Coumarin-based derivatives with potential anti-HIV activity

Coumarins as versatile therapeutic phytomolecules: A systematic review

BACKGROUND

Coumarins, abundantly distributed in a plethora of biologically active compounds, serve as a fundamental motif in numerous natural products, drugs, and therapeutic leads. Despite their small size, they exhibit a diverse range of biological activities, intriguing researchers with their immense pharmacological potential.

PURPOSE

This study consolidates the evidence regarding the essential role of coumarins in modern drug discovery, exploring their broad-spectrum pharmaceutical effects, structural versatility, and mechanisms of action across various domains.

METHODS

For literature search, we utilized PubMed, Google scholar, and SciFinder databases. Keyword and keyword combinations such as "coumarins", "natural coumarins", "specific natural coumarins for particular diseases", and "therapeutic effects" were employed to retrieve relevant studies. The search encompassed articles published between 2005 and 2023. Selection criteria included studies reporting on the pharmacological activities of natural coumarins against various diseases.

RESULTS

The results highlight the therapeutic potential of natural coumarins against various diseases, demonstrating anti-cancer, anti-oxidant, and anti-inflammatory activities. They also act as monoamine oxidase inhibitors and phosphodiesterase inhibitors, and as anti-thrombotic, anti-diabetic, and hepatoprotective agents. They also show efficacy against diabetic nephropathy, neurodegenerative diseases, microbial infections and many other diseases.

CONCLUSION

This review underscores the significant role of natural coumarins in medicinal chemistry and drug discovery. Their diverse biological activities and structural versatility make them promising therapeutic agents. This study serves as a catalyst for further research in the field, aiming to address emerging challenges and opportunities in drug development.

The nexus between Leishmania & HIV: Debilitating host immunity and Hastening Comorbid disease burden

The scintillating association between Leishmania and HIV has contributed exceptionally towards expansion of Visceral Leishmaniasis (VL) with Acquired Immunodeficiency Syndrome (AIDS). The co-infection poses a grievous threat to elimination of VL and containment of Human Immunodeficiency Virus (HIV). When coinfected, Leishmania and HIV complement each other's proliferation and survival by inducing immunesenescence, T cell fatigue and exhaustion. Antigen presentation is lost, co-stimulatory molecules are diminished whereas co-inhibitory molecules such as CTLA-4, TIGIT, LAG-3 etc. are upregulated to ensure a Th2-baised immune environment. As a consequence, Leishmania-HIV coinfection causes poor outcomes, inflates the spread of Leishmania parasites, enhances the severity of side-effects to drugs, as well as escalate the probability of treatment failure and mortality. What makes control extremely strenuous is that there are frequent episodes of VL relapse with no prognostic markers, no standard immunophenotype(s) and appearance of atypical clinical symptoms. Thus, a standard therapeutic regimen has been difficult to develop and treatment is majorly dependent upon a combination of liposomal Amphotericin B and Miltefosine, a therapy that is expensive and capable of causing drastic side-effects in recipients. As World Health Organization is committed to eliminate both VL and HIV in due course of future, the existing therapeutic interventions require advancements to grapple and overcome this hazardous co-infection. In this context, an overview of HIV-VL co-infection, immunopathology of HIV and Leishmania co-inhabitance, available therapeutic options and their limitations in the treatment of co-infection are discussed in-depth.

Identification of coumarin - benzimidazole hybrids as potential antibacterial agents: Synthesis, in vitro and in vivo biological assessment, and ADMET prediction

The direct-linked coumarin-benzimidazole hybrids, featuring aryl and n-butyl substituents at the N1-position of benzimidazole were synthesized through a Knoevenagel condensation reaction. This reaction involved the condensation of 1,2-diaminobenzene derivatives with coumarin-3-carboxylic acids in the presence of polyphosphoric acid (PPA) at 154 °C. The in vitro antibacterial potency of the hybrid molecules against different gram-positive and gram-negative bacterial strains led to the identification of the hybrids 6m and 6p with a MIC value of 6.25 μg/mL against a gram-negative bacterium, Klebsiella pneumonia ATCC 27736. Cell viability studies on THP-1 cells demonstrated that the compounds 6m and 6p were non-toxic at a concentration of 50 µM. Furthermore, in vivo efficacy studies using a murine neutropenic thigh infection model revealed that both compounds significantly reduced bacterial (Klebsiella pneumonia ATCC 27736) counts (more than 2 log) compared to the control group. Additionally, both compounds exhibited favorable physicochemical properties and drug-likeness characteristics. Consequently, these compounds hold promise as lead candidates for further development of effective antibacterial drugs.

An Overview on the Synthesis of Lamellarins and Related Compounds with Biological Interest

Lamellarins are natural products with a [3,4]-fused pyrrolocoumarin skeleton possessing interesting biological properties. More than 70 members have been isolated from diverse marine organisms, such as sponges, ascidians, mollusks, and tunicates. There is a continuous interest in the synthesis of these compounds. In this review, the synthetic strategies for the synthesis of the title compounds are presented along with their biological properties. Three routes are followed for the synthesis of lamellarins. Initially, pyrrole derivatives are the starting or intermediate compounds, and then they are fused to isoquinoline or a coumarin moiety. Second, isoquinoline is the starting compound fused to an indole moiety. In the last route, coumarins are the starting compounds, which are fused to a pyrrole moiety and an isoquinoline scaffold. The synthesis of isolamellarins, azacoumestans, isoazacoumestans, and analogues is also described. The above synthesis is achieved via metal-catalyzed cross-coupling, [3 + 2] cycloaddition, substitution, and lactonization reactions. The title compounds exhibit cytotoxic, multidrug resistance (MDR), topoisomerase I-targeted antitumor, anti-HIV, antiproliferative, anti-neurodegenerative disease, and anti-inflammatory activities.

