sidue. A small amount of the salt in the residue was removed by Sephadex LH-20 gel filtration using methanol as an eluation

Sir: In the course of the study on antitumor anthracyclic antibiotics, roseorubicins A and B, new members of the rhodomycin group, were isolated from the cultured broth of Actinomrccs rose oriolac:'us A 529 (1 FO 13081). Roseorubicins are produced as orange-red pigments l y the shaking culture of strain A 529 at 28'C for 5 days in a medium containing 4 sucrose, 2..i %, soybean meal, 0.1 °„ yeast extract, 0.25",', NaCI, 0.32 CaCOa, 0.0005'11, CUSOi 5H2O, 0.0005% MnCI2•4H:O and 0.0005",', ZnSO-I -7H 20, pH 7.4, and can be extracted from the mycelium and the culture filtrate with acetone or chloroform, and separated into two major component s with Rf 0.2 and 0.1 by silica gel thinlayer (60 F,.;1 Merck Co.) chromatography using chloroform methanol acetic acid (80: 20: 4). Roseorubicins are also produced by Actinomvices violascens A517 (IFO 12920), Act. violarus A530 (IFO 13104), Act. riolaceochrotnogenes A549 (IFO 131)0) and Streptomyces purpurasccus A519 (IFG 13077) as well as Act. roseoviolaceus. In an example, 24 liters of the cultured broth (pH 7.4) were filtered, and roseorubicins in the mycelium were extracted with acetone followed by concentration to a quarter volume under reduced pressure and re-extracted with chloroform. Orange-red pigments in the culture filtrate were extracted with chloroform. The chloroform extracts were combined and concentrated in vaccro, yielding 30g of an oily mixture of orange-red pigments. It was dissolved in 50 ml of chloroform-methanol mixture (I : 2) and subjected to Sephadex LH-20 gel filtration. Roseorubi,.in fractions were eluted with the same solvent mixture. By evaporating the eluates, the crude roseorubicins were obtained as a red powder. The crude red powder thus obtained was dissolved in 30 ml of 0.1 M acetate buffer, pH 3.0, and the insoluble residue which contained aglycones was extracted by addition of 30 nil of toluene.