Inhibitory effect of baicalein, a flavonoid in Scutellaria Root, on eotaxin production by human dermal fibroblasts.
Eotaxin is an eosinophil-specific chemokine associated with the recruitment of eosinophils to sites of allergic inflammation. "Saiboku-to" (Formula magnoliae et bupleuri) is a kampo herbal medicine used for the treatment of bronchial asthma in Japan. In this study, we investigated the effects of Scutellaria Root, a major herb in Saiboku-to and its components such as baicalein and baicalin on eotaxin production by IL-4 plus TNF-alpha-stimulated human fibroblasts. An extract of Scutellaria Root markedly inhibited eotaxin production. Four major flavonoids from Scutellaria Root were found to show inhibitory activity on eotaxin production at a concentration of 10 micrograms/ml in the order of baicalein > oroxylin A > baicalin > skullcapflavon II. The inhibitory effect of baicalein was expressed in a dose-dependent manner, and almost 50% inhibition was observed at 1.8 micrograms/ml. Furthermore, baicalein prevented human eotaxin mRNA expression in IL-4 plus TNF-alpha-stimulated human fibroblasts. These results help explain the pharmacological efficacy of Scutellaria Root in the treatment of bronchial asthma since it would suppress eotaxin associated recruitment of eosinophils.
Nakajima
T
T
Department of Bioregulatory Function, University of Tokyo Graduate School of Medicine, Tokyo, Japan.
Imanishi
M
M
Yamamoto
K
K
Cyong
J C
JC
Hirai
K
K
D001249:Asthma / Q000188:drug therapy*; D002478:Cells, Cultured / Q000187:drug effects; D054413:Chemokine CCL11; D019742:Chemokines, CC; D016207:Cytokines / Q000187:drug effects*; D020405:Dermis / Q000187:drug effects / Q000378:metabolism; D004365:Drugs, Chinese Herbal / Q000494:pharmacology* / Q000627:therapeutic use; D005347:Fibroblasts / Q000187:drug effects*; D044950:Flavanones; D005419:Flavonoids / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology* / Q000627:therapeutic use; D008297:Male; D020835:Medicine, Kampo
C515456:CCL11 protein, human; D054413:Chemokine CCL11; D019742:Chemokines, CC; D016207:Cytokines; D004365:Drugs, Chinese Herbal; D044950:Flavanones; D005419:Flavonoids; D007166:Immunosuppressive Agents; C045086:saiboku-to; C006680:baicalein