Senna (Cassia angustifolia / Senna alexandrina)

Description

Senna (Cassia angustifolia, oggi più correttamente Senna alexandrina) is a small perennial shrub of the Fabaceae family, best known for its dried leaves and pods used as a stimulant laxative rather than as a food. It is native to semi-arid regions of north-eastern Africa and the Indo-Pakistani area, where it grows in hot, dry and very sunny environments, on sandy or gravelly soils that are poor in organic matter but well drained.

The plant shows a bushy, relatively low habit, generally under 1 m in height. Stems are slender, green-yellowish, erect or slightly branching. The leaves are paripinnate, composed of several pairs of small, lanceolate leaflets, light green to grey-green in colour. These leaflets, together with the flat pods, constitute the main herbal drug used in phytotherapy. The flowers are bright yellow, typical of many legumes, and are grouped in axillary or sub-terminal inflorescences; they precede the formation of the fruit.

After pollination, the plant produces flat, slightly curved pods, which turn from green to yellow-brown or dark brown at full maturity and contain multiple flattened seeds. Leaves and pods are harvested, dried and selected to obtain a botanical material concentrated in anthracene glycosides (sennosides), which are responsible for the characteristic stimulant laxative action. The dried drug appears fragile, with thin leaflets and papery pods, has a faint herbal odour and a distinctly bitter, somewhat harsh taste, clearly unsuitable for normal culinary use.

Senna is therefore a plant with a modest aerial structure but a very strong functional identity: highly adapted to dry, sunny climates and poor soils, it has become one of the reference herbal laxatives in traditional and modern herbal medicine, used for centuries in teas, extracts and pharmaceutical preparations for the short-term treatment of occasional constipation.

Botanical classification

• Common name: Senna (senna leaves)

• Clade: Angiospermae

• Order: Fabales

• Family: Fabaceae

• Genus: Senna

• Species: Senna alexandrina Mill. (syn. Cassia angustifolia Vahl)

Climate
Senna is an officinal species typical of hot, dry environments, originally from semi–arid regions. It prefers a subtropical or dry tropical climate, with mild winters and hot, sunny summers. It tolerates drought fairly well, but is sensitive to intense cold: even short frosts can damage the aerial parts and compromise leaf and pod production.

Exposure
The ideal exposure is full sun, which is essential for good vegetative growth and a high yield of leaves, the main medicinal part. In shaded positions, the plant develops weaker stems, less dense foliage and a lower concentration of active constituents.

Soil
Senna grows well in sandy or sandy–loam soils, loose, low in organic matter but very well drained. It prefers soils from neutral to slightly subalkaline, typical of semi–arid areas. Waterlogging is highly unfavourable, as it promotes root rot, so compact, poorly structured clays should be avoided.

Irrigation
In cultivation, senna requires moderate irrigation, especially in the early growth stages, keeping the soil only slightly moist. Once well established, the plant is fairly resistant to water shortage and can be managed with supplementary watering only in periods of prolonged drought. It is advisable to let the topsoil dry between irrigations.

Temperature
The optimal temperature range for germination and growth is generally between 20 and 30 °C. The plant tolerates intense heat well, provided soil moisture is not completely lacking, while temperatures close to or below 0 °C can damage shoots and leaves. In areas at risk of late cold snaps, sowing should be scheduled to avoid the most sensitive stages coinciding with frost.

Fertilization
Senna is relatively undemanding in nutrients, being adapted to poor soils. Usually a light application of well–matured organic matter before planting is enough to improve soil structure. Excess fertilization, especially with nitrogen, is unnecessary and may encourage overly soft growth that is less suited to dry conditions and potentially poorer in active principles.

Crop care
Crop care focuses mainly on weed control during early development, using light hoeing that does not damage the root system. It is important to keep the soil surface loose and to ensure good drainage at all times. In very humid climates, attention must be paid to possible rot and fungal diseases, limiting waterlogging and improving air circulation between plants.

Harvest
Harvesting concerns mainly the leaves, which are rich in anthracene derivatives. It is generally carried out when the plants are well developed, by collecting healthy, fully expanded leaves, often just before or at the beginning of flowering. In some production systems, mature pods are also harvested. The plant material is then dried in a shaded, well–ventilated place to preserve its active constituents.

Propagation
Propagation is by seed, usually direct–sown in the field on well–prepared, finely worked soil. Seeds may benefit from slight scarification or brief soaking to aid imbibition and improve germination. After emergence, thinning is carried out to give each plant enough space to develop a good leaf canopy, which is important for achieving satisfactory yields of dried leaves.

