Design and synthesis of novel isatin derivatives as potent analgesic, anti-inflammatory and antimicrobial agents

Synthesis and characterization of a solvatochromic urea-schiff base derivative: Investigating optical properties, hydrogen bonding effect, copper ion sensing, computational analysis, DNA and β-cyclodextrin interactions

This study investigates the fluorescence behavior of the synthesized compound (E)-1-(4-chloro-2-(((2-hydroxynaphthalen-1-yl) methylene) amino) phenyl)-3-(naphthalen-1-yl) urea (3DB) in various solvents. A significant increase in fluorescence intensity was observed when transitioning from ethanol to less polar solvents like CH2Cl2, CHCl3, and CCl4, indicating enhanced fluorescence due to reduced non-radiative processes. Emission wavelengths remained stable with minor shifts (5-6 nm), while significant blue shifts in absorption occurred in water due to strong hydrogen bonding. Fluorescence spectra showed red shifts (519 nm in water, 508 nm in glycerol, and 486 nm in ethylene glycol), highlighting the impact of hydrogen bonding on electronic transitions. Emission intensity in water was six times higher than in ethylene glycol, suggesting that strong hydrogen bonds stabilize the excited state. The study also revealed that 3DB exhibits a large Stokes shift, avoiding reabsorption of emitted light (inner filter effect). Fluorescence was completely quenched by low concentrations of copper ions, demonstrating 3DB's potential as a copper sensor. Density functional theory (DFT) and time-dependent DFT (TDDFT) calculations indicated that luminescence quenching in the Cu(II) complex is due to intramolecular charge transfer (ICT). Additionally, 3DB formed stable complexes with DNA and β-cyclodextrin (β-CD), with binding constants (Kb) of 1.30 × 103 M-1 and 1.89 × 103 M-1, respectively, and negative Gibbs free energy values, indicating spontaneous interactions. Fluorescence spectroscopy confirmed DNA binding, showing a 49.62 % increase in intensity and a 4 nm blue shift, consistent with groove-binding. Docking studies further supported favorable interactions with DNA. These results underscore 3DB's potential in sensing, imaging, environmental monitoring, and biological applications.

Anticancer Activity and Safety Profile of Novel 1-(4-Fluorophenoxyacetyl)-4-substituted Thio/Semicarbazide Derivatives

Compounds with thiosemicarbazide and semicarbazide scaffolds are among the most promising structures in medicinal chemistry due to the possibility of forming multiple hydrogen bonds. Therefore, six new derivatives of 4-fluorophenoxyacetylthiosemicarbazide and 4-fluorophenoxyacetylthiosemicarbazide were designed to compare their physicochemical properties, biological activity, and in silico pharmacokinetic parameters. All compounds were characterized by 1H, 13C NMR, 19F, IR spectra. For selected derivatives (AB2 and AB5), X-ray studies were performed to confirm their synthetic route and identify the tautomeric forms and intra- and intermolecular interactions occurring in the crystalline state. In the in silico pharmacokinetic study, a clear difference in lipophilicity was observed between thiosemicarbazide and semicarbazide derivatives. In vitro biological studies have shown the promising activity of thiosemicarbazides against prostate cancer cell line LNCaP, with a higher safety profile than semicarbazides. The most active compound AB2 showed IC50 = 108.14 μM against LNCaP. Based on biological studies, topoisomerase IIα was proposed as a potential molecular target, which was confirmed by molecular docking studies.

Synthesis, cytotoxicity, apoptosis-inducing activity and molecular docking studies of novel isatin-podophyllotoxin hybrids

Podophyllotoxin, along with its numerous derivatives and related compounds, is well known for its broad-spectrum pharmacological activity, especially for anticancer potential. In this study, several isatin-podophyllotoxin hybrid compounds were successfully synthesized with good yields through microwave-prompted three-component reactions of 2-amino-1,4-naphthoquinone, various substituted isatins, and tetronic acid. Their cytotoxicity was assessed against four types of human cancer cell lines, HepG2 (hepatoma carcinoma), MCF7 (breast cancer), A549 (non-small lung cancer), and KB (epidermoid carcinoma), alongside nontumorigenic HEK-293 human embryonic kidney cells. Among 14 compounds screened, 7f possessed the strongest cytotoxicity to KB and A549 cell lines, with IC50 values of 1.99 ± 0.22 and 0.90 ± 0.09 μM, respectively. Further studies revealed that product 7f could arrest the cell cycle of A549 cells at S phase and induce apoptosis of A549 cells. This compound was examined for its binding ability against cyclin-dependent kinases (CDKs) and procaspase/caspase systems. The results indicated that 7f exhibited significant interactions with the residues of the ATP binding sites of CDK2/cyclin A and CDK5/p25 and also activated procaspase 6 through stable zinc chelation. Additionally, physicochemical and pharmacokinetic properties related to drug-likeness, in parallel with toxicity, were computationally assessed to identify the main issues that need to be addressed in structural optimization. Taken together, compound 7f was identified as a potent cytotoxic agent that could be considered for anticancer drug discovery and development.

