title: Optimized microwave-assisted extraction of 6-gingerol from Zingiber officinale Roscoeand evaluation of antioxidant activity in vitro.
abstract: BACKGROUND
  6-Gingerol is one of the most pharmacologically active and abundant components in ginger, which has a wide array of biochemical and pharmacologic activities. In recent years, the application of microwave-assisted extraction (MAE) for obtaining bioactive compounds from plant materials has shown tremendous research interest and potential. In this study, an efficient microwave-assisted extraction (MAE) technique was developed to extract 6-gingerol from ginger. The extraction efficiency of MAE was also compared with conventional extraction techniques.
  
  
  METHODS
  Fresh gingers (Zingiber officinale Rose.) were harvested at commercial maturity (originally from Shandong, laiwu, China). In single-factor experiments for the recovery of 6-gingerol, proper ranges of ratio of liquid to solid, ethanol proportion, microwave power, extraction time were determined. Based on the values obtained in single-factor experiments, a Box-Behnken design (BBD) was applied to determine the best combination of extraction variables on the yield of 6-gingerol.
  
  
  RESULTS
  The optimum extraction conditions were as follows: microwave power 528 W, ratio of liquid to solid 26 mL·g(-1), extraction time 31 s and ethanol proportion 78%. Furthermore, more 6-gingerol and total polyphenols contents were extracted by MAE than conventional methods including Maceration (MAC), Stirring Extraction (SE), Heat reflux extraction (HRE), Ultrasound-assisted extraction (UAE), as well as the antioxidant capacity.
  
  
  CONCLUSIONS
  Microwave-assisted extraction showed obvious advantages in terms of high extraction efficiency and antioxidant activity of extract within shortest extraction time. Scanning electron microscopy (SEM) images of ginger powder materials after different extractions were obtained to provide visual evidence of the disruption effect. To our best knowledge, this is the first report about usage of MAE of 6-gingerol extraction from ginger, which could be referenced for the extraction of other active compounds from herbal plants.
authors.affiliation: College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.affiliation: College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
authors.forename: Chun-Li
authors.initials: CL
authors.lastname: Zhou
authors.affiliation: College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.affiliation: College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
authors.forename: Dong
authors.initials: D
authors.lastname: Chen
authors.affiliation: College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
authors.forename: Quan-Hong
authors.initials: QH
authors.lastname: Li
mesh_terms: D000818:Animals; D002396:Catechols / Q000032:analysis* / Q000302:isolation & purification; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D000431:Ethanol; D005233:Fatty Alcohols / Q000032:analysis* / Q000302:isolation & purification; D016166:Free Radical Scavengers / Q000032:analysis; D020939:Zingiber officinale / Q000737:chemistry*; D008872:Microwaves; D010936:Plant Extracts / Q000032:analysis* / Q000302:isolation & purification; D018517:Plant Roots / Q000737:chemistry*; D059808:Polyphenols / Q000032:analysis
chemical_list: D002396:Catechols; D005233:Fatty Alcohols; D016166:Free Radical Scavengers; D010936:Plant Extracts; D059808:Polyphenols; D000431:Ethanol; C007845:gingerol