Synthesis and biological evaluation of novel benzyl-substituted (S)-phenylalanine derivatives as potent dipeptidyl peptidase 4 inhibitors

A series of novel benzyl-substituted (S)-phenylalanine derivatives were synthesized and evaluated for their dipeptidyl peptidase 4 (DPP-4) inhibitory activity and selectivity. It was found that most synthesized target compounds were potent DPP-4 inhibitors with IC₅₀ values in 3.79–25.52 nM, which were significantly superior to that of the marketed drug sitagliptin. Furthermore, the 4-fluorobenzyl substituted phenylalanine derivative 6g not only displayed the potent DPP-4 inhibition with an IC₅₀ value of 3.79 nM, but also showed better selectivity against DPP-4 over other related enzymes including DPP-7, DPP-8, and DPP-9. In an oral glucose tolerance test (OGTT) in normal Sprague Dawley rats, compound 6g reduced blood glucose excursion in a dose-dependent manner.     

Design,synthesis and anti-diabetic activity of triazolotriazine derivatives as dipeptidyl peptidase-4 (DPP-4) inhibitors

Type 2 diabetes mellitus (T2DM) is one of the major global metabolic disorders characterized by insulin resistance and chronic hyperglycemia. Inhibition of the enzyme, dipeptidyl peptidase-4 (DPP-4) has been proved as successful and safe therapy for the treatment of T2DM since last decade. In order to design novel DPP-4 inhibitors, various in silico studies such as 3D-QSAR, pharmacophore modeling and virtual screening were performed and on the basis of the combined results of them, total 50 triazolo[5,1-c][1,2,4]triazine derivatives were designed and mapped on the best pharmacophore model. From this, best 25 derivatives were docked onto the active site of DPP-4 enzyme and in silico ADMET properties were also predicted. Finally, top 17 derivatives were synthesized and characterized using FT-IR, Mass, ¹H NMR and ¹³C NMR spectroscopy. Purity of compounds was checked using HPLC. These derivatives were then evaluated for in vitro DPP-4 inhibition. The most promising compound 15q showed 28.05 μM DPP-4 IC₅₀ with 8–10-fold selectivity over DPP-8 and DPP-9 so selected for further in vivo anti-diabetic evaluation. During OGTT in normal C57BL/6J mice, compound 15q reduced blood glucose excursion in a dose-dependent manner. Chronic treatment for 28 days with compound 15q improved the serum glucose levels in type 2 diabetic Sprague Dawley rats wherein diabetes was induced by high fat diet and low dose streptozotocin. This suggested that compound 15q is a moderately potent and selective hit molecule which can be further optimized structurally to increase the efficacy and overall pharmacological profile as DPP-4 inhibitor.     

(R)-3-Amino-1-((3aS,7aS)-octahydro-1H-indol-1-yl)-4-(2,4,5-trifluorophenyl)butan-1-one derivatives as potent inhibitors of dipeptidyl peptidase-4: Design,synthesis, biological evaluation,and molecular modeling

A series of (R)-3-amino-1-((3aS,7aS)-octahydro-1H-indol-1-yl)-4-(2,4,5-trifluorophenyl)butan-1-one derivatives was designed, synthesized, and evaluated as novel inhibitors of dipeptidyl peptidase-4 (DPP-4) for the treatment of type 2 diabetes. Most of the synthesized compounds demonstrated good inhibition activities against DPP-4. Among these, compounds 3e, 4c, 4l, and 4n exhibited prominent inhibition activities against DPP-4, with IC₅₀s of 0.07, 0.07, 0.14, and 0.17 μM, respectively. The possible binding modes of compounds 3e and 4n with dipeptidyl peptidase-4 were also explored by molecular docking simulation. These potent DPP-4 inhibitors were optimized for the absorption, distribution, metabolism, and excretion (ADME) properties, and compound 4n displayed an attractive pharmacokinetic profile (F = 96.3%, t_1/2 = 10.5 h).     

Discovery of β-aminoacyl containing thiazolidine derivatives as potent and selective dipeptidyl peptidase IV inhibitors

A series of β-aminoacyl containing thiazolidine derivatives was synthesized and evaluated for their ability to inhibit DPP-IV. Several thiazolidine derivatives with an acid moiety were found to be potent DPP-IV inhibitors. Among them, compound 2da is the most active in this series with an IC₅₀ value of 1 nM, and it showed excellent selectivity over DPP-IV related enzymes including DPP-2, DPP-8, and DPP-9. Compound 2da is chemically and metabolically stable, and showed no CYP inhibition, hERG binding or cytotoxicity. Compound 2db, an ester prodrug of 2da, showed good in vivo DPP-IV inhibition after oral administration in rat and dog models.     

