Anti-inflammatory activity of pyridazinones: A review.

The pyridazinone core has emerged as a leading structure for fighting inflammation, with low ulcerogenic effects. Moreover, easy functionalization of various ring positions of the pyridazinone core structure makes it an attractive synthetic and therapeutic target for the design and synthesis of anti-inflammatory agents. The present review surveys the recent advances of pyridazinone derivatives as potential anti-inflammatory agents to provide insights into the rational design of more effective anti-inflammatory pyridazinones.

New pyridazine derivatives as selective COX-2 inhibitors and potential anti-inflammatory agents; design, synthesis and biological evaluation.

New pyridazinone and pyridazinthione derivatives were designed, synthesized and identified through performing 1H NMR, 13C NMR, IR and MS spectroscopic techniques. All the newly synthesized derivatives were evaluated for cyclooxygenase inhibitory activity and COX-2 selectivity using celecoxib and indomethacin, as reference drugs. All compounds showed highly potent COX-2 inhibitory activity with IC50 values in nano-molar range. Moreover, they demonstrated higher selectivity towards COX-2 inhibition compared to indomethacin. Compounds 3d, 3g and 6a exhibited significantly increased potency towards COX-2 enzyme compared to celecoxib with IC50 values of 67.23, 43.84 and 53.01 nM, respectively. They were 1.1-1.7 folds more potent than celecoxib (IC50 = 73.53 nM) and extremely much more potent than indomethacin (IC50 = 739.2 nM). Of particular interest, Compound 3g showed SI of 11.51 which was as high as that of celecoxib (SI 11.78). This compound was further challenged by in vivo anti-inflammatory activity assay and gastric ulcerogenic effect. It showed comparable anti-inflammatory activity to indomethacin as positive control. Moreover, the anti-inflammatory activity of compound 3g was found to be equipotent to celecoxib. Furthermore, the selective COX-2 inhibitor 3g exhibited a superior gastrointestinal safety profile compared to the reference drugs celecoxib and indomethacin with less number of ulcers and milder ulcer score. The molecular docking study of this compound with COX-2 protein revealed more favorable binding mode compared to celecoxib, explaining its remarkable COX-2 inhibitory potency.

Novel nalidixic acid derivatives targeting topoisomerase II enzyme; Design, synthesis, anticancer activity and effect on cell cycle profile.

AIM: Design and synthesis of novel nalidixic acid derivatives of potent anticancer and topoisomerase II inhibitory activities were our major aim. MATERIALS & METHODS: All the newly synthesized nalidixic acid derivatives were submitted to the National Cancer Institute (NCI), Bethesda, USA and were accepted for single dose screening. Further investigation via IC50 determination of the most potent compound 6a against K-562 and SR leukemia cell lines. Finally, the topoisomerase II inhibitory activity, the cell cycle analysis and molecular docking of 6a were performed in order to identify the possible mechanism of the anticancer activity. RESULTS: Compound 6a showed interesting selectivity against leukemia especially K-562 and SR subpanels with IC50 35.29 µM and 13.85 µM respectively. Moreover, compound 6a revealed potent topoisomerase IIα and topoisomerase IIß inhibitory activity compared with known topoisomerase inhibitors such as doxorubicin and topotecan with IC50 1.30 µM and 0.017 µM respectively. Cell cycle analysis indicated that compound 6a induced cell cycle arrest at G2-M phase leading to inhibition of cell proliferation and apoptosis. Molecular modeling demonstrated that the potent topoisomerase inhibitory activity of 6a was due to the interaction with the topoisomerase II enzyme through coordinate bonding with the magnesium ion Mg2+, hydrogen bonding with Asp 545 and arene cation interaction with His 759.

Design, synthesis and in vitro anticancer activity of some new lomefloxacin derivatives.

