Synthesis of new chromeno-annulated cis-fused pyrano[4,3-c]isoxazole derivatives via intramolecular nitrone cycloaddition and their cytotoxicity evaluation

Synthesis, DFT calculation, pharmacological evaluation, and catalytic application in the synthesis of diverse pyrano[2,3-c]pyrazole derivatives

Pyranopyrazole and its derivatives are classified to be a pharmacologically significant active scaffold for almost all modes of biological activities. In this work, An efficient, green, and facile three-component reaction for preparing pyrano[2,3-c]pyrazole derivatives via the condensation reaction of 5-methyl-2-phenyl-2,4-dihydro-3H-pyrazol-3-one, ethyl acetoacetate, and malononitrile in the presence of ZnO Nanoparticle. The products are produced with high yields and in shorter reaction times. It also is mild, safe, green, and environmentally friendly. The geometric parameters such as dipole moment, bond length, dihedral angles, total energy, heat of formation, atomic charges and energies at a highly accurate for prepared compounds were computed by Denisty Functional Theory along with the B3LYP functional. The newly synthesized compounds were screened for their anti-inflammatory and antioxidant activity. Some of the tested compounds displayed promising activities. The newly prepared compounds were found to be potent towards the antioxidant activity. Results indicated that compounds 11 and 12 exhibited significant (p ≥ 0.05) in vitro total antioxidant activity as 44.93 ± 0.15 and 39.60 ± 0.10 U/ML, respectively higher than standard ascorbic acid (29.40 ± 0.62).

Silver nanoparticles-decorated Preyssler functionalized cellulose biocomposite as a novel and efficient catalyst for the synthesis of 2-amino-4H-pyrans and spirochromenes

Silver nanoparticles-decorated Preyssler functionalized cellulose biocomposite (PC/AgNPs) was prepared and fully characterized by FTIR, UV–vis, SEM, and TEM techniques. The preparation of PC/AgNPs was studied systematically to optimize the processing parameters by Taguchi method using the amount of PC, reaction temperature, concentration of silver nitrate and pH of medium. Taguchi’s L9 orthogonal (4 parameters, 4 level) was used for the experimental design. The SEM analysis confirmed the presence of the Preyssler as a white cloud as well as spherical AgNPs on the surface of cellulose. The formation of AgNPs on the surface was observed by changing of the color from yellow to deep brown and confirmed by UV–vis spectroscopy. The best yield of AgNPs forming was obtained in pH 12.5 at 80 ºC in 20 min. TEM analysis confirmed the formation of spherical AgNPs with a size of 50 nm, at the 1% wt. loading of Preyssler. This easily prepared PC/AgNPs was successfully employed as an efficient, green, and reusable catalyst in the synthesis of a wide range of 2-amino-4H-pyran and functionalized spirochromene derivatives via a one-pot, multicomponent reaction. The chief merits realized for this protocol were the utilization of commercially available or easily accessible starting materials, operational simplicity, facile work-up procedure, obtaining of high to excellent yields of the products and being done under green conditions. The catalyst could be easily separated from the reaction mixture and reused several times without observing any appreciable loss in its efficiency.

Synthesis of new chromeno-carbamodithioate derivatives and preliminary evaluation of their antioxidant activity and molecular docking studies

New chromeno carbamodithioates (7a-i), have been synthesized from 2, 3-dimethyl-7-(oxiran-2-ylmethoxy)-4H-chromen-4-one (5), carbondisulphide and commercially available acyclic and cyclic secondary amines in acetonitrile with good to excellent yields. The free radical scavenging activity of novel chromone-carbamodithioate analogues was quantitatively estimated by spectrophotometric method. Whereas, molecular docking studies were performed with the active site of cyclooxygenase-2 to identify hydrogen bonding, hydrophobic and ionic interactions between protein and ligands. The compounds 7g and 7h demonstrated potent antioxidant activity with IC₅₀ of 1.405±0.019mM and 1.382±0.35mM respectively compared to Ascorbic acid.

