Synthesis and antiviral bioactivity of novel chalcone derivatives containing purine moiety

Ultrafast excited-state dynamics of 4-hydroxychalcone: role of intramolecular charge transfer and photoacidity

Diarylketones such as benzophenones, oxybenzones, chalcones and their derivatives exhibit promising applications as UV filters/sunscreen agents due to their effective absorption in the UV region and dissipation through non-radiative pathways. However, elucidation of the underlying photoreactive mechanism is non-trivial due to the ultrafast lifetimes of transient species, involvement of non-adiabatic curve crossings among the potential surfaces, etc. In this context, we investigate the excited-state photoreaction dynamics of 4-hydroxychalcone (4-HC) under various environments through femtosecond-transient absorption (fs-TA), nanosecond-transient absorption (ns-TA), and femtosecond-fluorescence upconversion (fs-FL) measurements. Steady-state fluorescence measurements of 4-HC in the presence of 1-methylimidazole (MI)/tert-butylamine (TBA) exhibit dual band emission. The fs-TA measurements of 4-HC in the presence of MI/TBA exhibit distinct spectral and associated lifetimes as compared to 4-HC alone indicating a significant interaction of the hydroxyl proton with bases and influencing the reaction dynamics. The 4-HC:MI/TBA adduct undergoes excited-state intermolecular proton transfer within a time scale of ∼500 fs and subsequently relaxes back to the ground state through a long-lived triplet state. The experimental observations of excited-state reaction dynamics of 4-HC in the presence of MI/TBA bases have been well corroborated with the computational analysis.

Antiviral activity evaluation and action mechanism of chalcone derivatives containing phenoxypyridine

In this paper, a series of phenoxypyridine-containing chalcone derivatives (L1-L28) were designed and synthesized, characterized on NMR and HRMS. Ningnanmycin (NNM) was used as a control agent. The results of the antiviral activity testing showed that the curative activity EC50 values of L1 and L4 against TMV were 140.5 and 90.7 μg/mL, respectively, which were superior to that of NNM (148.3 μg/mL). The EC50 values of 154.1, 102.6 and 140.0 μg/mL for the anti-TMV protective activities of L1, L4 and L15 were superior to that of NNM (188.2 μg/mL). The mechanism of action between L4 and NNM and tobacco mosaic virus capsid protein (TMV-CP) was preliminarily investigated. The results of microscale thermophoresis (MST) experiments showed that L4 had a strong binding affinity for TMV-CP with a dissociation constant Kd value of 0.00149 µM, which was better than that of NNM (2.73016 µM). The results of molecular docking experiments showed that L4 formed shorter hydrogen bonds with amino acid residues of TMV-CP than NNM and formed more amino acid residues than NNM, which indicated that L4 was more tightly bound to TMV-CP. This study suggested that phenoxypyridine-containing chalcone derivatives can be used as new anti-TMV drugs through further research and development.

Significance of Chalcone Scaffolds in Medicinal Chemistry

Chalcone is a simple naturally occurring α,β-unsaturated ketone with biological importance, which can also be easily synthesized in laboratories by reaction between two aromatic scaffolds. In plants, chalcones occur as polyphenolic compounds of different frameworks which are bioactive molecules that have been in traditional medicinal practice for many years. Chalcone-based lead molecules have been developed, possessing varied potentials such as antimicrobial, antiviral, anti-inflammatory, anticancer, anti-oxidant, antidiabetic, antihyperurecemic, and anti-ulcer effects. Chalcones contribute considerable fragments to give important heterocyclic molecules with therapeutic utilities targeting various diseases. These characteristic features have made chalcone a topic of interest among researchers and have attracted investigations into this widely applicable structure. This review highlights the extensive exploration carried out on the synthesis, biotransformations, chemical reactions, hybridization, and pharmacological potentials of chalcones, and aims to provide an extensive, thorough, and critical review of their importance, with emphasis on their properties, chemistry, and biomedical applications to boost future investigations into this potential scaffold in medicinal chemistry.

