Biological and Pharmaceutical Bulletin
Online ISSN : 1347-5215
Print ISSN : 0918-6158
ISSN-L : 0918-6158
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Correlation between Flavonoid Content and the NO Production Inhibitory Activity of Peel Extracts from Various Citrus Fruits
Soo-Youn ChoiHee-Chul KoSoo-Youn KoJoon-Ho HwangJi-Gweon ParkShin-Hae KangSang-Hun HanSu-Hyun YunSe-Jae Kim
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2007 Volume 30 Issue 4 Pages 772-778


We investigated the correlation between the flavonoid content and NO production inhibitory activity of fruit peel extracts using 20 citrus plants. The contents of seven flavonoids (naringin, naringenin, hesperidin, hesperetin, rutin, nobiletin, and tangeretin) were determined by HPLC analysis. Each citrus peel extract varied in flavonoid content, but the contents of nobiletin and tangeretin, which were contained in all 20 fruit peels, showed a positive and significant correlation with each other (r=0.879, p<0.0005 for immature fruit peels; r=0.858, p<0.0005 for mature fruit peels). All citrus peel extracts dose-dependently inhibited LPS-induced NO production in RAW 264.7 cells. This inhibitory effect was significantly and positively correlated with the content of nobiletin and tangeretin. Nobiletin showed a more potent NO production inhibitory activity (IC50=26.5 μM) compared to tangeretin (IC50=136.6 μM). This result supports the premise that nobiletin-rich citrus may provide protection against disease resulting from excessive NO production.

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© 2007 The Pharmaceutical Society of Japan
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