Pironetin binds to α-tubulin and is an effective inhibitor of microtubule polymerization. It also has cell cycle arrest and antitumor activity. Pironetin is an α/β unsaturated lactone isolated from Streptomyces species.

Pironetin (1-10000 ng/mL; 3 days; HeLa, A2780, and K-NRK cells) treatment suppresses cell proliferation. Pironetin (20-100 ng/mL; 24 hours; 3Y1 cells) treatment arrests the cell cycle progression at G2/M in 3Y1 cells. The IC50 values against these cell lines are almost 10 ng/mL[1].

Pironetin (0.78-6.25 mg/kg; intraperitoneal injection; daily; for 5 days; female CDF1-SLC mice) treatment displays a moderate antitumor effect. However, a severe weight loss is observed as a side effect[1].