Electrospray ionization tandem mass spectrometry of 4-aryl-3,4-dihydrocoumarins

We have investigated the gas-phase fragmentation reactions of 11 synthetic 4-aryl-3,4-dihydrocoumarins by electrospray ionization tandem mass spectrometry (ESI-MS/MS) on a quadrupole-time-of flight (Q-TOF) hybrid mass spectrometer. We have also estimated thermochemical data for the protonated coumarins (precursor ion A) and product ion structures by computational chemistry at a B3LYP level of theory to establish the ion structures and to rationalize the fragmentation pathways. The most abundant ions in the product ion spectra of coumarins 1-11 resulted from C8H8O2, CO2, C4H4O3, C8H10O3, C8H8O2, and CH3OH eliminations through retro-Diels-Alder (RDA) reactions, remote hydrogen rearrangements (β-eliminations), and β-lactone ring contraction. Although the investigated coumarins shared most of the fragmentation pathways, formation of a benzylic product ion and its corresponding tropylium ion was diagnostic of the substituents at ring C. The thermochemical data revealed that the nature and position of the substituents at ring C played a key role in the formation of this product ion and determined its relative intensity in the product ion spectrum. The results of this study contribute to knowledge of the gas-phase ion chemistry of this important class of organic compounds.

An Overview of the Synthesis of 3,4-Fused Pyrrolocoumarins of Biological Interest

3,4-Fused pyrrolocoumarins, synthetically prepared or naturally occurring, possess interesting biological properties. In this review, the synthetic strategies for the synthesis of the title compounds are presented along with their biological activities. Two routes are followed for that synthesis. In one, the pyrrole ring is formed from coumarin derivatives, such as aminocoumarins or other coumarins. In the other approach, the pyranone moiety is built from an existing pyrrole derivative or through the simultaneous formation of coumarin and pyrrole frameworks. The above syntheses are achieved via 1,3-dipolar cycloaddition reactions, Michael reaction, aza-Claisen rearrangement reactions, multi-component reactions (MCR), as well as metal-catalyzed reactions. Pyrrolocoumarins present cytotoxic, antifungal, antibacterial, α-glucosidase inhibition, antioxidant, lipoxygenase (LOX) inhibition, and fluorescent activities, as well as benzodiazepine receptor ability.

Neisseria gonorrhoeae carbonic anhydrase inhibition

Carbonic anhydrases (CAs) are ubiquitous enzymes that are found in all kingdoms of life. Though different classes of CAs vary in their roles and structures, their primary function is to catalyze the reaction between carbon dioxide and water to produce bicarbonate and a proton. Neisseria gonorrhoeae encodes for three distinct CAs (NgCAs) from three different families: an α-, a β-, and a γ-isoform. This chapter details the differences between the three NgCAs, summarizing their subcellular locations, roles, essentiality, structures, and enzyme kinetics. These bacterial enzymes have the potential to be drug targets; thus, previous studies have investigated the inhibition of NgCAs-primarily the α-isoform. Therefore, the classes of inhibitors that have been shown to bind to the NgCAs will be discussed as well. These classes include traditional CA inhibitors, such as sulfonamides, phenols, and coumarins, as well as non-traditional inhibitors including anions and thiocarbamates.

Anti-HIV Activity and Immunomodulatory Properties of Fractionated Crude Extracts of Alternaria alternata

Developing new anti-human immunodeficiency virus (HIV) drug candidates that target different sites in HIV-1 replication, with better resistance profiles and lower drug toxicity, is essential to eradicating HIV. This study investigated the potential of fractionated crude extracts of Alternaria alternata as immunomodulatory or anti-HIV drug candidates. Solid-phase extraction (SPE) was used to fractionate A. alternata PO4PR2 using three different columns: MAX (Mixed-mode, strong Anion-eXchange), MCX (Mixed-mode, strong Cation-eXchange), and HLB (Hydrophilic-Lipophilic Balance) with methanol gradient methods (5%, 45%, and 95%). An MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay was used to assess the cell viability and cytotoxicity of the fractionated crude extract A. alternata PO4PR2 in the TZM-bl cell lines. This was followed by a luciferase-based antiviral assay to assess the antiviral activity of A. alternata PO4PR2. A time of addition (TOA) assay was performed to ascertain the mechanism of inhibition employed by the fractionated crude extract of A. alternata PO4PR2 in the HIV life cycle. The p24 titer was determined using an ELISA, while a luciferase-based antiviral assay was used to evaluate the HIV percentage inhibition for different HIV-1 replication cycles. The TOA assay was established using antiviral drugs that target different sites in the HIV replication cycle. These included maraviroc, azidothymidine, raltegravir, and amprenavir. The immunomodulatory effect of the fractionated crude extracts on CD4+ T cells was measured by a flow cytometric analysis, for which fluorochrome-labelled monoclonal antibodies were used as markers for activation (CD38 and HLA-DR) and exhaustion (PD-1). The MCX fraction demonstrated a more significant anti-HIV inhibition than that of the fractions generated in other columns, with an IC50 of 0.3619 µg/mL, an HIV inhibition of 77%, 5% HLB (IC50: 0.7232 µg/mL; HIV inhibition of 64%), and 5% MAX (IC50: 5.240 µg/mL; HIV inhibition of 67%). It was evident from the time of addition data that the crude extract and the 5% MCX fraction inhibited viral binding (68%), reverse transcription (75%), integration (98%), and proteolysis (77%). It was shown that A. alternata (the MCX fraction) have a significant inhibitory effect on reverse transcription (75% HIV inhibition) and integration (100% HIV inhibition). The 5% MCX (p = 0.0062), 5% HLB (p = 0.0269), and 5% MAX (p = 0.0117) fractionated A. alternata crude extracts had low levels of CD4+ T cell (CD38 + HLA-DR+) activation compared to those of the AZT treatment, while CD4+ T cell activation was insignificant. The 5% MAX and HLB A. alternata fractions may possess immunomodulatory compounds with less anti-HIV-1 activity. A. alternata could be a key source of innovative anti-HIV drugs with immunomodulatory characteristics.

Michael Acceptors as Anti-Cancer Compounds: Coincidence or Causality?

