Probing the high potency of pyrazolyl pyrimidinetriones and thioxopyrimidinediones as selective and efficient non-nucleotide inhibitors of recombinant human ectonucleotidases

With the aim to discover novel, efficient and selective inhibitors of human alkaline phosphatase and nucleotide pyrophosphatase enzymes, two new series of pyrazolyl pyrimidinetriones (PPTs) (6a–g) and thioxopyrimidinediones (PTPs) (6h–n) were synthesized in good chemical yields using Knoevenagel condensation reaction between pyrazole carbaldehydes (4a–g) and pharmacologically active N-alkylated pyrimidinetrione (5a) and thioxopyrimidinedione (5b). The inhibition potential of the synthesized hybrid compounds was evaluated against human alkaline phosphatase (h-TNAP and h-IAP) and ectonucleotidase (h-NPP1 and h-NPP3) enzymes. Most of the tested analogs were highly potent with a variable degree of inhibition depending on the functionalized hybrid structure. The detailed structure-activity relationship (SAR) of PPT and PTP derivatives suggested that the compound with unsubstituted phenyl ring from PPT series led to selective and potent inhibition (6a; IC₅₀ = 0.33 ± 0.02 µM) of h-TNAP, whereas compound 6c selectively inhibited h-IAP isozyme with IC₅₀ value of 0.86 ± 0.04 µM. Similarly, compounds 6b and 6h were identified as the lead scaffolds against h-NPP1 and h-NPP3, respectively. The probable binding modes for the most potent inhibitors were elucidated through molecular docking analysis. Structure-activity relationships, mechanism of action, cytotoxic effects and druglikeness properties are also discussed.     

Synthesis and biological evaluation of novel dihydro-aryl/alkylsulfanyl-cyclohexylmethyl-oxopyrimidines (S-DACOs) as high active anti-HIV agents

A novel dihydro-aryl/alkylsulfanyl-cyclohexylmethyl-oxopyrimidines (S-DACOs) combinatory library was synthesized and evaluated with C8166 cells infected by the HIV-1_IIIB in vitro, using Nevirapine (NVP) and Zidovudine (AZT) as positive control. The anti-HIV screening results revealed that C-6-cyclohexylmethyl substituted pyrimidinones possessed higher selective index than its 6-arylmethyl counterparts. Compounds 1g, 1c, 1e and 1b showed potent anti-HIV activities with EC₅₀ values of 0.012, 0.025, 0.088 and 0.162 nM, respectively.     

Synthesis and structure–activity relationship studies of phenolic hydroxyl derivatives based on quinoxalinone as aldose reductase inhibitors with antioxidant activity

To enhance aldose reductase (ALR2) inhibition and add antioxidant ability, phenolic hydroxyl was introduced both to the quinoxalinone core and C3 side chain, resulting in a series of derivatives as ALR2 inhibitors. Biological activity tests suggested that most of the derivatives were potent and selective inhibitors with IC₅₀ values ranging from 0.059 to 6.825 μM, and 2-(3-(4-hydroxystyryl)-7-methoxy-2-oxoquinoxalin-1(2H)-yl)acetic acid (6b) was the most active. Particularly, it was encouraging to find that some derivatives endowed with obvious antioxidant activity, and among them the phenolic 3,4-dihydroxyl compound 6f with 7-hydroxyl in the quinoxalinone core showed the most potent activity, even comparable with the well-known antioxidant Trolox. Structure-activity relationship and docking studies highlighted the importance of phenolic hydroxyl both in C3 side chain and the core structure for constructing potent ALR2 inhibitors with antioxidant activity.     

Discovery of new indole-based acylsulfonamide Nav1.7 inhibitors

Screening of 100 acylsulfonamides from the Bristol-Myers Squibb compound collection identified the C3-cyclohexyl indole 6 as a potent Na_v1.7 inhibitor. Replacement of the C2 furanyl ring of 6 with a heteroaryl moiety or truncation of this group led to the identification of 4 analogs with hNa_v1.7 IC₅₀ values under 50?nM. Fluorine substitution of the truncated compound 12 led to 34 with improved potency and isoform selectivity. The inverted indole 36 also maintained good activity. Both 34 and 36 exhibited favorable CYP inhibition profiles, good membrane permeability and a low efflux ratio and, therefore, represent new leads in the search for potent and selective Na_v1.7 inhibitors to treat pain.     

