Synthesis and Evaluation of Salicylanilide Derivatives as Potential Epidermal Growth Factor Receptor Inhibitors

Two series of novel salicylanilide were synthesized as potential epidermal growth factor receptor (EGFR) inhibitors. The enzyme inhibitory activity against EGFR of all compounds was carried out, and their antiproliferative activities against the A549 and A431 cell lines were also evaluated. Of the compounds studied, majority of them exhibited high antiproliferative activities compared with gefitinib; especially, 12a and 12b exhibited stronger inhibitory activity against EGFR with IC₅₀ values of 10.4 ± 2.25 and 15.4 ± 2.33 nm , respectively, which were comparable to the positive control of gefitinib (IC₅₀ = 12.1 ± 2.21 nm ). Compound 12b also showed outstanding inhibitory activity against A431 and A549 cell lines with the IC₅₀ values of 0.42 ± 0.43 μm and 0.57 ± 0.43 μm , which was better than the positive controls. In the molecular modeling study, compound 12b was bound into the active pocket of EGFR with two hydrogen bond and with minimum binding free energy ▵G_b = −25.1125 kcal/mol. The result also suggested that compound 12b could bind the EGFR kinase well.     

Novel phthalimides regulating PD-1/PD-L1 interaction as potential immunotherapy agents

Programmed cell death 1(PD-1)/programmed cell death ligand 1(PD-L1) have emerged as one of the most promising immune checkpoint targets for cancer immunotherapy. Despite the inherent advantages of small-molecule inhibitors over antibodies, the discovery of small-molecule inhibitors has fallen behind that of antibody drugs. Based on docking studies between small molecule inhibitor and PD-L1 protein, changing the chemical linker of inhibitor from a flexible chain to an aromatic ring may improve its binding capacity to PD-L1 protein, which was not reported before. A series of novel phthalimide derivatives from structure-based rational design was synthesized. P39 was identified as the best inhibitor with promising activity, which not only inhibited PD-1/PD-L1 interaction (IC₅₀ = 8.9 nmol/L), but also enhanced killing efficacy of immune cells on cancer cells. Co-crystal data demonstrated that P39 induced the dimerization of PD-L1 proteins, thereby blocking the binding of PD-1/PD-L1. Moreover, P39 exhibited a favorable safety profile with a LD₅₀ > 5000 mg/kg and showed significant in vivo antitumor activity through promoting CD8⁺ T cell activation. All these data suggest that P39 acts as a promising small chemical inhibitor against the PD-1/PD-L1 axis and has the potential to improve the immunotherapy efficacy of T-cells.     

Ligand-based substituent-anchoring design of selective receptor-interacting protein kinase 1 necroptosis inhibitors for ulcerative colitis therapy

Receptor-interacting protein (RIP) kinase 1 is involved in immune-mediated inflammatory diseases including ulcerative colitis (UC) by regulating necroptosis and inflammation. Our group previously identified TAK-632 (5) as an effective necroptosis inhibitor by dual-targeting RIP1 and RIP3. In this study, using ligand-based substituent-anchoring design strategy, we focused on the benzothiazole ring to obtain a series of TAK-632 analogues showing significantly improving on the anti-necroptosis activity and RIP1 selectivity over RIP3. Among them, a conformational constrained fluorine-substituted derivative (25) exhibited 333-fold selectivity for RIP1 (K_d = 15 nmol/L) than RIP3 (K_d > 5000 nmol/L). This compound showed highly potent activity against cell necroptosis (EC₅₀ = 8 nmol/L) and systemic inflammatory response syndrome (SIRS) induced by TNF-α in vivo. Especially, it was able to exhibit remarkable anti-inflammatory treatment efficacy in a DSS-induced mouse model of UC. Taken together, the highly potent, selective, orally active anti-necroptosis inhibitor represents promising candidate for clinical treatment of UC.     

