Abstract
BackgroundFlavonoids are abundant plant phenolic compounds. More than 6000 have been identified to date, and some have been shown to possess antiparasitic activity. Here we investigate the effects of a range of common dietary flavonoids on the growth of two strains of the human malaria parasite Plasmodium falciparum.FindingsA chloroquine-sensitive (3D7) and a chloroquine-resistant (7G8) strain of P. falciparum were tested for in vitro susceptibility to a range of individual dietary flavonoids and flavonoid combinations. Parasite susceptibility was measured in 96-well plates over 96 h using a previously described [3H]hypoxanthine incorporation assay. Of the eleven flavonoids tested, eight showed antiplasmodial activity against the 3D7 strain (with IC50 values between 11 and 66 μM), and all showed activity against the 7G8 strain (with IC50 values between 12 and 76 μM). The most active compound against both strains was luteolin, with IC50 values of 11 ± 1 μM and 12 ± 1 μM for 3D7 and 7G8, respectively. Luteolin was found to prevent the progression of parasite growth beyond the young trophozoite stage, and did not affect parasite susceptibility to the antimalarial drugs chloroquine or artemisinin. Combining low concentrations of flavonoids was found to produce an apparent additive antiplasmodial effect.ConclusionCertain common dietary flavonoids inhibit the intraerythrocytic growth of the 3D7 and 7G8 strains of P. falciparum. Flavonoid combinations warrant further investigation as antiplasmodial agents.
Highlights
In the cases of apigenin, kaempferol, luteolin and quercetin, the IC50 values against both strains of P. falciparum are at least 4-fold lower than the IC50 values reported against both human cell lines
To investigate which stage of the parasite's intraerythrocytic lifecycle is inhibited by flavonoids, we prepared Giemsa-stained 7G8-infected erythrocyte smears at various time points following the addition of 20 M luteolin (~2 × IC50)
(page number not for citation purposes) http://www.biomedcentral.com/1756-0500/1/26 activities of the main conjugates of promising antiplasmodial flavonoids
Summary
A number of reports have demonstrated growth inhibitory effects of flavonoids, of the flavonol quercetin and of the flavone luteolin, on the protozoan parasite genera Toxoplasma [2], Trypanosoma [3] and Leish- The flavanone naringenin, the isoflavone genistein, and a range of flavonols (kaempferol, myricetin, quercetin and isoquercitrin) and flavones (acacetin, apigenin, baicalein, chrysin and luteolin) were tested against a chloroquine-sensitive (3D7) and a chloroquineresistant (7G8) strain of Plasmodium falciparum. A recent study demonstrated the in vitro antiplasmodial activities of a number of these compounds [13]; we confirm and extend these findings with different P. falciparum strains.
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