Recent Developments of Coumarin-based Hybrids in Drug Discovery

Antiproliferative activity of selenium-enriched coumarin derivatives on the SK-N-SH neuroblastoma cell line: Mechanistic insights

Thirty selenium-containing coumarin derivatives were synthesized and evaluated for inhibitory activity against 17 malignant tumor cell lines. Among these, compound 11i demonstrated the most potent inhibition of neuroblastoma SK-N-SH cells, with an IC50 of 2.5 ± 0.1 μM. Compound 11i notably inhibited SK-N-SH cell proliferation, migration, and invasion. Western blot and immunofluorescence analyses indicated that 11i increased the Bax/Bcl-2 protein expression ratio, promoted Cytochrome C release from mitochondria, and activated caspases 9 and 3, triggering the mitochondria-mediated apoptotic pathway and inducing endogenous tumor cell apoptosis. The compounds localized in the cytoplasm and co-localized with mitochondria, suggesting mitochondrial interaction and dysfunction. Computational docking studies revealed a strong binding affinity of 11i with Bcl-2 and mitochondrial G-quadruplexes. In a subcutaneous neuroblastoma-bearing mouse model, 11i showed notable anti-tumor efficacy with tumor inhibition rates of 79 % (10 mg/kg) and 93 % (20 mg/kg), exceeding that of cyclophosphamide. This study represents a novel finding on the anti-tumor activity of selenium-containing coumarin derivatives and provides a theoretical basis for developing coumarin-based therapeutics for neuroblastoma.

Stereoselective Synthesis of Biology-Oriented Pentacyclic Pyrrolo[2,1-a]isoquinoline Scaffolds by Photoredox-Induced Radical Annulations

We report a visible-light photoredox-induced stereoselective radical 1,3-dipolar cycloaddition between tetrahydroisoquinolines and coumarin derivatives, providing a platform for the efficient synthesis of pseudo-natural-inspired fused pentacyclic scaffolds. Using this protocol, a diverse range of valuable fused pentacyclic pyrrolo[2,1-a]isoquinolines were efficiently obtained in moderate to good yields and excellent diastereoselectivities. Mechanistic investigations including radical control experiments and light on/off studies indicated that the reaction underwent a visible-light induced radical process. The insights gained from our studies are expected to advance general efforts toward the green synthesis of biology-oriented pseudo-natural products and heterocyclic skeletons.

Dual Relaxant Effect of Coumarin-3-carboxamides Through the Nitric Oxide/Cyclic Guanosine Monophosphate Pathway and Ca2+ Channels Blockade

We aimed to determine the relaxant pathway of seventeen synthetic compounds derived from coumarin-3-carboxamide. An isolated rat aorta assay was used. To determine the vasorelaxant mode of action, receptor blockers and specific enzyme inhibitors involved in endothelial and smooth muscle signaling pathways were used. The compounds 2, 4, and 5 showed higher activity than the other compounds. N-nitro-L-arginine methyl ester (10 µM) and methylene blue (10 µM) significantly inhibited the relaxant effect of the compounds 2, 4, and 5 (p ≤ 0.05), but not tetraethylammonium (5 mM), indomethacin (10 µM), or atropine (1 µM). The compounds 2, 4, and 5 abated the contraction induced by CaCl2. The compounds 2, 4, and 5 exert a relaxing effect through the nitric oxide/cyclic guanosine monophosphate pathway activation and by blocking Ca2+ channels of the cell membrane. These findings propose coumarin-3-carboxamides as new drug entities with the potential to develop non-clinical and clinical.

Nordalbergin Synergizes with Novel β-Lactam Antibiotics against MRSA Infection

The synergetic strategy has created tremendous advantages in drug-resistance bacterial infection treatment, whereas challenges related to novel compound discovery and identifying drug-binding targets still remain. The mechanisms of antimicrobial resistance involving β-lactamase catalysis and the degradation of β-lactam antibiotics are being revealed, with relevant therapies promising to improve the efficacy of existing major classes of antibiotics in the foreseeable future. In this study, it is demonstrated that nordalbergin, a coumarin isolated from the wood bark of Dalbergia sissoo, efficiently potentiated the activities of β-lactam antibiotics against methicillin-resistant Staphylococcus aureus (MRSA) by suppressing β-lactamase performance and improving the bacterial biofilm susceptibility to antibiotics. Nordalbergin was found to destabilize the cell membrane and promote its permeabilization. Moreover, nordalbergin efficiently improved the therapeutic efficacy of amoxicillin against MRSA pneumonia in mice, as supported by the lower bacterial load, attenuated pathological damage, and decreased inflammation level. These results demonstrate that nordalbergin might be a promising synergist of amoxicillin against MRSA infections. This study provided a new approach for developing potentiators for β-lactam antibiotics against MRSA infections.