Novel isatin conjugates endowed with analgesic and anti-inflammatory properties: design, synthesis and biological evaluation

AIMS

This study aimed to develop novel molecular hybrid conjugates integrating isatin, rhodanine, and phthalimide pharmacophores to create effective analgesic and anti-inflammatory agents with improved safety profiles over existing treatments.

MATERIALS & METHODS

A series of hybrid conjugates (4a - l) were synthesized and evaluated through in vitro and in vivo biological assays. The most promising compound, 4c, underwent extensive pharmacological and toxicological evaluations. Molecular docking, molecular dynamics simulations, and 2D-QSAR studies were performed to elucidate the mechanism of action and validate the experimental findings.

RESULTS

Compound 4c exhibited potent analgesic and anti-inflammatory activity, effectively inhibiting COX-2 and pro-inflammatory cytokines (IL-6 and TNF-α). Its superior selectivity index (SI) was 1.11 compared to 0.67 for indomethacin. It demonstrated an ulcer index of 2.9 versus 10.23 for indomethacin, indicating reduced gastrointestinal toxicity. Molecular docking simulations revealed a strong binding affinity with COX-2 (-9.832 kcal/mol), and molecular dynamics confirmed the stability of the COX-2 complex.

CONCLUSIONS

Compound 4c emerged as a promising lead candidate for developing safer and more effective anti-inflammatory and analgesic agents. Its robust efficacy, safety profile, and computational validation highlight its potential for further optimization in therapeutic applications.

Synthesis of 5-hydroxyisatin thiosemicarbazones, spectroscopic investigation, protein-ligand docking, and in vitro anticancer activity

A series of novel modifications were performed at the N(4) position of 5-hydroxyisatin thiosemicarbazone (TSC). The structure-activity approach is applied to design and synthesize derivatives by condensing thiosemicarbazides with 5-hydroxy isatin. The TSCs were characterized by various spectroscopic techniques viz. FTIR, 1H NMR, 13C NMR, UV-Vis, HRMS data, CHN elemental analysis, and single crystal X-ray diffraction. Biological evaluation of the synthesized compounds revealed the anticancer potency of the TSC analogues against breast cancer (MD-AMD-231, MCF-7), lung cancer (A549, NCI-H460), prostate cancer (PC3), and skin cancer (A431). The molecules, L2, L3, and L6 showed activity in the micromolar range (IC50; 0.19-2.19 μM). L6 exhibited the highest potency against skin cancer A431 cell line, with an IC50 of 0.19 μM compared to 1.8 μM with triapine and showed low toxicity against PNT-2 cells with an SI index of >100 μM. The mechanistic study revealed that L6 inhibited cancer cell proliferation, colony formation, and 3-dimensional spheroid formation by targeting the Ras/MAPK axis. It induced DNA damage and impaired DNA damage repair machinery, which led to the accumulation of DSB. Also, it lowered the ERK1/2 expression, which affected the caspase 3 activity and showed higher binding affinity compared to the FDA-approved drug Lenalidomide in molecular docking studies. Our findings demonstrated the possible future anticancer drug potency of L6 in the skin cancer A431 cells.

Lead optimization study on indoline-2,3-dione derivatives as potential fatty acid amide hydrolase inhibitors

Based on the known isatin-based fatty acid amide hydrolase (FAAH) inhibitor BSS-7, we designed and synthesized two small sets (6-13 and 17-20) of N-1 and C-3 substituted isatin derivatives and evaluated them for their in vitro FAAH inhibition properties. The lead simplification by modification of bulky aryl moiety at N-1 with a flexible allyl group produced a nanomolar (IC50 = 6.7 nM, Ki = 5 nM) inhibitor 11 (Z)-3-((1H-benzo[d]imidazol-2-yl)imino)-1-allylindolin-2-one which exhibited a reversible and competitive FAAH inhibition with 1500 times more potency to BSS-7 (1.49 ± 0.03 µM). The lead compound 11 also showed a high blood-brain permeability and a significant antioxidant profile with no neurotoxicity. Docking results suggested that the inhibitor molecules occupied the active site of FAAH and offered optimal binding interactions. A molecular dynamics simulation study ascertained the stability of the lead inhibitor 11-FAAH complex. In silico ADMET profiling studies unveiled that compound 11 possesses good drug-like properties and merits further evaluation.Communicated by Ramaswamy H. Sarma.

