title: A validated Fourier transform infrared spectroscopy method for quantification of total lactones in Inula racemosa and Andrographis paniculata.
abstract: BACKGROUND
  Fourier transform infrared (FT-IR) spectroscopy is a technique widely used for detection and quantification of various chemical moieties. This paper describes the use of the FT-IR spectroscopy technique for the quantification of total lactones present in Inula racemosa and Andrographis paniculata.
  
  
  OBJECTIVE
  To validate the FT-IR spectroscopy method for quantification of total lactones in I. racemosa and A. paniculata.
  
  
  METHODS
  Dried and powdered I. racemosa roots and A. paniculata plant were extracted with ethanol and dried to remove ethanol completely. The ethanol extract was analysed in a KBr pellet by FT-IR spectroscopy. The FT-IR spectroscopy method was validated and compared with a known spectrophotometric method for quantification of lactones in A. paniculata.
  
  
  RESULTS
  By FT-IR spectroscopy, the amount of total lactones was found to be 2.12 ± 0.47% (n = 3) in I. racemosa and 8.65 ± 0.51% (n = 3) in A. paniculata. The method showed comparable results with a known spectrophotometric method used for quantification of such lactones: 8.42 ± 0.36% (n = 3) in A. paniculata. Limits of detection and quantification for isoallantolactone were 1 µg and 10 µg respectively; for andrographolide they were 1.5 µg and 15 µg respectively. Recoveries were over 98%, with good intra- and interday repeatability: RSD ≤ 2%.
  
  
  CONCLUSIONS
  The FT-IR spectroscopy method proved linear, accurate, precise and specific, with low limits of detection and quantification, for estimation of total lactones, and is less tedious than the UV spectrophotometric method for the compounds tested. This validated FT-IR spectroscopy method is readily applicable for the quality control of I. racemosa and A. paniculata.
authors.affiliation: Department of Phytochemistry, Unilever R&D Bangalore, 64 Main Road Whitefield, Bangalore 560066, India. shivali.garg@unilever.com
authors.forename: Garg
authors.initials: G
authors.lastname: Shivali
authors.forename: Lahorkar
authors.initials: L
authors.lastname: Praful
authors.forename: Gadgil
authors.initials: G
authors.lastname: Vijay
mesh_terms: D035685:Andrographis / Q000737:chemistry*; D002138:Calibration; D038143:Inula / Q000737:chemistry*; D007783:Lactones / Q000032:analysis* / Q000737:chemistry; D015394:Molecular Structure; D015203:Reproducibility of Results; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
chemical_list: D007783:Lactones