Purified compounds of formula I are described. Compounds include all stereoisomeric forms and all tautomeric forms of the compounds of formula I and pharmaceutically acceptable salts and derivatives. Processes for the production of the antibacterial compounds by fermentation of the microorganism belonging to Streptomyces species (PM0626271/MTCC 5447) and to pharmaceutical compositions containing one or more of the novel compounds as active ingredient and their use in medicines for treatment and prevention of diseases caused by bacterial infections are described.