8-Hydroxyquinolylnitrones as multifunctional ligands for the therapy of neurodegenerative diseases

We describe the development of quinolylnitrones (QNs) as multifunctional ligands inhibiting cholinesterases (ChEs: acetylcholinesterase and butyrylcholinesterase–hBChE) and monoamine oxidases (hMAO-A/B) for the therapy of neurodegenerative diseases. We identified QN 19, a simple, low molecular weight nitrone, that is readily synthesized from commercially available 8-hydroxyquinoline-2-carbaldehyde. Quinolylnitrone 19 has no typical pharmacophoric element to suggest ChE or MAO inhibition, yet unexpectedly showed potent inhibition of hBChE (IC₅₀ = 1.06 ± 0.31 nmol/L) and hMAO-B (IC₅₀ = 4.46 ± 0.18 μmol/L). The crystal structures of 19 with hBChE and hMAO-B provided the structural basis for potent binding, which was further studied by enzyme kinetics. Compound 19 acted as a free radical scavenger and biometal chelator, crossed the blood–brain barrier, was not cytotoxic, and showed neuroprotective properties in a 6-hydroxydopamine cell model of Parkinson's disease. In addition, in vivo studies showed the anti-amnesic effect of 19 in the scopolamine-induced mouse model of AD without adverse effects on motoric function and coordination. Importantly, chronic treatment of double transgenic APPswe-PS1δE9 mice with 19 reduced amyloid plaque load in the hippocampus and cortex of female mice, underscoring the disease-modifying effect of QN 19.     

Discovery of a highly selective VEGFR2 kinase inhibitor CHMFL-VEGFR2-002 as a novel anti-angiogenesis agent

Angiogenesis is an essential process in tumor growth, invasion and metastasis. VEGF receptor 2 (VEGFR2) inhibitors targeting tumor angiogenic pathway have been widely used in the clinical cancer treatment. However, most of currently used VEGFR2 kinase inhibitors are multi-target inhibitors which might result in target-associated side effects and therefore limited clinical toleration. Highly selective VEGFR inhibitors are still highly demanded from both basic research and clinical application point of view. Here we report the discovery and characterization of a novel VEGFR2 inhibitor (CHMFL-VEGFR2-002), which exhibited high selectivity among structurally closed kinases including PDGFRs, FGFRs, CSF1R, etc. CHMFL-VEGFR2-002 displayed potent inhibitory activity against VEGFR2 kinase in the biochemical assay (IC₅₀ = 66 nmol/L) and VEGFR2 autophosphorylation in cells (EC₅₀s ∼100 nmol/L) as well as potent anti-proliferation effect against VEGFR2 transformed BaF3 cells (GI₅₀ = 150 nmol/L). In addition, CHMFL-VEGFR2-002 also displayed good anti-angiogenesis efficacy in vitro and exhibited good in vivo PK (pharmacokinetics) profile with bioavailability over 49% and anti-angiogenesis efficacy in both zebrafish and mouse models without apparent toxicity. These results suggest that CHMFL-VEGFR2-002 might be a useful research tool for dissecting new functions of VEGFR2 kinase as well as a potential anti-angiogenetic agent for the cancer therapy.     

Discovery of a highly specific 18F-labeled PET ligand for phosphodiesterase 10A enabled by novel spirocyclic iodonium ylide radiofluorination