Michael acceptors represent a class of compounds with potential anti-cancer properties. They act by binding to nucleophilic sites in biological molecules, thereby disrupting cancer cell function and inducing cell death. This mode of action, as well as their ability to be modified and targeted, makes them a promising avenue for advancing cancer therapy. We are investigating the molecular mechanisms underlying Michael acceptors and their interactions with cancer cells, in particular their ability to interfere with cellular processes and induce apoptosis. The anti-cancer properties of Michael acceptors are not accidental but are due to their chemical structure and reactivity. The electrophilic nature of these compounds allows them to selectively target nucleophilic residues on disease-associated proteins, resulting in significant therapeutic benefits and minimal toxicity in various diseases. This opens up new perspectives for the development of more effective and precise cancer drugs. Nevertheless, further studies are essential to fully understand the impact of our discoveries and translate them into clinical practice.

Natural linear coumarin-heterocyclic conjugates: A review of their roles in phytotherapy

Heterocycle conjugates provide a fresh investigative scope to find novel molecules with enhanced phytotherapeutic characteristics. Coumarin-based products are widely used in the synthesis of several compounds with biological and medicinal properties since they are naturally occurring heterocycles with a broad dispersion. The investigation of coumarin-based phytochemicals with annulated heterocyclic rings is a promising approach to discovering novel conjugates with significant phytotherapeutic attributes. Due to the applicable coumarin extraction processes, a range of linear coumarin-heterocyclic conjugates were isolated from different natural resources and exhibited remarkable therapeutic efficacy. This review highlights the phytotherapeutic potential and origins of various natural linear coumarin-heterocyclic conjugates. We searched several databases, including Science Direct, Web of Science, Springer, Google Scholar, and PubMed. After sieving, we ultimately identified and included 118 pertinent studies published between 2000 and the middle of 2023. This will inspire medicinal chemists with extremely insightful ideas for designing and synthesizing therapeutically active lead compounds in the future that are built on the pharmacophores of coumarin-heterocyclic conjugates and have significant therapeutic attributes.

Synthesis and Antifungal Activity of Coumarin Derivatives Containing Hydrazone Moiety

Plant disease control mainly relies on pesticides. In this study, a series of coumarin derivatives containing hydrazone moiety were designed and synthesized. The synthesized compounds were characterized and used to evaluate the antifungal activity against four pathogens, Botrytis cinerea, Alternaria solani, Fusarium oxysporum, and Alternaria alternata. The results showed that the inhibition rate of some compounds at 100 μg/mL in 96 hours reached around 70 % against A. alternata, higher than that of the positive control. The corresponding EC50 values were found at around 30 μg/mL. Finally, the compound 3 b was screened out with the lowest EC50 value (19.49 μg/mL). The analysis of SEM and TEM confirmed that the compound 3 b can obviously damage the morphological structure of hyphae, resulting in the depletion of the cells by the destruction of morphological matrix and leakage of contents. RNA sequencing showed that compounds 3 b mainly affected the pentose phosphate pathway, which caused to destroy the layer of mitochondrial structure. Molecular docking showed that compounds 3 b fitted the binding pocket of yeast transketolase and interacted with lysine at the hydrazone structure. Our results suggested that the introduction of hydrazone was an effective strategy for the design of novel bioactive compounds.

Synthesis and Fluorescence Properties of Imidazopyridine-Linked Coumarins via Tandem C(sp2)-H Functionalization/Decarboxylation Reaction

A catalyst-, oxidant-free and green synthetic route for direct access to a series of novel imidazopyridine-linked coumarins has been devised through tandem C(sp2)-H functionalization/decarboxylation reaction in ethyl acetate as a sustainable medium. Moreover, the utilities of ensured products in further organic synthesis were conducted by Suzuki-Miyaura and Sonogashira cross-coupling reactions. The fluorescence characteristics of the produced molecules are appropriate, and the synthesized scaffolds could promisingly garner future attention in clinical diagnostics and bioimaging research.

Molecular modeling and biological investigation of novel s-triazine linked benzothiazole and coumarin hybrids as antimicrobial and antimycobacterial agents

A novel series of s-triazine linked benzothiazole and coumarin hybrids (6a-6d, 7a-7d, and 8a-8d) were synthesized and characterized by IR, NMR, and mass spectrometry. The compound's in vitro antibacterial and antimycobacterial activities were also evaluated. Remarkable antibacterial activity with MIC in the range of 12.5-62.5 μM and antifungal activity of 100-200 μM were demonstrated by in vitro antimicrobial analysis. Compounds 6b, 6d, 7b, 7d, and 8a strongly inhibited all bacterial strains, while 6b, 6c, and 7d had good to moderate efficacy against M. tuberculosis H37Rv. Synthesized hybrids are observed in the active pocket of the S. aureus dihydropteroate synthetase enzyme, according to a molecular docking investigations. Among the docked compounds, 6d had a strong interaction and a greater binding affinity, and the dynamic stability of protein-ligand complexes was examined using molecular dynamic simulation with various settings at 100 ns. The proposed compounds successfully maintained their molecular interaction and structural integrity inside the S. aureus dihydropteroate synthase, according to the MD simulation analysis. These in silico analyses supported the in vitro antibacterial results of compound 6d, which demonstrated outstanding in vitro antibacterial efficacy against all bacterial strains. In the quest for new antibacterial drug-like molecules, compounds 6d, 7b, and 8a have been identified as promising lead compounds.Communicated by Ramaswamy H. Sarma.

