title: Platelet-activating factor (PAF) receptor binding activity of the roots of Enicosanthellum pulchrum.
abstract: BACKGROUND
  Enicosanthellum pulchrum (King) Heusden (Annonaceae) is a coniferous tree that is confined to mountain forests. The chemical constituents of this species have been studied previously; however, its biological activity has never been investigated before and is reported here for the first time.
  
  
  OBJECTIVE
  The extracts, fractions and compounds from the roots of E. pulchrum were investigated for their inhibitory effects on platelet-activating factor (PAF) receptor binding to rabbit platelets using (3)H-PAF as a ligand.
  
  
  METHODS
  The PAF receptor binding inhibitory effect using rabbit platelets was determined in vitro by measuring the difference between total amount of bound (3)H-PAF in the presence and the absence of excess unlabelled PAF. The compounds were isolated by bioassay-guided fractionation and their structures were elucidated by spectroscopic techniques.
  
  
  CONCLUSIONS
  Among the extracts tested, the ethyl acetate extract was the most active with 85.6% inhibition, while hexane and methanol extracts showed 40.2 and 42.5% inhibition, respectively. Fractionation of the ethyl acetate extract using vacuum liquid chromatography (VLC) yielded six fractions AEA(I--VI). Chromatography fraction AEA(VI) yielded a new compound, 1-(2',3',4'-trimethoxyphenyl)hexan-1-ol, while fraction AEA(III) afforded three compounds, namely liriodenine, cleistopholine and dehydroanonaine. 1-(2',3',4'-Trimethoxyphenyl)hexan-1-ol, cleistopholine and dehydroanonaine showed relatively strong inhibition with IC(50) values of 26.6, 50.2 and 45.4 µM, respectively.
  
  
  CONCLUSIONS
  The results suggest that these compounds could be responsible for the PAF antagonistic activity of the ethyl acetate extract of this plant.
authors: Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abd. Aziz, 50300 Kuala Lumpur, Malaysia.
authors: Noraziah
authors: N
authors: Nordin
authors: Juriyati
authors: J
authors: Jalil
authors: Ibrahim
authors: I
authors: Jantan
authors: Shahnaz
authors: S
authors: Murad
mesh_terms: D000818:Animals; D029061:Annonaceae / Q000737:chemistry*; D001792:Blood Platelets / Q000378:metabolism*; D002853:Chromatography, Liquid; D066298:In Vitro Techniques; D020128:Inhibitory Concentration 50; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology*; D018517:Plant Roots; D010972:Platelet Activating Factor / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet
chemical_list: D010936:Plant Extracts; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor