Coumarin-based inhibitors of HIV integrase

Novel indolespiro bicoumarins: synthesis and their antifungal activity

This article reports a spiro cyclic system that contains an oxoindole and two coumarin rings. Dozens of compounds with this structure have been synthesized, via a facile three-component reaction of isatin and 4-aminocoumarins, in yields up to 90%. The antifungal activity of several indolespiro[4H-pyrido[3,2-c][5,6-c]bicoumarins] has also been evaluated, with some of them showing good antifungal activity against Physalospora piricola.

Benzopyrone, a privileged scaffold in drug discovery: An overview of FDA-approved drugs and clinical candidates

Natural products have always served as an important source of drugs for treating various diseases. Among various privileged natural product scaffolds, the benzopyrone class of compounds has a substantial presence among biologically active compounds. One of the pioneering anticoagulant drugs, warfarin approved in 1954 bears a benzo-α-pyrone (coumarin) nucleus. The widely investigated psoriasis drugs, methoxsalen, and trioxsalen, also contain a benzo-α-pyrone nucleus. Benzo-γ-pyrone (chromone) containing drugs, cromoglic acid, and pranlukast were approved as treatments for asthma in 1982 and 2007, respectively. Numerous other small molecules with a benzopyrone core are under clinical investigation. The present review discusses the discovery, absorption, distribution, metabolism, excretion properties, and synthetic approaches for the Food and Drug Administration-approved and clinical-stage benzopyrone class of compounds. The role of the pyrone core in biological activity has also been discussed. The present review unravels the potential of benzopyrone core in medicinal chemistry and drug development.

Synthesis, Structural, and Optical Properties of Azuleno[1,2-c]pyran-1-ones: Bro̷nsted Acid-Mediated Cyclization of 2-Azulenylalkynes

Pyrones and their aromatic ring-fused derivatives have gained significant attention due to their diverse biological activities and potential as foundational frameworks for advanced materials. In this paper, we describe a proficient approach for the preparation of azuleno[1,2-c]pyran-1-ones, which are difficult to produce by using conventional methods. The synthesis was achieved through Bro̷nsted acid-mediated cyclization of 2-azulenylalkynes. The structural and optical properties of azuleno[1,2-c]pyran-1-ones were characterized by single-crystal X-ray analysis, NMR, UV/vis, and fluorescence spectroscopies. Under acidic conditions, these compounds displayed notable spectral alterations and emission, distinct from their spectra in neutral medium. These results suggest that azuleno[1,2-c]pyran-1-ones hold great potential for applications in organic electronic materials and fluorescent pH sensors.

Pd-Catalyzed Alkyne and Aryne Annulations: Synthesis and Photophysical Properties of π-Extended Coumarins

A Pd-catalyzed alkyne and aryne annulation strategy via C-H activation has been implemented for the synthesis of π-extended coumarins. This synthetic strategy provides a wide range of π-extended coumarins in moderate to good yields with good functional group compatibility. Photophysical properties of the synthesized π-extended coumarins have been evaluated, and some of them show interesting fluorescent properties. Three of the synthesized coumarins have been unambiguously established by a single-crystal XRD study.

Designing Potent α-Glucosidase Inhibitors: A Synthesis and QSAR Modeling Approach for Biscoumarin Derivatives

Nineteen biscoumarins were synthesized, well-characterized, and evaluated against α-glucosidases in vitro. Of these, six compounds (10, 12, 16, and 17-19) were newly synthesized and not previously reported in the chemical literature. The majority of the synthesized derivatives demonstrated significant inhibitory activity. A quantitative structure-activity relationship (QSAR) model was developed, revealing a strong correlation between the anti-α-glucosidase activity and selected molecular descriptors. Based on this model, two new compounds (18 and 19) were designed, which exhibited the strongest inhibition with IC₅₀ values of 0.62 and 1.21 μM, respectively, when compared to the positive control (acarbose) with an IC₅₀ value of 93.63 μM. Enzyme kinetic studies of compounds 18 and 19 revealed their competitive inhibition with K_i values of 3.93 and 1.80 μM, respectively. Computational studies demonstrated that compound 18 could be inserted into the original binding site (OBS) of α-glucosidase MAL12 and form multiple hydrophobic interactions with nearby amino acids, with the bromo group playing an essential role in enhancing the binding strength and stability at the OBS of the enzyme based on the quantum mechanical calculations using the fragment molecular orbital method. These findings provide valuable insights into the design of potent α-glucosidase inhibitors, which may have potential therapeutic applications in the treatment of diabetes and related diseases.