Synthesis and biological evaluation of 1-(2-hydroxy-3-phenyloxypropyl)piperazine derivatives as T-type calcium channel blockers

To obtain selective and potent inhibitor for T-type calcium channel by ligand based drug design, 2-hydroxy-3-phenoxypropyl piperazine derivatives were synthesized and evaluated for in vitro activities. Compound 6m and 6q showed high selectivity over hERG channel (IC₅₀ ratio of hERG/α_1G 6m = 8.5, 6q = 18.38) and they were subjected to measure pharmacokinetics profiles. Among them compound 6m showed an excellent pharmacokinetic profile in rats.     

Synthesis and anti-hepatitis C virus activity of novel ethyl 1H-indole-3-carboxylates in vitro

A series of ethyl 1H-indole-3-carboxylates 9a_1–6 and 9b_1–2 were prepared and evaluated in Huh-7.5 cells. Most of the compounds exhibited anti-hepatitis C virus (HCV) activities at low concentration. The selectivity indices of inhibition on entry and replication of compounds 9a₂ (>10; >16.7) and 9b₁ (>6.25; >16.7) were higher than those of the other evaluated compounds, including the lead compound Arbidol (ARB, 6; 15). Moreover, the selective index of inhibition on entry of compound 9a₃ (>6.25) was higher than that of ARB (6). Of these three initial hits, compound 9a₂ was the most potent.     

Design of novel nicotinamides as potent and selective monoamine oxidase a inhibitors

A series of N-(2-morpholinoethyl)nicotinamide (1–13) and N-(3-morpholinopropyl)nicotinamide derivatives (14–26) have been designed, synthesized and evaluated in vitro for their monoamine oxidase (MAO) A and B inhibitory activity and selectivity. Most of these synthesized compounds proved to be potent, and selective inhibitors of MAO-A rather than of MAO-B. 5-Chloro-6-hydroxy-N-(2-morpholinoethyl)nicotinamide (13) displayed the highest MAO-A inhibitory potency (IC₅₀ = 0.045 μM) and a good selectivity. 2-Bromo-N-(2-morpholinoethyl)nicotinamide (3) was the most potent MAO-B inhibitor with the IC₅₀ value of 0.32 μM, but it was not selective. Molecular dockings of compound 13 were performed in order to give structural insights regarding the MAO-A selectivity.     

Development of substituted pyrido[3,2-d]pyrimidines as potent and selective dihydrofolate reductase inhibitors for pneumocystis pneumonia infection

Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii (pj) can lead to serious health consequences in patients with an immunocompromised system. Trimethoprim (TMP), used as first-line therapy in combination with sulfamethoxazole, is a selective but only moderately potent pj dihydrofolate reductase (pjDHFR) inhibitor, whereas non-clinical pjDHFR inhibitors, such as, piritrexim and trimetrexate are potent but non-selective pjDHFR inhibitors. To meet the clinical needs for a potent and selective pjDHFR inhibitor for PCP treatment, fourteen 6-substituted pyrido[3,2-d]pyrimidines were developed. Comparison of the amino acid residues in the active site of pjDHFR and human DHFR (hDHFR) revealed prominent amino acid differences which could be exploited to structurally design potent and selective pjDHFR inhibitors. Molecular modeling followed by enzyme assays of the compounds revealed 15 as the best compound of the series with an IC₅₀ of 80 nM and 28-fold selectivity for inhibiting pjDHFR over hDHFR. Compound 15 serves as the lead analog for further structural variations to afford more potent and selective pjDHFR inhibitors.     