Annulated Heterocyclic[g]Coumarin Composites: Synthetic Approaches and Bioactive Profiling

Coumarins, widely abundant natural heterocyclic compounds, are extensively employed in creating various biologically and pharmacologically potent substances. The hybridization of heterocycles presents a key opportunity to craft innovative multicyclic compounds with enhanced biological activity. Fusing different heterocyclic rings with the coumarin structure presents an intriguing method for crafting fresh hybrid compounds possessing remarkable biological effects. In the pursuit of creating heterocyclic-fused coumarins, a wide range of annulated heterocyclic[g]coumarin composites has been introduced, displaying impressive biological potency. The influence of the linear attachment of heterocyclic rings to the coumarin structure on the biological performance of the resulting compounds has been investigated. This review centers on the synthetic methodologies, structural activity relationship investigation, and biological potentials of annulated heterocyclic[g]coumarin composites. We conducted searches across several databases, including Web of Science, Google Scholar, PubMed, and Scopus. After sieving, we ultimately identified and included 71 pertinent studies published between 2000 and the middle of 2023. This will provide valuable perspectives for medicinal chemists in the prospective design and synthesis of lead compounds with significant therapeutic effects, centered around heterocycle-fused coumarin frameworks.

Gaafar AR, Gurusamy R, Akbar I. Synthesis of anthraquinone-connected coumarin derivatives via grindstone method and their evaluation of antibacterial, antioxidant, tyrosinase inhibitory activities with molecular docking, and DFT calculation studies

Anthraquinones and coumarins have excellent pharmacological activities and are an important class of natural plant metabolites with various biological activities. In this study, anthraquinone-9,10-dione and coumarin derivatives were combined to develop a novel anthraquinone-connected coumarin-derivative sequence. The synthesised novel anthraquinone-connected coumarin derivatives (1a-t) were screened for in vitro antibacterial, antioxidant, and tyrosinase inhibitory activities. The antibacterial activities of the synthesised compounds (1a-t) were tested against both gram-positive and gram-negative bacteria. Specifically, compound 1t was more active against E. aerogenes than ciprofloxacin. With regard to antioxidant activity, compound 1o (50.68 % at 100 μg/mL) was highly active compared to the other compounds, whereas it was less active than the standard BHT (76.74 % at 100 μg/mL). In terms of compound 1r (9.31 ± 0.45 μg/mL) was highly active against tyrosinase inhibitory activity compared with kojic acid (10.42 ± 0.98 μg/mL). In the molecular docking study, compound 1r had a higher docking score (-8.8 kcal mol-1) than kojic acid (-1.7 kcal mol-1). DFT calculations were performed to determine the energy gap of highly active compound 1r (ΔE = 0.11) and weakly active compound 1a (ΔE = 0.12). In this study, we found that every molecule displayed significant antibacterial, antioxidant, and tyrosinase inhibitory properties. Based on these reports, compounds 1r and 1t may act as multi-target agents.

Role of diosgenin extracted from Helicteres isora L in suppression of HIV-1 replication: An in vitro preclinical study

Background

Diosgenin, an essential sapogenin steroid with significant biological implications, is composed of a hydrophilic sugar moiety intricately linked to a hydrophobic steroid aglycone. While the antiviral properties of diosgenin against numerous RNA viruses have been extensively documented, its potential in combating Human Immunodeficiency Virus infections remains unexplored.

Experimental procedure

This current investigation presents a comprehensive and systematic analysis of extracts derived from the leaves of Helicteres isora, which are notably enriched with diosgenin. Rigorous methodologies, including established chromatographic techniques and Fourier-transform infrared spectroscopy were employed for the characterization of the active diosgenin compound followed by molecular interaction analyses with the key HIV enzymes and mechanistic validation of HIV inhibition.

Key results

The inhibitory effects of extracted diosgenin on the replication of HIV-1 were demonstrated using a permissive cellular system, encompassing two distinct subtypes of HIV-1 strains. Computational analyses involving molecular interactions highlighted the substantial occupancy of critical active site pocket residues within the key HIV-1 proteins by diosgenin. Additionally, the mechanistic underpinnings of diosgenin activity in conjunction with standard controls were elucidated through specialized colorimetric assays, evaluating its impact on HIV-1 Reverse Transcriptase and Integrase enzymes.

Conclusions

To our current state of knowledge, this study represents the inaugural demonstration of the anti-HIV efficacy inherent to diosgenin found in the leaves of Helicteres isora, and can be taken further for drug design and development for the management of HIV infection.

A coumarin hydrazone appended rotatable phenolic scaffold as fluorescent chemosensor for Ag+ ions and its bio imaging applications

A coumarin hydrazone-phenol conjugate, COH4 was designed, synthesized and utilized for the cation sensing studies by fluorimetry studies. The synthesized chemosensor was completely characterized by the usual spectroscopic and analytical studies. The COH4 receptor was examined for the detection of metal ions, in which it had a noticeable blue shifted fluorescence enhancement for Ag+ ions. Upon binding towards Ag+ ions, the photoinduced electron transfer (PET) process is inhibited via intramolecular charge transfer (ICT) process assisted by the arrest of the carbon-carbon single bond rotation. The binding stoichiometry of COH4 + Ag+ complexation ratio is noted to be 1:2, which was further confirmed by jobs plot method. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.41 µM and 0.13 µM respectively. Moreover, COH4 was successfully utilized for the practical applications of Ag+ ion detection in bacterial cell lines.

4-Phenylcoumarin derivatives as new HIV-1 NNRTIs: Design, synthesis, biological activities, and computational studies

A series of 4-phenylcoumarin derivatives was synthesized and evaluated for their cellular anti-HIV-1 and HIV-2 activities as well as their inhibitory effects against HIV-1 reverse transcriptase (RT). The hydrazone compound 8b and the ethylthiosemicarbazide derivative 4c showed the best inhibition activity against wild-type (WT) HIV-1. The promising compounds were further evaluated against HIV-1 RT and exhibited significant inhibitory activity with compound 8b showing comparable effect to the reference NNRTI Efavirenz (IC50 = 9.01 nM). Structure activity relationship study revealed the importance of 6-chloro and 4-phenyl substituents for optimum activity, as well as the 5-atoms linker (=N-NH-CO-CH2-O-) at position 7 of coumarin scaffold that can support the rotation and flexibility of compound 8b to fit well in the binding pocket. The molecular docking of compound 8b demonstrated a typical seahorse binding mode with better binding interactions that covered more residues when compared to Efavirenz.

