Refined-JQ (JQ-R) is a mixture of refined extracts from Coptis chinensis (Ranunculaceae), Astragalus membranaceus (Leguminosae) and Lonicera japonica (Caprifoliaceae), the three major herbs of JinQi-JiangTang tablet, a traditional Chinese medicine (TCM) formula. The mechanisms by which JQ-R regulates glucose metabolism and improves insulin sensitivity were studied in type 2 diabetic KKAy mice and insulin-resistant L6 myotubes. To investigate the mechanisms by which JQ-R improves insulin sensitivity, a model of insulin-resistant cells induced with palmitic acid (PA) was established in L6 myotubes. Glucose uptake and expression of factors involved in insulin signaling, stress, and inflammatory pathways were detected by immunoblotting. JQ-R showed beneficial effects on glucose homeostasis and insulin resistance in a euglycemic clamp experiment and decreased fasting insulin levels in diabetic KKAy mice. JQ-R also improved the plasma lipid profiles. JQ-R directly increased the activity of superoxide dismutase (SOD) and decreased malondialdehyde (MDA) as well as inducible nitric oxide synthase (iNOS) levels in insulin-resistant L6 cells, and elevated the insulin-stimulated glucose uptake with upregulated phosphorylation of AKT. The phosphorylation levels of nuclear factor kappa B (NF-κB p65), inhibitor of NF-κB (IκB α), c-Jun N-terminal kinase (JNK1/2) and extracellular-signal-regulated kinases (ERK1/2) were also changed after JQ-R treatment compared with the control group. Together these findings suggest that JQ-R improved glucose and lipid metabolism in diabetic KKAy mice. JQ-R directly enhanced insulin-stimulated glucose uptake in insulin-resistant myotubes with improved insulin signalling and inflammatory response and oxidative stress. JQ-R could be a candidate to achieve improved glucose metabolism and insulin sensitivity in type 2 diabetes mellitus.A mixture of refined extracts from three major herbs of JinQi-JiangTang tablets (JQ-R) improved glucose metabolism in diabetic KKAy mice and L6 myotubes by stimulating glucose uptake via the insulin-dependent PI3K-AKT pathway.Download high-res image (276KB)Download full-size image

•A series of xanthine derivatives targeting DPP-IV and GPR119 was synthesized.•Systematic optimization led to the identification of dual modulator 20i.•Compound 20i had a selective DPP-IV inhibition and good GPR119 agonism activity.•Compound 20i had a favorable metabolic stability.•Insulinotropic effect of compound 20i was glucose-concentration dependent.A series of xanthine derivatives as potent dual ligands targeting DPP-IV and GPR119 was discovered through an approach of the merged pharmacophores of GPR119 agonists and DPP-IV inhibitor linagliptin. Systematic optimization of general structure 5 led to the identification of compound 20i with selective DPP-IV inhibition, good GPR119 agonism activity and favorable metabolic stability. Docking study was performed to elucidate the potent DPP-IV inhibition of 20i. Compound 20i may serve as a tool compound for further design of anti-diabetic drugs targeting both DPP-IV and GPR119.A series of xanthine derivatives targeting DPP-IV and GPR119 was designed and synthesized through the pharmacophore merging strategy. Systematic optimization of general structure led to the identification of dual modulator 20i with selective DPP-IV inhibition, good GPR119 agonism activity and favorable metabolic stability.

Background and PurposeGlucokinase (GK) balances blood glucose levels via regulation of glucose metabolism and insulin secretion. Peroxisome proliferator activated receptor-γ (PPARγ) regulates gene expression in glucose and lipid metabolism. In this study, we investigated the therapeutic effect of a novel compound, SHP289-03, which activates both GK and PPARγ.MethodsGlucose metabolism was tested in primary hepatocytes of normal ICR mice, and insulin secretion was measured in NIT-1 insulinoma cells as well as in primary islets of normal ICR mice. The in vivo pharmacodynamics of SHP289-03 was assessed using the spontaneous type 2 diabetic mouse model, KKAy.Key ResultsIn hepatocytes, SHP289-03 promoted glucose consumption. In NIT-1 cells, it increased the concentration of intracellular ATP and calcium, and subsequently enhanced glucose-stimulated insulin secretion in both NIT-1 cells and primary islets. Moreover, SHP289-03 decreased the blood glucose level, improved glucose tolerance and reduced blood lipid levels in KKAy mice. It restored islet morphology and increased the beta cell/alpha cell mass ratio, in addition to up-regulating GK gene expression in the liver of KKAy mice.Discussion and ConclusionsSHP289-03 has significant therapeutic potential for the treatment of diabetes mellitus.

