Physiologically active substance esterastin

Abstract

A new physiologically active substance named esterastin is now provided, which inhibits the activity of esterase and is useful as an immunosuppressive drug. Esterastin is produced by cultivating a microorganism Streptomyces MD4-C1 identified as FERM-P 3723 or ATCC. 31336 in a culture medium under aerobic conditions and recovering it from the resulting culture. Esterastin is the compound having the formula ##STR1##

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