Synthesis, Molecular Electron Density Theory Study, Molecular Docking, and Pharmacological Evaluation of New Coumarin-Sulfonamide-Nitroindazolyl-Triazole Hybrids as Monoamine Oxidase Inhibitors

Inhibitors of monoamine oxidases (MAOs) are of interest for the treatment of neurodegenerative disorders and other human pathologies. In this frame, the present work describes different synthetic strategies to obtain MAO inhibitors via the coupling of the aminocoumarin core with arylsulfonyl chlorides followed by copper azide-alkyne cycloaddition, leading to coumarin-sulfonamide-nitroindazolyl-triazole hybrids. The nitration position on the coumarin moiety was confirmed through nuclear magnetic resonance spectroscopy and molecular electron density theory in order to elucidate the molecular mechanism and selectivity of the electrophilic aromatic substitution reaction. The coumarin derivatives were evaluated for their inhibitory potency against monoamine oxidases and cholinesterases. Molecular docking calculations provided a rational binding mode of the best compounds in the series with MAO A and B. The work identified hybrids 14a-c as novel MAO inhibitors, with a selective action against isoform B, of potential interest to combat neurological diseases.

Coumarin-furo[2,3-d]pyrimidone hybrid molecules targeting human liver cancer cells: synthesis, anticancer effect, EGFR inhibition and molecular docking studies

The design, synthesis and investigation of antitumor activities of some coumarin-furo[2,3-d]pyrimidone hybrid molecules are reported. In vitro, HepG2 cells were used to investigate the cytotoxicity of 6a-n and 10a-n. The results demonstrated that coupling a furopyrimidone scaffold with coumarin through a hydrazide linker can effectively improve their synergistic anticancer activity. The coumarin-furo[2,3-d]pyrimidone combination 10a exhibited significant inhibitory activity against HepG2 cells with IC50 = 7.72 ± 1.56 μM, which is better than those of gefitinib and sorafenib. It is worth mentioning that the coumarin-furo[2,3-d]pyrimidone combination 10a showed excellent inhibition of the EGFR enzymatic activity with IC50 = 1.53 μM and 90% inhibition at 10 μM concentration. In silico investigation predicts the possibility of direct binding between the new coumarin-furo[2,3-d]pyrimidone hybrid molecules and the EGFR. The results suggest that coumarin-furo[2,3-d]pyrimidone hybrid molecules are potential antitumor agents targeting human liver cancer cells.

Syntheses, reactivity, and biological applications of coumarins

This comprehensive review, covering 2021-2023, explores the multifaceted chemical and pharmacological potential of coumarins, emphasizing their significance as versatile natural derivatives in medicinal chemistry. The synthesis and functionalization of coumarins have advanced with innovative strategies. This enabled the incorporation of diverse functional fragments or the construction of supplementary cyclic architectures, thereby the biological and physico-chemical properties of the compounds obtained were enhanced. The unique chemical structure of coumarine facilitates binding to various targets through hydrophobic interactions pi-stacking, hydrogen bonding, and dipole-dipole interactions. Therefore, this important scaffold exhibits promising applications in uncountable fields of medicinal chemistry (e.g., neurodegenerative diseases, cancer, inflammation).

Comparison of Efficacy of Coumarin and Chymotrypsin/Trypsin in Patients Undergoing Surgical Removal of Lower Third Molars: A Prospective Study

