595600 Disclosed is 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 substantially free of a-unsaturated y-lactones, said method comprising: providing fresh biomass of a feverfew (Tanacetum parthenium) plant processing the fresh biomass under conditions effective to yield a cell juice supernatant that is at least substantially free of a-unsaturated y-lactones and a membrane fraction containing alpha-unsaturated gamma-lactones, said processing the fresh biomass comprising: separating the fresh biomass into a cell juice component and a fiber enriched material (ii) subjecting the cell juice component to a pH adjustment and microwave treatment step to yield the cell juice supernatant that is at least substantially free of a-unsaturated y-lactones treating the cell juice supernatant under conditions effective to yield a first cell juice serum supernatant and a cytoplasm fraction precipitate and isolating the cytoplasm fraction precipitate, wherein said cytoplasm fraction precipitate is a bioactive fraction that is substantially free of ?-unsaturated ?-lactones, wherein said a-unsaturated y-lactones comprise parthenolide.