Antiviral activity evaluation and action mechanism of myricetin derivatives containing thioether quinoline moiety

A variety of myricetin derivatives containing thioether quinoline moiety were designed and synthesized. Their structures of title compounds were determined by 1H NMR, 13C NMR, 19F NMR, and HRMS. Single-crystal X-ray diffraction experiments were carried out with B4. Antiviral activity indicated that some of the target compounds exhibited remarkable anti-tobacco mosaic virus (TMV) activity. In particular, compound B6 possessed significant activity. The half maximal effective concentration (EC50) value of the curative activity of compound B6 was 169.0 μg/mL, which was superior to the control agent ningnanmycin (227.2 μg/mL). Meanwhile, the EC50 value of the protective activity of compound B6 was 86.5 μg/mL, which was better than ningnanmycin (179.2 μg/mL). Microscale thermophoresis (MST) indicated that compound B6 had a strong binding capability to the tobacco mosaic virus coat protein (TMV-CP) with a dissociation constant (Kd) value of 0.013 μmol/L, which was superior to that of myricitrin (61.447 μmol/L) and ningnanmycin (3.215 μmol/L). And the molecular docking studies were consistent with the experimental results. Therefore, these novel myricetin derivatives containing thioether quinoline moiety could become potential alternative templates for novel antiviral agents.

Synthesis, antifungal activity and mechanism of action of novel chalcone derivatives containing 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole

A series of chalcone derivatives containing 1,2,4-triazolo-[3,4-b]-1,3,4-thiadiazole was designed and synthesized. Structures of all compounds were characterized by 1H NMR, 13C NMR, 19F NMR, and HRMS. The biological activities of the compounds were determined with the mycelial growth rate method, and further studies showed that some compounds had good antifungal activities at the concentration of 100 μg/mL. The EC50 value of compound L31 was 15.9 μg/mL against Phomopsis sp., which were better than that of azoxystrobin (EC50 value was 69.4 μg/mL). In addition, the mechanism of action of compound L31 shown that compound can affect mycelial growth by disrupting membrane integrity against Phomopsis sp., and that the higher the concentration of the compound is, the greater the disruption of membrane integrity is.

Recent Achievements in Antiviral Agent Development for Plant Protection

Plant virus disease is the second most prevalent plant diseases and can cause extensive loss in global agricultural economy. Extensive work has been carried out on the development of novel antiplant virus agents for preventing and treating plant virus diseases. In this review, we summarize the achievements of the research and development of new antiviral agents in the recent five years and provide our own perspective on the future development in this highly active research field.

Synthesis and antiviral activity of diverse heterocyclic scaffolds

Heterocyclic moieties form a major part of organic chemistry as they are widely distributed in nature and have wide scale practical applications ranging from extensive clinical use to diverse fields such as medicine, agriculture, photochemistry, biocidal formulations, and polymer science. By virtue of their therapeutic properties, they could be employed in combating many infectious diseases. Among the common infectious diseases, viral infections are of great public health importance worldwide. Thus, there is an urgent need for the discovery and development of antiviral drugs and clinical methods to prevent various viral infections so as to increase the life expectancy. This review presents the comprehensive overview of the synthesis and antiviral activity of different heterocyclic compounds 2015 onwards, which aids in present knowledge and helps the researchers and other stakeholders to explore their field.

Chalcone: A Promising Bioactive Scaffold in Medicinal Chemistry

Chalcones are a class of privileged scaffolds with high medicinal significance due to the presence of an α,β-unsaturated ketone functionality. Numerous functional modifications of chalcones have been reported, along with their pharmacological behavior. The present review aims to summarize the structures from natural sources, synthesis methods, biological characteristics against infectious and non-infectious diseases, and uses of chalcones over the past decade, and their structure-activity relationship studies are detailed in depth. This critical review provides guidelines for the future design and synthesis of various chalcones. In addition, this could be highly supportive for medicinal chemists to develop more promising candidates for various infectious and non-infectious diseases.

