Abstract

Although plants used to provide most medicines, for the past 40 years the industry, except in the field of antibiotics, has relied primarily on synthesised new compounds. Relative failures of drug discovery programmes, among other factors, have led to increased interest in plants sources. The absolute minimum cost of meeting all the regulatory requirements, even for a safe, plant-derived compound is around $100 million. Investment in a plant-derived drug will therefore be made only if this level of investment can be justified. To be successful as a source of raw material for manufacturing a drug, the drug should not be readily synthesised and should have multiple isomers with only one being biologically active and found in pure form in the plant. In turn the plant, possibly with some modification, should be capable of providing the required amounts of the drug in a form which is relatively easily extracted. Gamma-linolenic acid, derived from evening primrose oil and other plant oils, is used to illustrate the problems and opportunities.