Design,synthesis and biological evaluation of novel pyrimidinedione derivatives as DPP-4 inhibitors

A series of novel pyrimidinedione derivatives were designed and evaluated for in vitro dipeptidyl peptidase-4 (DPP-4) inhibitory activity and in vivo anti-hyperglycemic efficacy. Among them, the representative compounds 11, 15 and 16 showed excellent inhibitory activity of DPP-4 with IC₅₀ values of 64.47?nM, 188.7?nM and 65.36?nM, respectively. Further studies revealed that compound 11 was potent in vivo hypoglycemic effect. The structure–activity relationships of these pyrimidinedione derivatives had been discussed, which would be useful for developing novel DPP-4 inhibitors as treating type 2 diabetes.     

Discovery of potent dipeptidyl peptidase IV inhibitors derived from β-aminoamides bearing substituted [1,2,3]-triazolopiperidines for the treatment of type 2 diabetes

A series of novel [1,2,3]-triazolopiperidine derivatives 5a-5y were synthesized and evaluated as inhibitors of dipeptidyl peptidase IV (DPP-4) for the treatment of type 2 diabetes, most of the compounds exhibited excellent in vitro potency (IC₅₀ <50 nM) against DPP-4. Among these, compound 5d with potent in vitro activity against DPP-4 and good pharmacokinetic profiles exhibited pronounced in vivo efficacy in an oral glucose tolerance test (OGTT) in ICR mice. On the base of these properties, compound 5d was selected as a potential new candidate for the treatment of type 2 diabetes.     

Discovery of triazole-based uracil derivatives bearing amide moieties as novel dipeptidyl peptidase-IV inhibitors

Dipeptidyl peptidase-IV (DPP-4) is a validated target for T2DM treatment. We previously reported a novel series of triazole-based uracil derivatives bearing aliphatic carboxylic acids with potent DPP-4 inhibitory activities in vitro, but these compounds showed poor hypoglycemic effects in vivo. Herein we further optimized the triazole moiety by amidation of the carboxylic acid to improve in vivo activities. Two series of compounds 3a-f and 4a-g were designed and synthesized. By screening in DPP-4, compound 4c was identified as a potent DPP-4 inhibitor with the IC₅₀ value of 28.62 nM. Docking study revealed compound 4c has a favorable binding mode and interpreted the SAR of these analogs. DPP-8 and DPP-9 tests indicated compound 4c had excellent selectivity over DPP-8 and DPP-9. Further in vivo evaluations revealed that compound 4c showed more potent hypoglycemic activity than its corresponding carboxylic acid in ICR mice and dose-dependently reduced glucose levels in type 2 diabetic C57BL/6 mice. The overall results have shown that compound 4c could be a promising lead for further development of novel DPP-4 agents treating T2DM.     

Design and synthesis of quinazoline-3,4-(4H)-diamine endowed with thiazoline moiety as new class for DPP-4 and DPPH inhibitor

New N3-benzylidene (substituted)-2-phenyl-N4-(thiazol-2-yl)-quinazoline-3,4-(4H)-diamine derivatives were design and synthesized by a sequence of reactions starting from appropriate 6-methyl anthranilic acid. The title compounds were screened for in vitro dipeptidyl peptidase IV (DPP-4) inhibitory activity and diphenyl-2-picryl-hydrazyl (DPPH) assay and results showed significant to good activity in compared to Linagliptin for antidiabetic activity and Ascorbic acid for antioxidant activity. Compound 7g (IC₅₀ = 0.76 nM) exhibited most promising DPP-4 inhibitory activity and also showed good antioxid and result. Docking study was also performed to provide an insight about the binding mode into binding sites of DPP-4 enzyme. Hopefully in future, compound 7g could be used as a lead compound for developing new antidiabetic agent with good antioxidant property.     

