Search Results (723)

Chrysin (5,7-dihydroxyflavone) is a flavonoid widely distributed in propolis, honey, and various plant sources. It exhibits a wide range of pharmacological activities, including anti-inflammatory, antioxidant, anticancer, antimicrobial, and anti-diabetic effects. However, its clinical translation is hampered by poor aqueous solubility, low bioavailability, and rapid metabolic clearance. To address these limitations and expand the chemical space of this natural scaffold, extensive synthetic efforts have focused on generating structurally diverse chrysin derivatives that possess improved drug-like properties. This review systematically categorizes synthetic methodologies—such as etherification, esterification, transition-metal-mediated couplings, sigmatropic rearrangements, and electrophilic substitutions—and integrates them with corresponding biological outcomes. Particular emphasis is placed on recent (2020–present) advances that directly link structural modifications with pharmacological enhancements, thereby offering comparative structure–activity relationship (SAR) insights. In addition, transition-metal-catalyzed C–C bond-forming reactions are highlighted in a dedicated section, underscoring their growing role in accessing bioactive chrysin analogs previously unattainable by conventional chemistry. Unlike prior reviews that mainly summarized biological activities or broadly covered flavonoid scaffolds, this article bridges synthetic diversification with pharmacological evaluation. It provides both critical synthesis and mechanistic interpretation. Overall, this work consolidates current knowledge and suggests future directions that integrate synthetic innovation with pharmacological validation and address pharmacokinetic challenges in chrysin derivatives. Full article

This review of thiazolidinedione or glitazone, which have a five-membered heterocyclic ring C₃NS, shows their versatile properties in terms of pharmacological actions such as antimicrobial, antifungal, insecticidal, pesticidal, antidiabetic, anti-inflammatory, anti-proliferative, anti-neurotoxicity, anticonvulsant, anti-thyroidal, and anti-tubercular uses. While having a wide range of biological activities, the TZDs mainly act via binding to the peroxisome proliferator-activated receptor (PPAR) members. PPAR-γ are ligand-activated transcription factors, which are members of the nuclear hormone receptors group. Activations of PPAR-γ regulate cell proliferation and differentiation, glucose homeostasis, apoptosis, lipid metabolism, and inflammatory responses. This review explores the synthesis of a thiazolidinedione and its derivatives, focusing on their pharmacological profiles and antidiabetic activity. It highlights the benefits of synthesis, reaction profiles, and catalyst recovery, which may encourage further investigation into these scaffolds by researchers. Based on synthesized derivatives, some glimpses of the structure–activity relationships of some compounds have been compiled. All the synthesized derivatives have been reviewed concerning their standard drugs already available and concluded with the highly or moderately active synthesized derivatives of thiazolidinedione. The data for this review was collected by an extensive review of current scientific literature, including on the synthesis, biological evaluation, SAR, and patents (2015–25). Full article

Adenosine receptor (AR) antagonists have attracted considerable interest due to their therapeutic potential in a wide range of pathological conditions, including neurological, cardiovascular, and inflammatory disorders. Although a large number of AR antagonists have been developed worldwide, the interest in new derivatives remains high, and achieving subtype selectivity continue to be a major challenge. This review summarizes our research on adenosine receptor antagonists, highlighting the discovery of potent and selective compounds for the diverse AR subtypes across various chemical classes. Specifically, the paper focuses on the study of the triazolo[4,3-a]quinoxalin-1-one (TQX) and pyrazolo[3,4-c]quinoline (PQ) series, along with their simplified analogues, which have yielded highly potent and selective AR antagonists. An overview of the structure–activity relationship (SAR) studies and molecular docking investigations is provided, emphasizing the structural requirements for A_2A and A₃ receptor–ligand interaction. In addition, we present pharmacological studies of selected AR antagonists, in various in vitro and in vivo models of pain, depression, neuroinflammation-related diseases, and cancer. Full article

Recent studies on brominated tyrosine-derived marine natural products have significantly expanded the library of known structures and revealed their potent and diverse antitumor mechanisms. Building upon our previous research on the natural product itampolin A isolated from marine sponges, we conducted structural optimizations and explored the structure–-activity relationships (SARs) of novel scaffold derivatives concerning their inhibitory activities against lung cancer cells. In the present study, we further synthesized 15 novel derivatives, and compound 4l demonstrated selective anti-proliferative activity against gefitinib-resistant PC9/GR cells, showing 4-fold greater potency compared to parental PC9 cells. Building on this finding, the present study aims to investigate the molecular mechanisms underlying the anti-proliferative effects of 4l in drug-resistant NSCLC models. Through cell cycle analysis, apoptosis assays, and signaling pathway evaluation, we seek to establish a theoretical foundation for developing novel therapeutic agents against chemotherapy-resistant lung cancer. Full article

