In vitro inhibitory effect of Rubraxanthone isolated from Garcinia psrvifolia on platelet- Activating factor receptor binding

• Main Authors: Jantan, Ibrahim, Md Pisar, Mazura, Idris, Muhammad Sum, Bakhtiar, M. Taher, Mat Ali, Rasadah
• Format: Article
• Language: English
• Published: Thieme Verlagsgruppe 2002
• Subjects: RS Pharmacy and materia medica
• Online Access: http://irep.iium.edu.my/12052/1/Plantamedica.pdf; http://irep.iium.edu.my/12052/; http://www.thieme.de/plantamedica/

Rubraxanthone and isocowanol isolated from Garcinia parvifolia Miq. were investigated for their inhibitory effects on platelet-activating factor (PAF) binding to rabbit platelets using 3H-PAF as a ligand. Rubraxanthone showed a strong inhibition with IC 50 value of 18.2 microM. The IC 50 values of macluraxanthone, 6-deoxyjacareubin, 2-(3-methylbut-2-enyl)-1,3,5-trihydroxyxanthone, 2-(3-methylbut-2-enyl)-1,3,5,6-tetrahydroxyxanthone and 1,3,5-trihydroxy-6,6'-dimethylpyrano(2',3':6,7)-4-(1,1-dimethylprop-2-enyl)-xanthone were also determined for comparison. In the course of our study on structure-activity relationship of xanthones, the results revealed that a geranyl group substituted at C-8 was beneficial to the binding while a hydroxylated prenyl group at C-4 resulted in a significant loss in binding to the PAF receptor.