Salicylanilide diethyl phosphates: Synthesis, antimicrobial activity and cytotoxicity

A series of 27 salicylanilide diethyl phosphates was prepared as a part of our on-going search for new antimicrobial active drugs. All compounds exhibited in vitro activity against Mycobacterium tuberculosis, Mycobacterium kansasii and Mycobacterium avium strains, with minimum inhibitory concentration (MIC) values of 0.5-62.5μmol/L. Selected salicylanilide diethyl phosphates also inhibit multidrug-resistant tuberculous strains at the concentration of 1μmol/L. Salicylanilide diethyl phosphates also exhibited mostly the activity against Gram-positive bacteria (MICs ≥1.95μmol/L), whereas their antifungal activity is significantly lower. The IC50 values for Hep G2 cells were within the range of 1.56-33.82μmol/L, but there is no direct correlation with MICs for mycobacteria.