Structure-activity relationship studies on selected iso-alpha-carbolines. I.

: In the course of microbial transformation of the antitumor compounds, it has been found that iso-alpha-carbolines and their certain derivatives undergo N-1 methylation by Kitasatosporia setae. The resulting products, iso-alpha-carbolines exhibit antibacterial and antifungal properties in the concentration range of 0.2-2.5 mumol/ml. In the cytotoxicity test only derivatives substituted at C-2 and C-4 display moderate activity against KB cells. None of the compounds tested show a significant inhibitory effect against P388 lymphocytic leukemia.