title: Inhibitory effects of acetylmelodorinol, chrysin and polycarpol from Mitrella kentii on prostaglandin E₂ and Thromboxane B₂ production and platelet activating factor receptor binding.
abstract: Acetylmelodorinol, chrysin and polycarpol, together with benzoic acid, benzoquinone and stigmasterol were isolated from the leaves of Mitrella kentii (Bl.) Miq. The compounds were evaluated for their ability to inhibit prostaglandin E₂ (PGE₂) and thromboxane B₂ (TXB₂) production in human whole blood using a radioimmunoassay technique. Their inhibitory effect on platelet activating factor (PAF) receptor binding to rabbit platelet was determined using ³H-PAF as a ligand. Among the compounds tested, chrysin showed a strong dose-dependent inhibitory activity on PGE(2) production (IC₅₀ value of 25.5 µM), which might be due to direct inhibition of cyclooxygenase-2 (COX-2) enzymatic activity. Polycarpol, acetylmelodorinol and stigmasterol exhibited significant and concentration-dependent inhibitory effects on TXB₂ production with IC₅₀ values of 15.6, 19.1 and 19.4 µM, respectively, suggesting that they strongly inhibited COX-1 activity. Polycarpol and acetylmelodorinol showed strong dose-dependent inhibitory effects on PAF receptor binding with IC₅₀ values of 24.3 and 24.5 µM, respectively.
authors.affiliation: Drug and Herbal Research Centre, Faculty of Pharmacy, Universiti Kebangsaan Malaysia, Jalan Raja Muda Abdul Aziz, 50300 Kuala Lumpur, Malaysia.
authors.forename: Sakina
authors.initials: S
authors.lastname: Saadawi
authors.forename: Juriyati
authors.initials: J
authors.lastname: Jalil
authors.forename: Malina
authors.initials: M
authors.lastname: Jasamai
authors.forename: Ibrahim
authors.initials: I
authors.lastname: Jantan
mesh_terms: D000475:Alkenes / Q000302:isolation & purification / Q000494:pharmacology; D000818:Animals; D029061:Annonaceae / Q000737:chemistry*; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D051545:Cyclooxygenase 1 / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000302:isolation & purification / Q000494:pharmacology*; D015232:Dinoprostone / Q000096:biosynthesis*; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology; D006801:Humans; D020128:Inhibitory Concentration 50; D010936:Plant Extracts / Q000494:pharmacology*; D018515:Plant Leaves / Q000737:chemistry; D010972:Platelet Activating Factor / Q000378:metabolism; D010980:Platelet Membrane Glycoproteins / Q000037:antagonists & inhibitors*; D011084:Polycyclic Aromatic Hydrocarbons / Q000302:isolation & purification / Q000494:pharmacology; D011817:Rabbits; D011863:Radioimmunoassay; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors*; D013929:Thromboxane B2 / Q000096:biosynthesis*
chemical_list: D000475:Alkenes; D016861:Cyclooxygenase Inhibitors; D005419:Flavonoids; D010936:Plant Extracts; D010972:Platelet Activating Factor; D010980:Platelet Membrane Glycoproteins; D011084:Polycyclic Aromatic Hydrocarbons; D043562:Receptors, G-Protein-Coupled; C039351:platelet activating factor receptor; C460801:polycarpol; C043561:chrysin; D013929:Thromboxane B2; D051545:Cyclooxygenase 1; D015232:Dinoprostone