Our main goal was to design and synthesize novel lomefloxacin derivatives that inhibit the topoisomerase II enzyme, leading to potent anticancer activity. Lomefloxacin derivatives substituted at position 3 and 7 were synthesized and screened for cytotoxic activity utilizing 60 different human cancer cell lines. Furthermore, compounds 3a,b,c,e that revealed potent broad-spectrum anticancer activity (with mean percent GI more than 47%) were further evaluated using five dose concentrations and calculating the GI50. Compound 3e was then evaluated for cell cycle analysis and demonstrated cell cycle arrest at the G2-M phase. Moreover, the mechanism of action was determined by determining the topoisomerase inhibitory activity and the molecular modeling study. Compounds 3a,b,c,e showed broad spectrum anticancer activity. Lomefloxacin derivative 5f showed selective cytotoxic activity against melanoma SK-MEL-5 cell line. Compound 3e demonstrated comparable topoisomerase II inhibition to doxorubicin with IC50 of 0.98 µM.

Design, synthesis, molecular docking, and molecular dynamic studies of novel quinazoline derivatives as phosphodiesterase 7 inhibitors.

Introduction: Phosphodiesterase 7 (PDE7) is a high-affinity cyclic AMP (cAMP)-specific PDE that is expressed in immune and proinflammatory cells. In this work, we explore the possibility that selective small molecule inhibitors of this enzyme family could provide a novel approach to alleviate the inflammation that is associated with many inflammatory diseases. Methods: A series of novel substituted 4-hydrazinoquinazoline derivatives and fused triazoloquinazolines were designed, synthesized, and evaluated in vitro for their PDE7A inhibition activities, in comparison with Theophylline, a non-selective PDE inhibitor, and BRL50481, a selective PDE7A inhibitor. This series of novel quinazoline derivatives were synthesized via multi-step reactions. The reaction sequence began with selective monohydrazinolysis of compounds 2a,b to give 3a,b. Schiff bases 4a-h were synthesized by the reaction of the quinazolylhydrazines 3a,b with various substituted aromatic aldehydes. The reaction of 4a-h with bromine in acetic acid, in turn, gave fused triazoloquinazolines 5a-h. These compounds were characterized by satisfied spectrum analyses mainly including 1HNMR, 13CNMR, and MS together with elemental analyses. Results and discussion: The results of in vitro PDE7A inhibition activity clearly indicated that compounds 4b, 4g, 5c, and 5f exhibited good potency. Molecular docking and molecular dynamic simulation studies further supported our findings and provided the basis of interaction in terms of conventional hydrogen bonds and π-π stacking patterns. The present results lay the groundwork for developing lead compounds with improved phosphodiesterase seven inhibitory activities.

Selective COX-2 Inhibitors: Road from Success to Controversy and the Quest for Repurposing.

The introduction of selective COX-2 inhibitors (so-called 'coxibs') has demonstrated tremendous commercial success due to their claimed lower potential of serious gastrointestinal adverse effects than traditional NSAIDs. However, following the repeated questioning on safety concerns, the coxibs 'controversial me-too' saga increased substantially, inferring to the risk of cardiovascular complications, subsequently leading to the voluntary withdrawal of coxibs (e.g., rofecoxib and valdecoxib) from the market. For instance, the makers (Pfizer and Merck) had to allegedly settle individual claims of cardiovascular hazards from celecoxib and valdecoxib. Undoubtedly, the lessons drawn from this saga revealed the flaws in drug surveillance and regulation, and taught science to pursue a more integrated translational approach for data acquisition and interpretation, prompting science-based strategies of risk avoidance in order to sustain the value of such drugs, rather than their withdrawal. Looking forward, coxibs are now being studied for repurposing, given their possible implications in the management of a myriad of diseases, including cancer, epilepsy, psychiatric disorders, obesity, Alzheimer's disease, and so on. This article briefly summarizes the development of COX-2 inhibitors to their market impression, followed by the controversy related to their toxicity. In addition, the events recollected in hindsight (the past lessons), the optimistic step towards drug repurposing (the present), and the potential for forthcoming success (the future) are also discussed.

In Vitro Anticancer Activity Screening of Novel Fused Thiophene Derivatives as VEGFR-2/AKT Dual Inhibitors and Apoptosis Inducers.

