Dithiocarbamation of spiro-aziridine oxindoles: a facile access to C3-functionalised 3-thiooxindoles as apoptosis inducing agents

Facile access to S-methyl dithiocarbamates with sulfonium or sulfoxonium iodide as a methylation reagent

Efficient access to S-methyl dithiocarbamates was achieved with sulfonium or sulfoxonium iodide as a methylation reagent. This method is reliable for the synthesis of dithiocarbamates from primary or secondary amines, with sulfoxonium iodide demonstrating more robust methylation capability than sulfonium iodide. Moreover, it also enables facile access to S-trideuteromethyl dithiocarbamates via sulfoxonium metathesis between sulfoxonium iodide and DMSO-d6 with high yields.

Regioselective synthesis and in vitro cytotoxicity evaluation of 3-thiooxindole derivatives: Tubulin polymerization inhibition and apoptosis inducing studies

Herein, regiospecific nucleophilic ring-opening of spiroaziridine oxindoles has been established to afford 3-substituted-thiooxindole derivatives as anticancer agents. Among the new series, compounds 7d and 9c exhibited promising cytotoxic activity toward HCT-116 cells with IC₅₀ values of 6.73 ± 0.36 and 6.64 ± 0.95 µM, respectively. Further, AO/EB, DCFDA, and DAPI staining studies were executed to establish the underlying apoptosis mechanism which displayed significant nuclear and morphological alterations. JC-1 staining and annexin V binding assay inferred the loss of mitochondrial membrane potential in HCT-116 cancer cells. Cell cycle analysis showed the treatment of 9c against HCT-116 cells, arrested the cell cycle in G2-M phase. In addition, tubulin binding assay revealed that compound 9c exhibited tubulin polymerase inhibition with IC₅₀ value of 9.73 ± 0.18 μM. This inhibition of tubulin polymerase was further supported by binding interactions of 9c with tubulin through docking studies on PDB ID: 3E22.

Design, synthesis and in vitro cytotoxicity evaluation of indolo-pyrazoles grafted with thiazolidinone as tubulin polymerization inhibitors

In the pursuit of potential and effective chemotherapeutic agents, a series of 2-((3-(indol-3-yl)-pyrazol-5-yl)imino)thiazolidin-4-ones was designed and synthesized, conjoining salient pharmacophoric properties for directing prominent cytotoxicity. The in vitro cytotoxicity evaluation revealed potent compounds with IC50 values <10 μM on tested human cancer cell lines. Compound 6c exhibited the highest cytotoxicity with an IC50 value of 3.46 μM against melanoma cancer cells (SK-MEL-28) and was highly cytospecific and selective towards cancer cells. The traditional apoptosis assays revealed morphological and nuclear alterations such as apoptotic body formation, condensed/horseshoe-shaped/fragmented/blebbing nuclei, and the generation of ROS. Flow cytometric analysis revealed effective early-stage apoptosis induction and cell-cycle arrest in the G2/M phase. In addition, the enzyme-based effect of 6c on tubulin showed the inhibition of tubulin polymerization (about 60% inhibition, IC50 was <1.73 μM). Moreover, molecular modeling studies affirmed the constant accommodation of compound 6c at the active pocket of tubulin, establishing many electrostatic and hydrophobic interactions with the active pocket's residues. The tubulin-6c complex was stable during the MD simulation for 50 ns with the recommended range of RMSD value (2-4 Å) for each pose.

Synthesis of Oleanolic Acid-Dithiocarbamate Conjugates and Evaluation of Their Broad-Spectrum Antitumor Activities

Efficient and mild synthetic routes for bioactive natural product derivatives are of current interest for drug discovery. Herein, on the basis of the pharmacophore hybrid strategy, we report a two-step protocol to obtain a series of structurally novel oleanolic acid (OA)-dithiocarbamate conjugates in mild conditions with high yields. Moreover, biological evaluations indicated that representative compound 3e exhibited the most potent and broad-spectrum antiproliferative effects against Panc1, A549, Hep3B, Huh-7, HT-29, and Hela cells with low cytotoxicity on normal cells. In terms of the IC₅₀ values, these OA-dithiocarbamate conjugates were up to 30-fold more potent than the natural product OA. These compounds may be promising hit compounds for the development of novel anti-cancer drugs.

Cobalt-promoted synthesis of sulfurated oxindoles via radical annulation of N-arylacrylamides with disulfides

An efficient radical annulation of N-arylacrylamides with disulfides is developed for the synthesis of sulfurated oxindoles. The reaction occurs in a facile manner using CoBr₂ as both an initiator and a promoter for the first time and (NH₄)₂S₂O₈ as the oxidant. By controlling the CoBr₂/(NH₄)₂S₂O₈ ratio, a wide range of sulfurated and brominated/sulfurated oxindoles are selectively prepared in good to excellent yields. The present protocol is simple and highly atom economical, and can tolerate a broad range of substrates.

Diastereoselective aldol-type interception of phenolic oxonium ylides for the direct assembly of 2,2-disubstituted dihydrobenzofurans

A Rh₂(OAc)₄ catalyzed intermolecular aldol-type interception of phenolic oxonium ylides with isatins has been developed, which provides an effective access to 2,2-disubstituted dihydrobenzofuran derivatives containing 3-hydroxyoxindole in high yields and with high diastereoselectivities under mild reaction conditions. The antiproliferation activity of these synthesized dihydrobenzofuran and 3-hydroxyoxindole hybrid products has been tested via the CCK8 assay in different cancer cell lines; compounds 3s and 3t exhibit good anticancer potency against human colon cancer cells (HCT116 cells, 3s: IC₅₀ = 15.99 μM; 3t: IC₅₀ = 14.48 μM) compared to other tested compounds.