Synthesis of Chalcones Derivatives and Their Biological Activities: A Review

Chalcone derivatives are considered valuable species because they possess a ketoethylenic moiety, CO-CH=CH-. Due to the presence of a reactive α,β-unsaturated carbonyl group, chalcones and their derivatives possess a wide spectrum of antiproliferative, antifungal, antibacterial, antiviral, antileishmanial, and antimalarial pharmacological properties. Recent developments in heterocyclic chemistry have led to the synthesis of chalcone derivatives, which had been biologically investigated toward certain disease targets. The major aspect of this review is to present the most recent synthesis of chalcones bearing N, O, and/or S heterocycles, revealing their biological potential during the past decade (2010-2021). Based on a review of the literature, many chalcone-heterocycle hybrids appear to exhibit promise as future drug candidates owing to their similar or superior activities compared to those of the standards. Thus, this review may prove to be beneficial for the development and design of new potent therapeutic drugs based on previously developed strategies.

Novel Nitrogen-Based Chalcone Analogs Provoke Substantial Apoptosis in HER2-Positive Human Breast Cancer Cells via JNK and ERK1/ERK2 Signaling Pathways

Natural chalcones possess antitumor properties and play a role as inducers of apoptosis, antioxidants and cytotoxic compounds. We recently reported that novel nitrogen chalcone-based compounds, which were generated in our lab, have specific effects on triple-negative breast cancer cells. However, the outcome of these two new compounds on human epidermal growth factor receptor 2 (HER2)-positive breast cancer remains nascent. Thus, we herein investigated the effects of these compounds (DK-13 and DK-14) on two HER2-positive breast cancer cell lines, SKBR3 and ZR75. Our data revealed that these compounds inhibit cell proliferation, deregulate cell-cycle progression and significantly induce cell apoptosis in both cell lines. Furthermore, the two chalcone compounds cause a significant reduction in the cell invasion ability of SKBR3 and ZR75 cancer cells. In parallel, we found that DK-13 and DK-14 inhibit colony formation of both cell lines in comparison to their matched controls. On the other hand, we noticed that these two compounds can inhibit angiogenesis in the chorioallantoic membrane model. The molecular pathway analysis of chalcone compounds exposed cells revealed that these compounds inhibit the expression of both JNK1/2/3 and ERK1/2, the major plausible molecular pathways behind these events. Our findings implicate that DK-13 and DK-14 possess effective chemotherapeutic outcomes against HER2-positive breast cancer via the ERK1/2 and JNK1/2/3 signaling pathways.

Purine Nucleoside Derivatives Containing a Sulfa Ethylamine Moiety: Design, Synthesis, Antiviral Activity, and Mechanism

To find efficient and broad-spectrum viral agents, a series of purine nucleoside derivatives containing sulfa ethylamine moieties was designed and synthesized, and their antiviral activities against tobacco mosaic virus (TMV), cucumber mosaic virus (CMV), and potato virus Y (PVY) were evaluated. Some target compounds displayed good antiviral activities. Among them, compound 3 showed excellent protective activity against CMV and PVY with 50% effective concentration values (EC₅₀) of 137 and 209 μg/mL, respectively, which were better than that of the control agent ningnanmycin (508 and 431 μg/mL). Moreover, the EC₅₀ value of compound 3 for the inactivating activity against TMV was 48 μg/mL, which was better than that of ningnanmycin (88 μg/mL). In addition, compound 3 not only destroyed the structure of the TMV virus but also had a good interaction with the coat protein of the TMV virus. Therefore, compound 3 may further destroy the structure of the virus by binding to the coat protein of the TMV virus, thereby weakening the infectivity of the virus.

In vivo antiviral activity and disassembly mechanism of novel 1-phenyl-5-amine-4-pyrazole thioether derivatives against Tobacco mosaic virus

