ABSTRACT
Extracts from the leaves have been used medicinally since ancient times and they are a source of cardiotonic drugs. More detailed understanding of the physiology of the mechanisms of muscle contraction has allowed differentiation between the modes of action of the varied constituents of a number of plant extracts. Pyrethrum dust and extracts have been used as insecticides, their principal advantages being a spectacularly rapid "knock-down" effect on flying insects coupled with low mammalian toxicity. Screening of extracts and fractions obtained from them for immunostimulant activity has resulted in the identification of complex polysaccharides as the active constituents of several drugs. Treatment for liver complaints is found in the traditional medicine of many cultures and often uses plant extracts. In vitro screening for antihepatotoxic properties showed that extracts of these plants gave positive results but that the degree of activity varied considerably between batches.
