Isatin or 1H-indole-2,3-dione skeleton has been playing a significant role in drug de-sign and development. Isatin itself and many of its derivatives are widely distributed in naturally occurring bioactive compounds. Various synthetic isatin derivatives were found to possess a broad range of significant pharmacological efficacies especially anti-cancer activity against a wide variety of cancer cell lines. Interestingly, on a few occasions, some isatin-derived scaffolds were reported as more potent than the tested reputed drug molecules. As a result, isatin-derived compounds have been gaining significant attention in cancer-based drug developments. In this re-view, we have summarized literature reported during the last two decades related to the synthesis of structurally diverse isatin-derived scaffolds with promising anti-cancer activities.

Isatin-derived spirocyclic cores are found in several biologically active molecules. Here, we report nucleophilic domino reactions for the synthesis of α-methylene-γ-butyrolactone/lactam containing spirocyclic oxindoles. The Zn-mediated one-step reaction accommodates a range of substrates and can be used to rapidly generate focused libraries of highly substituted spirocyclic compound.

Inspired from the important applications of spirocyclic compounds in medicinal chemistry, a new series of pyrazoline Spiro-oxindole tethered 1,2,3-triazole hybrids was reported via Cu(I)-catalyzed click reaction from isatin-pyrazoline linked terminal alkynes with in situ derived benzyl azides. Antimicrobial evaluation data showed that all hybrids exhibited promising efficacy towards the tested microbial strains. Antimicrobial screening as well as docking studies suggested that hybrid 6a was found to be most potent towards Aspergillus niger (MIC = 0.0122 μmol/mL) and Escherichia coli (MIC = 0.0061 μmol/mL). Molecular docking studies of 6a within the binding pockets of antibacterial and antifungal targets revealed good interactions with the binding energies of - 144.544 kcal/mol and - 154.364 kcal/mol against 1KZN (E. coli) and 3D3Z (A. niger), respectively. Further, MD simulations were performed to study the stability of the complexes formed at 300 K. Based on the RMSD trajectories, it is evident that 3D3Z-6a complex exhibits minimal deviation, whereas the 1KZN-6a complex displayed little more deviation compared to the protein but, both are in acceptable range. Moreover, 3D3Z-6a and 1KZN-6a showed maximum number of hydrogen bonds at 50 ns and 70 ns, respectively, thereby complementing the stability of these complexes.

UNASSIGNED: Isatin derivatives have excited attention due to their biological attractions, especially, anticancer properties. Isatin analogs such as semaxanib and sunitinib were exposed to tyrosine kinase inhibitory properties. N-substituted isatins were reported to show cytotoxic activity. On the other, the extension of impressive and cost-effective agents against leishmaniasis is necessary in third-world countries. The capability of isatin derivatives to create novel anticancer and anti-leishmanial compounds has been identified in medicinal chemistry research. The current study aimed to synthesize N-alkyl-isatin-3-imino aromatic amine compounds and evaluate their biological effects.
UNASSIGNED: Synthesis started with the formation of 2-chloro-N-phenylacetamide derivatives by the reaction of aniline derivatives with chloroacetyl chloride. N-alkylation of isatin was performed in the presence of K2CO3 in N, N-dimethylformamide. Final products were prepared via the condensation of N-alkyl isatin derivatives with aromatic amines. Cell viability was checked out by using the MTT assay against cancer cells. Final compounds were screened for anti-leishmanial activity. The molecules were docked in the active sites of the epidermal growth factor receptor tyrosine kinase to define the possible interactions.
UNASSIGNED: Compounds 5c and 4d with IC50 value of 50 μΜ showed cytotoxic activity on the MCF-7 cell line. Compound 5b presented anti-leishmanial activity against promastigote form after 48 h (IC50:59 μΜ) and 72 h (IC50: 41 μΜ) incubations. The highest docking score was -7.33 kcal/mol for compound 4d.
UNASSIGNED: The nature of substitution in the N1 region of isatin seems to be able to influence the cytotoxic activity. Based on the obtained results of docking and cytotoxic tests, compound 4d seems to be a good compound for further investigations.

