Chemistry on Sarkomycin Chemical Studies on Antibiotics of Streptomyces. VI

Abstract

Sarkomycin is an antitumor substance produced by Streptomyces erythrochromogenes isolated by Umezawa and others¹⁾. As described in their first paper¹⁾, the antitumor substance produced by the shaking culture of this strain was first found to be transferred into butanol at pH 2–3, but not into other organic solvents such as ethyl acetate, butyl acetate, chloroform, etc. The sample used for the animal experiment in the first paper was obtained by freeze-drying of the concentrated neutral solution obtained by the retransfer of sarkomycin from butanol extract into water at pH 7, and it was not irritating, and exhibited strong antitumor effect against ascites type of Ehrlich carcinoma of mice. Thereafter, as described in the second report²⁾, when sarkomycin was produced by the deep aerated tank culture, the active agent was found to be transferred into ethyl or butyl acetate at pH 2–3. The sample obtained by this process was studied in detail, and it was confirmed to exhibit antitumor effect against both ascites type and solid type of Ehrlich carcinoma. But in was irritating. The present studies concern the active agent obtained by this solvent extraction process from the tank culture broth.

Sarkomycin, after it had been transferred into ethyl acetate at pH 2–3 from the culture broth, was concentrated by vacuum evaporation and it was purified by the carbon chromatography. The purified syrup of sarkomycin was colorless. It was dissolved in water and shaken with chloroform, then a main part of the activity was transferred into the solvent, but a part of that remained in the aqueous layer. The active fraction transferred into chloroform was named sarkomycin A and another active fraction left in the aqueous layer was named sarkomycin A’. The both fractions were further purified by a countercurrent distribution between ethyl acetate and water at pH 3.9–4.7. Then, sarkomycin A was distributed in two fractions, the one was a main fraction and another was a minor. The latter was named sarkomycin B. Sarkomycin B was confirmed to be a decomposition product of sarkomycin A. In the countercurrent distribution, the peaks of sarkomycin A and A’ were very closed, and, they were not differentiated by the countercurrent distribution. The different attitude to the chloroform extraction is the main difference of A and A’. But, it was found that sarkomycin A’, after it had been kept in the neutral aqueous solution in ice box, changed the transferability into chloroform, and it became identical with A. Therefore, the existence of A’ aside from A is not conclusive. Sarkomycin A, A’ and B were constituted from carbon, hydrogen, and oxygen, and the titration value suggested compounds of C_7–9) When their potency was determined by using their solution and their weight was determined after evaporating off the solvent, sarkomycin A and A’ were found to have the potency of about 10 mg units/mg or 7 mg units/mg, respectively. But, when the potency was determined after evaporating off the solvent, their potency was about 1–4 mg units/mg...Please see the PDF for the complete Abstract