Kyowa Hakko Kogyo Kabushiki Kaisha

Yutaka Ohsawa

Makoto Morimoto

Tadashi Ashizawa

Tokuyuki Kuroda

Koji Hisamura

Hideo Ueno

Tohru Sugaya

Mitomycin derivatives having potent antitumor activity having the formula: ##STR1## wherein A is ON--or R.sub.4 N.dbd.N--[wherein R.sub.4 is selected from ##STR2## and optionally substituted heterocyclic groups (wherein R.sub.5 and R.sub.8 are each independently selected from hydrogen, lower alkyl and lower cycloalkyl; R.sub.6 is selected from hydrogen, halogen, hydroxy, lower alkoxy, amino and nitro; R.sub.7 is selected from lower alkyl and lower cycloalkyl; and X is selected from oxygen, sulphur and imino)];

Mitomycin derivatives as antileukemia agents

Mitomycin derivatives having potent antitumour activity have the formula: ##STR1## wherein R represents lower alkyl, cycloalkyl or unsubstituted or substituted aralkyl;

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Shizuoka, Japan

Yutaka Ohsawa