[New antitumor antibiotics 5590 and 2928].

Antibiotics with an in vivo antiblastomic activity were isolated from the actinomycetous culture 5590 and 2928. The antibiotics were prepared in the crystalline form. The conditions for the biosynthesis of the antibiotics, their physicochemical constants and UV and IR spectra were determined. The acid hydrolysates of the antibiotics were studied. The antibiotics contained the same chromophore and different sets of amino acids. Antibiotics 5590 and 2928 were classified as peptides containing the chromophore group.