 Diabetes

In our efforts to develop second generation DPP-4 inhibitors, we endeavored to identify distinct structures with long-acting (once weekly) potential. Taking advantage of X-ray cocrystal structures of sitagliptin and other DPP-4 inhibitors, such as alogliptin and linagliptin bound to DPP-4, and aided by molecular modeling, we designed several series of heterocyclic compounds as initial targets. During their synthesis, an unexpected chemical transformation provided a novel tricyclic scaffold that was beyond our original design. Capitalizing on this serendipitous discovery, we have elaborated this scaffold into a very potent and selective DPP-4 inhibitor lead series, as highlighted by compound 17c.

Discovery of Imigliptin, a Novel Selective DPP-4 Inhibitor for the Treatment of Type 2 Diabetes

We report our discovery of a novel series of potent and selective dipeptidyl peptidase IV (DPP-4) inhibitors. Starting from a lead identified by scaffold-hopping approach, our discovery and development efforts were focused on exploring structure-activity relationships, optimizing pharmacokinetic profile, improving in vitro and in vivo efficacy, and evaluating safety profile. The selected candidate, Imigliptin, is now undergoing clinical trial.