Mechanism of action of psicofuranine.

Psicofuranine is a new antibiotic which was first described by Schroeder and Hoeksema (1959), Eble et al. (1959), and Vavra et al. (1959). It has good antibacterial activity in vivo (Lewis et al., 1959) and antitumor activity (Evans and Gray, 1959), but it shows no activity in vitro when assayed by conventional methods. The activity in vitro was demonstrated using the special media and assay techniques described by Hanka et al. (1959). Psicofuranine resembles closely Angustmycin C described by Yulnsten (1958); the latter was reported biologically and optically inactive however. The structural similarity of psicofuranine (figure 1) to adenosine suggested an antimetabolite mode of action. Therefore, studies were made for the reversal of inhibitory activity of psicofuranine by compounds containing purine and pyrimidine bases, and the results are reported herein.