Common Name: Alexandrian Senna

General Information

Alexandrian senna is a deciduous shrub growing up to 3 metres tall[].
Senna is one of the world's most commonly used laxatives, with a very long history of use dating back thousands of years. It is cultivated in many tropical areas, especially India, for its leaves and pods[].

Known Hazards

None known

Botanical References

Range

Tropical Africa through the Arabian Peninsula to India.

Habitat

Semi-desert scrub and grassland, particularly in valley bottoms, flood plains and on river banks, often associated with Acacia spp. It occurs from sea-level up to elevations of 1,300 metres[].

Properties

Medicinal Rating
Other Uses Rating
Habit	Deciduous Shrub
Height	3.00 m
Cultivation Status	Cultivated, Wild

Cultivation Details

Plants can be grown in the drier warm temperate to tropical zones.
Prefers a deep, well-drained, moderately fertile sandy loam and a position in full sun[]. Germination is hampered by salinity but older plants are salt-tolerant. Senna alexandrina does not tolerate continuous waterlogging or heavy irrigation[].
The plant is mostly grown as an annual crop, but it can be left standing to produce for another 2 - 3 years[].
Flowers and fruits are formed throughout the year[].
Yields vary considerably depending on the soil and water conditions. In India the average annual yield is about 700 kg of leaves and 100 kg of pods per ha under rainfed conditions. Under irrigation the yield of leaves and pods is about 1400 kg/ha and 150 kg/ha, respectively. Although the sennoside content is higher when plants are under stress, moderate irrigation and fertilization pay off through increased leaf and total sennoside yields[].
Although many species within the family Fabaceae have a symbiotic relationship with soil bacteria, this species is said to be devoid of such a relationship and therefore does not fix atmospheric nitrogen[].

Edible Uses

None known

Medicinal

The leaves and pods have been used as a laxative and purgative since ancient times and remains an important treatment in both traditional and conventional medicine[].

The active constituents of the leaves and the wall of the pods are essentially the same and consist of 2 - 5% anthraquinone derivatives and related dianthrone glycosides on dry weight basis. The dried drug contains mainly sennosides A and B, together with small quantities of related compounds. The sennosides are little resorbed in the small intestine but once in the colon, they are hydrolyzed by the bacterial flora and the anthraquinones formed are reduced to form the active anthrones, which are responsible for the laxative activity as they stimulate peristalsis. Pharmaceutical grade leaves must contain 5.5 - 8.0% sennoside B, whereas pods must contain at least 2.2% (‘Tinnevelly senna’) to 3.4% (‘Alexandrian senna’) sennoside B[].
Much medical research has been published on the possible health risks of using this plant as a laxative[]. No carcinogenic effects of prolonged use have been found, but even so it should only be used for occasional constipation, as prolonged use can lead to chronic ulcerative colitis[]. Use of the drug is contraindicated in case of intestinal obstruction and acute intestinal inflammation[]. Use for children under 12 years of age and pregnant or lactating women should be discouraged[]. The use of preparations for weight reduction is dangerous[].
Ethanol extracts of leaves of Senna alexandrina show inhibitory activity against Bacillus cereus, Staphylococcus aureus and Staphylococcus epidermidis, but not against gram-negative bacteria[].

The plant is also used traditionally to treat a number of other conditions.

A decoction of the pods is drunk to get rid of intestinal worms and to cure difficulties in breathing[]. An infusion of the pods is recommended as a purgative for pregnant women and also to suppress fever[].

An infusion of the leaves is drunk to overcome flatulence and convulsions and to stop nosebleeds[]

Agroforestry Uses:

The species has been recommended for soil conservation[].

Other Uses

The wood is used to make farm tools[].

Propagation

Seed - requires pre-treatment since untreated seed has a poor germination rate[]. Pre-soaking for 12 - 24 hours in warm water helps, but scarifying with sulphuric acid has proved to be more effective with larger quantities of seed[]. In small quantities, the seed can be sown in containers, in larger amounts it is usually broadcast at rates of 15 - 25 kg/ha[].

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