Disclosed is a novel physiologically active substance, MH435, represented by the formula: <IMAGE> (I) wherein R represents either of the following groups A and B A: -CH=CH-NHCHO B: -CH2-CH2-NHCHO. The substance MH435 has an inhibitory activity against tyrosine specific protein kinase, and the 50% inhibitory concentrations of the substances MH435-A and MH435-B are respectively 0.55 mu g/ml and 6.0 mu g/ml.