Flavonols and 4-thioflavonols as potential acetylcholinesterase and butyrylcholinesterase inhibitors: Synthesis,structure-activity relationship and molecular docking studies

To explore new scaffolds for the treat of Alzheimer’s disease appears to be an inspiring goal. In this context, a series of varyingly substituted flavonols and 4-thioflavonols have been designed and synthesized efficiently. All the newly synthesized compounds were characterized unambiguously by common spectroscopic techniques (IR, ¹H-, ¹³C NMR) and mass spectrometry (EI-MS). All the derivatives (1–24) were evaluated in vitro for their inhibitory potential against cholinesterase enzymes. The results exhibited that these derivatives were potent selective inhibitors of acetylcholinesterase (AChE), except the compound 11 which was selective inhibitor of butyrylcholinesterase (BChE), with varying degree of IC₅₀ values. Remarkably, the compounds 20 and 23 have been found the most potent almost dual inhibitors of AChE and BChE amongst the series with IC₅₀ values even less than the standard drug. The experimental results in silico were further validated by molecular docking studies in order to find their binding modes with the active pockets of AChE and BChE enzymes.     

Surrogating and redirection of pyrazolo[1,5-a]pyrimidin-7(4H)-one core,a novel class of potent and selective DPP-4 inhibitors

The initial focus on characterizing novel pyrazolo[1,5-a]pyrimidin-7(4H)-one derivatives as DPP-4 inhibitors, led to a potent and selective inhibitor compound b2. This ligand exhibits potent in vitro DPP-4 inhibitory activity (IC₅₀: 80?nM), while maintaining other key cellular parameters such as high selectivity, low cytotoxicity and good cell viability. Subsequent optimization of b2 based on docking analysis and structure-based drug design knowledge resulted in d1. Compound d1 has nearly 2-fold increase of inhibitory activity (IC₅₀: 49?nM) and over 1000-fold selectivity against DPP-8 and DPP-9. Further in vivo IPGTT assays showed that compound b2 effectively reduce glucose excursion by 34% at the dose of 10?mg/kg in diabetic mice. Herein we report the optimization and design of a potent and highly selective series of pyrazolo[1,5-a]pyrimidin-7(4H)-one DPP-4 inhibitors.     

Design,biological evaluation and 3D QSAR studies of novel dioxin-containing triaryl pyrazoline derivatives as potential B-Raf inhibitors

A series of novel dioxin-containing triaryl pyrazoline derivatives C1–C20 have been synthesized. Their B-Raf inhibitory and anti-proliferation activities were evaluated. Compound C6 displayed the most potent biological activity against B-Raf^V600E and WM266.4 human melanoma cell line with corresponding IC₅₀ value of 0.04 μM and GI₅₀ value of 0.87 μM, being comparable with the positive controls and more potent than our previous best compounds. Moreover, C6 was selective for B-Raf^V600E from B-Raf^WT, C-Raf and EGFR and low toxic. The docking simulation suggested the potent bioactivity might be caused by breaking the limit of previous binding pattern. A new 3D QSAR model was built with the activity data and binding conformations to conduct visualized SAR discussion as well as to introduce new directions. Stretching the backbone to outer space or totally reversing the backbone are both potential orientations for future researches.     

Synthesis and evaluation of two series of 4′-aza-carbocyclic nucleosides as adenosine A2A receptor agonists

The synthesis of two series of 4′-aza-carbocyclic nucleosides are described in which the 4′-substituent is either a reversed amide, relative to the carboxamide of NECA, or an N-bonded heterocycle. Using established purine substitution patterns, potent and selective examples of agonists of the human adenosine A_2A receptor have been identified from both series. The propionamides 14–18 and the 4-hydroxymethylpyrazole 32 were determined to be the most potent and selective examples from the 4′-reversed amide and 4′-N-bonded heterocyclic series, respectively.     

Structure–activity relationships of truncated adenosine derivatives as highly potent and selective human A3 adenosine receptor antagonists

On the basis of potent and selective binding affinity of truncated 4′-thioadenosine derivatives at the human A₃ adenosine receptor (AR), their bioisosteric 4′-oxo derivatives were designed and synthesized from commercially available 2,3-O-isopropylidene-d-erythrono lactone. The derivatives tested in AR binding assays were substituted at the C2 and N⁶ positions. All synthesized nucleosides exhibited potent and selective binding affinity at the human A₃ AR. They were less potent than the corresponding 4′-thio analogues, but showed still selective to other subtypes. The 2-Cl series generally were better than the 2-H series in view of binding affinity and selectivity. Among compounds tested, compound 5d (X = Cl, R = 3-bromobenzyl) showed the highest binding affinity (K_i = 13.0 ± 6.9 nM) at the hA₃ AR with high selectivity (at least 88-fold) in comparison to other AR subtypes. Like the corresponding truncated 4′-thio series, compound 5d antagonized the action of an agonist to inhibit forskolin-stimulated adenylate cyclase in hA₃ AR-expressing CHO cells. Although the 4′-oxo series were less potent than the 4′-thio series, this class of human A₃ AR antagonists is also regarded as another good template for the design of A₃ AR antagonists and for further drug development.     

