Synthesis, in vitro and in silico anti-proliferative activity of 4-aryl-4H-chromene derivatives

Indolyl-4H-Chromene Derivatives as Antibacterial Agents: Synthesis, in Vitro and in Silico Studies

In this study, indolyl-4H-chromene derivatives are designed and synthesised using an eco-friendly multicomponent one-pot synthesis using benzaldehydes, nitroketene N, S-acetals, and indoles combine with InCl3 , a Lewis acid catalyst, and ethanol, an environmentally acceptable solvent. Due to antibiotic resistance, assessed these Indolyl-4H-chromene derivatives for their in vitro antibacterial activity against Gram-positive and Gram-negative bacteria, including Streptococcus pyogenes, Staphylococcus aureus, Clostridium pyrogenes, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa, using the agar well diffusion method and Minimum Inhibition Concentration (MIC) assay. Three compounds, 4-(1H-indol-3-yl)-6-methoxy-N-methyl-3-nitro-4H-chromen-2-amine, 4-(1H-indol-3-yl)-3-nitro-N-phenyl-4H-chromen-2-amine and 4-(6-Fluoro-1H-Indol-3-yl)-N-methyl-3-nitro-4H-chromen-2-amine showed better zone of inhibition (mm) and Minimum Inhibition Concentration (MIC) values of 10 μg/mL to 25 μg/mL against all bacterial types. The Ki values of 278.60 nM and 2.21 nM for compound 4-(1H-indol-3-yl)-3-nitro-N-phenyl-4H-chromen-2-amine showed improved interactions with DNA gyrase B and topoIV ParE's ATP binding sites in in silico studies.

Synthesis of 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes via Er(OTf)3-catalyzed cascade reactions of p-quinone methides with 1,3-dicarbonyl compounds

The Er(OTf)₃-catalyzed cascade cyclization reaction of para-quinone methides (p-QMs) with various 1,3-dicarbonyl compounds has been developed, which efficiently constructed a series of versatile 4-aryl-3,4-dihydrocoumarins and 4-aryl-4H-chromenes. Herein, we not only propose a novel cyclization strategy of p-QMs, but also provide an easy access to structurally diverse coumarins and chromenes.

Isolation, characterisation, anticancer and anti-oxidant activities of 2-methoxy mucic acid from Rhizophora apiculata: an in vitro and in silico studies

The main objective of the present study is to isolate and characterise the novel bioactive molecule, 2-methoxy mucic acid (4) from Rhizophora apiculate Blume under the Rhizophoraceae family. In this study, the 2-methoxy mucic acid (4) was isolated for the first time from the methanolic extract of the leaves of R. apiculata. Anticancer activity of 2-methoxy mucic acid (4) was evaluated against HeLa and MDA-MB-231 cancer cell lines and they displayed promising activity with IC₅₀ values of 22.88283 ± 0.72 µg/ml in HeLa and 2.91925 ± 0.52 µg/ml in the case of MDA-MB-231, respectively. Furthermore, the antioxidant property of 2-methoxy mucic acid (4) was found to be (IC₅₀) 21.361 ± 0.41 µg/ml. Apart from in vitro studies, we also performed extensive in silico studies (molecular docking and molecular dynamics simulation) on four critical antiapoptotic Bcl-2 family members (Bcl-2, Bcl-w, Bcl-xL and Bcl-B) towards 2-methoxy mucic acid (4). The results revealed that this molecule showed higher binding affinity towards Bcl-B protein (ΔG = -5.8 kcal/mol) and the structural stability of this protein was significantly improved upon binding of this molecule. The present study affords vital insights into the importance of 2-methoxy mucic acid (4) from R. apiculata. Furthermore, it opens the therapeutic route for the discovery of anticancer drugs. Research HighlightsThis is a first report on a bioactive compound identified and characterised; a novel 2-methoxy mucic acid derived from methanolic crude extract from the leaves of R. apiculata from ANI.Estimated binding free energy of 2-methoxy mucic acid is found to be -5.8 kcal/mol to the anti-apoptotic Bcl-B protein.2-methoxy mucic acid showed both significant anti-cancer and anti-oxidant activity.Communicated by Ramaswamy H. Sarma.

