Focus on Alternative and Complementary Therapies
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Focus Alternat Complement Ther©2005 Pharmaceutical Press
Focus Altern Complement Ther 2006; 11: 03
The aim of this study was to investigate a mechanism of anti-inflammatory action of extracts of the root of Scutellaria baicalensis (huang qin) and the effects of its constituents on the drug metabolising enzyme cytochrome P450-3A4.
IL-6-Luciferease reporter assays were conducted using HeLa cells. Cytochrome P450-3A4 (CYP-3A4) was assessed using testosterone 6β-hydroxylation as a probe for enzyme activity in human liver microsomes.
At 100 μg/ml an ethyl acetate extract, but not the water or the methanol extracts of S. baicalensis, inhibited IL-6 promoter activity. Fractions and compounds (chrysin and wogonin) isolated from the methanolic extract, as well as standard compounds (baicalin and scutellarein) of the herb, demonstrated anti-inflammatory effect by inhibiting IL-6 promoter activity. Chrysin (5,7-dihy-droxyflavone) dose-dependently inhibited IL-6 promoter activity by 63% (P < 0.001), 91% (P < 0.001) and 98% (P < 0.001), at 50, 100 and 393 μM, respectively. Chrysin (79 μM), baicalein (74 μM) and scutellarein (69 μM) inhibited CYP-3A4 enzyme activity by 74% (P < 0.001), 41% (P < 0.05) and 40% (P < 0.05), respectively.
Constituents of S. baicalensis were found to exert anti-inflammatory action through the inhibition of IL-6 promoter activity. Also, preliminary results suggest that some constituents of S. baicalensis with anti-inflammatory properties are also inhibitors of CYP-3A4 activity in vitro. Therefore, co-administration of S. baicalensis with herbs or drugs metabolised by CYP-3A4 could lead to possible herb–herb or drug–herb interactions. S. baicalensis is a herb proposed as a potential alternative to bear bile (used in traditional medicine as an anti-inflammatory agent), either as an individual herb or in combination with others.
We thank DEFRA and IFAW charitable trust for their financial support.