Recent Progress in Synthesis, POM Analyses and SAR of Coumarin-Hybrids as Potential Anti-HIV Agents-A Mini Review

The human immunodeficiency virus (HIV) is the primary cause of acquired immune deficiency syndrome (AIDS), one of the deadliest pandemic diseases. Various mechanisms and procedures have been pursued to synthesise several anti-HIV agents, but due to the severe side effects and multidrug resistance spawning from the treatment of HIV/AIDS using highly active retroviral therapy (HAART), it has become imperative to design and synthesise novel anti-HIV agents. Literature has shown that natural sources, particularly the plant kingdom, can release important metabolites that have several biological, mechanistic and structural representations similar to chemically synthesised compounds. Certainly, compounds from natural and ethnomedicinal sources have proven to be effective in the management of HIV/AIDS with low toxicity, fewer side effects and affordability. From plants, fungi and bacteria, coumarin can be obtained, which is a secondary metabolite and is well known for its actions in different stages of the HIV replication cycle: protease, integrase and reverse transcriptase (RT) inhibition, cell membrane fusion and viral host attachment. These, among other reasons, are why coumarin moieties will be the basis of a good building block for the development of potent anti-HIV agents. This review aims to outline the synthetic pathways, structure-activity relationship (SAR) and POM analyses of coumarin hybrids with anti-HIV activity, detailing articles published between 2000 and 2023.

Hantavirus: an overview and advancements in therapeutic approaches for infection

Hantaviruses are a significant and emerging global public health threat, impacting more than 200,000 individuals worldwide each year. The single-stranded RNA viruses belong to the Hantaviridae family and are responsible for causing two acute febrile diseases in humans: Hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS). Currently, there are no licensed treatments or vaccines available globally for HTNV infection. Various candidate drugs have shown efficacy in increasing survival rates during the early stages of HTNV infection. Some of these drugs include lactoferrin, ribavirin, ETAR, favipiravir and vandetanib. Immunotherapy utilizing neutralizing antibodies (NAbs) generated from Hantavirus convalescent patients show efficacy against HTNV. Monoclonal antibodies such as MIB22 and JL16 have demonstrated effectiveness in protecting against HTNV infection. The development of vaccines and antivirals, used independently and/or in combination, is critical for elucidating hantaviral infections and the impact on public health. RNA interference (RNAi) arised as an emerging antiviral therapy, is a highly specific degrades RNA, with post-transcriptional mechanism using eukaryotic cells platform. That has demonstrated efficacy against a wide range of viruses, both in vitro and in vivo. Recent antiviral methods involve using small interfering RNA (siRNA) and other, immune-based therapies to target specific gene segments (S, M, or L) of the Hantavirus. This therapeutic approach enhances viral RNA clearance through the RNA interference process in Vero E6 cells or human lung microvascular endothelial cells. However, the use of siRNAs faces challenges due to their low biological stability and limited in vivo targeting ability. Despite their successful inhibition of Hantavirus replication in host cells, their antiviral efficacy may be hindered. In the current review, we focus on advances in therapeutic strategies, as antiviral medications, immune-based therapies and vaccine candidates aimed at enhancing the body's ability to control the progression of Hantavirus infections, with the potential to reduce the risk of severe disease.

Synthesis, characterization and crystal structure of methyl 2-(2-oxo-2H-chromen-4-yl-amino)-benzoate

Methyl 2-(2-oxo-2H-chromen-4-yl-amino)-benzoate, C17H13NO4 (1), was pre-pared by condensation between 4-hy-droxy-coumarin and methyl 2-amino-benzoate. It crystallizes in the ortho-rhom-bic space group Pca21 at 300 K. The mol-ecule of compound 1 consists of the 2H-chromen-2-one part connected by an amine moiety (-NH-) to the methyl benzoate ring. The supra-molecular array is formed by hydrogen bonds between the aromatic ring and the O atoms of the lactone and ester portions. The structural details match the spectroscopic data acquired from NMR and IR spectroscopy.

Synthesis of Structurally Related Coumarin Derivatives as Antiproliferative Agents

A library of structurally related coumarins was generated through synthesis reactions and chemical modification reactions to obtain derivatives with antiproliferative activity both in vivo and in vitro. Out of a total of 35 structurally related coumarin derivatives, seven of them showed inhibitory activity in in vitro tests against Taq DNA polymerase with IC₅₀ values lower than 250 μM. The derivatives 4-(chloromethyl)-5,7-dihydroxy-2H-chromen-2-one (2d) and 4-((acetylthio)methyl)-2-oxo-2H-chromen-7-yl acetate (3c) showed the most promising anti-polymerase activity with IC₅₀ values of 20.7 ± 2.10 and 48.25 ± 1.20 μM, respectively. Assays with tumor cell lines (HEK 293 and HCT-116) were carried out, and the derivative 4-(chloromethyl)-7,8-dihydroxy-2H-chromen-2-one (2c) was the most promising, with an IC₅₀ value of 8.47 μM and a selectivity index of 1.87. In addition, the derivatives were evaluated against Saccharomyces cerevisiae strains that report about common modes of actions, including DNA damage, that are expected for agents that cause replicative stress. The coumarin derivatives 7-(2-(oxiran-2-yl)ethoxy)-2H-chromen-2-one (5b) and 7-(3-(oxiran-2-yl)propoxy)-2H-chromen-2-one (5c) caused DNA damage in S. cerevisiae. The O-alkenylepoxy group stands out as that with the most important functionality within this family of 35 derivatives, presenting a very good profile as an antiproliferative scaffold. Finally, the in vitro antiretroviral capacity was tested through RT-PCR assays. Derivative 5c showed inhibitory activity below 150 μM with an IC₅₀ value of 134.22 ± 2.37 μM, highlighting the O-butylepoxy group as the functionalization responsible for the activity.

