Compounds identified as WS-9326A and WS-9326B which are obtained by culturing a WS-9326A and/or WS-9326B producing strain belonging to the genus Streptomyces in a nutrient medium. Salts thereof can also be obtained. These compounds or salts thereof can also be acylated to produce acyl derivatives. These compounds are useful as substance pantagonism, neurokinin A (substance K) antagonism and are therefore useful for the treatment and prevention of asthma. The use of a compound as identified above as well as a biologically pure culture of the microorganism Streptomyces violaceoniger No. 9326 (FERM BP-1667) are also disclosed.