The use of VEGFR-2 inhibitors as a stand-alone treatment has proven to be ineffective in clinical trials due to the robustness of cellular response loops that lead to treatment resistance when only targeting VEGFR-2. The over-activation of the signal transducer/activator of transcription 3 (STAT-3) is expected to significantly impact treatment failure and resistance to VEGFR-2 inhibitors. In this study, we propose the concept of combined inhibition of VEGFR-2 and STAT-3 to combat induced STAT-3-mediated resistance to VEGFR-2 inhibition therapy. To explore this, we synthesized new isatin-grafted phenyl-1,2,3-triazole derivatives \"6a-n\" and \"9a-f\". Screening on PANC1 and PC3 cancer cell lines revealed that compounds 6b, 6 k, 9c, and 9f exhibited sub-micromolar ranges. The most promising molecules, 6b, 6 k, 9c, and 9f, demonstrated the highest inhibition when tested as dual inhibitors on VEGFR-2 (with IC50 range 53-82 nM, respectively) and STAT-3 (with IC50 range 5.63-10.25 nM). In particular, triazole 9f showed the best results towards both targets. Inspired by these findings, we investigated whether 9f has the ability to trigger apoptosis in prostate cancer PC3 cells via the assessment of the expression levels of the apoptotic markers Caspase-8, Bcl-2, Bax, and Caspase-9. Treatment of the PC3 cells with compound 9f significantly inhibited the protein expression levels of VEGFR-2 and STAT-3 kinases compared to the control.

Aldehyde dehydrogenases (ALDHs) are a family of enzymes that aid in detoxification and are overexpressed in several different malignancies. There is a correlation between increased expression of ALDH and a poor prognosis, stemness, and resistance to several drugs. Several ALDH inhibitors have been generated due to the crucial role that ALDH plays in cancer stem cells. All of these inhibitors, however, are either ineffective, very toxic, or have yet to be subjected to rigorous testing on their effectiveness. Although various drug-like compounds targeting ALDH have been reported in the literature, none have made it to routine use in the oncology clinic. As a result, new potent, non-toxic, bioavailable, and therapeutically effective ALDH inhibitors are still needed. In this study, we designed and synthesized potent multi-ALDH isoform inhibitors based on the isatin and indazole pharmacophore. Molecular docking studies and enzymatic tests revealed that among all of the synthesized analogs, compound 3 is the most potent inhibitor of ALDH1A1, ALDH3A1, and ALDH1A3, exhibiting 51.32%, 51.87%, and 36.65% inhibition, respectively. The ALDEFLUOR assay further revealed that compound 3 acts as an ALDH broad spectrum inhibitor at 500 nM. Compound 3 was also the most cytotoxic to cancer cells, with an IC50 in the range of 2.1 to 3.8 µM for ovarian, colon, and pancreatic cancer cells, compared to normal and embryonic kidney cells (IC50 7.1 to 8.7 µM). Mechanistically, compound 3 increased ROS activity due to potent multi-ALDH isoform inhibition, which increased apoptosis. Taken together, this study identified a potent multi-isoform ALDH inhibitor that could be further developed as a cancer therapeutic.