Synthesis and antimicrobial activity of new series of thiazoles, pyridines and pyrazoles based on coumarin moiety

Microbial infections are currently a widespread disease in hospitals and community health centres and are a major cause of death worldwide. In pursuit of searching new antimicrobial agents, coumarin linked to thiazoles, pyridines and pyrazoles have been developed and evaluated for their antimicrobial properties against two Gram + bacteria, two Gram - bacteria as well as two fungi. Some of the prepared coumarins displayed high to moderate activity against the tested microorganisms with respect to the reference drugs. However, compound 3 exhibited antimicrobial effect equal to the reference drug Ciprofloxacin for Gram - baceria Enterobacter cloacae. Compound 12 was found to be the most potent compound against Bacillus pumilis with MIC of 7.69 (µmol/ml). Compounds 3, 4 and 12 showed remarkable activity against Streptococcus faecalis with MIC of 14.34, 3.67 and 15.36 (µmol/ml), respectively. Regarding Escherichia coli, most compounds recorded high to moderate MIC values (4.73-45.46 µmol/ml). Moreover, in case of E. cloacae compound 9 was the most potent compound with MIC value of 22.76 (µmol/ml).

Quinolines and isoquinolines as HIV-1 inhibitors: Chemical structures, action targets, and biological activities

Human immunodeficiency virus type 1 (HIV-1), a lentivirus that causes acquired immunodeficiency syndrome (AIDS), poses a serious threat to global public health. Since the advent of the first drug zidovudine, a number of anti-HIV agents acting on different targets have been approved to combat HIV/AIDS. Among the abundant heterocyclic families, quinoline and isoquinoline moieties are recognized as promising scaffolds for HIV inhibition. This review intends to highlight the advances in diverse chemical structures and abundant biological activity of quinolines and isoquinolines as anti-HIV agents acting on different targets, which aims to provide useful references and inspirations to design and develop novel HIV inhibitors for medicinal chemists.

Natural Coumarin Derivatives Activating Nrf2 Signaling Pathway as Lead Compounds for the Design and Synthesis of Intestinal Anti-Inflammatory Drugs

Nrf2 (nuclear factor erythroid 2-related factor 2) is a transcription factor related to stress response and cellular homeostasis that plays a key role in maintaining the redox system. The imbalance of the redox system is a triggering factor for the initiation and progression of non-communicable diseases (NCDs), including Inflammatory Bowel Disease (IBD). Nrf2 and its inhibitor Kelch-like ECH-associated protein 1 (Keap1) are the main regulators of oxidative stress and their activation has been recognized as a promising strategy for the treatment or prevention of several acute and chronic diseases. Moreover, activation of Nrf2/keap signaling pathway promotes inhibition of NF-κB, a transcriptional factor related to pro-inflammatory cytokines expression, synchronically promoting an anti-inflammatory response. Several natural coumarins have been reported as potent antioxidant and intestinal anti-inflammatory compounds, acting by different mechanisms, mainly as a modulator of Nrf2/keap signaling pathway. Based on in vivo and in vitro studies, this review focuses on the natural coumarins obtained from both plant products and fermentative processes of food plants by gut microbiota, which activate Nrf2/keap signaling pathway and produce intestinal anti-inflammatory activity. Although gut metabolites urolithin A and urolithin B as well as other plant-derived coumarins display intestinal anti-inflammatory activity modulating Nrf2 signaling pathway, in vitro and in vivo studies are necessary for better pharmacological characterization and evaluation of their potential as lead compounds. Esculetin, 4-methylesculetin, daphnetin, osthole, and imperatorin are the most promising coumarin derivatives as lead compounds for the design and synthesis of Nrf2 activators with intestinal anti-inflammatory activity. However, further structure-activity relationships studies with coumarin derivatives in experimental models of intestinal inflammation and subsequent clinical trials in health and disease volunteers are essential to determine the efficacy and safety in IBD patients.

Antimicrobial, Antiproliferative Effects and Docking Studies of Methoxy Group Enriched Coumarin-Chalcone Hybrids

Methoxy group enriched eight coumarin-chalcone hybrid derivatives were synthesized. Antimicrobial/ antiproliferative activities were tested against eight human pathogenic microorganisms and four cancer cell lines (AGS, HepG2, MCF-7 and PC-3), respectively. Antimicrobial results showed that most of the compounds were almost more active than used standard antibiotics. Cytotoxicity results showed that 2,3,4-trimethoxyphenyl and thiophene containing structures have promising antiproliferative effects against AGS gastric cell lines with ∼5 μg/ml IC₅₀ values. At the same time, 2,4-dimethoxyphenyl bearing derivative exhibited the lowest IC₅₀ values against HepG2 (∼10 μg/ml) and PC-3 (∼5 μg/ml) cell lines. Particularly, the cell viabilities of MCF-7 cell lines were remarkably inhibited by all the compounds with lower IC₅₀ values. Therefore, molecular docking studies between hybrid ligands and quinone reductase-2 enzyme (regulates in MCF-7 cancer cells) were performed. The results demonstrated that all the derivatives can smoothly interact with interested enzyme in agreement with the experimental results. Finally, ADME parameters were studied to reveal drug-likeness potentials of the coumarin-chalcone hybrids.

Coumarin derivatives with potential anticancer and antibacterial activity: Design, synthesis, VEGFR-2 and DNA gyrase inhibition, and in silico studies

A series of coumarin derivatives were designed, synthesized, and evaluated for their antiproliferative activity. Compound 3e exhibited significant antiproliferative activity and was further evaluated at five doses at the National Cancer Institute. It effectively inhibited vascular endothelial growth factor receptor-2 (VEGFR-2) with an IC₅₀ value of 0.082 ± 0.004 µM compared with sorafenib. While compound 3e significantly downregulated total VEGFR-2 and its phosphorylation, it markedly reduced the HUVEC's migratory potential, resulting in a significant disruption in wound healing. Furthermore, compound 3e caused a 22.51-fold increment in total apoptotic level in leukemia cell line HL-60(TB) and a 6.91-fold increase in the caspase-3 level. Compound 3e also caused cell cycle arrest, mostly at the G1/S phase. Antibacterial activity was evaluated against Gram-positive and Gram-negative bacterial strains. Compound 3b was the most active derivative, with the same minimum inhibitory concentration and minimum bactericidal concentration value of 128 μg/mL against K. pneumonia and high stability in mammalian plasma. Moreover, compounds 3b and 3f inhibited Gram-negative DNA gyrase with IC₅₀  = 0.73 ± 0.05 and 1.13 ± 0.07 µM, respectively, compared to novobiocin with an IC₅₀ value of 0.17 ± 0.02 µM. The binding affinity and pattern of derivative 3e toward the VEGFR-2 active site and compounds 3a-c and 3f in the DNA gyrase active site were evaluated using molecular modeling. Overall, ADME studies of the synthesized coumarin derivatives displayed promising pharmacokinetic properties.

