SYNTHESIS OF NEW 2,4-DIAMINO-5-BENZYLPYRIMIDINES ACTIVE AGAINST VARIOUS BACTERIAL SPECIES

New inhibitors of mycobacterial dihydrofolate reductase (DHFR) have been developed. These compounds show high inhibitory activities against Gram-negative and mycobacterial DHFR exceeding that for the commercially available DHFR blockers. Amongst these compounds K-130 shows a 100-fold lower MIC against M lufu than the most active derivatives known so far (TMP, BDP). Mycobacterium lufu was used as a model for the non cultivable strain M leprae. K-130 is also very active against other mycobacterial strains. Besides the higher affinity to the isolated enzyme, the increase in lipophilicity favours permeation of the mycobacterial cell wall and is responsible for the high inhibitory power of K-130 against mycobacteria. The lower activity against Gram-negative bacteria (E coli), despite high affinity to the enzyme, is explained by the hydrophilic nature of the outer score of the cell-wall components.