The present invention relates to bioactive ingredients that include isolated bioactive fractions derived from cell juice of fresh biomass of a feverfew (Tanacetum parthenium) plant. The bioactive fractions are either free of or substantially free of .alpha.-unsaturated .gamma.-lactones (e.g., parthenolide). Further, the bioactive fractions have anti-inflammatory and antioxidant activity. The present invention also relates to a method for isolating a bioactive fraction that is derived from cell juice of fresh biomass of a feverfew (Tanacetum parthenium) plant and that is at least substantially free of .alpha.-unsaturated .gamma.-lactones (e.g., parthenolide). The present invention also relates to a method for preparing a stabilized cell juice serum fraction and a stabilized concentrated cell juice serum fraction that are free of .alpha.-unsaturated .gamma.-lactones (e.g., parthenolide). The present invention also relates to a bioactive composition that includes a mixture of one or more of the isolated bioactive fractions of the present invention.