Major phytochemical composition of 3 native Korean citrus varieties and bioactive activity on V79-4 cells induced by oxidative stress.

Three citrus varieties grown in Korea, namely, Yuza (Citrus junos Sieb ex Tanaka), Kjool (Citrus unshiu Marcow), and Dangyooja (Citrus grandis Osbeck), were evaluated for their dietary fiber, total phenolics, total flavonoids, and total carotenoids as well as individual flavonoids composition. The biochemical characteristics of citrus varieties were examined by the antioxidant capacity (731 to 1221 micromol of Trolox equivalent/g), total phenolic (334 to 411 mg of chlorogenic acid equivalent/100 g), total flavonoid contents (214 to 281 mg of catechin equivalent/100 g), and total carotenoid contents (63 to 84 mg/100 g). Six flavonoids, including naringin, naringenin, hesperidin, hesperetin, neohesperidin, and luteolin, were tentatively identified. Naringin, hesperidin, and neohesperidin were the predominant flavonoids in 3 citrus varieties. Among the citrus varieties studied, Yuza showed higher antioxidant activity, total phenolics, total carotenoids, and lower superoxide radical scavenging assay (SRSA) IC(50) values than other varieties. Furthermore, Korean citrus showed higher protective effect on gap-junction intercellular communication (GJIC) as compared to vitamin C and luteolin.