Synthesis and Antibacterial Activity of 3-Substituted-6-(3-ethyl-4-methylanilino)uracils

Abstract

Numerous 3-substituted-6-(3-ethyl-4-methylanilino)uracils (EMAU) have been synthesized and screened for their capacity to inhibit the replication-specific bacterial DNA polymerase IIIC (pol IIIC) and the growth of Gram+ bacteria in culture. Direct alkylation of 2-methoxy-6-amino-4-pyrimidone produced the N3-substituted derivatives, which were separated from the byproduct 4-alkoxy analogues. The N3-substituted derivatives were heated with a mixture of 3-ethyl-4-methylaniline and its hydrochloride to effect displacement of the 6-amino group and simultaneous demethylation of the 2-methoxy group to yield target compounds in good yields. Certain intermediates, e.g. the 3-(iodoalkyl) compounds, were converted to a variety of (3-substituted-alkyl)-EMAUs by displacement. Most compounds were potent competitive inhibitors of pol IIIC (K(i)s 0.02-0.5 microM), and those with neutral, moderately polar 3-substituents had potent antibacterial activity against Gram+ organisms in culture (MICs 0.125-10 microg/mL). Several compounds protected mice from lethal intraperitoneal (ip) infections with S. aureus (Smith) when given by the ip route. A water soluble derivative, 3-(4-morpholinylbutyl)-EMAU hydrochloride, given subcutaneously, prolonged the life of infected mice in a dose dependent manner.

Clostridium difficile DNA Polymerase IIIC: Basis for Activity of Anti-Bacterial Compounds

“…DCBG derivatives appeared to be the most potent antibacterials against C. difficile strains. Compounds based on “EMAU” (6-anilinouracils) and “EMPG” (N 2 -phenylguanines) were less active, although these compounds have been found to be potent inhibitors of the growth of Gram-positive aerobes [11,12]. In particular, the 7-isomers of DCBGs were more active than 9-isomers (data not shown), and the morpholinyl derivatives, e.g.…”

Architecture and Conservation of the Bacterial DNA Replication Machinery, an Underexploited Drug Target

“…These hybrid compounds maintain dual anti-PolC and anti-DNA gyrase activity in vivo and have greater or equal potency against whole bacterial cells than their isolated 6-AU or fluoroquinolone parent compounds [116, 123, 124]. In fact when testing one representative hybrid (Fig.…”

DNA replication proteins as potential targets for antimicrobials in drug-resistant bacterial pathogens

“…Two promising AUs, 6-(3-ethyl-4-methylanilino) uracil (EMAU) and 6-([3,4-trimethylene]anilino) uracil (TMAU), were highly active against PolC in vitro , but required optimization to increase activity against various Gram-positive bacteria, including MRSA 46 , 48–50 . Improvement of solubility of AUs compromises antimicrobial activity, but allowed the production of compounds that could be delivered intravenously rather than subcutaneously in animal models of infection 46 , 50–52 . The frequencies of mutations leading to AU resistance ranged from 3.6 × 10 − 10 to 1.2 × 10 − 8 , comparable to the frequency of ciprofloxacin resistance 53 .…”