The antiprotozoal and antivermal activities of 22 species of Fungi imperfecti as well as a description of the method used for screening are presented. In the microorganisms studied a very high incidence of antiprotozoal and antivermal activities was found. The results indicate that this class of fungi is a good source of antiprotozoal and antivermal antibiotics.
By our method of screening for antiprotozoal antibiotics and for substances with antivermal activity1) 38 species of Oomycetes were tested. A very high incidence of species with antiprotozoal activity (92 %) a high incidence of species with antivermal activity (68 %) and a substantially lower incidence of species with antifungal and/or antibacterial activity (29 %) were found. The results indicate that the species tested as well as the class Oomycetes in general are rich sources of antiprotozoal and antivermal antibiotics.
The results of screening for antiprotozoal and antivermal antibiotics in fungi of the genus Penicillium isolated from soil samples from Indonesia are presented. The incidence of cultures with antiprotozoal activity was found to be rather high (60%), substances with antivermal activity were detected in 38% of the cultures studied and antibacterial and/or antifungal activities were present in 53% of the cultures. The results indicate that the Penicillia could be a rich source of antiprotozoal and antivermal substances.
The immune response to sheep red blood cells of the mice treated with mycophenolic acid was studied from both humoral and cellular aspects. Mycophenolic acid showed markedly immunosuppressive effect on the antibody formation when mice were treated with daily doses of more than 60mg/kg for 5 consecutive days starting on the day of antigen injection. Late treatment resulted in a weaker immunosuppressive effect, while pretreatment was ineffective on antibody formation. The pattern of antibody formation between control and mice treated with mycophenolic acid was different. In the primary response of mice immunized with sheep red blood cells, the administration of mycophenolic acid prolonged the induction period, suppressed the total titer, and the formation of 2-mercaptoethanol resistant antibody (7S) was not detected throughout experimental period. Compared with other agents, mycophenolic acid is approximately equipotent to 6-mercaptopurine in immunosuppressive effect, determined by the decreases in the number of plaque forming cells and hemolysin titer.
Siomycin, a sulfur-containing peptide antibiotic, has been found to consist of one major (A) and two minor components (B and C). Siomycins A, B and C were isolated as single components from crude siomycin preparations and characterized in detail. Physicochemical properties of the three antibiotics are similar. Siomycin B is derived from siomycin A during storage, while siomycin C is a natural product of Streptomyces sioyaensis.
Incubation of rifamycin S with washed mycelium of Streptomyces mediterranei gives rifamycin B, rifamycin Y and a new substance named rifamycin L. The structure of the latter has been established as the 4-glycolyl ester of rifamycin SV. The glycolic moieties of rifamycin B and L appear to have the same origin. The biogenetic relationships of these rifamycins are discussed.