Background/Objectives: RMC-113, a 3-alkynyl-6-aryl-disubstituted isothiazolo[4,3-b]pyridine, is a dual inhibitor of the lipid kinases PIKfyve and PIP4K2C with broad-spectrum antiviral activity. The aim was to study the structure–activity relationship (SAR) of isothiazolo[4,3-b]pyridines as dual PIKfyve/PIP4K2C inhibitors. Methods: A series of isothiazolo[4,3-b]pyridines was synthesized by introducing structural variety at positions 3 and 6 of the central scaffold. The primary assay to guide the synthetic chemistry was a biochemical PIKfyve assay, with a number of analogues also tested for PIP4K2C binding affinity. Finally, isothiazolo[4,3-b]pyridines were also evaluated for antiviral and antitumoral activity in cell-based assays. Results: PIKfyve inhibition tolerated a wide variety of substituents on the aryl ring at position 6 of the isothiazolo[4,3-b]pyridine scaffold, with the 4-carboxamide analogue emerging as the most potent (IC₅₀ = 1 nM). The SAR at position 3 was more restricted, although the introduction of electron-donating groups (such as a methyl and methoxy) on the pyridinyl ring yielded potent PIKfyve inhibitors, with IC₅₀ values in the low nM range. The acetylenic moiety was essential for PIKfyve inhibition, and only the saturated ethyl linker displayed potent PIKfyve inhibition, albeit less active than the acetylene counterpart. The compounds were 2- to 5-fold less potent on PIP4K2C relative to PIKfyve. These dual PIKfyve/PIP4K2C inhibitors displayed antiviral activity against both the venezuelan equine encephalitis virus (VEEV) and the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). A screening against a panel of cancer cell lines revealed antitumoral activity, although some of the potent PIKfyve/PIP5K2C inhibitors lacked antitumoral activity. Conclusions: Isothiazolo[4,3-b]pyridines are dual PIKfyve/PIP4K2C inhibitors displaying broad-spectrum antiviral, as well as antitumoral, activity. Full article

Background/Objective: The present study reports the design, synthesis, and biological evaluation of novel imidazo-triazole derivatives as potential antidiabetic agents. Methods: The novel series was synthesized by treating amino-triazole bearing carboxylic acid with substituted 2-bromo acetophenone and was biologically compared with acarbose under in vitro analysis. Results: Structure–activity relationship (SAR) analysis revealed that among these compounds, remarkable activity was shown by compound 5 (having three hydroxyl substituents) with IC₅₀ value of 6.80 ± 0.10 and 7.10 ± 0.20 µM for α-amylase and α-glucosidase in comparison to reference drug acarbose. To support experimental findings, computational investigations including molecular docking, pharmacophore modeling, molecular dynamics simulations, density functional theory (DFT), and absorption distribution metabolism excretion and toxicity (ADMET) profiling were employed. These studies confirmed the stability of ligand–protein interactions and provided insights into electronic and reactivity features governing enzyme inhibition. Conclusions: Collectively, the integration of in vitro and in silico approaches underscores the potential of novel imidazo-triazole scaffolds as promising leads for the development of safer and more effective therapeutics against diabetes mellitus. Full article

The search for bioactive compounds with antioxidant properties is critical in combating oxidative stress-related diseases and advancing novel therapeutic agents. Azo dyes, traditionally used in textiles, food, and cosmetics, have recently attracted attention due to their emerging biological activities, including antioxidant potential. In this study, we synthesized and characterized 267 azo dyes derived from natural phenolic cores such as salicylic acid, syringol, and 5,6,7,8-tetrahydro-2-naphthol. Eighteen of these compounds are novel. Structural characterization was performed using NMR, UV-Vis, IR spectroscopy, and mass spectrometry. Antioxidant activity was assessed using in vitro assays with ABTS radical scavenging method. SAR analysis revealed that dyes derived from syringol and 5, 6, 7, 8-tetrahydro-2-naphthol showed the most consistent and potent antioxidant activity. Notably, azo dyes bearing fluoro and nitro substituents in the para position exhibited the lowest IC₅₀ values, highlighting the influence of electron-withdrawing groups and substitution patterns on antioxidant behavior. This work establishes a precedent for SAR-driven evaluation of azo dyes using ABTS and supports their further exploration as functional antioxidant agents in medicinal chemistry. Full article