Effective Synthesis and Biological Evaluation of Dicoumarols: Preparation, Characterization, and Docking Studies

A series of 3,3-arylidene bis (4-hydroxycoumarins) 2 were synthesized by the reaction of aromatic aldehydes with 4-hydroxycoumarin using dodecylbenzenesulfonic acid as Brønsted acid-surfactant catalyst in aqueous media and under microwave irradiation. The present method is operationally simple and the use of water as the reaction medium makes the process environmentally benign. The epoxydicoumarins 5 were then obtained with a good yield by heating 3,3'-arylidenebis-4-hydroxycoumarins 2 in acetic anhydride. Techniques such as elemental analysis, ¹H, ¹³C-¹H NMR, and infrared spectroscopy were employed to characterize these compounds. The synthesized compounds displayed good antibacterial potential against Escherichia coli (ATCC 25988), Pseudomonas aeruginosa (ATCC 27853), Klebsilla pneumonia (ATCC 700603), Staphylococcus aureus (ATCC 29213), methicillin-resistant Staphylococcus aureus (ATCC 43300) and Candida albicans (ATCC 14053). The MIC values of 23 mg/mL for compound 5e against Escherichia coli (ATCC 25988) and 17 mg/mL for 2a were observed. Furthemore, a molecular docking simulation has been performed to evaluate the antibacterial activities and the probable binding modes of the studied compounds 2a-f and 5a-g toward the active sites of a series of well known antibacterial targets. Among the investigated compounds, the binding modes and docking scores demonstrate that 2a has the most antibacterial and antifungal activities. Additionally, DPPH (2,2-diphenyl-1-picrylhydrazyl) and ABTS has been tested for their ability to scavenge hydrogen peroxide and free radicals. According to our results, these compounds exhibit excellent radical scavenging properties. Furthermore, compounds 2-5 were evaluated for anti-inflammatory activity by indirect haemolytic and lipoxygenase inhibition assays and revealed good activity.

SnO2 nanoparticles: A recyclable and heterogeneous catalyst for Pechmann condensation of coumarins and Knoevenagel condensation-Michael addition of biscoumarins

Recyclable SnO2 nanoparticles catalyze the Pechmann condensation between phenolic alcohols and β-ketoesters at room temperature in ethanol leading to coumarins. Also, in another study the synthesis of biscoumarins catalyzed by SnO2 nanoparticles in the reaction between 4-hydroxycoumarin and aldehydes under same condition reactions. The corresponding coumarins and biscoumarins were produced efficiently with facility and excellent yields (93-98%). These approaches display the advantages of benign reaction conditions, non-chromatographic purification procedure, appropriate functional group tolerance and valuable process.

Syntheses of functionalized benzocoumarins by photoredox catalysis

Direct functionalization of inert C(sp³)-H bonds is an attractive synthetic technology for the preparation of pharmaceutically significant compounds in modern synthetic organic chemistry. In this work, we report a new method for the synthesis of functionalized benzocoumarins through the strategy of activation of multiple C-H bonds on 2-aryl toluenes under visible-light-enabled photoredox conditions. This method has the advantages of high functional group compatibility, mild reaction conditions, and effectively avoiding the use of strong oxidants and precious metal catalysts. Detailed mechanistic investigations, including spectroscopic and electrochemical studies, support the reaction's mechanistic course.

