Preparation of plant extracts for antitumor screening

Random collections of plants have been screened by the National Cancer Institute's screening program for almost two decades. The WARF Institute, Inc. (Madison, Wis) has been preparing most of the crude plant extracts for antitumor screening for the past 14 years. This paper describes our present method of extraction for preparation of crude plant extracts for screening and presents a history of past procedures used for the extraction of plant materials. Wherever possible, screening statistics have been included for plants which have been extracted by the various procedures.