Senna

Cassia acutifolia, syn. C. orientalis ;
Cassia angustifolia, syn. C. lanceolata, C. medicinalis, Senna Alexandria – Alexandrian senna
Caesalpiniaceae – Peacock flower subfamily

The raw materials include: the senna leaf – Sennae folium and fruit – Sennae fructus, harvested in Sudan and Upper Egypt as well as India and Pakistan. The entire plant is cut (from April to September) and sun-dried, after which individual leaflets are separated. The fruit are harvested when they are fully ripe and then sun-dried. Both of these raw materials, commonly known as senna, are sourced from two species of cassia – narrow-leafed and sharp-leafed.

Senna – appearance and origin:

Narrow-leafed senna – a subshrub found in Egypt, Central Africa in the Nile Basin; grown mainly in Sudan and North Africa. It grows up to 60-100 cm. The leaves are even-pinnate, composite; individual leaflets are ovate-lanceolate or linear-lanceolate, with an acute tip, grey-green, with less or more hairs, with bracts. The flowers are yellow, with a dorsal structure, on long pedicels, clustered in the leaf angles. It blooms from July to December. The fruit is a dry, flat pod, grey-brown and kidney-shaped, with brown, inversely heart-shaped seeds. Sharp-leafed senna – grows in the wild in Egypy, Sudan and North Africa. It is generally exported through Alexandria, therefore it is sometimes called Alexandrian senna. The harvested leaves are fully grown, blue-green and dried in thin layers in the shade. The fruit are harvested once they are fully ripe and dried in natural conditions in the shade.
Both species are similar to each other.

Senna – effects and use:

Both the leaves and the fruit contain anthranoid glycosides, dianthrone derivatives (sennosides A, B, C), aloe emodin derivatives and rhein derivatives in the form of glycosides and free aglycones, mucus compounds, flavonoids (derivatives of kaempferol and isorhamnetin) and resin compounds. The anthranoid content in the leaves reach 2.5%, and 4% in the fruit. The laxative mechanism of irritating compounds has been well-known since the 1930s. Dianthrone sennosides, influenced by the enzymes of the large intestine microbiome, are metabolised to monoanthrones and free aglycones – sennidins. The end product of the degradation is rhein-9-anthrone – a laxative derivative. The necessity to release aglycones and the activity in the lower gastrointestinal tract cause the therapeutic effect to onset only after 8-12 hours after taking. The large intestine microbiome plays a large role in the laxative effect of sennosides. This has been proven in studies on animals with normal gut flora, in which active sennoside metabolites were created, causing diarrhea. In case of animals with no gut flora, products of sennoside degradation were not created and senna did not induce diarrhea.

The laxative activity of anthranoids is based on the increased secretion of water and electrolytes by the mucosa to the lumen of the large intestine and on the inhibition of water reabsorption. It leads to an increase of fluid volume in the large intestine. Stimulation of sensory nerve endings activates longitudinal spasms of the colon and inhibits segmental spasms which allow transit. It leads to an increased speed of gastric transit and a laxative effect. The mechanism shows that sennosides exhibit pharmacological activity only after they are inside the large intestine and after bacterial enzymes degrade to the active metabolite rheinanthrone, therefore they are a kind of prodrug. The high hydrophilicity of sennoside particles together with the big particle size result in them not being absorped in the upper parts of the gastrointestinal tract, and they degrade only in the lower parts. It reduces the possibility of anthranoids getting absorped into the bloodstream.

Senna leaves and fruit are used as infusions and ingredients of combinations, and sometimes they are abused in weight loss.
Leaf extracts and leaves are used in choleretic preparations. Due to their origin, the leaves bear the trade name ”Folium Sennae alexandrinae”. The herbs are not to be given in appendicitis, volvulus, potassium insufficiency or dehydration. Long-term use can cause the large intestine mucosa to darken and become larger, and it can also lead to chronic constipation.