Correlation between Flavonoid Content and the NO Production Inhibitory Activity of Peel Extracts from Various Citrus Fruits

• Published in: Biological & pharmaceutical bulletin Vol. 30; no. 4; pp. 772 - 778
• Main Authors: Choi, Soo-Youn, Ko, Hee-Chul, Ko, Soo-Youn, Hwang, Joon-Ho, Park, Ji-Gweon, Kang, Shin-Hae, Han, Sang-Hun, Yun, Su-Hyun, Kim, Se-Jae
• Format: Journal Article
• Language: English
• Published: Japan The Pharmaceutical Society of Japan 01.04.2007; Japan Science and Technology Agency
• Subjects: Animals; Cell Line; Cell Survival - drug effects; Chromatography, High Pressure Liquid; Citrus - chemistry; Citrus - classification; citrus peel; Dose-Response Relationship, Drug; flavonoid; Flavonoids - analysis; Flavonoids - chemistry; Flavonoids - metabolism; Flavonoids - pharmacology; Fruit - chemistry; Inhibitory Concentration 50; Liposomes - pharmacology; Macrophages - chemistry; Macrophages - drug effects; Mice; Molecular Structure; nitric oxide (NO) production inhibitory activity; Nitric Oxide - antagonists & inhibitors; Nitric Oxide - biosynthesis; Nitrites - analysis; nobiletin; Plant Extracts - chemistry
• ISSN: 0918-6158; 1347-5215
• DOI: 10.1248/bpb.30.772

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.