Protomycin, a new antibiotic active against Endameba histolytica as well as yeast, was isolated from culture filtrate of a strain of Streptomyces (Isolation No. S-300) in the screening program, in which Endameba histolytica was employed as a test organism. The antibiotic was purified to give a pale yellow viscous liquid with a homogeneity proved by a counter-current distribution technique. While the physicochemical and biological properties of protomycin suggest to be an antibiotic of cycloheximide series, it was differentiated clearly from the known antibiotics in that series. The in vivo effect of the antibiotic on E. histolytica was proved in guinea pigs and described previously¹⁾. In the present report, the protomycin-producing strain was characterized according to the established manner for streptomyces and described.

The strain No. S-300 produced a brown pigment in the protein-nitrogen containing media at the time of isolation, but gradually lost this ability during maintenance and improvement of the strain and changed into variants, which were classified into two groups on the basis of growth findings: One group grew into thick colonies with deep folds on nutrient agar as observed in the original strain; the other group remained to be a minute colony with a 2～3 mm diameter. Accordingly, in this report, the protomycin producing strains were classified into three types.

Type I: The original strain, producing pigment in the media containing organic nitrogen sources.

Type II: A variant which have lost the ability of pigment production and grows to large colonies.

Type III: Another variant which have lost the ability of pigment production and grows only to minute colonies.

An active material was obtained from the fermentation liquor of a strain of streptomyces, Streptomyces reticuli var. protomycicus²⁾ selected in the screening with Endameba histolytica as a test organism ¹⁾. It was given a name of protomycin. The following is a description of the assay procedure, fermentation, extraction, purification and properties of the active principle.

It has been found that not a few antibiotics isolated from streptomyces and other species of microorganisms, such as mutomycin, violarin B, statolon and others, have antiviral and antiphage activities.

During screening for antiviral antibiotics in our laboratory, the strain, Streptomyces tanashiensis var. cephalomyceticus, which produces an active substance against Japanese B encephalitis virus in vivo, was isolated from a soil sample obtained in Tokyo. This active product was concluded to be a new substance and was named cephalomycin by Hata et al.¹⁾

Matumae and Onuma reported mycological characteristics of the producing strain, biological and chemical properties of cepholomycin²⁾, and activities against Japanese B encephalitis virus in mice³⁾. According to those previously reported data, cephalomycin, although not homogeneous, was supposed to be an acidic polypeptide, being precipitated at the pH range 2～5 as a brownish amorphous powder. It is non-dialysable, insoluble in organic solvents, and is inactivated when incubated with trypsin. It is positive in Sakaguchi, biuret, ninhydrin, diazo and Folin’s reactions. Acid hydrolysates gave ninhydrin positive spots by paper chromatography.

Cephalomycin was not only active against Japanese B encephalitis virus in the contact experiment, but was effective if given within 24 hours following to inoculation of Japanese B encephalitis virus. Also, the mice which have survived by treatment with cephalomycin gained a significant immunity against Japanese B encephalitis reinfection.

The object of the present work is to isolate a further purified sample of cephalomycin and to investigate its physicochemical and ultimately its biological properties.

A streptomyces, characters of which were resembling to those of Streptomyces mashiuensis produced an antibiotic which was completely different from streptomycin produced by the latter streptomyces. This antibiotic was isolated and named monazomycin. As shown in this paper, it contained one mole of nitrogen, and it was differentiated from known antibiotics by the physical and chemical properties. The taxonomic studies of the monazomycin-producing strain, properties and activities of this antibiotic are presented in this paper.

The decocted extract of Enmeiso, Amethystanthi Herba, has long been used as a local family remedy for gastrointestinal disorder in Japan. So-called enmeiso consists of dried leaves and stems of Hikiokoshi, Isodon japonicus Hara (Amethystanthus japonicus Nakai) or Kurobana hikiokoshi Isodon trichocarpus Kudo (Amethystanthus trichocarpus Nakai), which are perennial plants belonging to the Family Labiatae and grow in mountainous districts in Japan. Yagi¹⁾ first isolated plectranthin, C₂₅H₃₄O₈, from I. japonicus as a crystalline form in 1910. Ikeda and Kanatomo^4,7,8) isolated another bitter component of C₂₀H_26～28O₆, m.p. 297～299°C from I. trichocarpus and named it enmein in 1956. Takahashi et al.^3,5,10,11) also studied bitter components of I. trichocarpus, isolated enmein and four other compounds, and also investigated their chemical structure since 1956. Naya⁶⁾ independently isolated a bitter substance from I. trichocarpus in 1958 and designated it as isodonin, which later proved to be identical with enmein. As regards the biological activity of these components, Tanabe and Nishikawa’s²⁾ and Ohyama et al.’s⁹⁾ reports on antimicrobial activity of some components of I. japonicus or I. trichocarpus have appeared in the literature.

In a search for new antineoplastic compounds of biological origin, the authors came across new experimental finding that enmein exhibited antitumor activity against human malignant cell culture and ascites tumors in mice. Further studies on the active preparation proved that it contained enmein, dihydroenmein and possibly some minor components, the ratio of these components being variable according to each batch. Present experiments were undertaken in order to elucidate biological activity of purified enmein, dihydroenmein and diacetylenmein.

Both the aqueous extracts of fruit bodies of about 1,000 species of higher fungi and shake-flask culture filtrates of the isolated mycelial strains have been screened for the antitumor activities using Ehrlich ascites tumor. About 14% of the aqueous extracts of the sporophores and 8% of the culture filtrates of the mycelia proved to show the tumor-inhibiting properties. During the screening course, it was found that high molecular substances with antitumor activities were widely distributed among the aqueous extracts or culture filtrates¹⁾. In 1957, Lucas et al.²⁾ reported a tumor-inhibiting substance identified as either a peptide or protein from the mushroom Boletus edulis. In 1960, an antitumor antibiotic, calvacin, was isolated from Calvatia gigantea and identified as a nondiffusible, basic mucoprotein³⁾. The authors have isolated a basic protein, named flammulin, from a basidiomycete, Flammulina velutipes (Fr.) Sing. belonging to the genus Flammulina of Tricholomataceae. In this paper the isolation and some chemical and biological properties of flammulin are described.