title: Influence of bracken fern (Pteridium caudatum L. Maxon) pre-treatment on extraction yield of illudane glycosides and pterosins.
abstract: BACKGROUND
  Bracken (Pteridium spp) illudane glycosidess are labile biologically active terpenoids that undergo decomposition in mild alkali or acid, heat and enzymatic reactions. Hypothetically, quantitation of these weakly chromophoric carcinogens may be challenged by plant sample preparation procedures that may alter the yield of isolates.
  
  
  OBJECTIVE
  To study the influence of common plant sample pre-treatments on the recovery of Pteridium caudatum illudane glycoside carcinogens, ptaquiloside (1a), caudatoside (1c) and ptaquiloside Z (1d), and associated pterosins A, B and Z (2a, b, c) using HPLC-DAD.
  
  
  METHODS
  Bracken fronds were divided in equal left/right sections. One section was subjected to high vacuum desiccation (VD) and the other to freeze-drying (FD), air drying at room temperature (AD) for 7 days, air drying at 70 °C for 72 h (HD), or no treatment (fresh frond, FF). Quantitation was achieved by brief hot-water extraction, base-acid transformation of 1a, 1c and 1d to 2a, b, c and HPLC-DAD analysis against standards.
  
  
  RESULTS
  Substantial differences in extraction yields were found for all illudane glycosides in the order FF > FD ≈ VD > AD > HD. Illudane instability to HD was 1c > 1d > 1a. Significant losses also were recorded in yields of Pterosins A, B and Z.
  
  
  CONCLUSIONS
  Glycoside extraction suffers from substantial yield loss of all illudane glycosides and indigenous pterosins in all sample pre-treatments studied relative to fresh frond material.
authors.affiliation: Grupo de Química Ecológica, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101, Venezuela.
authors.forename: Yamile C
authors.initials: YC
authors.lastname: Cáceres-Peña
authors.forename: Marlene
authors.initials: M
authors.lastname: Naya
authors.forename: María Pía
authors.initials: MP
authors.lastname: Calcagno-Pissarelli
authors.forename: Miguel E
authors.initials: ME
authors.lastname: Alonso-Amelot
mesh_terms: D001671:Biochemistry / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005960:Glucosides / Q000032:analysis / Q000302:isolation & purification; D006027:Glycosides / Q000032:analysis / Q000302:isolation & purification*; D007189:Indans / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D059625:Liquid-Liquid Extraction / Q000379:methods*; D015394:Molecular Structure; D032498:Pteridium / Q000737:chemistry*; D012717:Sesquiterpenes / Q000032:analysis / Q000737:chemistry / Q000302:isolation & purification; D013696:Temperature
chemical_list: D005960:Glucosides; D006027:Glycosides; D007189:Indans; D012717:Sesquiterpenes; C116780:ptaquiloside Z; C010772:pterosin; C586063:pterosin A; C586064:pterosin B; C586065:pterosin Z; C043680:ptaquiloside