Synthesis,molecular docking and evaluation of thiazolyl-pyrazoline derivatives containing benzodioxole as potential anticancer agents

A series of novel thiazolyl-pyrazoline derivatives containing benzodioxole (C1–C20) have been designed and synthesized. Among of the synthesized compounds, 2-(5-(benzo[d][1,3]dioxol-5-yl)-3-(4-bromophenyl)-4,5-dihydro-1H-pyrazol-1-yl)-4-(4-bromophenyl)thiazole (C6) displayed the most potent inhibitory activity for HER-2 (IC₅₀ = 0.18 μM for HER-2). Antiproliferative assay results indicated that compound C6 owned high antiproliferative activity against MCF-7 and B16-F10 in vitro, with IC₅₀ value of 0.09 and 0.12 μM, respectively, being comparable with the positive control Erlotinib. Docking simulation was further performed to determine the probable binding model. Based on the preliminary results, compound C6 with potent inhibitory activity in tumor growth would be a potential anticancer agent.     

Synthesis and in vitro antiproliferative activity of C5-benzyl substituted 2-amino-pyrrolo[2,3-d]pyrimidines as potent Hsp90 inhibitors

A novel series of heat shock protein 90 (Hsp90) inhibitors was identified by X-ray crystal analysis of complex structures at solvent-exposed exit pocket C. The 2-amino-pyrrolo[2,3-d]pyrimidine derivatives, 7-deazapurines substituted with a benzyl moiety at C5, showed potent Hsp90 inhibition and broad-spectrum antiproliferative activity against NCI-60 cancer cell lines. The most potent compound, 6a, inhibited Hsp90 with an IC₅₀ of 36 nM and showed a submicromolar mean GI₅₀ value against NCI-60 cell lines. The interaction of 6a at the ATP-binding pocket of Hsp90 was confirmed by X-ray crystallography and Western blot analysis.     

Novel 5,6-disubstituted pyrrolo[2,3-d]pyrimidine derivatives as broad spectrum antiproliferative agents: Synthesis,cell based assays,kinase profile and molecular docking study

Two new series of 5-subtituted and 5,6-disubstituted pyrrolo[2,3-d]pyrimidine octamides (4a–o and 6a–g) and their corresponding free amines 5a–m and 7a–g have been synthesized and biologically evaluated for their antiproliferative activity against three human cancer cell lines. The 5,6-disubstituted octamides 6d–g as well as the amine derivative 7b have shown the best anticancer activity with single digit micromolar GI₅₀ values over the tested cancer cells, and low cytotoxic effects (GI₅₀?>?10.0?µM) against HFF-1 normal cell. A structure activity relationship (SAR) study has been established and disclosed that terminal octamide moiety at C2 as well as disubstitution with fluorobenzyl piperazines at C5 and C6 of pyrrolo[2,3-d]pyrimidine are the key structural features prerequisite for best antiproliferative activity. Moreover, the most active member 6f was tested for its antiproliferative activity over a panel of 60 cancer cell lines at NCI, and exhibited distinct broad spectrum anticancer activity with submicromolar GI₅₀ and TGI values over multiple cancer cells. Kinase profile of compound 6f over 53 oncogenic kinases at 10?µM concentration showed its highly selective inhibitory activity towards FGFR4, Tie2 and TrkA kinases. The observed activity of 6f against TrkA (IC₅₀?=?2.25?µM), FGFR4 (IC₅₀?=?6.71?µM) and Tie2 (IC₅₀?=?6.84?µM) was explained by molecular docking study, which also proposed that 6f may be a type III kinase inhibitor, binding to an allosteric site rather than kinase hinge region. Overall, compound 6f may serve as a promising anticancer lead compound that could be further optimized for development of potent anticancer agents.     