Design,synthesis, in-vitro thymidine phosphorylase inhibition,in-vivo antiangiogenic and in-silico studies of C-6 substituted dihydropyrimidines

Thymidine phosphorylase (TP) is an angiogenic enzyme. It plays an important role in angiogenesis, tumour growth, invasion and metastasis. In current research work, we study the effect of structural modification of dihydropyrimidine-2-ones (DHPM-2-ones) on TP inhibition. A series of eighteen new derivatives of 3,4-dihydropyrimidone-2-one were designed and synthesized through the structural modification at C-6 position. All these new derivatives were then assessed for in-vitro inhibition of thymidine phosphorylase (TP) from E. coli. Oxadiazole derivatives 4a-e exhibited excellent TP-inhibition at low micromolar concentration levels better than standard drug 7-deazaxanthine (7-DX). Among all these compounds, 4b was found to be the most potent with IC₅₀ = 1.09 ± 0.004 μM. Anti-angiogenesis potential of representative compounds were also studied in a chorioallantoic membrane (CAM) assay. Here again, compound 4b was found to be the potent anti-angiogenesis compound in a CAM assay. Docking studies were also performed with Molecular Operating Environment (MOE) to further analyse the mode of inhibition of these compounds. Binding mode analysis of the most active inhibitors showed that these are well accommodated into the binding site of enzyme though stable hydrogen bonding and hydrophobic interactions.     

Studies on depigmenting activities of dihydroxyl benzamide derivatives containing adamantane moiety

Six diphenolic compounds containing adamantane moiety were synthesized and evaluated as potent inhibitors on tyrosinase activity and melanin formation in melan-a cells. The inhibitory activity of 4-adamantyl resorcinol 1 was similar to that of 4-n-butyl resorcinol in both assays. However, dihydroxyl benzamide derivatives 6a–e showed different inhibitory patterns. All derivatives significantly suppressed the cellular melanin formation without tyrosinase inhibitory activities. These behaviors indicated that the introduction of amide bond changes the binding mode of dihydroxyl groups to tyrosinase. Among derivatives, 6d (3,4-dihydroxyl compound) and 6e (2,3-dihydroxyl compound) showed stronger inhibitory activities (IC₅₀ = 1.25 μM and 0.73 μM, respectively) as compared to 4-n-butyl resorcinol (IC₅₀ = 21.64 μM) and hydroquinone (IC₅₀ = 3.97 μM). This study showed that the position of dihydroxyl substituent at aromatic ring is important for the intercellular inhibition of melanin formation, and also amide linkage and adamantane moiety enhance the inhibition.     

Synthesis and biological evaluation of pyrrolidine-2-carbonitrile and 4-fluoropyrrolidine-2-carbonitrile derivatives as dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes

A novel series of pyrrolidine-2-carbonitrile and 4-fluoropyrrolidine-2-carbonitrile derivatives was designed, synthesized, and found to act as dipeptidyl peptidase-4 (DPP-4) inhibitors. From this series of compounds, compound 17a was identified as an efficacious, safe, and selective inhibitor of DPP-4. In vivo studies in ICR and KKAy mice showed that administration of this compound resulted in decreased blood glucose in these mice after an oral glucose challenge. Compound 17a showed high DPP-4 inhibitory activity (IC₅₀ = 0.017 μM), moderate selectivity against DPP-4 (selective ratio: DPP-8/DPP-4 = 1324; DPP-9/DPP-4 = 1164), and good efficacy in oral glucose tolerance tests in ICR and KKAy mice. These in vivo anti-diabetic properties and its desirable pharmacokinetic profile in Sprague–Dawley rats demonstrate that compound 17a is a promising candidate for development as an anti-diabetic agent.     

Antiviral action of membranotropic compounds modified by adamantane and norbornene pharmacophores exerted on different HIV-1 strains

The anti-HIV activity of new membranotropic compounds, i.e. of the polycarboxylate matrix and of its derivatives modified by adamantane and norbonene, was studied in respect of HIV-1 strains, whose tropicity to coreceptors CCR5 and CXCR4 was different, as well as in respect of HIV-1 variants resistant to azidothymidine (AZT) in a continuous culture of human lymphoid cells (MT-4) and in mononuclear cells of peripheral blood from healthy donors. Testing of complex compounds in a culture of infected MT-4 human lymphoid cells showed an effective inhibition of viral reproduction of LAV.04 (CXCR4-tropic variant) and of HIV11(EVK) as well as AZT-resistant variants. The studied pharmacophores-modified compounds displayed, in infection of the primary culture of human mononuclear cells of the HIV-1 R5 and X4 strains, a notable antiviral activity with their HIV efficiency significantly exceeding the one of the original matrix.     