A comprehensive in silico and in vitro studies on quinizarin: a promising phytochemical derived from Rhizophora mucronata Lam

Mangrove plants are a great source of phytomedicines, since from the beginning of human civilization and the origin of traditional medicines. In the present study, ten different mangrove leaf methanolic extracts were screened for the type of phytochemicals followed by assessing antimicrobial, anti-oxidant and anti-cancer activities. The efficient methanolic crude extract of Rhizospora mucornata was further purified and characterized for the presence of the bioactive compound. Based on UV-visible spectroscopy, FTIR, NMR and HRMS analysis, the bioactive compound was 1,4-dihydroanthraquinone; also termed as Quinizarin. This identified compound was potential in exhibiting antimicrobial, antioxidant, and cytotoxic activity. Quinizarin inhibited the growth of Bacillus cereus and Klebsiella aerogenes with minimum inhibitory concentration (MIC) of 0.78 and 1.5 mg/ml. The DPPH free radical scavenging assay revealed the maximum activity of 99.8% at the concentration of 200 µg/ml with an IC50 value of 12.67 ± 0.41 µg/ml. Cytotoxic assay against HeLa (cervical) and MDA-MB231(breast) cancer cell lines revealed IC50 values to be 4.60 ± 0.26 and 3.89 ± 0.15 µg/ml. Together the results of molecular docking and molecular dynamics simulation studies explained that Quinizarin molecule showed stronger binding affinity (-6.2 kcal/mol) and significant structural stability towards anti-apoptotic Bcl-2 protein. Thus, the study put forth the promising role of the natural molecule - Quinizarin isolated from R. mucornata in the formulation of therapeutic drugs against bacterial infections and cancer. Communicated by Ramaswamy H. Sarma.

Synthesis, Cytotoxic Activity, Crystal Structure, DFT Studies and Molecular Docking of 3-Amino-1-(2,5-dichlorophenyl)-8-methoxy-1H-benzo[f]chromene-2-carbonitrile

The target compound 3-amino-1-(2,5-d ichlorophenyl)-8-methoxy-1H-benzo[f]-chromene-2-carbonitrile (4) was synthesized via a reaction of 6-methoxynaphthalen-2-ol (1), 2,5-dichlorobenzaldehyde (2), and malononitrile (3) in ethanolic piperidine solution under microwave irradiation. The newly synthesized β-enaminonitrile was characterized by FT-IR, 1H NMR, 13C NMR, mass spectroscopy, elemental analysis and X-ray diffraction data. Its cytotoxic activity was evaluated against three different human cancer cell lines MDA-MB-231, A549, and MIA PaCa-2 in comparison to the positive controls etoposide and camptothecin employing the XTT cell viability assay. The analysis of the Hirshfeld surface was utilized to visualize the reliability of the crystal package. The obtained results confirmed that the tested molecule revealed promising cytotoxic activities against the three cancer cell lines. Furthermore, theoretical calculations (DFT) were carried out with the Becke3-Lee-Yang-parr (B3LYP) level using 6-311++G(d,p) basis. The optimization geometry for molecular structures was in agreement with the X-ray structure data. The HOMO-LUMO energy gap of the studied system was discussed. The intermolecular-interactions were studied through analysis of the topological-electron-density(r) using the QTAIM and NCI methods. The novel compound exhibited favorable ADMET properties and its molecular modeling analysis showed strong interaction with DNA methyltransferase 1.

Dual active 1, 4-dihydropyridine derivatives: Design, green synthesis and in vitro anti-cancer and anti-oxidant studies

