title: Microplate quantification of total phenolic content from plant extracts obtained by conventional and ultrasound methods.
abstract: BACKGROUND
  There is increasing interest in phenolic compounds around the world because of their potential positive impact on human health. Phenolic compounds are largely found in fruits and vegetables. Extraction of phenolic compounds is a very important step in their recovery. The newly developed technique of ultrasound-assisted extraction (UAE) appears to be an advantageous alternative compared with conventional techniques, because it is simple and environmental friendly. The potential of UAE needs to be evaluated in each plant in order to demonstrate its efficiency.
  
  
  OBJECTIVE
  The objective of the present study was to compare a conventional method and UAE on the extraction efficiency of phenolic compounds from Jatropha dioica, Fluorensia cernua, Turnera diffusa and Eucalyptus camaldulensis plants and evaluate the in vitro anti-oxidant potential.
  
  
  METHODS
  Validation of the new method was carried out using mixed-model methodology and regression analysis. Feasibility of this new method was shown and applied using several plants extracts obtained by different extraction methods from semi-arid Mexican plants, which were characterised by high levels of polyphenols. Additionally, the anti-oxidant potential of these extracts was determined by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity.
  
  
  RESULTS
  Results showed that the new microplate method can be used to determine total phenolic content in plant extracts. Additionally, an alternative extraction method by ultrasound was less efficient compared with the conventional method.
  
  
  CONCLUSIONS
  The tested plants are good candidates to obtain nutraceuticals and functional food ingredients.
authors.affiliation: Department of Food Science and Technology, School of Chemistry, Autonomous University of Coahuila, 25280, Saltillo, Coahuila, Mexico.
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Wong-Paz
authors.forename: Diana B
authors.initials: DB
authors.lastname: Muñiz-Márquez
authors.forename: Pedro
authors.initials: P
authors.lastname: Aguilar-Zárate
authors.forename: Raúl
authors.initials: R
authors.lastname: Rodríguez-Herrera
authors.forename: Cristóbal N
authors.initials: CN
authors.lastname: Aguilar
mesh_terms: D005591:Chemical Fractionation; D019684:Magnoliopsida / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D010636:Phenols; D010936:Plant Extracts
keywords: Ultrasound-assisted extraction; anti-oxidants; mixed model; polyphenols; semi-arid plants; standardisation