Publication Date:
2014-08-21
Description:
After the discovery of a potent natural flavonoid glucoside as a potent inhibitor of FabI, a large flavonoid library was screened against three important enzymes (i.e., FabG, FabZ, and FabI) involved in the fatty acid biosynthesis of P. falciparum. Although flavones with a simple hydroxylation pattern (compounds 4−9) showed moderate inhibitory activity toward the enzymes tested (IC50 10−100 μM), the more complex flavonoids (12−16) exhibited strong activity toward all three enzymes (IC50 0.5−8 μM). Isoflavonoids 26−28 showed moderate (IC50 7−30 μM) but selective activity against FabZ. The most active compounds were C-3 gallic acid esters of catechins (32, 33, 37, 38), which are strong inhibitors of all three enzymes (IC50 0.2−1.1 μM). Kinetic analysis using luteolin (12) and (−)-catechin gallate (37) as model compounds revealed that FabG was inhibited in a noncompetitive manner. FabZ was inhibited competitively, whereas both compounds behaved as tight-binding noncompetitive inhibitors of FabI. In addition, these polyphenols showed in vitro activity against chloroquine-sensitive (NF54) and -resistant (K1) P. falciparum strains in the low to submicromolar range.
Type:
Article
,
PeerReviewed
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