Effects of Plumbagin on Platelet Aggregation and Platelet-Neutrophil Interactions

Abstract

The effects of plumbagin were investigated on platelet aggregation in vitro and ex vivo, on the binding of thrombin-stimulated platelets to neutrophils, and platelet aggregation induced by intact neutrophils and N-formyl-methionyl-leucyl-phenylalanine (fMLP) or platelet activating factor (PAF) activated neutrophils, by use of the methods of Hamburger, McEver and Born, respectively. The results showed that plumbagin in vitro significantly inhibited adenosine diphosphate (ADP)-, arachidonic acid (AA)-, or platelet activating factor (PAF)-induced platelet aggregation, in a concentration-dependent manner. The medium inhibitory concentrations (IC 50 ) were 39.4, 82.7 and 38.1 microM, respectively. Intragastric plumbagin at 10 mg/kg markedly suppressed platelet aggregation induced by ADP, AA, or PAF. Plumbagin decreased the binding between thrombin-stimulated platelets and neutrophils with an IC 50 of 62.9 microM. Plumbagin significantly inhibited washed platelet aggregation stimulated by fMLP- or PAF-activated neutrophils. The IC 50 values were 54.3 and 47.6 microM, respectively. On the other hand, plumbagin and aspirin increased the inhibition of intact neutrophils on AA-induced platelet aggregation. It is suggested that plumbagin inhibited platelet aggregation in vitro and ex vivo, suppressed the binding of activated platelets to neutrophils, inhibited platelet aggregation induced by activated neutrophils, and increased inhibition of intact neutrophils on platelet reactivity. Abbreviations. DMSO:dimethyl sulphoxide fMLP: N-formyl-methionyl-leucyl-phenylalanine ADP:adenosine diphosphate AA:arachidonic acid PAF:platelet activating factor

Cytotoxic and Antimicrobial Constituents of the Bark of Diospyros maritima Collected in Two Geographical Locations in Indonesia

“…Crude extracts of D. maritima have displayed a range of biological effects, such as ichthyotoxicity and antibacterial activity. , Previous phytochemical studies on D. maritima have resulted in the isolation of structurally diverse secondary metabolites, including alkanol ester, aliphatic lactone, benzenoid, coumarin, ,, kaurane diterpene, naphthoquinone, ,,− phenylpropanoid, sterol, , and triterpenoid types. ,,,,,− Recently, several purified naphthoquinones from this plant were found to exhibit activity against bacteria, fungi, guppy fish, , human tumor cells, and seed germination of Lactuca sativa L. var. Great Lakes 1,9 and to effect platelet aggregation …”