Discovery of a new pyrido[2,3-d]pyridazine-2,8-dione derivative as a potential anti-inflammatory agent through COX-1/COX-2 dual inhibition

In this paper, we present the design and synthesis of a novel series of pyrido[2,3-d]pyridazine-2,8-dione derivatives via the annulation of the 2-pyridone pattern. The synthesized derivatives were evaluated for in vivo anti-inflammatory activity using an ear edema model. Compound 7c, which showed a greater inhibition of ear edema (82%), was further tested for its in vitro COX-1/COX-2 inhibitory activity. Compound 7c showed similar inhibitory activities against COX-1 and COX-2 isoenzymes. The structural features that ensure the dual inhibition of COX-1 and COX-2 were elucidated using molecular docking studies. Overall, the ring closing of 2-pyridone pattern I transformed this highly selective COX-2 inhibitor into a dual COX inhibitor (7c), which could serve as a model for determining selectivity for COX-2.

Efficient synthesis and antitumor evaluation of 4-aminomethyl-N-arylpyrazoles: Discovery of potent and selective agents for ovarian cancer

A new one-pot two-step sequential methodology for synthesis of novel 3-carboxyethyl 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives is reported. One-pot transformation of β-enamino diketones and arylhydrazines generated 4-iminium-N-arylpyrazole salt intermediates in situ, which were easily transformed into 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives by NaBH₃CN. The products could be isolated in the free or hydrochloride salt forms. Also, it was possible to obtain the products in the zwitterionic form by ester group hydrolysis. Furthermore, all synthesised compounds were evaluated in vitro against a panel of eight human tumor cell lines. The 4-[(tert-butylamino)methyl]-N-arylpyrazole derivatives were much more powerful than the hydrochloride and zwitterionic forms. Moreover, the results suggest that the N-aryl group at the pyrazole ring is vital for modulating antiproliferative activity. The 3-carboxyethyl 4-[(tert-butylamino)methyl]-N-phenylpyrazoles 3a-g exhibited higher inhibitory activities against OVCAR-3, with GI₅₀ values of 0.013-8.78 μM, and lower inhibitory activities against normal human cell lines. Molecular docking was performed to evaluate the probable binding mode of 3a into active site of CDK2.

Antiparasitic activities of novel pyrimidine N-acylhydrazone hybrids

In this article, a series of 29 new pyrimidine N-acylhydrazone hybrids were synthesized and evaluated in vitro against Leishmania amazonensis and Trypanosoma cruzi protozoa that cause the neglected diseases cutaneous leishmaniasis and Chagas disease, respectively. Eight of the target compounds showed significant antiprotozoal activities with IC₅₀ values in 4.3-33.6 μM range. The more active compound 4f exhibited selectivity index greater than 15 and drug-like properties based on Lipinski's rule.

Synthesis of novel 3,5,6-trisubstituted 2-pyridone derivatives and evaluation for their anti-inflammatory activity

The inflammatory response is the reaction of living tissue to an injury of a foreign nature, such as infection and irritants, and occurs as part of the body's natural defence response. Compounds capable of inhibiting cyclooxygenase (COX) enzymes, especially COX-2, have great potential as anti-inflammatory agents. Herein we present the regioselective synthesis of 49 novel compounds based on the 2-pyridone nucleus. The topical anti-inflammatory activity of seventeen compounds was evaluated in mice by croton oil (CO) induced ear edema assay. Most of the compounds exhibited a high level of in vivo anti-inflammatory activity, reducing ear edema and myeloperoxidase (MPO) activity. The most active compounds (2a and 7a) were inhibitors of COX enzymes. Compound 2a selectively inhibited the COX-2, while 7a was nonselective. Further, the compound 2a showed effective binding at the active site of COX-2 co-crystal by docking molecular study.

Development of methodologies for the regioselective synthesis of four series of regioisomer isoxazoles from β-enamino diketones

Four methodologies are reported for the regioselective synthesis of four series of regioisomer isoxazoles from cyclocondensation of β-enamino diketones and hydroxylamine hydrochloride. Regiochemical control was achieved by varying reaction conditions and substrate structure. The mild reaction conditions used to access 4,5-disubstituted, 3,4-disubtituted, and 3,4,5-trisubstituted regioisomer isoxazoles, as well as the pharmacological and synthetic potential of the products, make these novel methodologies very powerful.

Efficient and regioselective synthesis of isoxazoles was demonstrated through cyclocondensation of β-enamino diketones with hydroxylamine: four of the six possible regioisomers were obtained.

Synthesis and evaluation against Leishmania amazonensis of novel pyrazolo[3,4-d]pyridazinone-N-acylhydrazone-(bi)thiophene hybrids

A new series of pyrazolo[3,4-d]pyridazin-7-one derivatives were synthesised and evaluated for their in vitro antileishmanial activity against Leishmania amazonensis promastigote and axenic amastigote forms. The results showed that the pyrazolo[3,4-d]-pyridazin-7-one-N-acylhydrazone-(bi)thiophene hybrids 5b, 6b and 6d exhibit better antileishmanial activity with IC₅₀ 84.96, 3.63 and 10.79 μM, against the promastigote form and IC₅₀ 32.71, 2.32 and >100 μM against the axenic amastigote form, respectively. The active compounds had their cytotoxicity tested against macrophages and fibroblast cells with a higher selectivity index than 10 for compounds 6b and 6d. Molecular docking studies were performed for all active compounds using the enzyme trypanothione reductase (TR) to investigate a possible action mechanism. The results suggested that active compounds had interactions with the residues of amino acids Gly 13, Thr 51, Thr 160, Gly 161, Tyr 198, Arg 287, Asp 327, Thr 335, which may inhibit the enzyme TR.