Analogue and structure based approaches for modelling HIV-1 integrase inhibitors

A set of 220 inhibitors belonging to different structure classes and having HIV-1 integrase activity were collected along with their experimental pIC50 values. Geometries of all the inhibitors were fully optimized using B3LYP/6-31 + G(d) level of theory. These ligands were docked against 4 different HIV-1 integrase receptors (PDB IDs: 4LH5, 5KRS, 3ZSQ and 3ZSV). 30 docked poses were generated for all 220 inhibitors and ligand interaction of the first docked pose and the docked pose with the highest score were analysed. Residue GLU170 of 4LH5 receptor shows the highest number of interactions followed by ALA169, GLN168, HIS171 and ASP167 residues. Hydrogen bonding and stacking are mainly responsible for the interactions of these inhibitors with the receptor. We performed Molecular Dynamics (MD) simulation to observe the root-mean-square deviation (RMSD), for measure the average change of displacement between the atoms for a particular frame with respect to a reference and The Root Mean Square Fluctuation (RMSF) for characterization of local changes along the protein chain of the docked complexes. Analogue based models were generated to predict the pIC50 values for integrase inhibitors using various types of descriptors such as constitutional, geometrical, topological, quantum chemical and docking based descriptors. The best models were selected on the basis of statistical parameters and were validated by training and test set division. A few new inhibitors were designed on the basis of structure activity relationship and their pIC50 values were predicted using the generated models. All the designed new inhibitors a very high potential and may be used as potent inhibitors of HIV integrase. These models may be useful for further design and development of new and potent HIV integrase inhibitors.Communicated by Ramaswamy H. Sarma.

Dicoumarol: from chemistry to antitumor benefits

Dicoumarol, a coumarin-like compound, is known for its anticoagulant properties associated with the ability to inhibit vitamin K, being prescribed as a drug for several decades. The pharmaceutical value of dicoumarol turned it into a focus of chemists' attention, aiming its synthesis and of dicoumarol derivatives, bringing to light new methodologies. In recent years, several other bioactive effects have been claimed for dicoumarol and its derivatives, including anti-inflammatory, antimicrobial, antifungal, and anticancer, although the mechanisms of action underlying them are mostly not disclosed and additional research is needed to unravel them. This review presents a state of the art on the chemistry of dicoumarols, and their potential anticancer characteristics, highlighting the mechanisms of action elucidated so far. In parallel, we draw attention to the lack of in vivo studies and clinical trials to assess the safety and efficacy as drugs for later application.

Discovery, optimization, and target identification of novel coumarin derivatives as HIV-1 reverse transcriptase-associated ribonuclease H inhibitors

Despite significant advances in antiretroviral therapy, acquired immunodeficiency syndrome remains as one of the leading causes of death worldwide. New antiretroviral drugs combined with updated treatment strategies are needed to improve convenience, tolerability, safety, and antiviral efficacy of available therapies. In this work, a focused library of coumarin derivatives was exploited by cell phenotypic screening to discover novel inhibitors of HIV-1 replication. Five compounds (DW-3, DW-4, DW-11, DW-25 and DW-31) showed moderate activity against wild-type and drug-resistant strains of HIV-1 (IIIB and RES056). Four of those molecules were identified as inhibitors of the viral RT-associated RNase H. Structural modification of the most potent DW-3 and DW-4 led to the discovery of compound 8a. This molecule showed increased potency against wild-type HIV-1 strain (EC50 = 3.94 ± 0.22 μM) and retained activity against a panel of mutant strains, showing EC50 values ranging from 5.62 μM to 202 μM. In enzymatic assays, 8a was found to inhibit the viral RNase H with an IC50 of 12.3 μM. Molecular docking studies revealed that 8a could adopt a binding mode similar to that previously reported for other active site HIV-1 RNase H inhibitors.

The Synthesis and Evaluation of Aminocoumarin Peptidomimetics as Cytotoxic Agents on Model Bacterial E. coli Strains

This work presents the successful synthesis of a library of novel peptidomimetics via Ugi multicomponent reaction. Most of these peptidomimetics contain differently substituted aminocoumarin; 7-amino-4-methylcoumarin and 7-amino-4-(trifluoromethyl) coumarin. Inspired by the biological properties of coumarin derivatives and peptidomimetics, we proposed the synthesis of coumarin incorporated peptidomimetics. We studied the potential of synthesized compounds as antimicrobial drugs on model E. coli bacterial strains (k12 and R2–R4). To highlight the importance of coumarin in antimicrobial resistance, we also synthesized the structurally similar peptidomimetics, using benzylamine. Preliminary cellular studies suggest that the compounds with coumarin derivatives have more potential as antimicrobial agents compared to the compounds without coumarin. We also analyzed the effect of aldehyde, free acid group and ester group on the course of their antimicrobial properties.

