What is Senna?
Cassia senna is a small shrub, no taller than 1 m, which grows in tropical and subtropical regions all over the world, with the exception of Europe. It has straight, woody branches and yellow, occasionally white or red, flowers. The leaves are typically paripinnate with stipules.
Senna is a very old Arabic name. It was first used in texts by the Arabic doctors Serpion and Mesue in the 9th century. Botanists originally named only one species, Cassia senna, now over 400 subspecies are listed. The species most commonly used in medicine today are Cassia acutifolia, also called alexandrine senna, and Cassia angustifolia or tinnevelly senna.
Originally from tropical Africa, the plant is now grown all over that continent; Cassia angustifolia is cultivated mainly on the Indian subcontinent.
Propagation is carried out from seed in spring or from cuttings in summer. The leaves can be harvested before or after flowering, the pods after ripening in autumn.
How is senna used?
Both the leaves and fruits (pods) are turned into medicines, either in the form of cut leaves or pods, powder for infusions, decoctions or tinctures. The effect of the pods is considered to be milder.
How does senna work?
The effect of senna is due to the active substances not entering the bloodstream but remaining in the colon. Here they work in two ways: by stimulating the mucus membranes of the colon the muscles contract; in so doing, they take up water so the stool remains soft.
Which substances are responsible for the effect?
The main substance groups for the leaves and pods are anthraquinone glycoside, naphthaline glycoside, mucilage, flavonoids, essential oil. The laxative effect is caused by the anthraquinone glycosides, or so-called sennosides.