title: A simple method for the determination of bioactive antioxidants in virgin olive oils.
abstract: BACKGROUND
  The importance of olive polyphenols as bioactive compounds has grown in recent years as a result of intensive research on their anticancer, antiatherosclerotic and antihypertensive activities. However, there is currently no official method for determining the content of polyphenols in olive oils because of the technical difficulties in their determination. Here a simple method for the analysis of extra virgin olive oil o-diphenols by visible spectrometry is proposed and compared with the traditional method of solid phase extraction followed by colorimetric determination using sodium molybdate or Folin-Ciocalteu reagent or by high-performance liquid chromatography (HPLC) analysis using UV detection. This new approach to determining total o-diphenolic compounds exploits the oxidation of o-diphenols to quinones in a basic medium.
  
  
  RESULTS
  Preliminary results showed a better correlation between the total o-diphenol determination by HPLC and by the proposed method (R(2) = 0.9229) than between the total o-diphenol determination by HPLC and by the molybdate colorimetric method (R(2) = 0.8689). A good correlation was also observed between the total phenolic content determined by HPLC and by the proposed method (R(2) = 0.8196), but this correlation was a little lower than the one obtained between the HPLC method and the Folin-Ciocalteu method (R(2) = 0.8752).
  
  
  CONCLUSIONS
  The proposed method involves very little sample manipulation, requires inexpensive reagents and can be performed in less than 40 min for several samples at the same time, using olive oil samples of only 1-2 g.
authors.affiliation: Centro de Investigação em Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, No. 687, P-4169-007, Porto, Portugal.
authors.forename: Barbara
authors.initials: B
authors.lastname: Garcia
authors.forename: Joana
authors.initials: J
authors.lastname: Coelho
authors.forename: Marlene
authors.initials: M
authors.lastname: Costa
authors.forename: Joana
authors.initials: J
authors.lastname: Pinto
authors.forename: Fátima
authors.initials: F
authors.lastname: Paiva-Martins
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003124:Colorimetry / Q000379:methods*; D004032:Diet; D006801:Humans; D031658:Olea / Q000737:chemistry*; D000069463:Olive Oil; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis; D010938:Plant Oils / Q000737:chemistry*; D059808:Polyphenols / Q000032:analysis*; D011809:Quinones / Q000378:metabolism; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D000975:Antioxidants; D000069463:Olive Oil; D010636:Phenols; D010938:Plant Oils; D059808:Polyphenols; D011809:Quinones