Method for isolating terpene trilactones (ginkgolides, bilobadide) from leaves and pharmaceutical powders of ginkgo biloba

A method of isolating terpene trilactones from Ginkgo biloba plant material or extract comprising the steps of suspending the plant material or extract in either water or an aqueous solution of an oxidation reagent; extracting the terpene trilactones using an acceptable extraction agent; separating the organic layer from the aqueous layer; washing the organic layer with an acceptable aqueous salt or hydroxide solution, which may be an alkaline solution; and drying the organic layer to form a dried extract containing terpene trilactones. Further purification by treatment with or filtration over activated charcoal, by treatment with or filtration over alumina and by recrystallization with an acceptable solvent or solvent mixture leads to extracts with a content of terpene trilactones higher than 50%. Unwanted levels of ginkgolic acids are reduced to acceptable levels by reversed phase chromatography.