Discovery of 6,7-dihydro-3H-pyrano[4,3-c]isoxazol-3-ones as a new class of pathogen specific anti-leptospiral agents

A simple and efficient method for the synthesis of a series of 6,7-dihydro-3H-pyrano[4,3-c]isoxazol-3-one derivatives starting from 5-carboalkoxy-2,3-dihydropyranone (5-CDHPs) has been developed. Pyranoisoxazolones 10a-j, dihydronaphthopyran-4-one (DHNPs) class of natural product 12b and 12c and its analogues 12a and 13a-c were preliminarily screened against pathogenic leptospiral serovar Autumnalis strain N2 at various concentrations. Six pyranoisoxazolones, 10b, 10d, 10f, 10g, 10i and 10j which displayed very good anti-leptospiral activity was taken for secondary screening against twelve strains of pathogenic and one non-pathogenic leptospiral serovars. While all the compounds displayed significant anti-leptospiral activity against the pathogenic serovars at MIC of 62.5-500 μg/mL. Compounds 10d, 10g and 10j did not show any significant effect on non-pathogenic serovar. Inhibition of leptospires at a significant level by pyranoisoxazolone 10g was confirmed using RT-qPCR assay. In vivo treatment of BALB/c mice with compound 10g revealed that, it has 95% survivability against the pathogenic strain Canicola and also showed inhibition of renal colonization of leptospires. Compound 10g was found to show cytotoxicity against THP-1 cells only at higher concentration (≥75 μg/mL). Effective binding of compound 10g with leptospiral outer membrane protein LipL32 observed via in silico molecular docking provided a suitable explanation for pathogen specificity of compound 10g. Antibiotics acting against leptospirosis in human are very few. The results obtained from in vitro, in vivo and in silico study reveals that 6,7-dihydro-3H-pyrano[4,3-c]isoxazol-3-ones class of compounds are lead molecules for further development as pathogen specific anti-leptospiral agents.

The synthesis of angular heteroarenochromones based on 7-hydroxy-8-carbonylchromones

The present review highlights advanced strategies to the synthesis of the chromones annulated with O- and N-containing heterocycles at C(7)-C(8) bond. Due to the prevalence of such motives in different kinds of natural flavonoids and some alkaloids, fused chromones have attracted a great deal of attention so far. On the other hand a wide range of biological activities is displayed by the compounds of this type both among naturally occurring flavonoids and their synthetic analogues. 8-Carbonyl-7-hydroxychromones proved to be versatile synthones for the synthesis of angular hetarenochromones via approach of annulation of a heterocycle to the chromone core. It also addresses the question of the biological activity of naturally occurring and fused synthetic hetarenochromones.

Synthesis and biological evaluation of novel Δ2-isoxazoline fused cyclopentane derivatives as potential antimicrobial and anticancer agents

Novel Δ²-isoxazoline fused cyclopentane derivatives have been synthesized and evaluated for their antimicrobial and anticancer activities.

Advances in chemistry of chromone aminomethyl derivatives

Chromones play an important role in the design and discovery of new pharmacologically active compounds. A large volume of reports dedicated to synthesis and study of properties of nitrogen-containing chromone derivatives show important role of chromone alkaloid-like compounds. The present review covers achievements in the field of synthesis of chromone aminomethyl derivatives as one of perspective scaffolds.

Biological evaluation and SAR analysis of O-methylated analogs of quercetin as inhibitors of cancer cell proliferation

Using a high-throughout screening approach, the anticancer activities of 16 O-methylated (OMe) analogs of quercetin were assessed. The structure-activity relationships showed that OMe moieties at the 4' and/or 7 positions were important for maintaining inhibitory activities against the 16 cancer cell lines. Furthermore, when the OH groups at the 3' and 4' positions were both replaced by OMe moieties, anticancer activity was enhanced.