Pharmacological activity of phenylpropanoids of the mistletoe, Viscum album L., host: Pyrus caucasica Fed

Although a great number of compounds have been isolated from Viscum album (mistletoe, Viscaceae), none of them could be clearly shown to possess the established hypotensive, vasodilator, cardiotonic and antitumor activity of alcoholic preparations. In the course of our investigation of Armenian mistletoe Viscum album, host: Pyrus caucasica, which has been used in Armenian traditional medicine for the treatment of cardiovascular diseases and for stimulation of the immune system, four phenylpropanoid glycosides were isolated from EtOH-extract: coniferyl alcohol 4-O-β-D-glucopyranoside (coniferin), syringenin 4-O-β-D-glucopyranoside (syringin), and coniferylalcohol- and syringenin 4-O-β-D-apiofuranosyl (1→2)-β-D-glucopyranosides. The structures were established on the basis of the spectral and chemical data. All substances inhibited ADP-induced platelet aggregation, and the apiosyldiglycosides only inhibited leukotriene B4 release from TPA and calcium ionophore A-23187 stimulated human granulocytes. It is suggested that an antitumoral effect of ethanolic extract of Viscum album could be associated with the inhibition of protein kinase C (PKC).