First Synthesis of 2-Amino-5-hydroxy-4H-chromene-3-carbonitriles from 4-(2-Pyridylazo)resorcinol

Abstract

4-(2-Pyridylazo)resorcinol (PAR) sodium salt reacts with aromatic aldehydes and malononitrile in aqueous ethanol to form 2-amino-4-aryl-5-hydroxy-6-(2-pyridylazo)-4H-chromene-3-carbonitriles.

Experimental and Theoretical Study on the Homodimerization Mechanism of 3-Acetylcoumarin

In the present study, the reaction conditions for homodimerization process of 3-acetylcoumarin were achieved under sonication using combination of zinc and metallic salt (ZnCl2 or Zn(OAc)2). Appropriate frequency and sound amplitude have been identified as significant variables for the initiation of the reaction. On the base of first principal calculations and experimental results, the mechanism of the reaction was investigated. The relative stability of the possible intermediates has been compared, including evaluation on the ionic and radical reaction pathways for the dimerization process. Theoretical results suggested that the radical mechanism is more favorable. The C-C bond formation between the calculated radical intermediates occurs spontaneously (∆G = −214 kJ/mol for ZnCl2, −163 kJ/mol in the case of Zn(OAc)2), which proves the possibility for the homodimerization of 3-acetylcoumarin via formation of radical species. Both experimental and theoretical data clarified the activation role of the solvent on the reactivity of the Zn-salt. The formation of complexes of solvent molecules with Zn-atom from the ZnCl2 reduces the energy barrier for the dissociation of Zn-Cl bond and facilitate the formation of the dimeric product.

Characterization of novel heterocyclic compounds based on 4-aryl-4H-chromene scaffold as anticancer agents: Design, synthesis, antiprofilerative activity against resistant cancer cells, dual β-tubulin/c-Src inhibition, cell cycle arrest and apoptosis induction

In this study, three novel sets of 4-aryl-4H-chromene derivatives 4a-c, 6a-d and 7a-c were synthesized and evaluated for anticancer activity. Characterization of new compounds was established on basis of elemental analyses and spectral data. All new compounds were investigated for their antiproliferative activity against HCT-116, HepG-2 and MCF-7 cell lines using vinblastine and staurosporine as positive controls. Compounds 4b, 4c and 6d showed superior cytotoxicity against HCT-116, HepG-2 and MCF-7 cell lines, respectively with IC₅₀ ranged from 3.31 to 4.95 μM. Additionally, compound 4b showed excellent cytotoxic activity (IC₅₀ = 39.83 μM) against resistant HCT-116 better than doxorubicin (IC₅₀ = 164.60 μM), while compounds 4c and 6d exhibited moderate cytotoxic activity against resistant HepG-2 and resistant MCF-7 cell lines. The most potent compounds inhibited both β-tubulin polymerization (IC₅₀ = 8.78 - 16.47 μM) and c-Src kinase (IC₅₀ = 0.07 - 0.18 μM) enzymes. Compounds 4b, 4c and 6d activated caspase-3, caspase-7, and caspase-9 proteins relative to untreated cells, revealing apoptosis induction. Apoptosis was also confirmed through up-regulation of Bax and down-regulation of Bcl-2 protein expression levels. Cell cycle analysis of compound 6d showed accumulation of cells in pre-G1 phase and cell cycle arrest at S phase in MCF-7 treated cells. As well 6d caused 7- and 63- fold increase in apoptotic cell population at early and late apoptosis stages. Finally, molecular modeling study was performed to predict the binding pattern of the target compounds inside c-Src kinase receptor.

A review on diverse heterocyclic compounds as the privileged scaffolds in non-steroidal aromatase inhibitors

Breast cancer, emerging malignancy is common among women due to overexpression of estrogen. Estrogens are biosynthesized from androgens by aromatase, a cytochrome P450 enzyme complex, and play a pivotal role in stimulating cell proliferation. Therefore, deprivation of estrogen by blocking aromatase is considered as the effective way for the inhibition and treatment of breast cancer. In recent years, various non-steroidal heterocyclic functionalities have been extensively developed and studied for their aromatase inhibition activity. This review provides information about the structural-activity relationship of heterocycles (Type II) towards aromatase. This aids the medicinal chemist around the significance of different heterocyclic moieties and helps to design potent aromatase inhibitors.

N-Aryl iminochromenes inhibit cyclooxygenase enzymes via π–π stacking interactions and present a novel class of anti-inflammatory drugs

Cyclooxygenase enzymes (COX1/2) have been widely studied and noted for their role in the biosynthesis of inflammation-induced proteins, prostaglandins and thromboxane. Multiple anti-inflammatory drugs have been developed to target these two enzymes, but most of them appeared to have notable adverse effects, especially on the cardiovascular system and lower gastrointestinal tract, suggesting an urgent need for new potent anti-inflammatory drugs. In this study, we screened twenty-two previously synthesized N-aryl iminochromenes (NAIs) for their anti-inflammatory activity by performing COX-1/2 inhibitory assays. Five compounds (1, 10, 14, 15, and 20) that gave the best in vitro anti-inflammatory results were subjected to an in vivo anti-inflammatory assay using the formalin-induced hind rat paw oedema method, followed by in silico studies using indomethacin and celecoxib as standard drugs. Among them, compound 10 stood out as the best candidate, and the percentage reduction in paw oedema at the dose of 20 mg kg⁻¹ body weight was found to be substantially higher with compound 10 than that with indomethacin. This is mostly due to the excellent suitability of the chromene-phenyl scaffold with a highly concentrated area of aromatic residues, which produced good π–π stacking interactions. Taken together, this study strongly suggests compound 10 as a potential candidate for anti-inflammatory drug research.

Screening of N-aryl iminochromenes for their anti-inflammatory activities by performing in vitro, in vivo, and in silico studies.

Novel Alkylimidazolium Ionic Liquids as an Antibacterial Alternative to Pathogens of the Skin and Soft Tissue Infections

Keeping in mind the concept of green chemistry, this research aims to synthesize and characterize new ionic liquids (ILs) derived from N-cinnamyl imidazole with different sizes of alkyl chains (1, 6, 8, and 10 carbon atoms), and evaluate their antibacterial activity against Skin and soft tissue infections (SSTIs) causative bacteria. The antibacterial screening was carried out by agar well diffusion and the Minimum Inhibitory Concentration (MIC) and Half Maximum Inhibitory Concentration (IC₅₀) of the different ILs were determined by microdilution in broth, also Molecular dynamics simulations were performed to study the interaction mechanism between ILs and membranes. The MIC value in Gram-positive bacteria showed that as the hydrocarbon chain increases, the MIC value decreases with a dose-dependent effect. Furthermore, Gram-negative bacteria showed high MIC values, which were also evidenced in the antibacterial screening. The molecular dynamics showed an incorporation of the ILs with the longer chain (10 C), corresponding to a passive diffusion towards the membrane surface, for its part, the ILs with the shorter chain due to its lack of hydrophobicity was not incorporated into the bilayer. Finally, the new ILs synthesized could be an alternative for the treatment of Gram-positive bacteria causative of SSTIs.

First intramolecular Diels–Alder reactions using chromone derivatives: synthesis of chromeno[3,4-b]xanthones and 2-(benzo[c]chromenyl)chromones

Chromeno[3,4-b]xanthones and 2-(benzo[c]chromenyl) chromones were obtainedviaan MW-assisted intramolecular DA reaction, followed byin situdehydrogenation.