The detection of alkaloids in herbarium material

Abstract

Webb used the method several years ago and discussed the limitations of it in some detail (1, 2); he found that well preserved herbarium speeimens containing relatively stable alkaloids gave positive tests after periods of storage of up to 125 years. In another experiment, one of us was able to detect trace amounts of alkaloids in plant material which had been stored under ideal conditions for approximately 1300 years (3), and other workers have reported success in the study of certain non-alkaloidal plant constituents in herbarium material (4, 5). A recent editorial review of the subject (6) prompted us to record how we discovered and developed a "new" alkaloidal family of plants by this means. The amount and nature of the samplings which can be obtained from the herbarium sheet are of primary concern; our testing was done on ca. 100 mg of material carefully selected by the herbarium botanist so as to preserve the integrity of the specimen in all essential detail. Often, bits of material left from earlier microscopic examination, a few fragments of bark or root shavings, or a seed or two were sufficient to give a satisfactory result. The following results were obtained with the famnily Lythraceae.