title: Characterization of increased phenolic compounds from fermented Bokbunja (Rubus coreanus Miq.) and related antioxidant activity.
abstract: This study examined the changes in the phenolic acid-content and antioxidant activity of Rubi Fructus (RF), the fruit of Rubus coreanus Miq., after fermentation with yeast (Saccharomyces cerevisiae). The phenolic acids were fractionated into three forms, free (Fr. A), ester (Fr. B), and insoluble-bound phenolic acids (Fr. C) and quantified by high performance liquid chromatography with a diode array detector (HPLC-DAD). This method was validated and allowed the successful identification of 11 phenolic acids in the RF extracts. HPLC-DAD analysis of the samples showed substantial increases in the levels of protocatechuic, vanillic and p-coumaric acid as the result of yeast fermentation. The total phenolic content (TPH) was also increased by fermentation. The total phenolics in Fr. A and Fr. B increased from 117 to 173 mg GAE/100 g and from 488 to 578 mg GAE/100 g, respectively. The total phenolics in Fr. C decreased from 264 to 175 mg GAE/100 g. The antioxidant activity of the fermented RF was measured as the 1,1-diphenoly-2-picrylhydrazyl (DPPH) radical scavenging capacity, which is expressed as the IC(50). The IC(50) for Fr. A and Fr. B decreased from 5.9 to 4.0 mg/ml (mg of dried RF equiv./ml) and from 1.2 to 0.8 mg/ml, respectively. In Fr. C, the IC(50) value increased from 2.1 to 2.8 mg/ml. In summary, the fermented RF had a higher total phenolic content and better DPPH radical-scavenging activity than the unfermented material.
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
authors.forename: Hyun Kyoung
authors.initials: HK
authors.lastname: Ju
authors.forename: Eun Jung
authors.initials: EJ
authors.lastname: Cho
authors.forename: Moon Hee
authors.initials: MH
authors.lastname: Jang
authors.forename: Yong Yook
authors.initials: YY
authors.lastname: Lee
authors.forename: Soon Sun
authors.initials: SS
authors.lastname: Hong
authors.forename: Jeong Hill
authors.initials: JH
authors.lastname: Park
authors.forename: Sung Won
authors.initials: SW
authors.lastname: Kwon
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D001713:Biphenyl Compounds / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D003373:Coumaric Acids / Q000737:chemistry; D005285:Fermentation; D016166:Free Radical Scavengers / Q000737:chemistry; D062385:Hydroxybenzoates / Q000737:chemistry; D007202:Indicators and Reagents; D010636:Phenols / Q000032:analysis*; D010851:Picrates / Q000737:chemistry; D012015:Reference Standards; D015203:Reproducibility of Results; D027824:Rosaceae / Q000737:chemistry*; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D003373:Coumaric Acids; D016166:Free Radical Scavengers; D062385:Hydroxybenzoates; D007202:Indicators and Reagents; D010636:Phenols; D010851:Picrates; C004931:1,1-diphenyl-2-picrylhydrazyl