Indirubin 3′-(O-oxiran-2-ylmethyl)oxime: A novel anticancer agent

Indirubin is a potent inhibitor of cell cycle-related protein kinases by binding to the ATP-binding site and thus is a promising compound for development as an antitumor drug. We prepared indirubin 3′-(O-oxiran-2-ylmethyl)oxime (Epox/Ind), in which the ATP-binding site orientated part was attached by non-specific alkylating group. The IC50 value of Epox/Ind at 1.7 μM in HepG2 cells is comparable to that of cisplatin (4.0 μM). Furthermore, Epox/Ind was shown to be metabolized by a HepG2 cell lysate into indirubin 3′-(O-2,3-dihydroxypropyl)oxime (E804), the sole extractable metabolite. The lower toxicity of this metabolite may explain the lack of cytotoxicity of 1 μM Epox/Ind observed in HepG2 cells beyond an initial loss of viability in the first 24 h of treatment.

Graphical abstractIndirubin 3′-(O-oxiran-2-ylmethyl)oxime (Epox/Ind).Figure optionsDownload full-size imageDownload as PowerPoint slide