In the previous paper¹⁾, bandamycin produced by Streptomyce goshikiensis n. sp. was reported to be a new crystalline antibiotic containing no nitrogen.

In the course of production studies of bondamycin, another crystalline antibiotic of different nature was isolated and designated bandamycin B. Consequently the previous one was named bandamycin A.

A new antibiotic, bandamycin B was active principally against Gram-positive bacteria and low toxic to mice. Between these two bandamycins A and B, the synergistic relation was not observed.

In the present publication, production process of bandamycins, and isolation and characterization of bandamycin B are described.

The investigation of the antimicrobial activity of filtrates of cultures of organisms pathogenic to plants has shown, as previously reported¹⁾, that the fungi belonging to Helminthosporium are the most promising source of new antibiotics. Of this group of fungi, it was reported that six species, Ophiobolus miyabeanus, Helminthosporium turcicum, Ophiobolus heterostrophus, Helminthosporium leersii, Helminthosporium panici-miliacei and Helminthosporium zizaniae, produced ophiobolin,^2,3,4) that under certain cultural conditions Helminthosporium zizaniae yielded zizanin,⁵⁾ a new antibiotic different from ophiobolin, and that pyrenophorin,⁶⁾ a new antibiotic, was produced by Pyrenophora avenae.

This report concerns the study of the effective substance obtained from the BH-34 strain of Helminthosporium siccans. Extraction of the culture filtrate of the BH-34 strain yielded an antibiotic substance in crystalline form which differed from ophiobolin, zizanin and pyrenophorin. Inasmuch as no antibiotic substance produced by Helminthosporium siccans has yet been reported and as its physical and chemical properties as well as its antimicrobial spectrum demonstrate it to be a new antibiotic. This effective substance was named siccanin.

The production, physical and chemical properties and spectrum of antimicrobial activity of this substance are described herein.

In 1960, Melander¹⁾ reported that, among various types of synthetic biguanides tested for anti-influenza activity, N¹, N¹-anhydrobis-(£>-hydroxyethyl) biguanide HCl (ABOB) was active against influenza A (PR8) and B (Lee) viruses in mice. In his experiment, suppression of lung consolidation was used as the criterion of effectiveness. However, the effect of reducing lung pathology with this compound should be said rather marginal.

Similar experiment was performed in our laboratory against PR8 virus infection in the mice of dd strain²⁾ under the established infection condition3l, but delay in the death of mice receiving ABOB was hardly observed. Scoring the lung consolidation, again no significant effect was observed. Meanwhile, clinical application of the compound has been reported⁴⁾⁵⁾, and the fact that the toxicity af ABOB is extremely low seemed to suggest the importance of exploring the compound both in laboratory and clinic.

Although the significance of the biguanide structure of ABOB for its antiviral activity is unclear, it should be emphasized that three antibiotics having guanidine or amidine groups in their structure are known to have antiviral activity; noformicin^6,7) and myxoviromycin^8,9,10) are active against influenza in mice, and netropsin¹¹⁾ (sinanomycin ¹²) against vaccinia in mice. The synthetic guanidines described by Lum et al.¹³⁾ also revealed antiviral activity against influenza virus infection in mice.

Having these considerations in mind, possible antiviral effect of ABOB was tested against Sendai virus (Myxovirus para-influenzae 1) in various tissue culture systems. These systems were believed to be most favorable in examining the effect of ABOB for the following reasons. First, production of egg-infectious particles has been proved in the studies of the growth characteristics of Sendai virus in L, HeLa, and FL cells^14-16). No such a complete growth has been found with other influenza viruses, which only produce noninfectious hemagglutinins in these cells. Secondly, one-cycle growth of Sendai virus in these tissue culture cells has also been proved^14,15). The study on the site of action of antiviral compounds should be done with such a system. Thirdly, in tissue culture studies, the enumerable monolayered cells in closed tubes with the simple medium of definite quantity afford kinetic evaluation of results. A number of tubes can be easily handled in a reproducible manner, and withdrawal of the compound or of the medium can be freely made. This was thought to be most favorable to purse the site of action of the compound in concern.

As a matter of fact, a definite antiviral effect of ABOB was revealed when Sendai virus growth was examined in these tissue culture cells, although the inhibition was not complete. The present paper is chiefly concerned with the effects obtained in S₃ clone of Hela cells. The preliminary studies on the site of action of ABOB is also involved.

Several biological assay methods have been used usually to investigate the pharmacology of penicillin. Even though biological methods of penicillin assay are sensitive and very useful, however, they have somehow limitations inherent to themselves. Recently many radioisotope techniques have been used for the investigations of antibiotics with pharmacological and biochemical respects. Rowlands et al.¹⁾ (1948) reported the excretion of biosynthetized radioactive penicillin in the unne. Sebek²⁾ also reported the method of biosynthesis of ¹⁴C-labeled benzylpenicillin. Radioactive antibiotics, ¹⁴C-oxytetracycline,^{3,4,5) 3}H-tetracycline⁶ , ³H-dehydrostreptomycin6l and ¹⁴C-chloramphenicol etc., have been studied by several investigators. These research works by use of the radioactive tracers can be devided into two ways, to study the distribution of antibiotics in the body tissue quantitatively on one side, and to illustrate the tissue distribution with autoradiographically on the other side. More detailed informations can be yielded by autoradiography in terms of histological site of distribution. Ullberg⁷ reported the tissue distribution of ³⁵S-labeled penicillin (³⁵S-PC) by use of autoradiographical method in detail.

In this paper, studies on the pharmacology of ³⁵S-PC compared with bioassay, the degradation of penicillin in the body and protein binding will be presented.

A new strain Str. mariensis^1,2), isolated by M. Soeda from a soil sample collected at Jiyugaoka, Meguro-ku, Tokyo in 1957, produced an antitumor antibiotic named marinamycin. The present report concern with the purification method of miramycin, its chemical properties and several interesting informations in biological properties.