The present work describes the design of 1,4-dihydropyridines (1,4-DHPs) with diverse variations in structural and functional groups. The physico-chemical properties and drug-like molecule nature evaluations were carried out using SWISSADME. A simple, economical, eco-friendly, water-mediated and Para-Toluene sulfonic acid catalysed multicomponent and one-pot synthetic method from nitroketene N, S- acetals (NMSM) and corresponding aldehydes has been developed. All compounds (6a-u and 13a-h) were subjected to in vitro assays against two important human cancer cell lines Viz. are Laryngeal carcinoma (Hep2) and Lung adenocarcinoma (A549) cells. The reduction level of DPPH (%) used to evaluate the anti-oxidant properties. The 1,4-DHP derivatives, 6o, 6u and 6l displayed the potent anti-cancer activity with IC₅₀ value of 10 µM, 14 µM and 10 µM against the Hep2 and 8 µM, 9 µM and 50 µM against the A549 cells. Similarly, the anti-oxidant properties of 6o, 6l and 6u at a standard concentration of 50 µg, are found to be 70.12%, 63.90% and 59.57% respectively favours the 1,4-DHP derivatives dual activity potentials. The compounds, 6o and 6l found to be equivalent with standard drug, Doxorubicin.

A proficient microwave synthesis with structure elucidation and the exploitation of the biological behavior of the newly halogenated 3-amino-1H-benzo[f]chromene molecules, targeting dual inhibition of topoisomerase II and microtubules

In our endeavors to develop novel and powerful agents with antiproliferative activities, a series of β-enamionitriles, linked to the 8-bromo-1H-benzo[f]chromene moieties (4a-m), was designed and synthesized under microwave irradiation conditions. The structures of the target compounds were established on the basis of their spectral data: IR, ¹H NMR, ¹³C NMR, ¹³C NMR-DEPT/APT, ¹⁹F NMR and MS. Furthermore, the antiproliferative properties were evaluated against the human cancer cell lines MCF-7, HCT-116, and HepG-2 in comparison to the positive controls Vinblastine and Doxorubicin, employing the viability assay. The obtained results confirmed that most of the tested molecules revealed strong and selective cytotoxic activities against the three cancer cell lines. The most potent cytotoxic compounds 4b, 4d, 4e, 4i, and 4k were elected for further examination, such as the cell cycle analysis, the apoptosis assay, the Caspase production, and the DNA fragmentation. This study also revealed that the desired compounds stimulate cell cycle arrest at the G2/M phases, increase the production of Caspases 3, 8, and 9, and finally cause intrinsic and extrinsic apoptotic cell death. Moreover, these compounds suppress the action of the topoisomerase II enzyme and also disrupt the microtubule functions. The SAR study of the synthesized compounds verified that the substitution on the phenyl ring of the 1H-benzo[f]chromene nucleus, accompanied with the presence of the bromine atom at the 8-position, increases the ability of these molecules against different cell lines.

One-Pot Synthesis of Densely Substituted Pyrazolo[3,4-b]-4,7-dihydropyridines

We have achieved a facile synthesis of a combinatorial library of densely substituted pyrazolo[3,4-b]-4,7-dihydropyridines- the mimics of antigenital wart drug podophyllotoxin-from 5-aminopyrazoles and 4-(methylthio) 4H-chromenes. The C(4) pyrazolyl 4H-chromenes, which also possess structural features of podophyllotoxin, were isolable intermediates in the two-step, one-pot condensation. The condensation took place in a one-pot, multicomponent manner when 3-oxo-3-phenylpropanenitriles, hydrazine (precursors for 5-aminopyrazoles) and 4-(methylthio)-4H-chromenes were heated in refluxing ethanol. The condensation, however, stops at 4H-chromene stage when methyl hydrazine or phenylhydrazine were employed. Our findings offer an opportunity for synthesis of a combinatorial library of podophyllotoxin mimics, thus paving the way for discovery of lead candidates for cancer treatment.

9-Fluoro-2,4,4a,6-tetrahydrospiro[benzo[c]chromene-3,2′-[1,3]dioxolane]

In the title compound, C15H15FO3, the dihedral angle between the mean plane through all the non-H atoms of the dioxolane ring with those of the rest of the atoms of the chromene ring system, including the substituent F atom, is 81.1 (1)°. The pyran ring has an envelope conformation with the O atom as the flap. The cyclohexene ring has a half-chair conformation, while the dioxolane ring has a twisted conformation on an –O—CH2– bond. In the crystal, molecules are linkedviaC—H...O hydrogen bonds, forming chains along [100]. The chains are linked by C—H...π interactions, involving the fluorobenzene ring, forming layers parallel to theacplane.