Synthesis and reactivity of new amide-substituted oxindole derivatives

Discovery of Novel 2-Oxindoles as Compounds with Antiglaucoma Activity

Oxindole-based natural indoles analogues retain the rigidity and size of the original indole ring system whilst introducing more 3-dimensionality and potential increased water solubility. We report the first preparation of a diverse series of new melatonin analogues 4, 6, 11, 12 based on 3-hydroxy-2-oxindoles (11) and hydroxy-free 2-oxindoles (4, 6, 12) and evaluated their ability to reduce intraocular pressure as well as their neuroprotective and antioxidant properties. Reductive amination was used to obtain new 5-(benzylamino)-substituted (indolin-3-yl)acetonitriles 11 and (indolin-3-yl)acetic acids 12 with high yields. Compounds 4 a, c, 6 a and 11 a, d, h, j-l demonstrated IOP reduction effect in range 15-27 % similar to the effect of reference compounds melatonin and timolol (12 % and 18 % reduction, respectively). 5-(Benzylamino)-substituted 3-hydroxy-2-oxindoles 11, unlike compounds 4, 6, inhibited lipid peroxidation in range 2.075-13.012 μM. Inhibition of NQO2 associated with antioxidant properties of melatonin was also evaluated for synthesized compounds and it was found that compound 11 h showed the best NQO2 inhibitory activity with an IC50=39 μM (vs. melatonin IC50=64 μM). All synthesized compounds 4, 6, 11, 12 at a concentration of 30 μM do not possess the mitochondrial toxicity. Moreover, no disruption of tubulin polymerization was observed even in the presence of 100 μM of the compounds. Thus, 3-hydroxy-2-oxindole derivatives 11 can be used for drug design of first-in-class antiglaucoma drugs with antioxidant and neuroprotective properties.

Synthesis, Characterization, Bioevaluation, and Docking Studies of Spiroisatin-Based Hydrazide Conjugates

A series of spiroisatin-based hydrazide conjugates IV(a-t) was synthesized and structurally characterized using spectral data, with compound IV-a further confirmed by x-ray diffraction analysis. All the synthesized compounds were evaluated for their biological potential in a cell painting assay. Among the synthesized spiroisatin derivatives, compound IV-p exhibited significant activity in inducing cellular morphological changes, with an induction value of 30.6%. In addition, some compounds showed high biosimilarities with marketed drugs. Specifically, the compounds IV-n and IV-p showed a high biosimilarity with the orally active iron chelator deferasirox, and IV-m showed a high biosimilarity with the kinase inhibitor alisertib. Furthermore, compounds IV-p showed significant inhibition against human breast cancer (MDA-MB-231 = 82.37%) and colorectal carcinoma cell lines (HCT-116 = 86.25%) during preliminary investigations. Moreover, it was revealed through molecular docking analysis that IV-p possesses a good binding score against ferroportin and Aurora A kinase (-9.3 and -9.2 kcal/mol), which are quite comparable with the deferasirox (-9.2 kcal/mol) and alisertib (-9.8 kcal/mol). Pharmacokinetic studies revealed that the synthesized conjugates have good oral bioavailability, balanced hydrophilicity, and minimal toxicity. The results of this study clearly highlight the potential of these conjugates as promising small bioactive molecules.

Intramolecular noncovalent C-bonding driven conformational preference in spiroisatin-based N-acyl hydrazones

Noncovalent carbon bonding (C-bonding), a recently explored σ-hole interaction, has primarily been characterized through X-ray structural and computational studies. Evidence of C-bonds in solution is scarce, especially in highly polar solvents like DMSO where solvation effects typically overshadow weak non-covalent interactions. In this work, we present three novel spiroisatin-based N-acyl hydrazones (1-3) in which C-bonds play a critical role in stabilizing the cis conformation in solution. Despite the steric preference for the NH-amide bond to adopt the trans geometry (H-N-C[double bond, length as m-dash]O ≈ 180°), 1H and 13C NMR spectra of compounds 1 and 2 in DMSO-d 6 reveal a rotameric mixture with a higher percentage of the cis conformation (82% and 76%, respectively), attributed to the stability provided by intramolecular C-bonding. Compound 3 also predominantly adopts the cis conformation in DMSO but to a lesser extent (60%) than compounds 1 and 2, due to competing intramolecular hydrogen bonding. Single-crystal X-ray analysis of compounds 1 and 2 confirmed the cis conformation, consistent with the solution-state preference. In contrast, compound 3 crystallized in the trans form, likely due to intramolecular hydrogen bonding and solid-state packing effects, which reinforce the steric preference for the trans geometry. Density functional theory (DFT) calculations corroborated the experimental data, predicting greater stability for the cis conformations in compounds 1, 2, and 3 in solution. The ability of intramolecular C-bonding to stabilize the cis conformation, even in highly polar solvents like DMSO, highlights the broader significance of this interaction in supramolecular chemistry and related fields.

The rational design of novel 5-amino-2-oxindole derivatives with antiglaucomic activity

Compounds with a 2-oxindole scaffold play an important role in organic synthesis and especially in the synthesis of bioactive organic compounds, therefore, the development of new methods for modifying this scaffold is a very interesting and urgent task. In the framework of this study, we have created a rational approach to the synthesis of 5-amino-substituted derivatives of 2-oxindole. The approach is characterized by good total yield and a small number of steps. One-stage modification of obtained 5-amino-2-oxindoles leads to compounds with promising antiglaucomic activity. The most active compound 7a reduce intraocular pressure by 24% in normotensive rabbits (18% for reference drug timolol).

Single-crystal X-ray structural characterization, Hirshfeld surface analysis, electronic properties, NBO, and NLO calculations and vibrational analysis of the monomeric and dimeric forms of 5-nitro-2-oxindole

The information of interactions is given by RDG versus sign(λ₂)ρ product of the sign of the second largest eigenvalue of electron density Hessian matrix and electron density) investigated by RDG surface analysis.

Synthesis and biological evaluation of 3-substituted 2-oxindole derivatives as new glycogen synthase kinase 3β inhibitors

Glycogen synthase kinase 3β (GSK-3β) is a widely investigated molecular target for numerous diseases including Alzheimer's disease, cancer, and diabetes mellitus. Inhibition of GSK-3β activity has become an attractive approach for treatment of diabetes and cancer. We report the discovery of novel GSK-3β inhibitors of 3-arylidene-2-oxindole scaffold with promising activity. The most potent compound 3a inhibits GSK-3β with IC₅₀ 4.19 nM. In a cell-based assay 3a shows no significant leucocyte toxicity at 10 µM and is moderately cytotoxic against A549 cells. Compound 3a demonstrated high antidiabetic efficacy in obese streptozotocin-treated rats improving glucose tolerance at a dose of 50 mg/kg body weight thus representing an interesting lead for further optimization.