Rugulopteryx okamurae is an invasive brown alga that has colonised Mediterranean and northeastern Atlantic coastlines, posing significant ecological and economic challenges. Its biomass is rich in structurally diverse metabolites—including polysaccharides (alginate, fucoidan, laminaran), phlorotannins, diterpenoids, fatty acids, and peptides—many of which exhibit notable antioxidant, anti-inflammatory, antimicrobial, and anticancer activities. Comparative assessment of extraction yields, structural features, and bioactivity data highlights phlorotannins and diterpenoids as particularly promising, demonstrating low-micromolar potencies and favourable predicted interactions with key inflammatory and apoptotic targets. Algal polysaccharides exhibit various bioactivities but hold strong potential for scalable and sustainable industrial applications. Emerging compound classes such as fatty acids and peptides display niche bioactivities; however, their structural diversity and mechanisms of action remain insufficiently explored. Insights from in vitro and in silico studies suggest that phlorotannins may modulate NF-κB and MAPK signalling pathways, while diterpenoids are implicated in the induction of mitochondrial apoptosis. Despite these findings, inconsistent extraction methodologies and a lack of in vivo pharmacokinetic and efficacy data limit translational potential. To overcome these limitations, standardized extraction protocols, detailed structure–activity relationship (SAR) and pharmacokinetic studies, and robust in vivo models are urgently needed. Bioactivity-guided valorisation strategies, aligned with ecological management, could transform R. okamurae biomass into a sustainable source for functional foods, cosmetics, and pharmaceuticals applications. Full article

Cathepsin L (CatL) is a critical protease involved in cleaving the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), facilitating viral entry into host cells. Inhibition of CatL is essential for preventing SARS-CoV-2 cell entry, making it a potential therapeutic target for drug development. Six QSAR models were established to predict the inhibitory activity (expressed as IC₅₀ values) of candidate compounds against CatL. These models were developed using statistical method heuristic methods (HMs), the evolutionary algorithm gene expression programming (GEP), and the ensemble method random forest (RF), along with the kernel-based machine learning algorithm support vector regression (SVR) configured with various kernels: radial basis function (RBF), linear-RBF hybrid (LMIX2-SVR), and linear-RBF-polynomial hybrid (LMIX3-SVR). The particle swarm optimization algorithm was applied to optimize multi-parameter SVM models, ensuring low complexity and fast convergence. The properties of novel CatL inhibitors were explored through molecular docking analysis. The LMIX3-SVR model exhibited the best performance, with an $R^2$ of 0.9676 and 0.9632 for the training set and test set and RMSE values of 0.0834 and 0.0322. Five-fold cross-validation $R_{5-fold}^2$ = 0.9043 and leave-one-out cross-validation $R_{loo}^2$ = 0.9525 demonstrated the strong prediction ability and robustness of the model, which fully proved the correctness of the five selected descriptors. Based on these results, the IC₅₀ values of 578 newly designed compounds were predicted using the HM model, and the top five candidate compounds with the best physicochemical properties were further verified by Property Explorer Applet (PEA). The LMIX3-SVR model significantly advances QSAR modeling for drug discovery, providing a robust tool for designing and screening new drug molecules. This study contributes to the identification of novel CatL inhibitors, which aids in the development of effective therapeutics for SARS-CoV-2. Full article

Integrase is a key protein during HIV-1 replication as it catalyzes the integration of viral DNA into the host DNA. After several decades of research, highly potent and selective active site inhibitors have emerged. The new challenge is now to develop molecules with an original mode of action, targeting integrase out of its catalytic site. During a previous study, we developed an in vitro assay to monitor the interaction between HIV-1 integrase and one of its cellular partners, GCN2. This AlphaLISA-based assay was validated as a platform for chemical modulator screening. In the present study, we used a library of natural products from the Developmental Therapeutics Program (NIH) to identify novel chemical leads. The best modulators were characterized and a structure–activity relationship study was initiated with a limited number of derivatives. We found that most inhibitors were tricylic or tetraclyclic molecules, with the most potent belonging to the anthracyclines/anthraquinones. Of note, several molecules exhibited interesting cellular activities and may be suitable for further optimization. Full article

Cancer mortality and the development of cancer resistance present significant challenges that must be addressed to ensure global health. Among anticancer agents, microtubule-targeting agents (MTAs) represent a well-recognized therapeutic approach that disrupts microtubule dynamics, thereby inhibiting cell division, and has been widely used to treat several types of cancers. However, even though MTAs are widely regarded as effective, their potential is limited primarily due to cancer resistance and toxicity. Consequently, in the last years, the exploration of new MTAs with the aim of identifying agents with improved cytotoxicity, selectivity, and adequate pharmacokinetic profile, as well as the ability to evade drug resistance mechanisms, has remained a major concern in the development of anticancer treatment. This review highlights the discovery of new MTAs since 2020, with the goal of understanding the advancements made in this field and its future directions. Special attention is given to structure–activity relationship (SAR) studies that could be important for the discovery of more effective MTAs in the future. Full article

