Pharmacological Activity of Feverfew (Tanacetum parthenium (L.) Schultz-Bip.): Assessment by Inhibition of Human Polymorphonuclear Leukocyte Chemiluminescence In-vitro

The bioactivity of feverfew (Tanacetum parthenium) leaf extracts has been analysed, by use of a human polymorphonuclear leukocyte (PMNL) bioassay, to assess the relative contributions of solvent extraction and parthenolide content to the biological potency of the extract. Extracts prepared in acetone‐ethanol (system 1) contained significantly more parthenolide (mean ± s.d. 1.3 ± 0.2% dry leaf weight) than extracts in chloroform–PBS (phosphate‐buffered saline; system 2; 0.1 ± 0.04% dry leaf weight) or PBS alone (system 3; 0.5 ± 0.1% dry leaf weight). Extract bioactivity, measured as inhibition of phorbol 12‐myristate 13‐acetate‐induced, 5‐amino‐2,3‐dihydro‐1,4‐phthalazinedione (luminol)‐enhanced PMNL chemiluminescence, followed a similar trend. Extracts inhibited phorbol 12‐myristate 13‐acetate‐induced oxidative burst by amounts which, if solely attributable to parthenolide, indicated parthenolide concentrations for the respective solvent systems of 2.2 ± 0.6%, 0.2 ± 0.1% and 0.9 ± 0.1% dry leaf weight. The mean ratio of parthenolide concentration to the parthenolide equivalent/PMNl‐bioactivity value, for acetone–ethanol and PBS extracts were both 1:1.7. Parthenolide, although a key determinant of biological activity for T. parthenium leaf extracts based on the PMNl‐bioassay, seems not to be the sole pharmacologically‐active constituent. The identical and elevated bioactivity‐parthenolide ratios for both organic and aqueous‐phase leaf extracts suggest that a proportion of the other bioactive compounds have solubilities similar to that of parthenolide.