To find aldose reductase inhibitors, two previously unreported compounds, grandifolias H and I, and five known compounds, including rosmarinic acid and rosmarinic acid derivatives, were isolated from the roots of Salvia grandifolia. A series of rosmarinic acid derivatives was obtained from rosmarinic acid using simple synthetic methods. The aldose reductase inhibitory activity of the isolated and synthesized compounds was assessed. Seven of the tested compounds showed moderate aldose reductase inhibition (IC50 = 0.06–0.30 μM). The structure-activity relationship of aldose reductase inhibitory activity of rosmarinic acid derivatives was discussed for the first time. This study provided useful information that will facilitate the development of aldose reductase inhibitors.Download high-res image (165KB)Download full-size image

IntroductionDipeptidyl peptidases (DPPs) 8 and 9 are homologous, cytoplasmic postproline-cutting enzymes, which have similar enzymatic activity and preferred substrates as DPP4. DPP4 is a well-known target for treating diabetes mellitus. With the increased concern of non-selectivity and toxicities caused by DPP4 inhibitors, it is essential to establish new ex vivo system to investigate DPP4 inhibitors' effect on DPP8 and DPP9.MethodHere we reported a newly established cell model system by cloning and transfecting human DPP8/9 genes into HEK 293 cells. We then used this model to evaluate the clinically applied DPP4 inhibitors' effect on DPP8/9, by direct enzymatic activity assay. Given the difference of cellular locations between DPP4 and DPP8/9, we also evaluated the influence of these drugs on intracellular DPP8/9 activity and cell viability by extracellular treatment with different inhibitors.ResultsDirect enzymatic activity assay revealed significant and concentration-dependent inhibition effect of vildagliptin, saxagliptin on DPP8/9. Extracellular incubation of DPP8/9 over expressed cells with sitagliptin, vildagliptin, saxagliptin, alogliptin and linagliptin, showed only mild inhibition on DPP8/9. Moreover, all of these drugs showed no significant influence on cell viability.DiscussionOur results demonstrated that the DPP8/9 over-expressing cell model system is a very useful and promising system for investigating the selectivity and associated toxicity of DPP4 inhibitors on DPP8/9.

Dipeptidyl peptidase 4 (DPP4) is recognised as an attractive anti-diabetic drug target, and several DPP4 inhibitors are already on the market. As members of the same gene family, dipeptidyl peptidase 8 (DPP8) and dipeptidyl peptidase 9 (DPP9) share high sequence and structural homology as well as functional activity with DPP4. However, the inhibition of their activities was reported to cause severe toxicities. Thus, the development of DPP4 inhibitors that do not have DPP8 and DPP9 inhibitory activity is critical for safe anti-diabetic therapy. To achieve this goal, we established a selective evaluation method for DPP4 inhibitors based on recombinant human DPP8 and DPP9 proteins expressed by Rosetta cells. In this method, we used purified recombinant 120 kDa DPP8 or DPP9 protein from the Rosetta expression system. The optimum concentrations of the recombinant DPP8 and DPP9 proteins were 30 ng/mL and 20 ng/mL, respectively, and the corresponding concentrations of their substrates were both 0.2 mmol/L. This method was highly reproducible and reliable for the evaluation of the DPP8 and DPP9 selectivity for DPP4 inhibitor candidates, which would provide valuable guidance in the development of safe DPP4 inhibitors.A highly reproducible and selective method to evaluate the DPP8 and DPP9 selectivity for DPP4 inhibitor candidates based on recombinant human DPP8 and DPP9 proteins expressed by Rosetta cells was established, which would provide valuable guidance in the development of safe DPP4 inhibitors.Download full-size image

The sodium/glucose cotransporter 2 (SGLT2) is responsible for the majority of glucose reabsorption in the kidney, and currently, SGLT2 inhibitors are considered as promising hypoglycemic agents for the treatment of type 2 diabetes mellitus. By constructing CHO cell lines that stably express the human SGLT2 transmembrane protein, along with a fluorescent glucose transporter assay that uses 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]2-deoxyglucose (2-NBDG) as a glucose analog, we have developed a nonradioactive, cell-based assay for the discovery and characterization of SGLT2 inhibitors.Graphical abstractA nonradioactive, cell-based assay for the discovery and characterization of SGLT2 inhibitors was developed using 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]2-deoxyglucose (2-NBDG) as a glucose analog.Download full-size image