Two new anti-plasmodial flavonoid glycosides from Duranta repens

The CHCl(3)-soluble fraction of the whole plant of Duranta repens showed anti-plasmodial activity against the chloroquine-sensitive (D6) and chloroquine-resistant (W2) strains of Plasmodium falciparum, with IC(50) values of 8.5 ± 0.9 and 10.2 ± 1.5 μg/mL, respectively. From this fraction, two new flavonoid glycosides, 7-O-α-d-glucopyranosyl-3,4'-dihydroxy-3'-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (1) and 7-O-α-d-glucopyranosyl(6'''-p-hydroxcinnamoyl)-3,4'-dihydroxy-3'-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (2), along with five known flavonoids, 3,7,4'-trihydroxy-3'-(4-hydroxy-3-methylbutyl)-5,6-dimethoxyflavone (3), 3,7-dihydroxy-3'-(4-hydroxy-3-methylbutyl)-5,6,4'-trimethoxyflavone (4), 5,7-dihydroxy-3'-(2-hydroxy-3-methyl-3-butenyl)-3,6,4'-trimethoxyflavone (5), 3,7-dihydroxy-3'-(2-hydroxy-3-methyl-3-buten-yl)-5,6,4'-trimethoxyflavone (6), and 7-O-α-d-glucopyranosyl-3,5-dihydroxy-3'-(4''-acetoxy-3''-methylbutyl)-6,4'-dimethoxyflavone (7), have been isolated as anti-plasmodial principles. Their structures were deduced by spectroscopic analysis including 1D and 2D NMR techniques. The compounds (1-7) showed potent anti-plasmodial activities against D6 and W2 strains of Plasmodium falciparum, with IC(50) values in the range of 5.2-13.5 μM and 5.9-13.1 μM, respectively.