Biological studies on the antibiotics produced by Streptomyces griseoluteus. II. The effect of griseolutein B in vitro and in vivo.

As recorded in previous papers(1,2), griseolutein inhibited the growth of gram-positive bacteria and a few gram-negative bacteria at 0.1-2.0 mcg/ml and its minimal lethal dosis to mice by subcutaneous injection was larger than 1,600 mg/kg. The bacteriostatic effect and the low toxicity suggested that griseolutein was one of hopeful antibiotics. Serum and cysteine lowered the bacteriostatic effect, but it was not so strong as to exclude the possibility of the effect in vivo. The influence of serum was almost the same order as that on . aureomycin and that of cysteine was not complete even in its high concentration such as 100 mcg/ml. As shown in the first papð¤r(1), the strain No. P-37, Streptomyces griseoluteus (3), produced more than an antibiotic and one of them which was transferred into ethyl acetate at pH 2.0 was named griseolutein. In further studies for the purpose to increase the yield of griseolutein, as reported by. Yagishita and others (4), the strain and the suitable media were selected. Then it was found that there were two kinds of griseolutein. Therefore griseolutein described in the previous paper was named griseolutein A and another, griseolutein B. Both of them are transferred into ethyl acetate or butyl acetate at pH 2.0. They are different in their ultraviolet absorption as will be reported by Maeda and Osato(5). Their bacteriostatic effects are very resembling except that to Proteus vulgaris. Griseolutein B is slightly more toxic than A, but the preventive and curative effect of the former to the infection of M. pyogenes was confirmed. In the present paper the experiments on the effect of griseolutein B in vitro and in vivo are described.