The corallopyronins, new inhibitors of bacterial RNA synthesis from Myxobacteria.

Abstract
From the culture broth of the myxobacterium, Corallococcus (Myxococcus) coralloides, 3 new antibiotics were isolated: corallopyronin A, B and C. The compounds, which are chemically related to the recently discovered myxopyronins, act mainly on gram-positive bacteria, with MIC [minimal inhibitory concentration] values between 0.1-10 .mu.g/ml, and only exceptionally or at much higher concentrations (MIC values; 100 and more .mu.g/ml) on gram-negatives. They do not inhibit eukaryotic organisms and show no toxicity for mice. The corallopyronins appear to block specifically eubacterial RNA polymerase.