A series of novel 1-phenyl-5-amine-4-pyrazole thioether derivatives containing a 1,3,4-oxadiazole moiety was designed and synthesised. In vivo antiviral bioassay results showed that most of the target compounds exhibited excellent inactivation activity against Tobacco mosaic virus (TMV). The EC₅₀ values of the inactivation activities for T₂, T₇, T₉, T₂₄, T₂₅ and T₂₇ were 15.7, 15.7, 15.5, 11.9, 12.5 and 16.5 μg/mL, respectively, which were remarkably superior over that of the commercialised antiviral agent ningnanmycin (40.3 μg/mL). Morphological study using AFM and TEM of TMV treated with T₂₄ showed that T₂₄ could significantly shorten the polymerization length of TMV particles and formed a distinct break on the rod-shaped TMV. Investigations for virus infection efficiency on tobacco leaves demonstrated that infectivity of virion had been reduced obviously upon T₂₄ treatment. Subsequently, a strong interaction between T₂₄ and TMV-CP (K_d = 3.8 μM, score 6.11) was observed through MST experiments. Molecular docking study further revealed that target compounds interact with amino acid residue Glu50 in TMV CP, causing disassembly of virion, shorting the length of the virion and reducing the infectivity of virion, and resulting in high inactivating activity of target compounds. This study provides a new insight for discovery of antiviral compounds through a new action mechanism with a new binding site.

Rhodium-catalyzed ortho-acrylation of aryl ketone O-methyl oximes with cyclopropenones

An efficient Rh-catalyzed ortho-acrylation reaction for the synthesis of chalcones from O-methyl ketoximes and cyclopropenones via C-H bond activation has been described. This cross-coupling reaction exhibits high functional group tolerance and regioselectivity. A wide range of chalcone derivatives are obtained in moderate to good yields under mild conditions.

New chalcone derivatives: synthesis, antiviral activity and mechanism of action

In this work, twenty-eight chalcone derivatives containing a purine (sulfur) ether moiety were synthesized and their antiviral activities were evaluated. Biological results showed that compound 5d exhibited outstanding inactive activity against tobacco mosaic virus (TMV) in vivo (EC₅₀ = 65.8 μg mL⁻¹), which is significantly superior to that of ribavirin (EC₅₀ = 154.3 μg mL⁻¹). Transmission electron microscopy indicated that compound 5d can break the integrity of TMV particles. The results of microscale thermophoresis, fluorescence titration and molecular docking showed that compound 5d had stronger combining affinity (K_a = 1.02 ×10⁵ L mol⁻¹, K_d = 13.4 μmol L⁻¹) with TMV coat protein (TMV-CP), which is due to the formation of five hydrogen bonds between compound 5d and the amino-acid residues of TMV-CP. These findings revealed that compound 5d can effectively inhibit the infective ability of TMV. This work provides inspiration and reference for the discovery of new antiviral agents.

The chalcone derivatives containing a purine (sulfur) ether moiety were synthesized. The antiviral mechanism suggested that the antiviral activity of compound 5d may depend on its stronger binding affinity with TMV-CP.

Synthesis, Antiviral Activity, and Mechanisms of Purine Nucleoside Derivatives Containing a Sulfonamide Moiety

Novel purine nucleoside derivatives containing a sulfonamide moiety were prepared, as well as their antiviral activities against potato virus Y (PVY), cucumber mosaic virus (CMV), and tobacco mosaic virus (TMV) were evaluated. The antiviral mechanisms of the compounds were investigated. Results showed that most of the compounds had good antiviral activities. Compound 5 at 500 μg/mL exhibited excellent curative and protective activities of 52.5% and 60.0% and of 52.0% and 60.2% for PVY and CMV, respectively, which are higher than those of ningnanmycin (48.1%, 49.6%; 45.3%, 47.7%), ribavirin (38.3%, 48.2%; 40.8%, 45.5%), and chitosan oligosaccharide (32.5%, 33.8%; 35.1%, 34.6%). Moreover, compound 5 displayed good inactivating activity against TMV, with an EC₅₀ value of 48.8 μg/mL, which is better than that of ningnanmycin (84.7 μg/mL), ribavirin (150.4 μg/mL), and chitosan oligosaccharide (521.3 μg/mL). The excellent antiviral activity of compound 5 is related to its immune induction effect which can regulate the physiological and biochemical processes in plants, including defense-related enzyme activities, defense-related genes, and photosynthesis-related proteins. These results indicate that purine nucleoside derivatives containing a sulfonamide moiety are worthy of further research and development as new antiviral agents.

