The characteristics of flavonoids in ten sour citrus fruits (lemon, niihime, genko, yuukou, kabosu, sudachi, yukou, yuzu, nagato-yuzukichi, hebesu) of local special products in Japan were studied. The content of eleven flavonoids (eriocitrin, neoeriocitrin, narirutin, naringin, hesperidin, neohesperidin, diosmin, didymin, poncirin, nobiletein, tangeretin) in whole fruit and juice of each sour citrus was determined by HPLC. The contents of the flavonoids in each whole fruit were studied for the characteristics of the flavonoid composition in the citrus by principal component analysis of multiple classification analyses. Based on the results, each lemon and niihime was shown to have flavonoid compositions different from other citrus based on the principal component analysis. Lemon contained abundant amount of eriocitrin and diosmin, while niihime contained abundant amount of heperidin, dydmin, and nobiletin in comparison to the other citrus by HPLC analysis. These compounds were shown to be the characteristic flavonoids of each citrus fruit by the principal component analysis. Furthermore, the antioxidative activity of the flavonoid fraction from the whole fruit of the sour citrus was examined by measurement of the scavenging activity of the DPPH radical. Niihime, lemon, and sudachi exhibited high activities. The total amount of ten flavonoids in sour citrus (whole fruit) had a positive correlation with the antioxidative activity (R=0.772). Especially, the amount of eriocitrin, neoeriocitrin, hesperidin, and neohesperidin had a high correlation with the antioxidative activity (R=0.899).
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