<p>This application relates to new compounds called WS-9326A, WS-9326B, and their derivatives having valuable pharmaceutical properties and which are obtainable by culturing a WS-9326A and/or WS-9326B producing strain belonging to the genus Streptomyces in nutrient medium and recovering such compounds or salts thereof from the resultant cultured broth. The invention also relates to a process for the production of such compounds and to pharmaceutical compositions containing them or a pharmaceutically acceptable salt thereof as an active ingredient. The invention furthermore relates to a biologically pure culture of the microorgnism Streptomyces violaceoniger No. 9326 (FERM BP-1667).</p>