Synthesis and Biological Evaluation of NH2-Sulfonyl Oseltamivir Analogues as Influenza Neuraminidase Inhibitors

A series of NH₂-sulfonyl oseltamivir analogues were designed, synthesized, and their inhibitory activities against neuraminidase from H5N1 subtype evaluated. The results indicated that the IC₅₀ value of compound 4a, an oseltamivir analogue via methyl sulfonylation of C5-NH₂, was 3.50 μM. Molecular docking simulations suggested that 4a retained most of the interactions formed by oseltamivir carboxylate moieties and formed an additional hydrogen bond with the methylsulfonyl group. Meanwhile, 4a showed high stability towards human liver microsomes. More importantly, 4a without basic moieties is not a zwitterion as reported on the general structure of neuraminidase inhibitors. This research will provide valuable reference for the research of new types of neuraminidase inhibitors.

Novel chalcone derivatives containing a 1,2,4-triazine moiety: design, synthesis, antibacterial and antiviral activities

A series of novel chalcone derivatives containing the 1,2,4-triazine moiety were synthesized and their structures were confirmed by 1H NMR, 13C NMR and elemental analyses. Antiviral bioassays revealed that most of the compounds exhibited good antiviral activity against tobacco mosaic virus (TMV) at a concentration of 500 μg mL-1. The designated compound 4l was 50% effective in terms of curative and protective activities against TMV with 50% effective concentrations (EC50) of 10.9 and 79.4 μg mL-1, which were better than those of ningnanmycin (81.4 and 82.2 μg mL-1). Microscale thermophoresis (MST) also showed that the binding of compound 4l to coat protein (TMV-CP) yielded a K d value of 0.275 ± 0.160 μmol L-1, which was better than that of ningnanmycin (0.523 ± 0.250 μmol L-1). At the same time, molecular docking studies for 4l with TMV-CP (PDB code:1EI7) showed that the compound was embedded well in the pocket between the two subunits of TMV-CP. Meanwhile, compound 4a demonstrated excellent antibacterial activities against Ralstonia solanacearum (R. solanacearum), with an EC50 value of 0.1 μg mL-1, which was better than that of thiodiazole-copper (36.1 μg mL-1) and bismerthiazol (49.5 μg mL-1). The compounds act by causing folding and deformation of the bacterial cell membrane as observed using scanning electron microscopy (SEM). The chalcone derivatives thus synthesized could become potential alternative templates for novel antiviral and antibacterial agents.

Synthesis of New 1,3,5-Triazine-Based 2-Pyrazolines as Potential Anticancer Agents

A new series of 1,3,5-triazine-containing 2-pyrazoline derivatives (8⁻11)a⁻g was synthesized by cyclocondensation reactions of [(4,6-bis((2-hydroxyethyl)amino)-1,3,5-triazin-2-yl)amine]chalcones 7a⁻g with hydrazine hydrate and derivatives. Chalcones 7a⁻g were obtained by Claisen-Schmidt condensation between aromatic aldehydes and triazinic derivative 5, which was synthesized in high yield by a microwave-assisted reaction. Seventeen of the synthesized compounds were selected and tested by the US National Cancer Institute (NCI) for their anticancer activity against 58 different human tumor cell lines. Compounds 7g and 10d,e,g showed important GI50 values ranging from 0.569 to 16.6 µM and LC50 values ranging from 5.15 to >100 µM.

Antiviral properties and interaction of novel chalcone derivatives containing a purine and benzenesulfonamide moiety

A new concise and facile method was explored to synthesize a series of novel chalcone derivatives containing a purine and benzenesulfonamide moiety and their antiviral properties were evaluated against TMV and CMV. Biological assays indicated that several of the derivatives exhibited significant anti-TMV and anti-CMV activities in vivo. In particular, compound d2 displayed excellent inactivating activity against TMV, with the EC50 value of 51.65 μg/mL, which was better than that of ribavirin (150.45 μg/mL). Molecular docking showed that there are four hydrogen bonds between compound d2 and TMV coat protein (TMV-CP). Compound d2 demonstrated strong binding capacity to TMV-CP with Ka = 1.58 × 105 L/mol and Kd = 12.16 μM. These findings indicated that chalcone derivatives are worthy of further research and development as templates for new antiviral agents.