EFFECTS OF EXTRACTS OF TANACETUM SPECIES ON HUMAN POLYMORPHONUCLEAR LEUKOCYTE ACTIVITY IN-VITRO

The inhibitory effects of whole and fractionated acetone extracts of l eaves of four species of Tanacetum were assessed in vitro, using a hum an polymorphonuclear leucocyte-based bioassay. Biochemical investigati on detected the bioactive germacranolide, parthenolide, at high concen trations, in extracts from T. parthenium and T. niveum (1.72%+/-0.16% and 2.62%+/-0.23% leaf dry weight, respectively; n=5). The compound wa s present at much lower concentrations (<0.03% leaf dry weight) in ext racts of T. ptarmiciflorum and T. vulgare. All extracts inhibited phor bol myristate acetate-induced chemiluminescence of human polymorphonud ear leucocytes, with IC(50)s from 0.79+/-0.19 to 2.46+/-0.39 mg leaf d ry weight/mL whole blood for T. parthenium and T. vulgare, respectivel y, Fractionation of crude leaf extracts revealed a number of fractions , in addition to those containing parthenolide, which influenced polym orphonuclear leucocyte activity by > 5%. Such fractions presumably con tained compounds that augmented the pharmacological activity of extrac ts beyond that predicted on the basis of parthenolide content alone, a nd were responsible, in part, for the pharmacological activity of the extracts lacking parthenolide, These effects on phorbol myristate acet ate-induced chemiluminescence suggested the activity of the responsibl e compound(s) was a result of inhibition of protein kinase C, or subse quent events, in polymorphonuclear leucocyte activation in vitro. (C) 1997 John Wiley & Sons, Ltd.