In the present work, a new class of thiazole-isatin-1,2,3-triazole hybrids (5a-5p) and precursor alkyne hybrids (6a-6d) has been reported with their in-silico studies. After structural identifications using different spectroscopic technique such as FTIR, 1H and 13C NMR and HRMS, the synthesized hybrids were explored for their biological potential using molecular docking and molecular dynamics calculations. Molecular docking results revealed that compound 5j showed maximum binding energy i.e. -10.3 and -12.6 kcal/mol against antibacterial and antifungal enzymes; 1KZN (E. coli) and 5TZ1 (C. albicans), respectively.Top of FormBottom of Form Molecular dynamics simulations for the best molecule (100 ns) followed by PBSA calculations  suggested a stable complex of 5j with 5TZ1 with binding energy of -118.760 kJ/mol as compared to 1KZN (-94.593 kJ/mol). The mean RMSD values for the 1KZN with 5j complex remained approximately 0.175 nm throughout all the time span of 100 ns in the production stages and is in the acceptable range.  Whereas, 5TZ1 with 5j complex, RMSD values exhibited variability within the range of 0.15 to 0.25 nm.

The reaction mechanism of tthe formation of azomethine ylides from isatins and sarcosine is addressed in the literature in a general manner. This computational study aims to explore the mechanistic steps for this reaction in detail and to assess the reactivity of formed ylide in a 1,3-dipolar cycloaddition reaction with 7-oxabenzonorbornadiene. For this purpose, density functional theory (DFT) calculations at the M06-2X(SMD,EtOH)/6-31G(d,p) level were employed. The results indicate that CO2 elimination is the rate-determining step, the activation barrier for 1,3-dipolar cycloaddition is lower, and the formed ylide will readily react with dipolarophiles. The substitution of isatine with electron-withdrawal groups slightly decreases the activation barrier for ylide formation.

Fluorescent cytotoxic compounds with readout delivery are crucial in chemotherapy. The growing demands of these treatment strategies require the novel heterocyclic molecules with better selectivity alongside fluorescence marker potential. In this context, a series of nine isatin Schiff base derivatives 4a-i were synthesized, characterized and evaluated for UV-visible, fluorescence, thermal and bioanalysis in order to explore the effect of structure on their bioprofiles. The analogue 4d exhibited maximum cytotoxic activity on Hella cells with percentage inhibition of 83% at 50 µM and 100% at 150 µM concentrations while 4c showed minimum cytotoxic activity with the value of 19% at 50 µM and 22% at 150 µM concentrations. Meanwhile, 4g was found to exhibit maximum inhibition potential towards Vero Cells with the percentage inhibition values of 83 at 50 µM concentration. The overall SAR study showed that the para-fluoro-substituted isatin moieties exhibited the appreciable percentage inhibition while the least activity was delivered by the isatin derivatives with para-bromo substitution.

An efficient and anions fluorescence \"on-off\" sensor of 1-(prop-2-yn-1-yl)-3-(quinolin-3-ylimino)indolin-2-one (PQI) has been developed for the selective sensing of dual anions of F- and NO3- ions in aqueous medium. Active hydrogen and Lewis acidic binding sites free, Z- isomer of isatin based π-conjugated quinoline exhibited excellent sensing activity against F- and NO3- ions in UV light. The fluorescence turns on the process accomplished via the PET \"on-off\" mechanism. The interaction between probe molecule and anions is thought to be a non-covalent interaction of the low electron density covalently bonded N-methylene moiety of propargyl isatin (-N-CH2-) of probe molecule with F- ion and the terminal acidic proton of propargyl group of isatin (-C≡C-H) with NO3- ions. The modes of anions binding with PQI and plausible mechanisms are proposed by 1H and 13C NMR titrations. The selectivity of anions sensing may be offered by the bucked structure of the Z-isomer. The calculated association constant values for PQI and F- and NO3- are ions 2.5 × 104 M-1 and 2.2 × 103 M-1, respectively, indicating strong binding interaction between the PQI and anions. The association nature of anions and probes was analyzed by a Jobs plot and the finding indicates both F- and NO3- ions are in 1:1 complexation with PQI. The limit of detection (LOD) of the probe with F- and NO3- ions is calculated and is to be 6.91 × 10-7 M and 9.93 × 10-7 M, respectively. The proposed PQI fluorophore possesses a low limit of detection (LOD) for both F- and NO3- ions which is within the WHO prescribed detection limit.