Structure-Activity Relationship Studies of Coumarin-like Diacid Derivatives as Human G Protein-Coupled Receptor-35 (hGPR35) Agonists and a Consequent New Design Principle

A series of coumarin-like diacid derivatives were designed and synthesized as novel agonists of human G-protein-coupled receptor 35 (hGPR35). Active compounds were characterized to possess one acidic group on both sides of a fused tricyclic aromatic scaffold. Most of them functioned as full agonists selective to hGPR35 and exhibited excellent potency at low nanomolar concentrations. Substitution on the middle ring of the scaffold could effectively regulate compound potency. Structure-activity relationship studies and docking simulation indicated that compounds that carried two acidic groups with a proper special distance and attached to a rigid aromatic scaffold would most likely show a potent agonistic activity on hGPR35. Following this principle, we screened a list of known compounds and some were found to be potent GPR35 agonists, and compound 24 even had an EC₅₀ of 8 nM. Particularly, a dietary supplement pyrroloquinoline quinone (PQQ) was identified as a potent agonist (EC₅₀ = 71.4 nM). To some extent, this principle provides a general strategy to design and recognize GPR35 agonists.

α-Amidoamids as New Replacements of Antibiotics-Research on the Chosen K12, R2-R4 E. coli Strains

A preliminary study of α-amidoamids as new potential antimicrobial drugs was performed. Special emphasis was placed on selection of structure of α-amidoamids with the highest biological activity against different types of Gram-stained bacteria by lipopolysaccharide (LPS). Herein, Escherichia coli model strains K12 (without LPS in its structure) and R1-R4 (with different length LPS in its structure) were used. The presented work showed that the antibacterial activity of α-amidoamids depends on their structure and affects the LPS of bacteria. Moreover, the influence of various newly synthesized α-amidoamids on bacteria possessing smooth and rought LPS and oxidative damage of plasmid DNA caused by all newly obtained compounds was indicated. The presented studies clearly explain that α-amidoamids can be used as substitutes for antibiotics. The chemical and biological activity of the analysed α-amidoamids was associated with short alkyl chain and different isocyanides molecules in their structure such as: tetr-butyl isocyanide or 2,5-dimethoxybenzyl isocyanide. The observed results are especially important in the case of the increasing resistance of bacteria to various drugs and antibiotics.

Coumarin Derivatives as New Toxic Compounds to Selected K12, R1-R4 E. coli Strains

Coumarins are natural compounds that were detected in 80 species of plants. They have numerous applications including the medical, food, tobacco, perfumery, and spirit industries. They show anti-swelling and diastolic effects. However, excess consumption of coumarins may adversely affect our health, because they are easily absorbed from the intestines into the lymph and blood, causing cirrhosis of the liver. Peptidomimetics are molecules whose structure and function are similar to those of peptides. They are an important group of compounds with biological, microbiological, anti-inflammatory, and anti-cancer properties. Therefore, studies on new peptidomimetics, which load the effect of native peptides, whose half-life in the body is much longer due to structural modifications, are extremely important. A preliminary study of coumarin analogues and its derivatives as new potential antimicrobial drugs containing carboxylic acid or ester was performed to determine their basic structure related to their biological features against various types of Gram-stained bacteria by lipopolysaccharide (LPS). We hypothesized that the toxicity (antibacterial activity) of coumarin derivatives is dependent on the of LPS in bacteria and nature and position of the substituent which may be carboxylic acid, hydroxyl groups, or esters. In order to verify this hypothesis, we used K12 (smooth) and R1–R4 (rough) Escherichia coli strains which are characterized by differences in the type of LPS, especially in the O-antigen region, the outermost LPS layer. In our work, we synthesized 17 peptidomimetics containing a coumarin scaffold and checked their influence on K12 and R1–R4 E. coli strains possessing smooth and rough LPS. We also measured the damage of plasmid DNA caused by target compounds. The results of our studies clearly support the conclusion that coumarin peptidomimetics are antagonistic compounds to many of the currently used antibiotics. The high biological activity of the selected coumarin peptidomimetic was associated with identification of the so-called magic methyl groups, which substantially change the biochemical properties of target compounds. Investigating the effects of these compounds is particularly important in the era of increasingly common resistance in bacteria.