Selective Syntheses of Coumarin and Benzofuran Derivatives Using Phenols and α-Methoxy-β-ketoesters

Selective syntheses of coumarin and benzofuran derivatives were achieved via HClO4-mediated intermolecular annulation using phenols and α-methoxy-β-ketoesters. Coumarins are formed under dehydrated conditions, whereas benzofurans are formed in the presence of water. In the synthetic process of benzofurans, α-methoxy-β-ketoesters are converted into α-methoxyacetophenones, and the methoxy group is an important element in the intermolecular annulation.

Design, synthesis and anticancer activity studies of 3-(coumarin-3-yl)-acrolein derivatives: Evidenced by integrating network pharmacology and vitro assay

Coumarin derivatives have diverse structures and show various significant biological activities. Aiming to develop more potent coumarin derivatives for cancer treatment, a series of coumarin acrolein hybrids were designed and synthesized by using molecular hybridization approach, and investigated for their antiproliferative activity against A549, KB, Hela and MCF-7 cancer cells as well as HUVEC and LO2 human normal cells. The results indicated that most of the synthesized compounds displayed remarkable inhibitory activity towards cancer cells but low cytotoxicity on normal cells. Among all the compounds, 5d and 6e were the most promising compounds against different cancer cell lines, especially for A549 and KB cells. The preliminary action mechanism studies suggested that compound 6e, the representative compound, was capable of dose-dependently suppressing migration, invasion and inducing significant apoptosis. Furthermore, the combined results of network pharmacology and validation experiments revealed that compound 6e induced mitochondria dependent apoptosis via the PI3K/AKT-mediated Bcl-2 signaling pathway. In summary, our study indicated compound 6e could inhibit cell proliferation, migration, invasion and promote cell apoptosis through inhibition of PI3K/AKT signaling pathway in human oral epidermoid carcinoma cells. These findings demonstrated the potential of 3-(coumarin-3-yl)-acrolein derivatives as novel anticancer chemotherapeutic candidates, providing ideas for further development of drugs for clinical use.

Direct Synthesis of 3-Aryl Substituted Isocoumarins and Phthalides through Palladium Acetate Catalyzed C(sp2 )-H Activation in Ionic Liquids

A novel Pd-catalysed oxidative coupling between benzoic acids and vinylarenes or acrylates to furnish isocoumarins and phthalides is reported. The reaction proceeds smoothly in molten tetrabutylammonium acetate via a selective C-H bond activation, with very low percentage of ligand-free palladium acetate as the catalyst, under atmospheric pressure of oxygen. Sub-stoichiometric amount of copper acetate is also required as a reoxidant for the palladium.

[CMMIM][BF4 -] Ionic Liquid-Catalyzed Facile, One-Pot Synthesis of Chromeno[4,3-d]pyrido[1,2-a]pyrimidin-6-ones: Evaluation of Their Photophysical Properties and Theoretical Calculations

Herein, we have developed a novel synthetic route for the synthesis of chromeno[4,3-d]pyrido[1,2-a]pyrimidin-6-one derivatives 8a-q using an acid ionic liquid [CMMIM][BF₄ ^-] 4 via one-pot, three-component synthesis in aqueous ethanol at room temperature. A series of 17 derivatives have been successfully prepared with up to 93% yield. All the synthesized derivatives were well characterized using ¹H-NMR, ¹³C-NMR, and FT-IR spectral techniques. Additionally, the photophysical properties of 12 selected derivatives including molar extinction coefficient (ε), Stokes shift (Δυ̅), and quantum yield (Φ) varying from 0.52095 × 10⁴ to 0.93248 × 10⁴, 4216 to 4668 cm^-1, and 0.0088 to 0.0459, respectively, have been determined. Furthermore, the experimental data are supported by density functional theory (DFT) and time-dependent DFT calculations. Theoretical investigations showed a trend similar to experimental results.

Phytochemicals with Chemopreventive Activity Obtained from the Thai Medicinal Plant Mammea siamensis (Miq.) T. Anders.: Isolation and Structure Determination of New Prenylcoumarins with Inhibitory Activity against Aromatase

With the aim of searching for phytochemicals with aromatase inhibitory activity, five new prenylcoumarins, mammeasins K (1), L (2), M (3), N (4), and O (5), were isolated from the methanolic extract of Mammea siamensis (Miq.) T. Anders. flowers (fam. Calophyllaceae), originating in Thailand. The stereostructures of 1–5 were elucidated based on their spectroscopic properties. Among the new compounds, 1 (IC₅₀ = 7.6 µM) and 5 (9.1 µM) possessed relatively strong inhibitory activity against aromatase, which is a target of drugs already used in clinical practice for the treatment and prevention of estrogen-dependent breast cancer. The analysis through Lineweaver–Burk plots showed that they competitively inhibit aromatase (1, Ki = 3.4 µM and 5, 2.3 µM). Additionally, the most potent coumarin constituent, mammea B/AB cyclo D (31, Ki = 0.84 µM), had a competitive inhibitory activity equivalent to that of aminoglutethimide (0.84 µM), an aromatase inhibitor used in therapeutics.

