Senna alexandrina Miller (Alexandrian) Senna
Family: Leguminosae
Synonyms: Cassia senna L., C. acutifolia Delile
Description: “Shrubby perennial with thin, hairy, divided leaves. In spring and summer, small tawny flowers are borne in axillary racemes, followed by straight pods up to 7cm long. H 1m, S 50-60cm” (Bown, 1995: 202).
Habitat: Subtropical; native to Arabia, Djibouti and Somalia (as above).
Harvest: “Leaves are picked before and during flowering; pods are collected in autumn when ripe” (Bown, 1995: 352).
Parts used: Leaves and Pods
Dosage: Preparations containing 10-60mg hydroxyanthracene glycosides, once daily (Bradley, 1992)
Action: STIMULANT LAXATIVE
Indications:
-Atonic/ Sluggish constipation;
-to ‘re-educate’ bowel, especially with change in diet (GT);
-“conditions in which easy defecation desirable, eg. anal fissure or haemorrhoids” (Bradley, 1992).
Safety: Should only be taken for short periods, max. 10 days (as above).
Contra-indications: Intestinal obstruction; inflammatory disorders of colon [eg. Crohns disease, ulcerative colitis]; appendicitis; abdominal pains of unknown cause; [children under 12]. During pregnancy and lactation use only after medical advice (as above).
Key Constituents (Wren, 1988):
-Anthraquinone glycosides:- In the leaf: sennosides A and B based on aglycones sennidin A and B and sennosides C and D (glycosides of heterodianthrones of aloe-emodin and rhein); also palmidin A, rhein anthrone and aloe-emodin glycosides, some free anthraquinones and others.
In the fruit: sennosides A and B and closely related glycoside sennoside A1.
-Napthalene glycosides
-Misc.: mucilage, flavonoids, volatile oil, sugars, resins, etc.
Pharmacology (Bradley, 1992): Anthraquinone glycosides not absorbed in upper gut but are converted by microflora of large intestine into active aglycones (mainly rhein anthrone), which in turn exert their laxative effect on colon: 1) stimulation of colonic motility -augmented propulsion -accelerated colonic transit (reduces opportunity for fluid absorption from faecal mass); and 2) an influence on fluid and electrolyte absorption/ excretion by colon, resulting in net fluid secretion. [Studies on rats suggest sennosides may be weak tumour promoters -AD handout]
Toxicology (Bradley, 1992): Long term use/ abuse may result in electrolyte losses, especially of potassium (may intensify action of cardiac glycosides), albuminuria and haematuria (excretion of protein and blood into urine), pigmentation of intestinal mucosa and impairment of intestinal nerves (myenteric plexus).
History: Use of Senna as laxative was introduced to Europe by Arab physicians in 9th and 10th centuries.
Traditional and Practitioner sources:
“Prescribe with carminative of high volatile oil content, eg. Fennel, to avoid griping.” (GT)
NB. Entry for Cassia angustifolia, Tinnevellian senna, in Priest and Priest, (1983: 96).