Synthesis and biological evaluation of bis-N2,N2'-(4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccinodihydrazides

A series of N²,N²'-bis[4-hydroxycoumarin-3-yl)ethylidene]-2,3-dihydroxysuccino-hydrazides, containing 4-hydroxycoumarin, hydrazine and tartaric acid moieties, have been prepared and examined for possible biological activity. Several of these compounds exhibit promising HIV-1 integrase inhibition (IC₅₀ = 3.5 μM), and anti-T. brucei (32% viability) and anti-mycobacterial (Visual MIC90 = 15.63 μM) activity.

Building Molecular Complexity from Quinizarin: Conjoined Coumarins and Coronene Analogs

The double Knoevenagel condensation of 1,4-dibenzoyloxyanthraquinone with methyl esters of arylacetic acids affords a series of compounds based upon a previously unknown 1,8-dioxa-benzo[e]pyrene-2,7-dione heterocyclic core. The aryl groups incorporated in the 3- and 6-positions can be oxidatively coupled to the π-expanded backbone to produce a further new heterocyclic core: 1,10-dioxa-dibenzo[dj]coronene-2,9-dione. The intriguing optical properties of these π-expanded coumarin derivatives are discussed and rationalized through quantum chemical calculations. The broad absorption bands of 1,8-dioxa-benzo[e]pyrene-2,7-dione-based dyes are attributed to both HOMO-1→LUMO and HOMO→LUMO transitions, which have a similar energy. Weakly coupled electron-donating aryl substituents result in a moderate bathochromic shift of both the absorption and emission by 30-60 nm in toluene. The emissive properties of these compounds are in part determined by the oscillator strength of the main transition, lifetimes of the excited state, and by the energy match of the excited state with a triplet state of a similar energy. The 1,10-dioxa-dibenzo[dj]coronene-2,9-dione displays a much smaller Stokes shift, yet a markedly increased fluorescence quantum yield of 90 % owing to the increased rigidity compared with the 1,8-dioxa-benzo[e]pyrene-2,7-dione core.

Synthesis of 2-amino-3-ethoxycarbonyl-4-aryl-4H,5H-pyrano-[3,2-c]benzopyran-5-one

A series of 2-amino-3-ethoxycarbonyl-4-aryl-4 H,5 H-pyrano-[3,2- c]benzopyran-5-ones have been were synthesised by the reaction of 4-hydroxycoumarin, an aromatic aldehyde and ethyl cyanoacetate under microwave irradiation with short times and high yields.

Synthesis of 4H,5H-pyrano[3,2-c][1]benzopyran-5-ones in aqueous media

The reaction of substituted cinnamonitriles with 4-hydroxycoumarin in water in the presence of triethylbenzyl-ammonium chloride affords 2-amino-4-aryl-4H,5H-pyrano [3,2-c] [1]benzopyran-5-one derivatives.

Dicoumarol derivatives: Green synthesis and molecular modelling studies of their anti-LOX activity

Dicoumarol derivatives were synthesized in the InCl3 catalyzed pseudo three-component reactions of 4-hydroxycoumarin with aromatic aldehydes in excellent yields. The reactions were performed in water under microwave irradiation. All synthesized compounds were characterized using NMR, IR, and UV-Vis spectroscopy, as well as with TD-DFT. Obtained dicoumarols were subjected to evaluation of their in vitro lipid peroxidation and soybean lipoxygenase inhibition activities. It was shown that five of ten examined compounds (3e, 3h, 3b, 3d, 3f) possess significant potential of antilipid peroxidation (84-97%), and that compounds 3b, 3e, 3h provided the highest soybean lipoxygenase (LOX-Ib) inhibition (IC50 = 52.5 µM) and 3i somewhat lower activity (IC50 = 55.5 µM). The bioactive conformations of the best LOX-Ib inhibitors were obtained by means of molecular docking and molecular dynamics. It was shown that, within the bioactive conformations interior to LOX-Ib active site, the most active compounds form the pyramidal structure made of two 4-hydroxycoumarin cores and a central phenyl substituent. This form serves as a spatial barrier which prevents LOX-Ib Fe2+/Fe3+ ion activity to generate the coordinative bond with the C13 hydroxyl group of the α-linoleate. It is worth pointing out that the most active compounds 3b, 3e, 3h and 3i can be candidates for further examination of their in vitro and in vivo anti-inflammatory activity and that molecular modeling study results provide possibility to screen bioactive conformations and elucidate the mechanism of dicoumarols anti-LOX activity.