Recent Developments in Nanocatalyzed Green Synthetic Protocols of Biologically Potent Diverse O-Heterocycles—A Review

The dynamic growth in green organic synthetic methodologies for diverse heterocyclic scaffolds has substantially contributed to the field of medicinal chemistry over the last few decades. The use of hybrid metal nanocatalysts (NCs) is one such benign strategy for ensuring the advancement of modern synthetic chemistry by adhering to the principles of green chemistry, which call for a sustainable catalytic system that converts reacting species into profitable chemicals at a faster rate and tends to reduce waste generation. The metal nanoparticles (NPs) enhance the exposed surface area of the catalytic active sites, thereby making it easier for reactants and metal NCs to have an effective interaction. Several review articles have been published on the preparation of metal NCs and their uses for various catalytic heterocyclic transformations. This review will summarize different metal NCs for the efficient green synthesis of various O-heterocycles. Furthermore, the review will provide a concise overview of the role of metal NCs in the synthesis of O-heterocycles and will be extremely useful to researchers working on developing novel green and simple synthetic pathways to various O-heterocyclic-derived molecules.

Degradation of emerging contaminant coumarin based on anodic oxidation, electro-Fenton and subcritical water oxidation processes

The degradation of emerging contaminant coumarin was separately investigated in anodic, electro-Fenton and subcritical water oxidation processes. With respect to the anodic and electro-Fenton oxidation, the influence of constant current, treatment time and initial concentration of coumarin was studied. Regarding subcritical water oxidation, the effect of the oxidant concentration, temperature, treatment time and initial coumarin concentration was investigated. In anodic and electro-Fenton oxidation processes, coumarin degradation proceeded in a similar manner, achieving 99% degradation, after 180 min at a constant current of 200 mA. In both set-ups, further increasing the applied current lowered the degradation efficiency due to the formation of by-products and the increasing occurrence of side-reactions. The highest degradation of 88% was achieved in subcritical conditions, specifically at 200 °C, using 150 mM H₂O₂ and after 37.5 min of treatment. Under subcritical conditions, temperature was the most prominent parameter, followed by the H₂O₂ concentration. Under all methodologies, increasing treatment time had a small positive effect on coumarin degradation, indicating that time is not the most influential parameter. A comparison of the three methodologies in terms of performance as well as energy consumption and simplicity of operation highlighted the advantages of subcritical water oxidation.

SAR analysis of heterocyclic compounds with monocyclic and bicyclic structures as antifungal agents

Infections caused by eukaryotic organisms, such as fungi, are generally more difficult to treat than bacterial infections. With the widespread use of antifungal drugs in humans and plants, resistance and toxicity have emerged. Therefore, it is desirable to develop new antifungal drugs with low toxicity that are not susceptible to the development of resistance. This review presents a summary of the past 2017 to 2021 years of research on heterocyclic compounds as antifungal agents for use in humans and plants, focusing on the structure-activity relationships (SAR) of these compounds. This review may provide ideas and data for designing and developing new antifungal drugs with fewer side effects compared with currently available drugs.

Diverse and efficient catalytic applications of new cockscomb flower-like Fe3O4@SiO2@KCC-1@MPTMS@CuII mesoporous nanocomposite in the environmentally benign reduction and reductive acetylation of nitroarenes and one-pot synthesis of some coumarin compounds

In this research, Fe3O4@SiO2@KCC-1@MPTMS@CuII as a new cockscomb flower-like mesoporous nanocomposite was prepared and characterized by various techniques including Fourier transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), SEM-based energy-dispersive X-ray (EDX) spectroscopy, inductively coupled plasma-optical emission spectrometry (ICP-OES), thermogravimetric analysis/differential thermal analysis (TGA/DTA), vibrating sample magnetometry (VSM), UV-Vis spectroscopy, and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. The as-prepared Fe3O4@SiO2@KCC-1@MPTMS@CuII mesoporous nanocomposite exhibited satisfactory catalytic activity in the reduction and reductive acetylation of nitroarenes in a water medium and solvent-free one-pot synthesis of some coumarin compounds including 3,3'-(arylmethylene)bis(4-hydroxy-2H-chromen-2-ones) (namely, bis-coumarins) (3a-n) and 2-amino-4-aryl-7,7-dimethyl-5-oxo-5,6,7,8-tetrahydro-4H-chromene-3-carbonitriles (6a-n) along with acceptable turnover numbers (TONs) and turnover frequencies (TOFs). Furthermore, the mentioned CuII-containing mesoporous nanocatalyst was conveniently recovered by a magnet from reaction environments and reused for at least seven cycles without any significant loss in activity, which confirms its good stability.

Coumarin Derivative N6 as a Novel anti-hantavirus Infection Agent Targeting AKT

Hantaviruses are globally emerging zoonotic viruses that can cause hemorrhagic fever with renal syndrome (HFRS) in Asia and Europe, which is primarily caused by Hantaan virus (HTNV) infection, results in profound morbidity and mortality. However, no specific treatment is available for this disease. Coumarin derivatives have been reported as antiviral molecules, while studies about the bioactivity of coumarin derivatives against HTNV infection are limited. To study the potential antiviral activity of coumarin derivatives, 126 coumarin derivatives are synthesized, and their inhibitory activity against HTNV is analyzed in vitro. Among these compounds, N6 inhibits HTNV with relatively high selectivity index at 10.9, and the viral titer of HTNV is reduced significantly after 5, 10, and 20 μM N6 treatments. Furthermore, the administration of N6 at the early stage of HTNV infection can inhibit the replication and production of infectious HTNV in host cell, this therapeutic efficacy is confirmed in HTNV-infected newborn mice at the early stage of infection. The molecular docking results show that N6 forms interactions with the key amino acid residues at its active site, and reveals several molecular interactions responsible for the observed affinity, and the treatment of N6 can inhibit the expression of p (Ser473)Akt and HTNV nucleocapsid protein significantly. As such, these observations demonstrate that coumarin derivative N6 might be used as a potential agent against HTNV infection.