Medicinal Plants Classification Biosynthesis and ... - Index of

Biosyntheses and Bioactivities of Flavonoids in the Medicinal...
activities against RSV with 50% inhibition concentration (IC50) ranging from 6.3 to 52.1
g/ml, and with selectivity index (SI) ranging from 2.0 to 32.1. Further purification of the
active extracts from S. baicalensis Georgi led to the identification of wogonin and oroxylin A
as the potent anti-RSV components [Ma et al., 2002]. In addition, commercial antiviral agents
and pure chemical compounds extracted from traditional Chinese medicinal herbs were
screened against 10 clinical isolates of severe acute respiratory syndrome (SARS)
coronavirus by neutralisation tests with confirmation by plaque reduction assays, and baicalin
showed strong antiviral activity [Chen et al., 2004].
The aqueous and methanol extracts of thirty-one herbs traditionally used as anti-fever
remedies in China were screened for their in vitro inhibition on human immunodeficiency
virus type-1 (HIV-1) protease. The aqueous extracts of S. baicalensis elicited significant
inhibition (>90%) at a concentration of 200 g/ml [Lam et al., 2000]. Baicalin at the
noncytotoxic concentration inhibited both T cell tropic (X4) and monocyte tropic (R5) HIV-1
Env protein mediated fusion with cells expressing CD4/CXCR4 or CD4/CCR5. Furthermore,
presence of baicalin at the initial stage of HIV-1 viral adsorption blocked the replication of
HIV-1 early strong stop DNA in cells. Since baicalin did not inhibit binding of HIV-1 gp120
to CD4, it might interfere with the interaction of HIV-1 Env with chemokine coreceptors and
block HIV-1 entry of target cells [Li et al., 2000b]. Anti-HIV activities of S. baicalensis,
baicalein and baicalin have been emphasized in review paper [Wu et al., 2001].
By using an hepatitis B virus (HBV)-producing cell line in vitro culture system, wogonin
could suppress HBV surface antigen production (P < 0.001) without evidence of cytotoxicity.
By assaying the endogenous HBV DNA polymerase activity, both the relaxed circular and
the linear forms of HBV DNA were significantly reduced in the wogonin-treated group
[Huang et al., 2000]. In another study, wogonin's anti-HBV activity both in vitro and in vivo
was investigated. In the human HBV-transfected liver cell line HepG2.2.15, wogonin
effectively suppressed the secretion of the HBV antigens with an IC50 of 4 g/ml at day 9 for
both HBsAg and HBeAg. Consistent with the HBV antigen reduction, wogonin also reduced
HBV DNA level in a dose-dependent manner. Duck hepatitis B virus (DHBV) DNA
polymerase was dramatically inhibited by wogonin with an IC50 of 0.57 g/ml. In DHBVinfected
ducks wogonin dosed i.v. once a day for 10 days reduced plasma DHBV DNA level
with an ED50 of 5 mg/kg. The in vivo anti-HBV effect of wogonin in ducks was confirmed
by Southern blotting of DHBV DNA in the liver. Histopathological evaluation of the liver
revealed significant improvement by wogonin. In addition, in human HBV-transgenic mice,
wogonin dosed i.v. once a day for 10 days significantly reduced plasma HBsAg level.
Immunohistological staining of the liver confirmed the HBsAg reduction by wogonin. This
suggested that wogonin possessed potent anti-HBV activity both in vitro and in vivo [Guo et
al., 2007].
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