title: (1) H-NMR analysis of terpene trilactones (TTLs) in Ginkgo biloba: green female leaves contain the most TTLs.
abstract: BACKGROUND
  Terpene trilactones (TTLs), unique components of Ginkgo biloba extracts, are believed to play important roles in the biological activity of these materials. The investigation of seasonal and gender-related variations in the natural content of TTLs in the leaves is a challenging problem that must be addressed in order to establish more efficient extraction/isolation protocols for TTLs.
  
  
  OBJECTIVE
  The aims of this work were (i) to modify the extraction/isolation protocols of TTLs from G. biloba leaves by means of boiling and filtration procedures, and (ii) to investigate seasonal and gender-related variations in the TTL content of the leaves via (1) H-NMR analysis.
  
  
  METHODS
  When extracting TTLs from G. biloba leaves, procedures for boiling and filtration were improved in this work. Moreover, quantitative (1) H-NMR analysis using DMF as a reference was performed and correlated to the colour (green/yellow) and gender (male/female) variations in the natural compositions of TTLs in the leaves.
  
  
  RESULTS
  Extraction procedures were modified to include boiling in ethyl acetate and filtration was achieved with celite. (1) H-NMR analysis of TTLs suggested that green female leaves contained the largest amount of TTLs, while no TTLs were present in yellow male leaves.
  
  
  CONCLUSIONS
  The present results provide a method for quickly supplying laboratory-scale quantities of TTLs from natural sources to enable the study of their structure-activity relationships.
authors.affiliation: Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, Chiyoda-ku, Tokyo, 102-8554, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Goto
authors.forename: Toyonobu
authors.initials: T
authors.lastname: Usuki
mesh_terms: D000085:Acetates / Q000737:chemistry; D020441:Ginkgo biloba / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D007783:Lactones / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D009682:Magnetic Resonance Spectroscopy; D008516:Medicine, Chinese Traditional; D010936:Plant Extracts / Q000737:chemistry* / Q000302:isolation & purification; D018515:Plant Leaves / Q000737:chemistry*; D010946:Plants, Medicinal / Q000737:chemistry; D012621:Seasons; D013329:Structure-Activity Relationship; D013696:Temperature; D013729:Terpenes / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D000085:Acetates; D007783:Lactones; D010936:Plant Extracts; D013729:Terpenes; C007650:ethyl acetate; D006861:Hydrogen Peroxide