Background Third-molar surgeries are very commonly done by oral and maxillofacial surgeons. Pain and swelling that is associated with this procedure is a frequent reason for the patient's discomfort and apprehension. There is a need to look for a drug that can substantially reduce postoperative swelling amongst the patients. Pain, swelling, and trismus are common complications that are encountered after third molar surgery. These complications have a major impact on the quality of life of patients undergoing minor surgical procedures. Aim The aim of this study was to compare the effectiveness of coumarin and trypsin/chymotrypsin in the reduction of postoperative sequelae for mandibular third molar surgeries. Materials and methods The research was carried out at Saveetha Dental College and Hospital in the Department of Oral and Maxillofacial Surgery. The study consisted of 50 individuals, 25 individuals received tablets of coumarin, and 25 individuals received tablets containing a combination of trypsin/chymotrypsin postoperatively. Patients were evaluated postoperatively for pain and swelling. Postoperative pain was measured on days one, three, and seven after surgery using a visual analog scale. The postoperative swelling was measured on postoperative days three and day seven via a four-point technique. Data were analyzed using IBM SPSS Statistics for Windows, Version 23 (Released 2015; IBM Corp., Armonk, New York, United States). P-values less than 0.05 were considered statistically significant. The independent samples t-test was used to compare the outcomes between the two groups. Results It was found that study participants in the trypsin/chymotrypsin group reported statistically significantly less pain postoperatively than participants receiving coumarin (p=0.001). There was more reduction in swelling postoperatively in patients who were given trypsin/chymotrypsin as compared to the participants who were given coumarin, and the results were statistically significant. Conclusion Based on the data obtained, it can be inferred that the trypsin/chymotrypsin combination was more effective in reducing postoperative sequelae like pain and swelling than coumarin in the mandibular third molar surgeries.

Cytogenotoxicity assessment of 3-(3,4-dihydroxyphenyl)-7,8-dihydroxycoumarin on HepG2/C3A cells and leukocytes

3-(3,4-Dihydroxyphenyl)-7,8-dihydroxycoumarin is a newly synthesized coumarin derivative with a potent antioxidant effect. The aim of the present study is to investigate the safety of this compound, determining the in vitro cytotoxic and genotoxic in human peripheral blood mononuclear cells (PBMC) and in HepG2/C3A cells. Cell viability has been investigated by the trypan blue staining test and MTT assay and the genotoxicity by the comet assay and micronucleus test, using concentrations between 0.01 and 10 μg/ml. The compound proved to be noncytotoxic in both cell lines, at all tested concentrations, protecting the cells from the DNA damage. In addition, this molecule does not show clastogenic/aneugenic effects when performing the micronucleus test with cytokinesis blockade. Based on the obtained data, and the conditions of the experiments, we can conclude that the 3-(3,4-dihydroxyphenyl)-7,8-dihydroxycoumarin is a safe molecule up to a concentration of 10 μg/ml, which encourages further studies aiming to explore its potential as a drug candidate.

Ru(ii)-catalysed oxidative (4 + 2) annulation of chromene and coumarin carboxylic acids with alkynes/propargylic alcohols: isolation of Ru(0) complexes

Ru(ii)-catalysed oxidative (4 + 2) annulation of chromene and coumarin carboxylic acids with alkynes affords pyrano-chromones via vinylic C–H bond activation; use of methyl-tethered propargylic alcohols instead of alkynes gives Ru(0) complexes.

Anti-Tumor Secondary Metabolites Originating from Fungi in the South China Sea's Mangrove Ecosystem

A mangrove is a unique ecosystem with abundant resources, in which fungi are an indispensable microbial part. Numerous mangrove fungi-derived secondary metabolites are considerable sources of novel bioactive substances, such as polyketides, terpenoids, alkaloids, peptides, etc., which arouse people's interest in the search for potential natural anti-tumor drugs. This review includes a total of 44 research publications that described 110 secondary metabolites that were all shown to be anti-tumor from 39 mangrove fungal strains belonging to 18 genera that were acquired from the South China Sea between 2016 and 2022. To identify more potential medications for clinical tumor therapy, their sources, unique structures, and cytotoxicity qualities were compiled. This review could serve as a crucial resource for the research status of mangrove fungal-derived natural products deserving of further development.

Design, synthesis, and insecticidal activity evaluation of piperine derivatives

Structural optimization of natural products has become one of the most effective ways to develop novel pesticides. In this study, 30 novel pesticide derivatives containing a linear bisamide were synthesized. Then, their insecticidal activities against P. xylostella were evaluated. Results indicate that different bisamide substitutes show different larvicidal structure–activity relationships. At the same time, 2-trifluoroethyl is the most efficient substituent. The bioactivity results showed that most of the desired compounds exhibited better insecticidal activity against P. xylostella than piperine. Among them, compound D28 resulted in 90% mortality at 1 mg/ml concentration. This study provides a novel protocol for the discovery of new insecticides. The molecular docking results indicated that compound D28 could act on γ-aminobutyric acid receptors.