Candidiasis arises from the proliferation of Candida species in the human body, especially in individuals with compromised immune systems. Efficient therapeutic management of candidiasis is often hampered by the limited availability of potent antifungal drugs and the emergence of drug-resistant strains. We have previously identified the N-[(4-sulfamoylphenyl)methyl][1,1′-biphenyl]-4-carboxamide to have fungistatic and fungicidal properties, likely due to the hydrophobic biphenyl–chemical features affecting the structural organization of Candida spp. cell membrane. Here, we designed and synthesized a novel series of twelve 5-arylfuran-2-carboxamide derivatives bearing a new hydrophobic tail as bioisosteric replacement of the diphenyl fragment. Its antifungal effectiveness against C. albicans, C. glabrata, and C. parapsilosis, including ATCC and clinically isolated strains, was assessed for all compounds. The most active compound was N-benzyl-5-(3,4-dichlorophenyl)furan-2-carboxamide (6), with fungistatic and fungicidal effects against C. glabrata and C. parapsilosis strains (MIC = 0.062–0.125 and 0.125–0.250 mg/mL, respectively). No synergistic effects were observed when combined with fluconazole. Interestingly, fluorescent microscopy analysis after staining with SYTO 9 and propidium iodide revealed that compound 6 affected the cell membrane integrity in C. albicans strain 16. Finally, carboxamide 6 exhibited a dose-dependent cytotoxicity on erythrocytes, based on assessing the LDH release. Full article

This study details how 3-(naphthalen-2-yl)-1-phenylprop-2-en-1-one (3NPEO) behaves in terms of photophysics when exposed to different solvents. The solvatochromic effect study reveals significant polarity shifts in the excited states of the 3NPEO compound, likely due to an intramolecular proton transfer mechanism. Measurements of dipole moments provide insight into their resonance structures in both ground and excited states. Electrochemical analysis revealed a reversible redox process, indicating a favorable charge transport potential. HOMO and LUMO energies of the compound were computed via oxidation and reduction potential standards. 3NPEO exhibits optimal one-photon and two-photon absorption characteristics, validating its suitability for visible wavelength laser applications in photonic devices. Furthermore, molecular docking and dynamics simulations demonstrated strong interactions between 3NPEO and the progesterone receptor enzyme, supported by structure–activity relationship (SAR) analyses. In vitro cytotoxicity assays on the MDAMB-231 breast cancer cell line showed moderate tumor cell inhibitory activity. Apoptosis studies confirmed the induction of both early and late apoptosis. These findings suggest that 3NPEO holds promise as a potential anticancer agent targeting the progesterone receptor in breast cancer cells. Overall, the findings highlight the substantial influence of solvent polarity on the photophysical properties and the design of more effective and stable therapeutic agents. Full article

Benzothiazole derivatives have emerged as being highly significant in drug discovery due to their versatile biological activities and structural adaptability. Incorporating nitrogen and sulfur, this fused heterocyclic scaffold exhibits wide-ranging pharmacological properties, including anticancer, antimicrobial, anti-inflammatory, antidiabetic, neuroprotective, and diagnostic applications. A diverse set of clinically approved and investigational compounds, such as flutemetamol for Alzheimer’s diagnosis, riluzole for ALS, and quizartinib for AML, illustrates the scaffold’s therapeutic potential in varied applications. These agents act via mechanisms such as enzyme inhibition, receptor modulation, and amyloid imaging, demonstrating the scaffold’s high binding affinity and target specificity. Advances in synthetic strategies and our understanding of structure–activity relationships (SARs) continue to drive the development of novel benzothiazole-based therapeutics with improved potency, selectivity, and safety profiles. We also emphasize recent in vitro and in vivo studies, including drug candidates in clinical trials, to provide a comprehensive perspective on the therapeutic potential of benzothiazole-based compounds in modern drug discovery. This review brings together recent progress to help guide the development of new benzothiazole-based compounds for future therapeutic applications. Full article

Type 2 diabetes mellitus (T2DM) demands safer and more effective therapies to control postprandial hyperglycemia. Here, we report the synthesis and in vitro evaluation of ten salicylic acid-derived Schiff base derivatives (4a–4j) as α-glucosidase inhibitors. Compounds 4e, 4g, 4i, and 4j exhibited potent enzyme inhibition, with IC₅₀ values ranging from 14.86 to 18.05 µM—substantially better than acarbose (IC₅₀ = 45.78 µM). Molecular docking and 500 ns molecular dynamics simulations revealed stable enzyme–ligand complexes driven by π–π stacking, halogen bonding, and hydrophobic interactions. Density Functional Theory (DFT) calculations and molecular electrostatic potential (MEP) maps highlighted key electronic factors, while ADMET analysis confirmed favorable drug-like properties and reduced nephrotoxicity. Structure–activity relationship (SAR) analysis emphasized the importance of halogenation and aromaticity in enhancing bioactivity. Full article