title: Analysis of eleven phenolic compounds including novel p-coumaroyl derivatives in lettuce (Lactuca sativa L.) by ultra-high-performance liquid chromatography with photodiode array and mass spectrometry detection.
abstract: BACKGROUND
  Lettuce is a widely consumed vegetable and a good source of phenolic compounds. Several factors (genetic, agronomical and environmental) can influence the lettuce composition; their effects are not completely defined and more studies are needed on this topic.
  
  
  OBJECTIVE
  To develop an improved ultra-high-performance liquid chromatography (UHPLC) method to quantify the main target intact phenolic compounds in lettuce.
  
  
  METHODS
  UHPLC identification of the compounds was supported by PAD spectra and MS(n)  analyses. Quantification was carried out by PAD, by creating matrix-matched calibration curves at the specific wavelength for each compound.
  
  
  RESULTS
  Sample pretreatment was simplified, with neither purification nor hydrolysis steps. Chromatographic conditions were chosen to minimise matrix interferences and to give a suitable separation of the major phenolic compounds within 27 min. The method allowed the quantification of 11 intact phenolic compounds in Romaine lettuces, including phenolic acids (caffeoyl and p-coumaroyl esters) and flavonoids (quercetin glycosides). Four p-coumaroyl esters were tentatively identified and quantified for the first time in lettuce.
  
  
  CONCLUSIONS
  The main intact phenolic compounds, including four novel p-coumaroyl esters, were simultaneously quantified in lettuce with optimal performances and a reduced total time of analysis. These findings make headway in the understanding of the lettuce phytochemicals with potential nutritional relevance.
authors: Institute for Food and Agriculture Research-IRTA, Food Technology, Finca Camps i Armet s/n, Monells, 17121 Girona, Catalonia, Spain.
authors: Albert
authors: A
authors: Ribas-Agustí
authors: Marta
authors: M
authors: Gratacós-Cubarsí
authors: Carmen
authors: C
authors: Sárraga
authors: José-Antonio
authors: JA
authors: García-Regueiro
authors: Massimo
authors: M
authors: Castellari
mesh_terms: D002109:Caffeic Acids / Q000032:analysis / Q000737:chemistry; D002726:Chlorogenic Acid / Q000032:analysis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid / Q000295:instrumentation / Q000379:methods / Q000592:standards; D003373:Coumaric Acids / Q000032:analysis* / Q000737:chemistry; D004952:Esters / Q000032:analysis / Q000737:chemistry; D005960:Glucosides / Q000032:analysis / Q000737:chemistry; D018545:Lactuca / Q000737:chemistry*; D013058:Mass Spectrometry; D015394:Molecular Structure; D010636:Phenols / Q000032:analysis* / Q000737:chemistry; D010936:Plant Extracts / Q000032:analysis / Q000737:chemistry; D011422:Propionates; D011786:Quality Control; D011794:Quercetin / Q000031:analogs & derivatives / Q000032:analysis / Q000737:chemistry; D011801:Quinic Acid / Q000032:analysis / Q000737:chemistry; D012431:Rutin; D013386:Succinates / Q000032:analysis / Q000737:chemistry; D013997:Time Factors
chemical_list: D002109:Caffeic Acids; D003373:Coumaric Acids; D004952:Esters; D005960:Glucosides; D010636:Phenols; D010936:Plant Extracts; D011422:Propionates; D013386:Succinates; D011801:Quinic Acid; D002726:Chlorogenic Acid; D012431:Rutin; D011794:Quercetin; C495469:p-coumaric acid; C100435:chicoric acid