As a member of cyclic nucleotide phosphodiesterase (PDE) enzyme family, PDE10A is in charge of the degradation of cyclic adenosine (cAMP) and guanosine monophosphates (cGMP). While PDE10A is primarily expressed in the medium spiny neurons of the striatum, it has been implicated in a variety of neurological disorders. Indeed, inhibition of PDE10A has proven to be of potential use for the treatment of central nervous system (CNS) pathologies caused by dysfunction of the basal ganglia–of which the striatum constitutes the largest component. A PDE10A-targeted positron emission tomography (PET) radioligand would enable a better assessment of the pathophysiologic role of PDE10A, as well as confirm the relationship between target occupancy and administrated dose of a given drug candidate, thus accelerating the development of effective PDE10A inhibitors. In this study, we designed and synthesized a novel ¹⁸F-aryl PDE10A PET radioligand, codenamed [¹⁸F]P10A-1910 ([¹⁸F]9), in high radiochemical yield and molar activity via spirocyclic iodonium ylide-mediated radiofluorination. [¹⁸F]9 possessed good in vitro binding affinity (IC₅₀ = 2.1 nmol/L) and selectivity towards PDE10A. Further, [¹⁸F]9 exhibited reasonable lipophilicity (logD = 3.50) and brain permeability (P_app > 10 × 10^?6 cm/s in MDCK-MDR1 cells). PET imaging studies of [¹⁸F]9 revealed high striatal uptake and excellent in vivo specificity with reversible tracer kinetics. Preclinical studies in rodents revealed an improved plasma and brain stability of [¹⁸F]9 when compared to the current reference standard for PDE10A-targeted PET, [¹⁸F]MNI659. Further, dose–response experiments with a series of escalating doses of PDE10A inhibitor 1 in rhesus monkey brains confirmed the utility of [¹⁸F]9 for evaluating target occupancy in vivo in higher species. In conclusion, our results indicated that [¹⁸F]9 is a promising PDE10A PET radioligand for clinical translation.     

Development of the novel ACLY inhibitor 326E as a promising treatment for hypercholesterolemia

Hepatic cholesterol accumulation is an important contributor to hypercholesterolemia, which results in atherosclerosis and cardiovascular disease (CVD). ATP-citrate lyase (ACLY) is a key lipogenic enzyme that converts cytosolic citrate derived from tricarboxylic acid cycle (TCA cycle) to acetyl-CoA in the cytoplasm. Therefore, ACLY represents a link between mitochondria oxidative phosphorylation and cytosolic de novo lipogenesis. In this study, we developed the small molecule 326E with an enedioic acid structural moiety as a novel ACLY inhibitor, and its CoA-conjugated form 326E-CoA inhibited ACLY activity with an IC₅₀ = 5.31 ± 1.2 μmol/L in vitro. 326E treatment reduced de novo lipogenesis, and increased cholesterol efflux in vitro and in vivo. 326E was rapidly absorbed after oral administration, exhibited a higher blood exposure than that of the approved ACLY inhibitor bempedoic acid (BA) used for hypercholesterolemia. Chronic 326E treatment in hamsters and rhesus monkeys resulted in remarkable improvement of hyperlipidemia. Once daily oral administration of 326E for 24 weeks prevented the occurrence of atherosclerosis in ApoE^?/? mice to a greater extent than that of BA treatment. Taken together, our data suggest that inhibition of ACLY by 326E represents a promising strategy for the treatment of hypercholesterolemia.     

Novel small molecule retrograde transport blocker confers post-exposure protection against ricin intoxication

Ricin is a highly toxic type 2 ribosome-inactivating protein (RIP) which is extracted from the seeds of castor beans. Ricin is considered a potential bioterror agent and no effective antidote for ricin exists so far. In this study, by structural modification of a retrograde transport blocker Retro-2^cycl, a series of novel compounds were obtained. The primary screen revealed that compound 27 has an improved anti-ricin activity compare to positive control. In vitro pre-exposure evaluation in Madin–Darby Canine Kidney (MDCK) cells demonstrated that 27 is a powerful anti-ricin compound with an EC₅₀ of 41.05 nmol/L against one LC (lethal concentration, 5.56 ng/mL) of ricin. Further studies surprisingly indicated that 27 confers post-exposure activity against ricin intoxication. An in vivo study showed that 1 h post-exposure administration of 27 can improve the survival rate as well as delay the death of ricin-intoxicated mice. A drug combination of 27 with monoclonal antibody mAb4C13 rescued mice from one LD (lethal dose) ricin challenge and the survival rate of tested animals is 100%. These results represent, for the first time, indication that small molecule retrograde transport blocker confers both in vitro and in vivo post-exposure protection against ricin and therefore provides a promising candidate for the development of anti-ricin medicines.     

