The antiphage activity of the compounds was determined in a phage-bacterium system (DNA-containing phage T6 and E. coli, and RNA-containing phage Ms-2 and E. coli HFrl). The number of surviving phage particles was determined by Grazia's agar slope method. Antiphage activity was expressed as percentage inactivation, calculated by the formula [3]:[i- (No/Nk)]" 100%, where No is the number of surviving phage particles in the test, and N k ...