3-Arylidene-2-oxindoles as Potent NRH:Quinone Oxidoreductase 2 Inhibitors.

The enzyme NRH:quinone oxidoreductase 2 (NQO2) plays an important role in the pathogenesis of various diseases such as neurodegenerative disorders, malaria, glaucoma, COVID-19 and cancer. NQO2 expression is known to be increased in some cancer cell lines. Since 3-arylidene-2-oxindoles are widely used in the design of new anticancer drugs, such as kinase inhibitors, it was interesting to study whether such structures have additional activity towards NQO2. Herein, we report the synthesis and study of 3-arylidene-2-oxindoles as novel NRH:quinone oxidoreductase inhibitors. It was demonstrated that oxindoles with 6-membered aryls in the arylidene moiety were obtained predominantly as E-isomers while for some 5-membered aryls, the Z-isomers prevailed. The most active compounds inhibited NQO2 with an IC50 of 0.368 µM. The presence of a double bond in the oxindoles was crucial for NQO2 inhibition activity. There was no correlation between NQO2 inhibition activity of the synthesized compounds and their cytotoxic effect on the A549 cell line.

Synthesis of New 2,3-Dihydroindole Derivatives and Evaluation of Their Melatonin Receptor Binding Affinity.

2,3-Dihydroindoles are promising agents for the synthesis of new compounds with neuroprotective and antioxidant properties. Usually, these compounds are obtained by direct reduction of the corresponding indoles containing acceptor groups in the indole ring for its activation. In this work, we propose a synthetic strategy to obtain new 2,3-dihydroindole derivatives from the corresponding polyfunctional 2-oxindoles. Three methods were proposed for reduction of functional groups in the 2-oxindole and 2-chloroindole molecules using various boron hydrides. The possibility of chemoselective reduction of the nitrile group in the presence of an amide was shown. The proposed synthetic strategy can be used, for example, for the synthesis of new analogs of the endogenous hormone melatonin and other compounds with neuroprotective properties.

Towards multi-target antidiabetic agents: In vitro and in vivo evaluation of 3,5-disubstituted indolin-2-one derivatives as novel α-glucosidase inhibitors.

Type 2 diabetes mellitus is a chronic progressive disease that usually requires polypharmacological treatment approaches. Previously we have described a series of 2-oxindole derivatives as GSK3ß inhibitors with in vivo antihyperglycemic activity. α-Glucosidase is another antidiabetic target that prevents postprandial hyperglycemia and corresponding hyperinsulinemic response. Herein we report a study of 3,5-disubstituted indolin-2-one derivatives as potent α-glucosidase inhibitors. These inhibitors were identified via efficient synthesis, in vitro screening, and biological evaluation. The most active compound 5f inhibits yeast α-glucosidase with IC50 of 6.78 µM and prevents postprandial hyperglycemia in rats after maltose and sucrose challenge at 5.0 mg/kg dose. Two lead glucosidase inhibitors, 5f and 5m, are also GSK3ß inhibitors with submicromolar potency. Hence, structure-activity studies elucidate foundation for development of dual GSK3ß/α-glucosidase inhibitors for treatment of type 2 diabetes.

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

Glycogen synthase kinase 3ß (GSK-3ß) is a widely investigated molecular target for numerous diseases including Alzheimer's disease, cancer, and diabetes mellitus. Inhibition of GSK-3ß activity has become an attractive approach for treatment of diabetes and cancer. We report the discovery of novel GSK-3ß inhibitors of 3-arylidene-2-oxindole scaffold with promising activity. The most potent compound 3a inhibits GSK-3ß 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.