Abstract:
Lusianthridin is a phenanthrene derivative isolated from Dendrobium venustum. Some phenanthrene compounds have antiplatelet aggregation activities via undefined pathways. The objective of this study is to determine the inhibitory effects and potential mechanisms of lusianthridin on platelet aggregation. Turbidometric aggregometry method was used to measure the extent of platelet aggregation, then cyclic adenosine monophosphate (cAMP) levels were measured by ELISA kit. Inhibitory effect of lusianthridin on cyclooxygenase enzymes was analyzed by COX fluorescent inhibitor screening assay kit. The results indicated that Lusianthridin most potently inhibited arachidonic acid -induced platelet aggregation by maximum percent inhibition of aggregation of 89.7 ± 1.2 % at 0.025 mM; whereas lusianthridin at 0.4 mM inhibited collagen and ADP-induced platelet aggregation by 84.5 ± 2.2 % and 51.9 ± 4.8 %, respectively. Lusianthridin also increased the delaying time of arachidonic acid-stimulated and the lag time of collagen-stimulated aggregations. Lusianthridin showed the inhibitory effect on the secondary wave of ADP-stimulated aggregation. Furthermore lusianthridin at 0.4 mM inhibited ADP-induced by significantly increase cAMP level in platelets (p < 0.05). Molecular docking analysis revealed that lusianthridin bound to the entrance site of cyclooxygenase -1 (COX-1) enzyme and probably the active region of COX-2 enzyme. In addition, lusianthridin showed inhibitory effects on both COX-1 and COX-2 enzymatic activities with the IC50 value of 11.92 ± 0.00 µM and 0.21 ± 0.17 µM, respectively. These findings suggested that possible mechanisms of lusianthridin on antiplatelet activity might act via arachidonic acid-thromboxane and ADP-adenylate cyclase pathways.
