Optically active camptothecin derivative and its production

PURPOSE: To obtain the subject derivative having excellent optical purity due to no side reaction under mild conditions and useful as a synthetic intermediate, etc., for synthetic anticancer agents, etc., by reacting a specific racemic modifica tion with a SH enzyme. CONSTITUTION: A racemic modification (preferably in the concentration of 0.1-0.2wt.%) of 20-O-acyl-7-ethyl-10-methoxycamptothecin of formula I (RCO is acyl) is made to react with an SH enzyme derived from a plant or an animal, preferably in an amount of 1-50 times by weight based on the racemic modification to provide the objective derivative of formula II. COPYRIGHT: (C)1993,JPO&Japio