Discovery of [1,2,3]triazolo[4,5-d]pyrimidine derivatives as highly potent,selective, and cellularly active USP28 inhibitors

Ubiquitin specific peptidase 28 (USP28) is closely associated to the occurrence and development of various malignancies, and thus has been validated as a promising therapeutic target for cancer therapy. To date, only few USP28 inhibitors with moderate inhibitory activity have been reported, highly potent and selective USP28 inhibitors with new chemotypes remain to be discovered for pathologically investigating the roles of deubiquitinase. In this current study, we reported the synthesis and biological evaluation of new [1,2,3]triazolo[4,5-d]pyrimidine derivatives as potent USP28 inhibitors. Especially, compound 19 potently inhibited USP28 (IC₅₀ = 1.10 ± 0.02 μmol/L, K_d = 40 nmol/L), showing selectivity over USP7 and LSD1 (IC₅₀ > 100 μmol/L). Compound 19 was cellularly engaged to USP28 in gastric cancer cells. Compound 19 reversibly bound to USP28 and directly affected its protein levels, thus inhibiting the proliferation, cell cycle at S phase, and epithelial-mesenchymal transition (EMT) progression in gastric cancer cell lines. Docking studies were performed to rationalize the potency of compound 19. Collectively, compound 19 could serve as a new tool compound for the development of new USP28 inhibitors for exploring the roles of deubiquitinase in cancers.     

Synthesis,molecular structure and urease inhibitory activity of novel bis-Schiff bases of benzyl phenyl ketone: A combined theoretical and experimental approach

BackgroundUrease belongs to the family of amid hydrolases with two nickel atoms in their core structure. On the basis of literature survey, this research work is mainly focused on the study of bis-Schiff base derivatives of benzyl phenyl ketone nucleus.ObjectiveSynthesis of benzyl phenyl ketone based bis-Schiff bases in search of potent urease inhibitors.MethodIn the current work, bis-Schiff bases were synthesized through two steps reaction by reacting benzyl phenyl ketone with excess of hydrazine hydrate in ethanol solvent in the first step to get the desired hydrazone. In last, different substituted aromatic aldehydes were refluxed in catalytic amount of acetic acid with the desired hydrazone to obtain bis-Schiff base derivatives in tremendous yields. Using various spectroscopic techniques including FTIR, HR-ESI-MS, and ¹H NMR spectroscopy were used to clarify the structures of the created bis-Schiff base derivatives.ResultsThe prepared compounds were finally screened for their in-vitro urease inhibition activity. All the synthesized derivatives (3–9) showed excellent to less inhibitory activity when compared with standard thiourea (IC₅₀ = 21.15 ± 0.32 µM). Compounds 3 (IC₅₀ = 22.21 ± 0.42 µM), 4 (IC₅₀ = 26.11 ± 0.22 µM) and 6 (IC₅₀ = 28.11 ± 0.22 µM) were found the most active urease inhibitors near to standard thiourea among the synthesized series. Similarly, compound 5 having IC₅₀ value of 34.32 ± 0.65 µM showed significant inhibitory activity against urease enzyme. Furthermore, three compounds 7, 8, and 9 exhibited less activity with IC₅₀ values of 45.91 ± 0.14, 47.91 ± 0.14, and 48.33 ± 0.72 µM respectively. DFT used to calculate frontier molecular orbitals including; HOMO and LUMO to indicate the charge transfer from molecule to biological transfer, and MEP map to indicate the chemically reactive zone suitable for drug action. The electron localization function (ELF), non-bonding orbitals, AIM charges are also calculated. The docking study contributed to the analysis of urease protein binding.     

