Antitumor Activity of Phenylahistin in Vitro and in Vivo

Phenylahistin is a new cell cycle inhibitor produced by Aspergillus ustus. Since phenylahistin was produced as a scalemic mixture of (-)-phenylahistin and its enantiomer, we separated each enantiomer and evaluated their antitumor activity in vitro. (-)-Phenylahistin exhibited antitumor activity against 8 tumor cell lines with IC 50 values ranging from 1.8×10 -7 to 3.7×10 -6 , while (+)-phenylahistin exhibited 33-100-fold less potent activity than (-)-phenylahistin did. (-)-Phenylahistin also showed antitumor activity against P388 leukemia and Lewis lung carcinoma cells in vivo.