Design, synthesis, in vitro and in silico anti-cancer activity of 4H-chromenes with C4-active methine groups

Isocyanide-based multicomponent reactions for the synthesis of benzopyran derivatives with biological scaffolds

Benzopyrans (BZPs) are among the most privileged and influential small O-heterocycles that form the core of many natural compounds, commercial drugs, biological compositions, agrochemicals, and functional materials. BZPs are divided into six general categories including coumarins, chromans, 2H-chromenes, 4H-chromenes, chromones, and 4-chromanones, each of which is abundant in many plants and foods. These oxygenated heterocyclic compounds are fascinating motifs and have extensive applications in biology and materials science. Hence, numerous efforts have been made to develop innovative approaches for their extraction and synthesis. However, most of them are step-by-step or multi-step strategies that suffer from waste material generation and a tedious extraction process. Isocyanide-based multicomponent reactions (I-MCRs) offer a highly efficient method for overcoming these problems. The I-MCR is a simple and environmentally friendly one-pot domino procedure that does not require intermediate isolation or workup and is generally more efficient in material usage. This review covers all research articles related to I-MCRs for synthesizing BZP derivatives from the beginning to the middle of the year 2023. This strategy will be useful for organic and pharmaceutical chemists to design new drugs and optimize the synthesis steps of biological compounds and commercial drugs with benzopyran cores.

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.

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.

Isolation and biological evaluation 7-hydroxy flavone from Avicennia officinalis L: insights from extensive in vitro, DFT, molecular docking and molecular dynamics simulation studies

The flavonoid based 7-hydroxy flavone (PubChem CID: 5281894; molecular formula: C₁₅H₁₀O₃) molecule has been isolated for the first time from the methanolic extract from the leaves of Avicennia officinalis L. in the tropical mangrove ecosystem of Andaman and Nicobar Islands (ANI), India. The molecular structure of bioactive compound was characterized by spectroscopic analysis, including FT-IR, ¹H, ¹³C NMR spectroscopy and ESI-HRMS and elucidated as 7-hydroxy flavone. An anticancer activity of isolated 7-hydroxy flavone was evaluated by in vitro study against two different human cancer cell lines namely, HeLa (cervical cells) and MDA-MB231 (breast cells) and they exhibited promising anticancer activity with IC₅₀ values are 22.5602 ± 0.21 µg/mL and 3.86474 ± 0.35 µg/mL, respectively. The antioxidant property of 7-hydroxy flavone at a standard concentration of 50 µg, was found to be (IC₅₀) 5.5486 ± 0.81 µg/mL. In summary, this investigation provides evidence that 7-hydroxy flavone exhibits both anticancer and antioxidant properties. Meanwhile, the antimicrobial activity ability of 7-hydroxy flavone were also evaluated using three Gram positive and two Gram negative strain exhibited no antimicrobial activities. Density-functional theory (DFT) studies confirm the structure is global minima in the PES, from the optimized geometry FMO and MESP map analyzed. Further, the molecular docking and molecular dynamics simulation studies result shows that 7-hydroxy flavone has the better binding ability with anti-apoptotic Bcl-2 protein with the estimated free energy of binding of -6.3 kcal/mol. This bioactive compound may be act as drug candidate for treating various kinds of cancers. HighlightsA 7-hydroxy flavone molecule has been isolated from Avicennia officinalis.The isolated pure compound was subjected to spectral analysis such as FT-IR, ¹H NMR, ¹³C NMR spectral data and HRMS analysis for skeleton of the molecule.The anticancer activity of 7-hydroxy flavone studied against Cervical (HeLa) cancer cell lines and breast (MDA-MB231) cancer cell lines with the IC₅₀ values of 22.5602 ± 0.21 µg/mL and 3.86474 ± 0.35 µg/mL), respectively.The antioxidant properties of 7-hydroxy flavone were found to be (IC₅₀) 5.5486 ± 0.81 µg/mL at a standard concentration of 50 µg.DFT, molecular docking and MD simulation results explained that 7-hydroxy flavone could be the most promising candidate to inhibit the function of anti-apoptotic Bcl-2 protein in cancerous cell.Communicated by Ramaswamy H. Sarma.

Development of potential anticancer agents and apoptotic inducers based on 4-aryl-4H chromene scaffold: Design, synthesis, biological evaluation and insight on their proliferation inhibition mechanism

An array of 4-aryl-2-amino-4H chromene derivatives were designed, synthesized, and evaluated for cytotoxic activity against four cancer cell lines and two non-cancerous cell lines. The most active candidates were further screened for their in vitro anticancer activity on NCI panel of 60 human cancer cell lines where compounds 2a, 2b, 4a-2, and 2e showed promising activity against various leukemia, non-small lung, renal, prostate, and breast cancer cell lines, particularly against NCI-H522 non-small lung cancer cell line (GI₅₀ of 0.35-0.60 µM), MCF7 breast cancer cell line (GI₅₀ of 0.34-0.59 µM), and MDA-MB-468 breast cancer cell line (GI₅₀ of 0.23-0.40 µM). Compound 2b was the most potent against all leukemia and prostate cancer cell lines with GI₅₀ values (0.29-0.60 µM). Compound 2b inhibited the proliferation of MCF-7 and HepG2 cells by inducing cell cycle arrest and apopotosis. 2b downregulated the mRNA abundance of BAX, Apaf-1 and caspase-3 and upregulated BCL-2. The activities of caspase-3 and caspase-9 were declined in MCF-7 and HepG2 cells treated with compound 2b. Compounds 2b and 4a-2 inhibited tubulin polymerization, with an IC₅₀ values of 0.92 and 1.13 µM, respectively. These findings indicate that these synthesized compounds may represent potential drug candidates to inhibit the proliferation of different types of cancer cells.

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.

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.

Synthesis of new 3H-chromeno[2,3-d]pyrimidine-4,6(5H,7H)-diones via the tandem intramolecular Pinner/Dimroth rearrangement

The reaction of 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles with excess aliphatic carboxylic acids in the presence of phosphoryl chloride (POCl3) afforded new 2-alkyl-5-aryl-8,8-dimethyl-8,9-dihydro-3H-chromeno[2,3-d]pyrimidine-4,6(5H,7H)-diones in high yields. The suggested mechanism involves a tandem intramolecular Pinner/Dimroth rearrangement. The synthesized compounds were characterized by infrared (IR), proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR) and elemental analysis.

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.

Synthesis, in vitro and in silico antimalarial activity of 7-chloroquinoline and 4H-chromene conjugates

A new series of chloroquinoline-4H-chromene conjugates incorporating piperizine or azipane tethers were synthesized and their anti-malarial activity were evaluated against two Plasmodium falciparum strains namely 3D7 chloroquine sensitive (CQS) and K1 chloroquine resistant (CQR). Chloroquine was used as the standard and also reference for comparison. The conjugates exhibit intense UV absorption with λmax located at 342 nm (log ε=4.0), 254 nm (log ε=4.2), 223 nm (log ε=4.4) which can be used to spectrometrically track the molecules even in trace amounts. Among all the synthetic compounds, two molecules namely 6-nitro and N-piperazine groups incorporated 7d and 6-chloro and N-azapane incorporated 15b chloroquinoline-4H-chromene conjugates showed significant anti-malarial activity against two strains (3D7 and K1) of P. falciparum. These values are lesser than the values of standard antimalarial compound. Molecular docking results suggested that these two compounds showing strong binding affinity with P. falciparum lactate dehydrogenase (PfLDH) and also they occupy the co-factor position which indicated that they could be the potent inhibitors for dreadful disease malaria and specifically attack the glycolytic pathway in parasite for energy production.