Fusarithioamide B,a new benzamide derivative from the endophytic fungus Fusarium chlamydosporium with potent cytotoxic and antimicrobial activities

Fusarithioamide B (6), a new aminobenzamide derivative with unprecedented carbon skeleton and five known metabolites: stigmast-4-ene-3-one (1), stigmasta-4,6,8(14),22-tetraen-3-one (2), p-hydroxyacetophenone (3), tyrosol (4), and fusarithioamide A (5) were separated from Fusarium chlamydosporium EtOAc extract isolated from Anvillea garcinii (Burm.f.) DC. leaves (Asteraceae). The structure elucidation and complete assignment of the isolated metabolites were performed mainly by the aid of various NMR and MS data. Fusarithioamide B (6) has been assessed for antibacterial and antifungal activities towards various microbial strains by disc diffusion assay. It exhibited selective antifungal activity towards C. albicans (MIC 1.9?µg/ml and IZD 14.5?mm), comparing to clotrimazole (MIC 2.8?µg/ml and IZD 17.9?mm). Also, it possessed high antibacterial potential towards E. coli, B. cereus, and S. aureus compared to ciprofloxacin. Furthermore, 6 was tested for the in vitro cytotoxic effect against KB, HCT-116, BT-549, MCF-7, SKOV-3, and SK-MEL cell lines. It had selective and potent effect towards BT-549, MCF-7, SKOV-3, and HCT-116 cell lines with IC₅₀s 0.09, 0.21, 1.23, and 0.59?μM, respectively compared to doxorubicin (IC₅₀s 0.046, 0.05, 0.321, and 0.24?μM, respectively). Fusarithioamide B may provide a lead molecule for future developing of antitumor and antimicrobial agents.     

A new series of 3-phenylcoumarins as potent and selective MAO-B inhibitors

6-Methyl-3-phenylcoumarins 3–6 were designed, synthesized and evaluated as monoamine oxidase A and B (MAO-A and MAO-B) inhibitors. The synthesis of these new compounds (resveratrol–coumarin hybrids) was carried out with good yield by a Perkin reaction, from the 5-methylsalicylaldehyde and the corresponding phenylacetic acid. They show high selectivity to the MAO-B isoenzyme, with IC₅₀ values in the nanomolar range. Compound 5 is the most active compound and is several times more potent and selective than the reference compound, R-(?)-deprenyl.     

Antitumor agents 270. Novel substituted 6-phenyl-4H-furo[3,2-c]pyran-4-one derivatives as potent and highly selective anti-breast cancer agents

6-Phenyl-4H-furo[3,2-c]pyran-4-one derivatives based on neo-tashinlactone (1) were synthesized and evaluated as novel anti-breast cancer agents. Compounds 10–13, 23, 25, and 27 showed potent inhibition against the SK-BR-3 breast cancer cell line. Importantly, 25 and 27 showed the highest cancer cell line selectivity, being approximately 100–250-fold more potent against SK-BR-3 (ED₅₀ 0.28 and 0.44 μM, respectively) compared with other cancer cell lines tested. In addition, 25 displayed low cytotoxicity against normal breast cell lines 184A1 and MCF10A. Compounds 25 and 27 merit further investigation in our continuing program to generate and develop selective anti-breast cancer agents.     

Development and characterization of a CNS-penetrant benzhydryl hydroxamic acid class IIa histone deacetylase inhibitor

We have identified a potent, cell permeable and CNS penetrant class IIa histone deacetylase (HDAC) inhibitor 22, with >500-fold selectivity over class I HDACs (1,2,3) and ～150-fold selectivity over HDAC8 and the class IIb HDAC6 isoform. Dose escalation pharmacokinetic analysis demonstrated that upon oral administration, compound 22 can reach exposure levels in mouse plasma, muscle and brain in excess of cellular class IIa HDAC IC₅₀ levels for ～8?h. Given the interest in aberrant class IIa HDAC function for a number of neurodegenerative, neuromuscular, cardiac and oncology indications, compound 22 (also known as CHDI-390576) provides a selective and potent compound to query the role of class IIa HDAC biology, and the impact of class IIa catalytic site occupancy in vitro and in vivo.