Immunosuppressive efficacy of tetrandrine combined with methylprednisolone against mitogen‐activated peripheral blood mononuclear cells of haemodialysis patients

Immunosuppressive therapy for prevention of acute rejection episode occasionally causes serious adverse effects, and thus it is important to develop new therapeutic approach for renal transplant recipients. This study evaluated the immunosuppressive pharmacodynamics of tetrandrine (TET) and/or methylprednisolone (MP) in haemodialysis patients in vitro by using the peripheral blood mononuclear cells (PBMCs) isolated from whole blood of haemodialysis patients. The median (range) of MP IC₅₀ values against the proliferation of patients PBMCs was 7.04 (2.30‐500.00) ng/mL. In contrast, the median (range) of MP IC₅₀ values against the proliferation of healthy PBMCs was 4.44 (3.19‐5.08) ng/mL. The median (range) of TET IC₅₀ values against the proliferation of patients PBMCs was 1.61 (1.04‐4.79) μmol/L. Lower concentrations of TET (0.3‐300 nmol/L) were able to decrease the IC₅₀ values of MP and thus potentiate the MP immunosuppressive effect on patient PBMCs. The median (range) of MP IC₅₀ values in combination with 0.3, 3, 30, and 300 nmol/L TET were 0.92 (0.49‐8.39), 2.10 (0.45‐20.00), 0.35 (0.092‐1.05), and 0.14 (0.05‐6.78) ng/mL, respectively. TET potentiates the MP immunosuppressive pharmacodynamics and thus, it was possible to use the combination of MP and TET to attenuate MP side effects. There were significant correlations between the IC₅₀ values of TET and stimulation indices (P=0.04, r=.58), the IC₅₀ values of TET and the haemodialysis periods (P=0.04, r=.57), or the IC₅₀ values of MP combined with 0.3 nmol/L TET and C‐reactive protein concentrations (P=0.04, r=.64), respectively.     

Discovery of highly selective and orally available benzimidazole-based phosphodiesterase 10 inhibitors with improved solubility and pharmacokinetic properties for treatment of pulmonary arterial hypertension

Optimization efforts were devoted to discover novel PDE10A inhibitors in order to improve solubility and pharmacokinetics properties for a long-term therapy against pulmonary arterial hypertension (PAH) starting from the previously synthesized inhibitor A. As a result, a potent and highly selective PDE10A inhibitor, 14·3HCl (half maximal inhibitory concentration, IC₅₀ = 2.8 nmol/L and >3500-fold selectivity) exhibiting desirable solubility and metabolic stability with a remarkable bioavailability of 50% was identified with the aid of efficient methods of binding free energy predictions. Animal PAH studies showed that the improvement offered by 14·3HCl [2.5 mg/kg, oral administration (p.o.)] was comparable to tadalafil (5.0 mg/kg, p.o.), verifying the feasibility of PDE10A inhibitors for the anti-PAH treatment. The crystal structure of the PDE10A−14 complex illustrates their binding pattern, which provided a guideline for rational design of highly selective PDE10A inhibitors.     

Synthetic transformation of 6-Fluoroimidazo[1,2-a]Pyridine-3-carbaldehyde into 6-Fluoroimidazo[1,2-a]Pyridine-Oxazole Derivatives: In vitro urease inhibition and in silico study

PurposeUlcer is a serious disease that is caused due to different bacteria and over usage of various NSAIDs which caused to reduce the defensive system of stomach. Therefore, some novel series are needed to overcome these issues.MethodsOxazole-based imidazopyridine scaffolds (4a-p) were designed and synthesized by two step reaction protocol and then subjected to urease inhibition profile (in vitro). All the newly afforded analogs (4a-p) were found potent and demonstrated moderate to significant inhibition profile.ResultsParticularly, the analogs 4i (IC₅₀ = 5.68 ± 1.66 μM), 4o (IC₅₀ = 7.11 ± 1.24 μM), 4 g (IC₅₀ = 9.41 ± 1.19 μM) and 4 h (IC₅₀ = 10.45 ± 2.57 μM) were identified to be more potent than standard thiourea drug (IC₅₀ = 21.37 ± 1.76 μM). Additionally, the variety of spectroscopic tools such as ¹H NMR, ¹³C NMR and HREI-MS analysis were employed to confirm the precise structures of all the newly afforded analogs.DiscussionThe structure–activity relationship (SAR) studies showed that analogs possess the substitution either capable of furnishing strong HB like –OH or had strong EW nature such as -CF₃ & –NO₂ groups displayed superior inhibitory potentials than the standard thiourea drug. A good PLI (protein–ligand interaction) profile was shown by most active analogs when subjected to molecular study against corresponding target with key significant interactions such as pi-pi stacking, pi-pi T shaped and hydrogen bonding.     

