Large scale studies made by the Taiyo Fishing Company in the last two years confirmed the economical value of fish preservation with chlortetracycline. In the main part of these studies the fish were preserved in the boat with crushed ice containing chlortetracycline at 5 mcg/g, and the amount of fish wasted was reduced to less than half of the control without chlortetracycline. Prior to the study presented in this paper, a method was required to determine the amount of chlortetracycline contained in fish meat preserved with chlortetracycline ice. The cylinder plate method or the turbidimetric method used for the determination of chlortetracycline in a drug gives the exact value, but it is limited to the determination of the material containing this antibiotic at not less than 5mcg/g. Ogata1) has devised a paper disk method which can measure chlortetracycline as low as 0.06–0.125mcg/g. The plate method with Bacillus cereus published by the Food and Drug Administration, U.S.A.2) is described as being able to measure an antibiotic as low as 0.005–0.01mcg/g. The authors traced these two methods, and, on the basis of the combination of the principles in these two methods, the plate method presented in this paper was established. In this method, 0.03 mcg/ml solution exhibits the inhibition diameter of 13.8 mm, and 0.06mcg/ml that of 17mm. This method, being combined with the extraction procedure with acid acetone, gave the relatively accurate value of chlortetracycline contained in the fish meat to which a known amount of chlortetracycline had been injected.
Since the method of determination of chlortetracycline at a low concentration was estabished, the authors examined the amount of the antibiotic in the fish preserved with the chlortetracycline ice. For this purpose, it was necessary to prepare ice in which an exact amount of the antibiotic was evenly distributed. During studies on the preparation of ice, the authors confirmed Tarr’s observation3) that something in water quickly inactivates chlortetracycline. The authors found that the most important point in the preparation of chlortetracycline ice is to eliminate the chlorine in the water. In the experiment preserving fish with distilled water ice containing chlortetracycline at 5mcg/g for 12 days, the authors determined the amount of chlortetracycline contained in the skin and the meat. The maximum amount in the skin was 0.005mcg/g, and that in the meat less than 0.005mcg/g. The authors measured the antibiotic in fish which had been preserved with chlortetracycline ice for from 8 to 17 days. This ice was prepared by dissolving chlortetracycline at 5mcg/ml in the city water, but the activity was reduced to 1.3mcg/g. The maximum amount of chlortetracycline in the skin was 0.05~0.14 mcg/g (0.01~0.03 mcg/cm2), and that in the meat was 0.06mcg/g. The number of bacteria and ammonium nitrogen in the fish meat which will be reported in another paper by Higashi and others indicated that the fish preserved with the chlortetracyclne ice were fresher than the control with the ordinary ice. It was suggested that a careful determination of chlortetracycline in the ice and the use of ice containing an exact amount of the active antibiotic would increase the effect of the antibiotic for fish preservation.
Kanamycin is an antibiotic discovered by Ueda, Maeda, Yagishita, Kondō, Okami, Utahara, Osato, Nitta, Takeuchi, and Umezawa(1). Characters of the kanamycin-producing strain and properties of the antibiotic are described in another paper(1). It has basic characters. The hydrochloride is soluble in water and methanol, slightly in ethanol and almost insoluble in esters, ether and petroleum ether. It shows an antibacterial spectrum resembling to streptomycin or fradiomycin (neomycin). It is dextrorotatory. It is negative in Sakaguchi and Elson-Morgan reactions. It exhibits strong inhibition against B. subtilis and K. pneumoniae both by a broth dilution test and a cylinder plate test. These properties differentiate kanamycin from known antibiotics.
Kanamycin has no delayed toxicity. Aqueous soluble and basic antibiotics which show no delayed toxicity, such as streptomycin, fradiomycin (neomycin) and viomycin, are known to exhibit therapeutic effect in vivo. As described in the present paper, kanamycin showed therapeutic effect against mice infection of pneumococcus and typhoid bacilli. The present paper describes acute and chronic toxicity of kanamycin to animals, absorption and excretion in rabbits, and distribution of kanamycin in various organs of rabbits.
Ractinomycins A and B were obtained from the cultured liquid of a strain of Streptomyces phaeochromogenus group, and their isolation and properties were presented in the previous paper1). In this paper, further details on properties of ractinomycin A are presented. The nature of the ractinomycin-producing strain and an improved process for the extraction are also described.
During the course of the search for new antibiotics produced by streptomyces, the culture filtrate of a new isolated streptomyces, Str. caespitosus, active against gram-positive and gram-negative bacteria, was found also to exert a destructive action upon the cells on experimental malignant tumors. The effective principles were isolated and fractionated into mitomycin A and mitomycin B, of which the physico-chemical properties have been described in a previous paper1). Mitomycin C was isolated shortly thereafter. All of them possess, in common antibacterial and antitumor activities, though their physico-chemical properties are different.
Experiments were then conducted to determine their effects upon the malignant tumors, Ehrlich carcinomaand Yoshida sarcoma. Mitomycins A and C were employed as they were available insufficient quantity at that time.
In the screening experiments of antitumor activity, the supension of Ehrlich carcinoma cells was transplanted intraperitoneally to mice. This was followed after 24 hours by the intraperitoneal injection of 0.2–0.5ml of the culture filtrate. The ascitic fluid was taken 16–18 hours after the injection, and the number of tumor cells in the ascitic fluid was counted2). In contrast to 70–90% of tumor cells in the smeared specimen from control animals, the proportion of tumor cells in cellular elements in the ascitic fluid from the mice, which had received the injection of the culture filtrate decreased to about 10%. In addition, this culture filtrate showed some ability to prolong the survival time of mice inoculated with Ehrlich carcinoma. These results suggested the existence of tumor-inhibitory substances in the culture filtrate of Str. caespitosus.
The tumor-inhibitory activity of the culture filtrate was proved to be in good correlation with its activity against Bacillus subtilis PCI 219. Experiments on fermentation and extraction of mitomycins, based upon this relationship, have been performed as described in the previous paper1).
Wide differences exist in the antibacterial activity and acute toxicity between each fraction of the culture filtrate of crude preparation of mitomycin obtained in the earlier stage of extraction. Therefore the experiments were performed with each fraction and the results are described in this paper.
Au cours de nos recherches sur la production d’antibiotiques par Streptomyces, nous avons isolé, à partir d’un prélèvement de terre effectué à Mt. Zinba (Japon), une souche de Streptomyces que nous avons nommé "Streptomyces No. 964-A", qui s’est montrée douée de propriétés antibiotiques antifongiques particulièrement intéressantes. Les caractéristiques et le procede qui a donné lieu à l’identification de cette souche seront d’écrites dans d’autres papiers.
Nous avons isolé à l’état cristallisé un antibiotique, qui inhibite fortement les fongiques et les protozoaires, extrait des myceliums cultures submergées. Nous le considérons comme un nouvel antibiotique de polyene pour ses caractères physiques, chimiques et biologiques et nous l’avons nommé Protocidine pour son caractere antiprotozoairique.