Anticoccidial activity of alborixin.

Alborixin, a polyether antibiotic with ionophore properties, was evaluated to determine the effect of the drug on weight gain of chickens and to define the anticoccidial spectrum of activity. The 50-ppm concentration in the diet was identified as the maximum level that did not significantly reduce weight gain beyond that of monensin (standard drug); consequently, the drug was evaluated for anticoccidial activity at this dilution. At the 50-ppm level, alborixin demonstrated broad-spectrum anticoccidial activity; however, the drug lacked Eimeria necatrix efficacy.

Steffimycin C, a new member of the steffimycin anthracyclines. Isolation and structural characterization.

Mother liquors from steffimycin B crystallizations have been processed to yield steffimycin C, a new member of the steffimycin family of anthracyclines. It has been identified, using spectroscopic methods, as 10-deoxysteffimycin B. Steffimycin C has antibacterial activity only against Streptococcus pneumoniae.

Clindamycin activity against chloroquine-resistant Plasmodium falciparum.

The clindamycin dose-response curves observed with both chloroquine-resistant and chloroquine-susceptible strains of Plasmodium falciparum in vitro demonstrated a plateau region that extended from 10(-2) to 10(1) micrograms/ml of drug (22 nM to 22 microM). Similar dose-response curves were also observed with the three major metabolites of clindamycin (clindamycin sulfoxide, de-N-methyl clindamycin, and de-N-methyl clindamycin sulfoxide). The position of this plateau was time dependent and rose from 20%-25% to 90%-95% inhibition of parasite growth between 24 and 72 hr of exposure to the drug.

U-56,407, a new antibiotic related to asukamycin: isolation and characterization.

U-56,407, a bright yellow, crystalline antibiotic was isolated from fermentations of Streptomyces hagronensis (strain 360). This antibiotic was extracted from fermentation broths with halogenated hydrocarbons and purified by silica gel chromatography and crystallization. U-56,407 is active in vitro against Gram-positive bacteria but not Gram-negative organisms.

Paulomycins A and B. Isolation and characterization.

Paulomycin A, C34H46N2O17S and paulomycin B, C33H44N2O17S are two antibiotics produced by Streptomyces paulus strain 273 (UC 5142). Both antibiotics, which are mainly active against a variety of Gram-positive bacteria, contain an isothiocyanate group and in this respect they are related to senfolomycins A and B and proceomycin.