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Flavonoids and a Limonoid from the Fruits of Citrus unshiu and Their Biological Activity

Eom, Hee Jeong, Lee, Dahae, Lee, Seulah, Noh, Hyung Jun, Hyun, Jae Wook, Yi, Pyoung Ho, Kang, Ki Sung, Kim, Ki Hyun
Journal of agricultural and food chemistry 2016 v.64 no.38 pp. 7171-7178
Citrus unshiu, bioactive compounds, citrus fruits, flavonoids, fruits, functional foods, glycosides, inflammation, metabolites, natural resources, nephrotoxicity, nitric oxide, nuclear magnetic resonance spectroscopy, Korean Peninsula
The fruits of Citrus unshiu are one of the most popular and most enjoyed fruits in Korea. As we continue to seek for bioactive metabolites from Korean natural resources, our study on the chemical constituents of the fruits of C. unshiu resulted in the isolation of a new flavonoid glycoside, limocitrunshin 1, along with seven other flavonoids 2–8 and a limonoid 9. All structures were identified by spectroscopic methods, namely 1D and 2D NMR, including HSQC, HMBC, and 1H–1H COSY experiments, HRMS, and other chemical methods. Compounds 3, 5, and 9 are reported to be isolated from this fruit for the first time. The isolated compounds were applied to activity tests to verify their inhibitory effects on inflammation and nephrotoxicity. Compounds 6 and 9 showed the most potent inhibitory activity on renal cell damage and nitric oxide production, respectively. Thus, the fruits of C. unshiu could serve as a valuable natural source of bioactive components with health benefits for potential application in functional foods.