Analysis of chemical constituents from Polygonatum cyrtonema after “Nine-Steam-Nine-Bask” processing

Seven new compounds, known as polygonatine N₁‒N₇ (1‒7), and a known compound (8) were isolated from the ‘Nine-Steam-Nine-Bask’ processing product of Polygonatum cyrtonema Hua. The compounds’ structures were determined by spectroscopic analysis. All compounds were tested for dipeptidyl peptidase-4 (DPP-4) inhibition, glucose transport, and anti-inflammatory activities. Compound 8 suppressed NO production with an IC₅₀ of 35.4 μM.     

Synthesis and biological evaluation of novel 2,4,5-substituted pyrimidine derivatives for anticancer activity

A series of novel 2,4,5-substituted pyrimidine derivatives were synthesized and evaluated for inhibition against the human hepatocellular carcinoma BEL-7402 cancer cell line. Several compounds showed potent inhibition with an IC₅₀ value less than 0.10 μM. Structure–activity relationships for this class of compounds at the 2- and 5-position of the pyrimidine scaffold have been elucidated. The most active compound 7gc showed good inhibition of several different human cancer cell lines with IC₅₀ values from 0.024 to 0.55 μM.     

Synthesis of novel antimitotic agents based on 2-amino-3-aroyl-5-(hetero)arylethynyl thiophene derivatives

Microtubules are dynamic structures that play a crucial role in cellular division and are recognized as an important target for cancer therapy. In search of new compounds with strong antiproliferative activity and simple molecular structure, a new series of 2-amino-3-(3′,4′,5′-trimethoxybenzoyl)-5-(hetero)aryl ethynyl thiophene derivatives was prepared by the Sonogashira coupling reaction of the corresponding 5-bromothiophenes with several (hetero)aryl acetylenes. When these compounds were analyzed in vitro for their inhibition of cell proliferation, the 2- and 3-thiophenyl acetylene derivatives were the most powerful compounds, both of which exerted cytostatic effects at submicromolar concentrations. In contrast, the presence of a more flexible ethyl chain between the (hetero)aryl and the 5-position of the thiophene ring resulted in significant reduction in activity relative to the 5-(hetero)aryl acetylene substituted derivatives. The effects of a selected series of compounds on cell cycle progression correlated well with their strong antiproliferative activity and inhibition of tubulin polymerization. We found that the antiproliferative effects of the most active compounds were associated with increase of the proportion of cells in the G₂/M and sub-G₁ phases of the cell cycle.     

Synthesis and molecular docking studies of some 4-phthalimidobenzenesulfonamide derivatives as acetylcholinesterase and butyrylcholinesterase inhibitors

A series of 4-phthalimidobenzenesulfonamide derivatives were designed, synthesized and evaluated for the inhibitory activities against acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE). Structures of the title compounds were confirmed by spectral and elemental analyses. The cholinesterase (ChE) inhibitory activity studies were carried out using Ellman’s colorimetric method. The biological activity results revealed that all of the title compounds (except for compound 8) displayed high selectivity against AChE. Among the tested compounds, compound 7 was found to be the most potent against AChE (IC₅₀=?1.35?±?0.08?μM), while compound 3 exhibited the highest inhibition against BuChE (IC₅₀=?13.41?±?0.62?μM). Molecular docking studies of the most active compound 7 in AChE showed that this compound can interact with both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE.     

New aryldithiolethione derivatives as potent histone deacetylase inhibitors

A series of dithiolethione derivatives was synthesized and the in vitro HDAC inhibitory activity was tested. The most active compounds, 1 and 2, exhibited an IC₅₀ in nM range with a strong hyperacetylation of histone H4 in A549 cells. The HDAC inhibitory activity comparable to that of SAHA and the inhibition of A549 cell proliferation suggest that these compounds are worthy of further studies as potential anticancer agents.     

1-((3S,4S)-4-amino-1-(4-substituted-1,3,5-triazin-2-yl) pyrrolidin-3-yl)-5,5-difluoropiperidin-2-one inhibitors of DPP-4 for the treatment of type 2 diabetes

A 3-amino-4-substituted pyrrolidine series of dipeptidyl peptidase IV (DPP-4) inhibitors was rapidly developed into a candidate series by identification of a polar valerolactam replacement for the lipophilic 2,4,5-trifluorophenyl pharmacophore. The addition of a gem-difluoro substituent to the lactam improved overall DPP-4 inhibition and an efficient asymmetric route to 3,4-diaminopyrrolidines was developed. Advanced profiling of a subset of analogs identified 5o with an acceptable human DPP-4 inhibition profile based on a rat PK/PD model and a projected human dose that was suitable for clinical development.