Antimicrobial natural products as beta-ketoacyl-acyl carrier protein synthase III inhibitors.

Beta-ketoacyl-acyl carrier protein synthase III (KAS III) initiates bacterial fatty acid biosynthesis, making it one of the most promising condensing enzymes. In a previous study, we developed three pharmacophore maps from receptor-oriented pharmacophore-based in silico screening and proposed a potent antimicrobial inhibitor for KAS III. Using these pharmacophore maps, we examined a natural product database and chose 4 natural compounds as possible KAS III inhibitors. Here, we propose that YKAF01 (3,6-dihydroxyflavone) and YKAF04, 3-(4-hydroxyphenyl)-1-(2,4,6-tri-hydroxyphenyl)propan-1-one (or 4,2',4',6'-tetra-hydroxychalcone, phloretin) are potent antimicrobial inhibitors of KAS III with high binding affinity. In particular, these compounds display an excellent antimicrobial effect against Staphylococcus aureus and MRSA in the range of 16-32 microM.