Pyridindolols Kl and K 2 , New Alkaloids from Streptomyces sp . K 93-0711

Chemical screening for secondary metabolites of microbial origin has led to the discovery of natural products with different types of structures and biological activities1*. In the course of selective screening for amines using special staining reagents on TLC, new /?-carboline derivatives, termed pyridindolols Kl (1) and K2 (2), were isolated from the culture broth of Streptomyces sp. K93-071 1 together with a known alkaloid, pyridindolol (3) reported as an /J-galactosidase inhibitor (Fig. 1). This paper describes the isolation, physico-chemical properties, structural determination including the absolute configuration, and biological characteristics of 1 and 2.