title: Extraction of brown pigment from Rosa laevigata and its antioxidant activities.
abstract: BACKGROUND
  Rosa laevigata Michx. (Rosaceae), widespread in China, contains many valuable nutrients and has long been used as food and medicine in Chinese folklore. Nowadays, due to its favorable property of coloring, the brown pigment of R. laevigata has an attractive potential as an available additive in food.
  
  
  OBJECTIVE
  The aims of this study were to optimize the extraction process of brown pigment from R. laevigata and investigate its antioxidant activities on the basis of its abilities to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, hydroxyl radical and superoxide radical.
  
  
  METHODS
  Extraction conditions of brown pigment from R. laevigata were investigated through an orthogonal design of L₉(3)⁴ assay. Ethanol concentration, extraction temperature, time, and ratio of material to solvent were the main factors affecting the extraction rate. Subsequently, the antioxidant activity of brown pigment was assessed using DPPH method, while hydroxyl radicals and superoxide free radicals were respectively determined by the Fenton-RhB (Rhodamine B) system and using the pyrogallol-luminol system.
  
  
  RESULTS
  The optimum extraction conditions were determined: temperature 70°C, ethanol concentration was 60%, extraction time 2 h and ratio of material to solvent was 1:6. Brown pigment showed a good radical scavenging activity, and exhibited a concentration-dependent inhibition of hydroxyl radical and superoxide free radical at low concentrations. When the concentration of brown pigment was 1 mg/mL, the scavenging percentage of hydroxyl radical reached 67.33%.
  
  
  CONCLUSIONS
  The brown pigment of R. laevigata could potentially be used as a promising natural antioxidant in the food and pharmaceutical industries.
authors.affiliation: College of Food and Bioengineering, South China University of Technology, Guangzhou 510640, China.
authors.forename: Kai-Jun
authors.initials: KJ
authors.lastname: Xiao
authors.forename: Xian-Ke
authors.initials: XK
authors.lastname: Zhong
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Jiang
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D016166:Free Radical Scavengers / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology; D017665:Hydroxyl Radical / Q000378:metabolism; D008516:Medicine, Chinese Traditional; D010860:Pigments, Biological / Q000008:administration & dosage / Q000302:isolation & purification / Q000494:pharmacology*; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D027826:Rosa / Q000737:chemistry*; D013696:Temperature
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D010860:Pigments, Biological; D010936:Plant Extracts; D017665:Hydroxyl Radical