Design and Development of COX-II Inhibitors: Current Scenario and Future Perspective

Innate inflammation beyond a threshold is a significant problem involved in cardiovascular diseases, cancer, and many other chronic conditions. Cyclooxygenase (COX) enzymes are key inflammatory markers as they catalyze prostaglandins production and are crucial for inflammation processes. While COX-I is constitutively expressed and is generally involved in "housekeeping" roles, the expression of the COX-II isoform is induced by the stimulation of different inflammatory cytokines and also promotes the further generation of pro-inflammatory cytokines and chemokines, which affect the prognosis of various diseases. Hence, COX-II is considered an important therapeutic target for drug development against inflammation-related illnesses. Several selective COX-II inhibitors with safe gastric safety profiles features that do not cause gastrointestinal complications associated with classic anti-inflammatory drugs have been developed. Nevertheless, there is mounting evidence of cardiovascular side effects from COX-II inhibitors that resulted in the withdrawal of market-approved anti-COX-II drugs. This necessitates the development of COX-II inhibitors that not only exhibit inhibit potency but also are free of side effects. Probing the scaffold diversity of known inhibitors is vital to achieving this goal. A systematic review and discussion on the scaffold diversity of COX inhibitors are still limited. To address this gap, herein we present an overview of chemical structures and inhibitory activity of different scaffolds of known COX-II inhibitors. The insights from this article could be helpful in seeding the development of next-generation COX-II inhibitors.

Medicinal importance and chemosensing applications of Schiff base derivatives for the detection of metal ions: A review

Schiff bases, named after Hugo Schiff, are formed when primary amine reacts with carbonyl compounds (aldehyde or ketone) under specific conditions. Schiff bases are economical, simple synthetic routes, and easily accessible in laboratories. They have medicinal and biological applications such as antiviral, antioxidant, antifungal, anticancer, anthelmintic, antibacterial, antimalarial, anti-inflammatory, antiglycation, anti-ulcerogenic, and analgesic potentials. A number of Schiff bases are reported for the detection of various metal ions. They are also used as catalysts, polymer stabilizers, intermediates in organic synthesis, and corrosion inhibitors. In this review, we have highlighted the recent advancements in the development of bioactive Schiff base derivatives and their sensing applications for detecting metal cations. Additionally, various spectroscopic techniques for structural characterization, such as X-ray diffraction analysis (XRD), FT-IR, UV-vis, and NMR spectroscopy were also discussed.

Therapeutic Outcomes of Isatin and Its Derivatives against Multiple Diseases: Recent Developments in Drug Discovery

Isatin (1H indole 2, 3-dione) is a heterocyclic, endogenous lead molecule recognized in humans and different plants. The isatin nucleus and its derivatives are owed the attention of researchers due to their diverse pharmacological activities such as anticancer, anti-TB, antifungal, antimicrobial, antioxidant, anti-inflammatory, anticonvulsant, anti-HIV, and so on. Many research chemists take advantage of the gentle structure of isatins, such as NH at position 1 and carbonyl functions at positions 2 and 3, for designing biologically active analogues via different approaches. Literature surveys based on reported preclinical, clinical, and patented details confirm the multitarget profile of isatin analogues and thus their importance in the field of medicinal chemistry as a potent chemotherapeutic agent. This review represents the recent development of isatin analogues possessing potential pharmacological action in the years 2016-2020. The structure-activity relationship is also discussed to provide a pharmacophoric pattern that may contribute in the future to the design and synthesis of potent and less toxic therapeutics.

DBU Catalyzed Phospho-Aldol-Brook Rearrangement for Rapid Preparation of α-Phosphates Amide in Solvent-Free Conditions

The 1,8-diazabicyclo [5.4.0] undec-7-ene DBU-catalyzed Phospho-Aldol-Brook Rearrangement reaction of α-ketoamide and dialkyl phosphites was developed under solvent-free at room temperature. The novel α-Phosphate Amide derivatives could be obtained with good yield (86–96%), which also exhibited good tolerance of various dialkyl phosphites and α-ketoamide, including isatins. In addition, the reaction was conducted in both gram-scale and mol-scale, and the title compounds could also be obtained in excellent yield (more than 91%) within 5 min.