Synthesis, immunomodulating effects and structure-activity relationships of new N-phenyl-5-amino-3-methylisoxazole-4-carboxamides

Design, synthesis, and biological evaluation of 5-(1H-indol-5-yl)isoxazole-3-carboxylic acids as novel xanthine oxidase inhibitors

Xanthine oxidase (XO) is a key enzyme for the production of uric acid in the human body. XO inhibitors (XOIs) are clinically used for the treatment of hyperuricemia and gout, as they can effectively inhibit the production of uric acid. Previous studies indicated that both indole and isoxazole derivatives have good inhibitory effects against XO. Here, we designed and synthesized a novel series of N-5-(1H-indol-5-yl)isoxazole-3-carboxylic acids according to bioisosteric replacement and hybridization strategies. Among the obtained target compounds, compound 6c showed the best inhibitory activity against XO with an IC50 value of 0.13 μM, which was 22-fold higher than that of the classical antigout drug allopurinol (IC50 = 2.93 μM). Structure-activity relationship analysis indicated that the hydrophobic group on the nitrogen atom of the indole ring is essential for the inhibitory potencies of target compounds against XO. Enzyme kinetic studies proved that compound 6c acted as a mixed-type XOI. Molecular docking studies showed that the target compound 6c could not only retain the key interactions similar to febuxostat at the XO binding site but also generate some new interactions, such as two hydrogen bonds between the oxygen atom of the isoxazole ring and the amino acid residues Ser876 and Thr1010. These results indicated that 5-(1H-indol-5-yl)isoxazole-3-carboxylic acid might be an efficacious scaffold for designing novel XOIs and compound 6c has the potential to be used as a lead for further the development of novel anti-gout candidates.

Synthesis, Immunosuppressive Properties, and Mechanism of Action of a New Isoxazole Derivative

This work describes the synthesis of a new series of isoxazole derivatives, their immunosuppressive properties, and the mechanism of action of a representative compound. A new series of N′-substituted derivatives of 5-amino-N,3-dimethyl-1,2-oxazole-4-carbohydrazide (MM1⁻MM10) was synthesized in reaction of 5-amino-N,3-dimethyl-1,2-oxazole-4-carbohydrazide with relevant carbonyl compounds. The isoxazole derivatives were tested in several in vitro models using human cells. The compounds inhibited phytohemagglutinin A (PHA)-induced proliferation of peripheral blood mononuclear cells (PBMCs) to various degrees. The toxicity of the compounds with regard to a reference A549 cell line was also differential. 5-amino-N′-(2,4-dihydroxyphenyl)methylidene-N,3-dimethyl-1,2-oxazole-4-carbohydrazide (MM3) compound was selected for further investigation because of its lack of toxicity and because it had the strongest antiproliferative activity. The compound was shown to inhibit lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF α) production in human whole blood cell cultures. In the model of Jurkat cells, MM3 elicited strong increases in the expression of caspases, Fas, and NF-κB1, indicating that a proapoptotic action may account for its immunosuppressive action in the studied models.

3-(4-Chloro-phen-yl)-7-methyl-4-(4-methyl-phen-yl)-1-oxa-2,7-diaza-spiro-[4.5]dec-2-en-10-one

In the title compound, C₂₁H₂₁ClN₂O₂, the dihydro­isoxazole ring adopts an envelope conformation and the piperidinone ring is in a chair conformation. The dihedral angle between the two benzene rings is 84.2 (1)°. The crystal used was an inversion twin.

Reactions of 5-amino-3-methylisoxazole-4-carboxylic acid hydrazide with carbonyl compounds: immunological activity and QSAR studies of products

A series of 4-imino derivatives of the 5-amino-3-methylisoxazole-4-carboxylic acid hydrazide and 5-amino-3-methylisoxazole[5,4-d]-6,7-dihydropyrimidine has been prepared by condensation of 5-amino-3-methylisoxazole-4-carboxylic acid hydrazide with carbonyl compounds. The resulting products were evaluated for their immunological activities in the models of the humoral and cellular immune responses of mice in vivo and concanavalin A (Con A) and lipopolysaccharide (LPS)-induced splenocyte proliferation. In addition, effects on polyclonal antibody production by human peripheral blood cells in culture were investigated. For all studied compounds we carried out quantum chemical calculations at ab initio B3LYP 6-31G(d, p) level. The stimulatory or inhibitory effects depended strongly on the origin and location of substitunets, which is described in the conclusions and was supported by QSAR studies.