Discovery of novel KRAS‒PDEδ inhibitors with potent activity in patient-derived human pancreatic tumor xenograft models

KRAS?PDEδ interaction is revealed as a promising target for suppressing the function of mutant KRAS. The bottleneck in clinical development of PDEδ inhibitors is the poor antitumor activity of known chemotypes. Here, we identified novel spiro-cyclic PDEδ inhibitors with potent antitumor activity both in vitro and in vivo. In particular, compound 36l (K_D = 127 ± 16 nmol/L) effectively bound to PDEδ and interfered with KRAS–PDEδ interaction. It influenced the distribution of KRAS in Mia PaCa-2 cells, downregulated the phosphorylation of t-ERK and t-AKT and promoted apoptosis of the cells. The novel inhibitor 36l exhibited significant in vivo antitumor potency in pancreatic cancer patient-derived xenograft (PDX) models. It represents a promising lead compound for investigating the druggability of KRAS?PDEδ interaction.     

Chemical composition and anticancer,antiinflammatory, antioxidant and antimalarial activities of leaves essential oil of Cedrelopsis grevei

The essential oil from Cedrelopsis grevei leaves, an aromatic and medicinal plant from Madagascar, is widely used in folk medicine. Essential oil was characterized by GC–MS and quantified by GC–FID. Sixty-four components were identified. The major constituents were: (E)-β-farnesene (27.61%), δ-cadinene (14.48%), α-copaene (7.65%) and β-elemene (6.96%). The essential oil contained a complex mixture consisting mainly sesquiterpene hydrocarbons (83.42%) and generally sesquiterpenes (98.91%). The essential oil was tested cytotoxic (on human breast cancer cells MCF-7), antimalarial (Plasmodium falciparum), antiinflammatory and antioxidant (ABTS and DPPH assays) activities. C. grevei essential oil was active against MCF-7 cell lines (IC₅₀ = 21.5 mg/L), against P. falciparum, (IC₅₀ = 17.5 mg/L) and antiinflammatory (IC₅₀ = 21.33 mg/L). The essential oil exhibited poor antioxidant activity against DPPH (IC₅₀ > 1000 mg/L) and ABTS (IC₅₀ = 110 mg/L) assays. A bibliographical review was carried out of all essential oils identified and tested with respect to antiplasmodial, anticancer and antiinflammatory activities. The aim was to establish correlations between the identified compounds and their biological activities (antiplasmodial, anticancer and antiinflammatory). According to the obtained correlations, 1,4-cadinadiene (R² = 0.61) presented a higher relationship with antimalarial activity. However, only (Z)-β-farnesene (R² = 0.73) showed a significant correlation for anticancer activity.     

Flavanols from the Camellia sinensis var. assamica and their hypoglycemic and hypolipidemic activities

α-Glucosidase and lipase inhibitors play important roles in the treatment of hyperglycaemia and dyslipidemia. To identify novel naturally occurring inhibitors, a bioactivity-guided phytochemical research was performed on the pu-erh tea. One new flavanol, named (–)-epicatechin-3-O-(Z)-coumarate (1), and 16 known analogs (217) were isolated from the aqueous extract of the pu-erh tea. Their structures were determined by spectroscopic and chemical methods. Furthermore, the water extract of pu-erh tea and its fractions exhibited inhibitory activities against α-glucosidases and lipases in vitro; compound 15 showed moderate inhibitory effect against sucrase with an IC₅₀ value of 32.5 μmol/L and significant inhibitory effect against maltase with an IC₅₀ value of 1.3 μmol/L. Compounds 8, 10, 11 and 15 displayed moderate activity against a lipase with IC₅₀ values of 16.0, 13.6, 19.8, and 13.3 μmol/L, respectively.