Protein kinases are seen as promising targets in controlling cell proliferation and survival in treating cancer where fused thiophene synthon was utilized in many kinase inhibitors approved by the FDA. Accordingly, this work focused on adopting fused thienopyrrole and pyrrolothienopyrimidine scaffolds in preparing new inhibitors, which were evaluated as antiproliferative agents in the HepG2 and PC-3 cell lines. The compounds 3b (IC50 = 3.105 and 2.15 µM) and 4c (IC50 = 3.023 and 3.12 µM) were the most promising candidates on both cells with good selective toxicity-sparing normal cells. A further mechanistic evaluation revealed promising kinase inhibitory activity, where 4c inhibited VEGFR-2 and AKT at IC50 = 0.075 and 4.60 µM, respectively, while 3b showed IC50 = 0.126 and 6.96 µM, respectively. Moreover, they resulted in S phase cell cycle arrest with subsequent caspase-3-induced apoptosis. Lastly, docking studies evaluated the binding patterns of these active derivatives and demonstrated a similar fitting pattern to the reference ligands inside the active sites of both VEGFR-2 and AKT (allosteric pocket) crystal structures. To conclude, these thiophene derivatives represent promising antiproliferative leads inhibiting both VEGFR-2 and AKT and inducing apoptosis in liver cell carcinoma.

Synthesis and biological evaluation of pyridazinone derivatives as selective COX-2 inhibitors and potential anti-inflammatory agents.

A series of pyridazinone derivatives, bearing an aryl or pyridyl moiety linked through an ethenyl spacer to position-6 was designed and synthesized. The newly synthesized compounds were screened for preferential inhibition of COX-2 over COX-1 isoforms. Compounds 2c, 2d, 2e, 2f, 3a, 3b, 3c, 3d and 3e are highly potent COX-2 inhibitors with IC50 values in nano-molar range. Moreover, they showed clear preferential COX-2 over COX-1 inhibition with selective indices (SIs) ranging from 4 to 38. Of particular interest, compounds 2d, 2f, 3c and 3d exhibited the most prominent COX-2 inhibitory activity with IC50 values range of 15.56-19.77 nM. They showed SIs of 24, 38, 35 and 24, respectively which were 1.4-2.2 fold higher than celecoxib (SI 17). These four compounds were further investigated in vivo for anti-inflammatory activity using the carrageenan induced rat paw edema method and ulcerogenic liability. Compounds 2f, 3c and 3d demonstrated superior anti-inflammatory activity relative to both indomethacin and celecoxib. None of these compounds showed gastric ulcerogenic effect. On the other hand, compound 2d was found equipotent to celecoxib at the second hour of oral administration. At the fourth hour, it exhibited more potent anti-inflammatory activity than celecoxib, becoming equipotent to indomethacin. It showed mild hyperemia in vivo compared to indomethacin and celecoxib. The molecular docking study of compounds 2d, 2f, 3c and 3d into COX-2 active site revealed a similar binding mode to celecoxib, explaining their remarkable COX-2 inhibitory activity. Taken together, these results indicated that these derivatives are good leads for potential COX-2 inhibitors to be used as potent and safe anti-inflammatory agents.

Synthesis of Novel Thieno[2,3-d]pyrimidine Derivatives and Evaluation of Their Cytotoxicity and EGFR Inhibitory Activity.

BACKGROUND: 4-Substitutedaminoquinazoline scaffolds were reported to possess potent cytotoxic and EGFR inhibitory activity such as gefitinib (Iressa), erlotinib (Tarceva) and tandutinib. OBJECTIVE: Synthesis of novel 4-substitutedaminothieno[2,3-d]pyrimidine derivatives as bioisosters of 4-substitutedaminoquinazoline derivatives with potential cytotoxic and EGFR inhibitory activity. METHODS: Novel 4-substitutedaminothieno[2,3-d]pyrimidine derivatives 4a-i and 5a-c were synthesized via reacting corresponding 4-chlorothieno[2,3-d]pyrimidine derivatives 3a-c with N-methylpiperazine, morpholine, N-phenylpiperazine or 1,3-propanediamine. Six compounds (2a, 4d, 4e, 5a-c) were selected by the National Cancer Institute (USA) for evaluating their cytotoxic activity using 60 different human tumor cell lines using a single dose (10-5 Molar). The rest of the synthesized compounds (2b, 2c, 3a-c, 4a-c and 4f-i) were subjected to screening against T47D breast cancer cell line using a single dose (10-5 Molar) at Pharmacology lab., Cancer biology lab., Egyptian National Institute. Moreover, compounds 2a and 4b-e were subjected to further evaluation by IC50 determination. Finally, the inhibition of epidermal growth factor receptor (EGFR) was then investigated for the most active compounds 2a and 4d. RESULTS: Compounds 2a and 4b-e showed significant cytotoxic activity. Compound 2a was more potent than doxorubicin against lung cancer cell line A549 with IC50 = 13.40 µM and comparable activity against MCF7. Compound 4d exhibited more potent activity than Doxorubicin against prostate PC3 (IC50 = 14.13 µM) while showed comparable activity against MCF7 and T47D. CONCLUSION: 4-Substitutedaminothieno[2,3-d]pyrimidine is a promising backbone for the design and synthesis of potent cytotoxic leads.

