Antitumor activity of echinosporin

Echinosporin isolated from a Streptomyces culture showed antitumor activity against rodent tumor models such as leukemia P388, P388/VCR, and fibrosarcoma Meth 1. It was marginally active against melanoma B16 and sarcoma 180. It was not active against Lewis lung carcinoma and xenograft MX-1. It inhibited the colony formation of HeLa S3 cells with a wide shoulder at low dose ranges. DNA, RNA, and protein synthesis were inhibited by echinosporin. It depressed WBC with nadir on day 3, but the recovery to the normal level after echinosporin injection was more rapid than that after mitomycin C.