title: Rapid identification of cyclic tetrapyrrolic photosensitisers for photodynamic therapy using on-line hyphenated LC-PDA-MS coupled with photo-cytotoxicity assay.
abstract: BACKGROUND
  Photodynamic therapy is a treatment modality that involves site-directed generation of cytotoxic reactive oxygen species by light-activated photosensitisers.
  
  
  OBJECTIVE
  In order to rapidly identify new photosensitisers from natural extracts, we developed a liquid chromatography-photodiode array-mass spectrometry (LC-PDA-MS) method to rapidly identify plant extracts that contain photosensitisers, particularly those possessing a cyclic tetrapyrrole structure.
  
  
  METHODS
  Six previously isolated compounds (1-6) were identified in bioactive fractions derived from 15 plant extracts on the basis of their chromatographic retention times, UV-visible profiles, accurate mass and fragmentation patterns.
  
  
  RESULTS
  Samples containing uncommon photosensitisers were rapidly identified using this method, and subsequent scale-up isolation efforts led to two new compounds (7 and 8) which were confirmed to be active photosensitisers in a photo-cytotoxicity assay.
  
  
  CONCLUSIONS
  This method serves as a useful tool in prioritising samples that may contain new photosensitisers out of a larger group of photo-cytotoxic natural products extracts.
authors.affiliation: Cancer Research Initiatives Foundation, Second floor, Outpatient Centre, Sime Darby Medical Centre, 47500, Subang Jaya, Selangor Darul Ehsan, Malaysia.
authors.forename: P J
authors.initials: PJ
authors.lastname: Tan
authors.forename: D R
authors.initials: DR
authors.lastname: Appleton
authors.forename: M R
authors.initials: MR
authors.lastname: Mustafa
authors.forename: H B
authors.initials: HB
authors.lastname: Lee
mesh_terms: D001681:Biological Assay; D002470:Cell Survival / Q000187:drug effects; D002853:Chromatography, Liquid / Q000379:methods*; D018922:HL-60 Cells; D006801:Humans; D008296:Malaysia; D013058:Mass Spectrometry / Q000379:methods*; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology / Q000528:radiation effects; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology / Q000528:radiation effects; D018515:Plant Leaves / Q000737:chemistry; D018547:Plant Stems / Q000737:chemistry; D010944:Plants / Q000737:chemistry*; D045725:Tetrapyrroles / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D017319:Photosensitizing Agents; D010936:Plant Extracts; D045725:Tetrapyrroles