Extraction of Plant Secondary Metabolites

Plant secondary metabolites are currently the subject of much research interest, but their extraction as part of phytochemical or biological investigations presents specific challenges that must be addressed throughout the solvent extraction process. Successful extraction begins with careful selection and preparation of plant samples, and thorough review of the appropriate literature for indications of which protocols are suitable for a particular class of compounds or plant species. During the extraction of plant material, it is important to minimize interference from compounds that may coextract with the target compounds, and to avoid contamination of the extract, as well as to prevent decomposition of important metabolites or artifact formation as a result of extraction conditions or solvent impurities. This chapter presents an overview of the process of plant extraction, with an emphasis on common problems encountered and methods for reducing or eliminating these problems. In addition to generally applicable extraction protocols, methods are suggested for more or less selectively extracting specific classes of compounds, and phytochemical methods are presented for detection of classes of compounds commonly encountered during plant extraction, including selected groups of secondary metabolites and interfering compounds.