A new antibiotic 45449 A belonging to the neomycin-group and a new antibiotic 45449 B belonging to the streptomycin-group were isolated from the culture broth of Streptomyces pulveraceus nov. sp. A was different from neomycin, hydroxymycin and paromomycin in physiocochemical and biological properties, and in the natures of their decomposition products, while B was distinguished from streptomycin and hydroxystreptomycin by color reaction, and from dihydrostreptomycin and dihydrodexystreotomycin by mixed melting point determination and by difference in the X-ray diffraction pattern of their sulfates.

Recently a tentative structure of pimaricin¹⁾ and partial structures of fungichromin,²⁾ lagosin,³⁾, filipin⁴⁾ have been proposed, but few structural studies with regard to members of hexaene and heptaene groups have been hitherto reported. It is the purpose of the present paper to report structural studies on trichomycin A.

New antibituberculous antibiotics, tubermycins A and B were reported in 1958 by K. Isono et al.¹⁾ Both substances were monobasic acids having the formulas C₁₂H₁₆N₂O₂ and C₁₃H₃N₂O₂ respectively. The former was proved to be identical with phenazine α-carboxylic acid, and the latter its analogous compound. The strain No. 1755 producing tubermycins A and B seemed to be a new species of streptomyces and was named Streptomyces misakiensis. The present paper deals with morphological and cultural studies on Streptomyces misakiensis (No. 1755 strain) from the view point of taxonomy.

A new antibiotic tubercidin has been reported in the previous paper by Anzai et al.¹⁾ It inhibits the growth of tubercle bacilli and Candida albicans, and shows a strong antitumor activity in vitro against NF mouse sarcoma. The present paper deals with morphological and cultural studies on tubercidin producing strain No. 585.

In the course of screening new antibiotics active against tubercle bacilli, a nucleoside type antibiotic was obtained from the culture broth of streptomyces, and proved to be identical with 9-β-D-ribofuranosylpurine which was produced by a mushroom, Agaricus nebularis and named as neblarin. It has never been reported the production of this substance from streptomyces. The studies on isolation, purification and identification were already reported by Isono and Suzuki.¹⁾ The present paper deals with morphological and cultural studies of the 9-β-D-ribofuranosylpurine- producing strain No. B-34.

As reported in the previous papers^1–3), angustmycins A and C were observed to exhibit antimicrobial activity against gram-positive organisms and mycobacteria in synthetic or semisynthetic media; but their activity markedly decreased in organic media. Their antimicrobial effects were reversed by guanine, guanosine, adenosine, xanthosine, inosine and other related substances. The chemical structures of angustmycins were determined by Yüntsen.^4,5) A is 6-amino-9-(L-1,2-fucopyranoseenyl)-purine and C is 6-amino-9-(β-D-psicofuranosyl)-purine. The in vivo activity of angustmycin against some of experimental infections and transplantable tumors in animals was investigated, and the result are presented in this paper.

A Streptomyces isolated from a soil sample collected at Shizuoka Prefecture produced an antibiotic inhibiting B. subtilis in a cylinder plate and this active substance was isolated and the structure, N-(2’-amidinoethyl)-3-aminocyclopentanecarboxamide, was determined. This antibiotic showed an incomplete inhibition against spore-forming bacteria and had relatively strong toxicity to mice. This paper presents characters of Streptomyces producing the antibiotic and processes for production and isolation. Structural studies will be reported in another paper¹⁾.