ABSTRACT
Viscum album L. is a widely used medicinal plant in cancer treatment, known since ancient times. The aim of this study was to investigate the antimetastatic properties of the ethanolic extracts of synergistic plants V. album L. (epiphyte) and Abies alba (host) used alone or in combination (mixture). Inhibition of platelet aggregation was evaluated in washed rabbit and human platelets. Levels of thromboxane A2 (TXA2 ) were estimated by radioimmune assay and natural killer cells (NKCs) cytotoxicity by flow cytometry. The antimetastatic properties of V. album L. and A. alba were studied in a tumor-bearing Wistar rat model. All extracts inhibited platelet aggregation in a dose-dependent manner as well as TXA2 production by three pathways of aggregation (adenosine diphosphate, platelet-activating factor, and arachidonic acid) while the mixture significantly increased NKCs cytotoxicity against cancer cells. In tumor-bearing Wistar rats, the treatment with the mixture of V. album L. and A. alba extract reduced the metastatic locations almost by 77%. These data suggest that V. album L. and A. alba extract reduced metastasis through inhibition of platelet aggregation and amplification of the body defense mechanisms against cancer cells.