Design, synthesis and biological evaluation of some novel sulfonamide derivatives as apoptosis inducers.

Several novel thiazolidinone and fused thiazolidinone derivatives bearing benzenesulfonamide moiety were synthesized and confirmed via spectral and elemental analyses. The newly synthesized compounds were evaluated for their cytotoxic activity on colorectal cancer cell line (Caco-2). All the synthesized compounds showed better activity than the reference standards (Doxorubicin and 5-FU). Investigation of the apoptotic activity of the most active compounds revealed that compounds 3a, 5a, 5c and 6c activate both caspase-3 and Fas-ligand in Caco-2 cell line. Compound 3a was the most active compound with caspase-3 concentration of 0.43 nmol/mL and Fas-ligand concentration of 775.2 pg/mL in treated Caco-2 cells. Compound 3a was radiolabeled with 99mTc and its biodistribution pattern was evaluated in vivo using normal Swiss Albino mice. 99mTc-compound 3a complex didn't exhibit any accumulation in any body organs except for its accumulation in the colon; target organ; where it showed 8.97 ± 1.35 %ID/g at 15min p. i. that elevated till 16.02 ± 2.43 %ID/g at 120min p. i.

Design, Synthesis and Biological Evaluation of New Thieno[2,3- d]pyrimidines as Anti-inflammatory Agents.

BACKGROUND: Long term use of NSAIDS is mainly accompanied by major health implications such as gastrointestinal erosions, ulcerations and nephrotoxicity. These side effects arise from local irritation by the carboxylic acid moiety, that is common to most of NSAIDs (topical effect), in addition to decreased cytoprotective prostaglandin production. Therefore, in the medicinal chemistry research area, there is an ongoing need for the discovery of new, potent and safer anti-inflammatory lead compounds devoid of the irritant carboxylic acid moiety. METHODS: A series of new 3-substituted-2-thioxo-thieno[2,3-d]pyrimidine derivatives were synthesized through reacting the starting 3-amino-2-thioxo-thieno[2,3-d]pyrimidines with different aromatic aldehydes. The structure of all newly synthesized compounds was confirmed with spectral and elemental analyses. The synthesized thieno[2,3-d]pyrimidines were investigated for in vivo anti-inflammatory activity, using the carrageenan induced paw edema test. The possible antiinflammatory mechanism was also evaluated by determining the concentration of prostaglandin E2 (PGE2) in blood serum using a rat specific PGE2 ELISA kit. RESULTS: All test compounds could significantly reduce carrageenan induced paw edema comparable to diclofenac sodium as a potent anti-inflammatory drug. Moreover, they could decrease the concentration of PGE2 in blood serum. Interestingly, compound 4c exhibited the most potent in vivo anti-inflammatory activity with protection of 35%, 36% and 42% against carrageenan-induced paw edema after 1h, 2h and 3h, representing 92%, 86% and 88% respectively of diclofenac activity. It also decreased the concentration of PGE2 in blood serum to 19 pg/ mL which is comparable to diclofenac with PGE2 concentration of 12 pg/ mL. Moreover, Compounds 4f, 4a, 4i and 4e exerted significant anti-inflammatory activity after 4h, representing 71%, 69%, 63% and 61% respectively of diclofenac activity. Furthermore, they significantly decreased the concentration of PGE2 in blood serum. CONCLUSION: These thienopyrimidines may be used as good candidates for the search of promising, potent and safe antiinflammatory leads for being free from acidic functions.