Imidazolium and benzimidazolium-containing compounds: from simple toxic salts to highly bioactive drugs

The toxicity of simple imidazolium and benzimidazolium salts started to be more and more investigated in the last few years and was taken in consideration in the context of microorganisms, plants and more evolved organisms' exposure. However, the toxicity of these salts can be exploited in the development of different biological applications by incorporating them in the structure of compounds that specifically target microorganisms and cancer cells. We highlight in this minireview the way researchers became aware of the inherent problem of the stability and bioaccumulation of imidazolium and benzimidazolium salts and how they found inspiration to exploit their toxicity by incorporating them into new highly potent drugs.

A nano-composite of magnetite and hot-water-soluble starch: a cooperation resulting in an amplified catalytic activity on water

A cooperation between magnetite and hot-water-soluble starch led to an efficient catalytic activity of their nano-composite in the pseudo three-component synthesis of bis-coumarins and xanthenes.

Development of pyridine dicoumarols as potent anti HIV-1 leads, targeting HIV-1 associated topoisomeraseIIβ kinase

Aim: A structural study of a series of pyridine dicoumarol derivatives with potential activity against a novel Topoisomerase IIβ kinase which was identified in the HIV-1 viral lysate, compounds were designed and synthesized based on a 3D-QSAR study. Materials & methods: Based on QSAR model we have designed and synthesized a series of pyridine dicoumarol derivatives and characterized by spectral studies, all the molecules are biologically evaluated by kinase assay, cytotoxicity assay, ELISA and PCR method. Result: We demonstrated the achievement of water soluble disodium pyridine dicoumarate derivatives showing high anti-HIV-1 activity (IC50 <25 nM) which provides a crucial point for further development of pyridine dicoumarol series as HIV-1-associated topoisomerase IIβ kinase inhibitors for clinical application against AIDS. Conclusion: A new class of anti-HIV-1 lead compounds have been designed and tested. Further studies would result in development of  novel and potential drugs.

Study of Photophysical Properties on Newly Synthesized Coumarin Derivatives

Herein, we have studied the photophysical properties for three newly synthesized coumarin derivatives; 4-((2,6-dibromo-4-methylphenoxy)methyl)-2H-benzo[h]chromen-2-one (DMB), 4-((3,4-dihydro-6,7-dimethoxyisoquinolin-1-yl)methyl)-6-methyl-2H-chromen-2-one (DIM) and 4-((p-tolyloxy)methyl)-6-methoxy-2H-chromen-2-one (TMC). The absorption and emission spectra for above said molecules were recorded in different solvents at room temperature in order to calculate their ground and excited state dipole moments. The ground (μ _g ) and excited state dipole (μ _e ) moments of these coumarin derivatives were calculated using Lippert's, Bakshiev's and Kawski-Chamma-Viallet's equations by the solvatochromic shift method, which involves a variation of Stokes shift with the solvent dielectric constant and refractive index. Ground state dipole moments (μ _g ) were also calculated from the Guggenheim method using the dielectric constant and refractive index of the solute molecule. The value of ground state dipole moment obtained from these two methods is well correlated. Further, it is notified that the excited state dipole moment is larger than the ground state dipole moment for all three solute molecules. It inferred that the excited state for above said molecules is more polar than the ground state. The present investigations may shine in the design of nonlinear optical materials. Graphical Abstract The photophysical properties for novel coumarin derivatives were studied in different solvents.Ground and excited state dipole moments were estimated by the solvatochromic shift method. The excited state dipole moment is greater than the ground state dipole moment in systems studied. The excited state is more polar than the ground state. The present investigation may be shine in the design of non linear optical materials.