leptomycin B

Leptomycin B is a secondary metabolite produced by Streptomyces species and was originally discovered as a potent antifungal compound. It is now recognized primarily as a specific inhibitor of nuclear export in eukaryotic cells. Leptomycin B acts by covalently modifying and inhibiting CRM1 (also known as exportin 1 or XPO1), which is responsible for the nuclear export of proteins containing a nuclear export sequence (NES). This inhibition leads to the accumulation of NES-containing proteins in the nucleus, resulting in cell cycle arrest (notably G1 arrest) and potent anti-tumor activity in preclinical models. Leptomycin B has demonstrated antifungal, antibacterial, and antitumor properties but is mainly used as a research tool due to its toxicity profile[1].