is an economically important fruit on Jeju Island, Korea, but byproducts are a major source of agricultural waste. The aim of this study is to examine changes in phytochemical, antioxidant, and antibacterial activities of four byproducts: citrus flesh byproduct (CFB), fermented citrus flesh byproduct (FCFB), citrus peel byproduct (CPB), and fermented citrus peel byproduct (FCPB). Fermented citrus byproducts (FCFB and FCPB) exhibited greater inhibition effect on radical scavenging abilities of 2,2-diphenyl-1-picrylhtdrazyl, 2,2'-azinobis(3-ethylbenzothiazolin-6-sulfonic acid)-diammonium salt, and superoxide anion compared with those of CFB and CPB. Total polyphenol contents of FCFB and FCPB were significantly increased compared to those of CFB and CPB. Significant bioconversion of the flavonoid glucosides into corresponding bioactive aglycones during citrus byproduct fermentation was observed. Fermented citrus byproducts exhibited antibacterial activity against and suggesting that FCFB and FCPB are potent antioxidant and antibacterial sources due to the remarkable contents of bioactive compounds in them.

:This study was designed to analyze the chemical composition of essential oil in 'Shiranuhi' immature fruit and to test their biological activities. 'Shiranuhi' immature essential oils (SIEO) were obtained by steam distillation from fruits collected from Jeju Island and were analyzed using gas chromatograph (GC)-flame ionization detectors (FID) and GC-MS. Fourteen components were identified in the essential oil. Limonene (75.21%) and terpineol (8.68%) were the major components in SIEO. Since acne vulgaris is the combined result of a bacterial infection and the inflammatory response to that infection, we examined whether SIEO possessed antibacterial against skin pathogens. As a result, SIEO showed excellent antibacterial activities against drug-susceptible and -resistant Propionibacterium acnes and Staphylococcus epidermidis, which are acne-causing bacteria. In this study, SIEO was examined on DPPH radical scavenging activities, which showed moderate antioxidant activity (SC 50 , 15.36 µL/mL). In order to determined whether SIEO can be safely applied to human skin, the cytotoxicity effects of SIEO were determined by colorimetric MTT assays in normal human fibroblasts and keratinocyte HaCaT cells. They exhibited low cytotoxicity at 0.5 µL/mL in both celllines. Based on these results, we suggest the possibility that essential oil of 'Shiranuhi' maybe considered as an antibacterial and antioxidant agent.