Background:

Indirubin-3'-monoxime is a potent GSK-3β inhibitor, and weakly inhibits 5-Lipoxygenase, with IC50s of 22 nM and 7.8-10 μM, respectively; Indirubin-3'-monoxime also shows inhibitory activities against CDK5/p25 and CDK1/cyclin B, with IC50s of 100 and 180 nM.
Indirubin-3'-monoxime inhibits GSK-3β by competing with ATP, with Ki of 0.85 μM, and Km of 110 μM. Indirubin-3'-monoxime also inhibits tau phosphorylation by GSK-3β, with an IC50 value of around 100 nM. Indirubin-3'-monoxime completely inhibits the phosphorylation of the AT100 epitope[1]. Indirubin-3'-monoxime inhibits vascular smooth muscle cell (VSMC) proliferation with IC50 of ～2 μM. Indirubin-3'-monoxime blunts migration of VSMC stimulated with the PDGF. Indirubin-3'-monoxime interferes with the migratory response in VSMC, and also suppresses the production of pro-migratory LT in monocytes. Moreover, Indirubin-3'-monoxime inhibits 5-lipoxygenase (5-LO) product synthesis in monocytes and neutrophils, with the same potency (IC50=5.0±1.1 and 3.7±1.2 μM, respectively). Indirubin-3'-monoxime is an inhibitor of 5-LO, with IC50 of 7.8-10 μM in cell-free assay[3].
Indirubin-3'-monoxime (0.1, 0.2 and 0.4 mg/kg, i.p) dose dependently reverses the cognitive impairment and combats the elevated oxidative stress markers in HFD fed mice. Indirubin-3'-monoxime also dose dependently lowers the serum glucose, TGs, TC and insulin levels, and improves the β-cell functioning in HFD fed mice. Moreover, Indirubin-3'-monoxime treatment significantly decreases HOMA-IR levels compared to HFD group. Indirubin-3'-monoxime (0.4 mg/kg) significantly attenuates the increased EL in the HFD group[2].
Reference:
[1]. Leclerc S, et al. Indirubins inhibit glycogen synthase kinase-3 beta and CDK5/p25, two protein kinases involved in abnormal tau phosphorylation in Alzheimer's disease. A property common to most cyclin-dependent kinase inhibitors? J Biol Chem. 2001 Jan 5;276(1):251-60.
[2]. Sharma S, et al. Neuroprotective role of Indirubin-3'-monoxime, a GSKβ inhibitor in high fat diet induced cognitive impairment in mice. Biochem Biophys Res Commun. 2014 Oct 3;452(4):1009-15.
[3]. Blazevic T, et al. Indirubin-3'-monoxime exerts a dual mode of inhibition towards leukotriene-mediated vascular smooth muscle cell migration. Cardiovasc Res. 2014 Mar 1;101(3):522-32.