Bioactive Compounds from Medicinal Plants in Myanmar
157
O
O
O
OH
HO
HO 3 S
99 (niruriflavone)
100 (isoquercetin)
O
HO
OH O
OH
OH
O
O
OH
OH
O
O
OH
OH
OH
HO
101 (quercetin-3-O-β-D-glucopyranosyl(1 4)-α-rhamnopyranoside)
O
HO
OH O
OH
OH
O
O
HO
OH
OH
CH 2 OH
Fig. 20 Structures of flavone sulfonic acid 99 and flavonoid glycosides 100 and 101 isolated from
a 70% ethanol extract of P. niruri
O
O
HO
HO
OH
HO
OH
OH
O
O
O
HO
OH
O
O
OH
OH
OH
102 (corilagin)
O
O
HO
HO
OH
HO
OH
OH
O
O
O
HO
OH
O
O
OH
OH
OH
103 (isocorilagin)
Fig. 21 Structures of ellagitannins 102 and 103 isolated from the 70% ethanol extract of P. niruri
salt) cation radical reduction assay revealed that niruriflavone (99) showed radicalscavenging properties at concentration levels between 20 and 100 μM. However,
niruriflavone (99) did not exhibit any antiperoxidant effects at 10 μM in an
assay using the bioluminescent dinoflagellate Lingulodinium polyedrum as a test
organism, although gallic acid (105) and quercetin-3-O-β-d-glucopyranosyl(1→4)α-rhamnopyranoside (101) were active in this regard [132].