L-4-OXALYSINE, A NEW ANTITUMOR AGENT OF NATURAL ORIGIN

L-4-oxalysine (OXL) is an antibiotic isolated from a new species of st reptomyces roseoviridofuscus sp. in China. In vitro, OXL at high conce ntrations significantly inhibited the growth of mouse ascites hepatoma -22 (H-22) cells. In vivo, OXL had a suppressive action on the growth of several implanted mouse solid tumors such as sarcoma-180 (S-180), s arcoma-37 (S-37), Ehrlich ascites carcinoma (EAC) and brain tumor-22 ( B-22). An obvious therapeutic effect on B-22 tumor was also observed w ith different routes of administration (either i.v., i.p., i.g. or i.m .) and different schedules of treatment. When used in combination with 5-fluorouracil (5-FU), the inhibitory effect of OXL on the growth of in vitro H-22 cells or in vivo S-37 tumor was significantly strengthen ed. The antimetastatic action of OXL could be detected in vivo when tr eatment was started on day 2 or day 8 after the implantation of Lewis lung carcinoma.