Indicative nutritional values per 100 g

(dried leaves or pods)

Senna is not used as a food. Its leaves and pods are not intended for nutritional intake, only for medicinal / herbal use in small doses.
For this reason, classic nutritional values per 100 g are not meaningful and are generally not reported.

Key constituents

• Anthracene glycosides (sennosides A, B, C, D, etc.)

  • main active group responsible for stimulant laxative effects

• Anthraquinone derivatives and aglycones

  • such as rhein, chrysophanol, emodin, aloe-emodin

• Flavonoids

  • derivatives of kaempferol, isorhamnetin and related structures

• Mucilages and plant polysaccharides

• Mild tannins, resins, organic acids

• Minor amounts of sugars and minerals (nutritionally negligible)

Production process

• Cultivation

  • grown in warm, semi-arid climates with low rainfall

  • prefers sandy or sandy-loam, well-drained soils

  • sown or transplanted in open field, with moderate irrigation

• Harvesting

  • leaves harvested from well-developed plants, commonly within the first 1–2 years of growth

  • pods collected when fully formed and near maturity, but still intact and healthy

• Drying

  • thin layers, in shade and well-ventilated areas, or in low-temperature dryers

  • proper drying supports both stability and optimal sennoside formation

• Selection and packaging

  • damaged or discoloured material is removed

  • dried herbal material is packed in suitable containers protected from light and moisture

For pharmaceutical use, senna is often further processed into standardised extracts with defined sennoside content.

Physical properties

• dried leaves: thin, lanceolate, yellow-green or grey-green

• dried pods: flat, papery legumes, yellow-brown to dark brown, containing flattened seeds

• the dried herbal drug is brittle and easy to crumble

• ground senna: brownish powder with variable particle size

• low residual moisture is required for stable storage

Sensory and technological properties

• taste: distinctly bitter, somewhat harsh and unpleasant, often masked by blending with other herbs or flavours

• odour: faint, herbal, slightly green

• technological behaviour:

  • active glycosides extract well in water and hydroalcoholic solvents

  • reasonably stable when protected from light, air and high humidity

  • readily formulated into teas, powders, dry extracts, tablets, syrups, oral drops

Food applications

Senna has no food application.

• teas or infusions containing senna are considered medicinal preparations, not ordinary beverages

• preparations are intended for short-term relief of occasional constipation, not for regular nutritional use

Nutrition and health

In the context of “nutrition and health”, senna is relevant as a herbal medicinal laxative, not as a nutrient source.

• sennosides reach the colon largely unchanged and are transformed by colonic flora into active compounds (anthrones)

• these stimulate intestinal motility and reduce water reabsorption, leading to softer stools and accelerated transit

• effect is typically strong, with laxative action appearing after several hours (often 8–12 h)

Risks and cautions

• prolonged or excessive use may cause:

  • abdominal cramps, pain, diarrhoea

  • fluid and electrolyte loss (especially potassium)

  • risk of laxative dependence and reduced spontaneous bowel motility

• not recommended in:

  • intestinal obstruction, acute inflammatory bowel diseases, unexplained abdominal pain

  • pregnancy and breastfeeding unless specifically advised by a healthcare professional

Senna must therefore be regarded as a powerful herbal drug, suitable only for short-term use and under appropriate guidance.

Portion note

There is no serving size in the dietary sense.

• doses are expressed in mg of dried drug or mg of sennosides per day, according to pharmacopoeial or product guidance

• administration is typically in the evening, to obtain an effect the following morning

Allergens and intolerances

• possible hypersensitivity reactions in individuals sensitive to senna or related species

• excessive use may irritate the intestinal mucosa and aggravate pre-existing conditions

• individuals with irritable bowel, chronic inflammatory bowel disease or other intestinal pathologies should use senna only under medical supervision

Storage and shelf-life

• keep dried herbal material in closed containers, protected from light, heat and humidity

• leaves tend to degrade faster than pods; limiting exposure to air and light helps preserve sennoside content

• dry and liquid extracts must be stored according to manufacturer instructions (often in well-closed, opaque containers)

With correct storage, senna preparations maintain their characteristics for the declared shelf-life of the product.

Safety and regulatory

• in Europe and many other regions, senna (leaves/pods) is classified as a herbal medicinal product for the short-term treatment of occasional constipation

• its use is regulated via:

  • defined ranges of sennoside content

  • clear indications, duration limits and age restrictions

• senna is not regarded as a food ingredient and is not used as such

Labeling

For teas, extracts or herbal medicines based on senna, labels should indicate:

• botanical name: Cassia angustifolia (or synonym Senna alexandrina), and plant part (leaf, pod)

• dosage form (tea, dry extract, tablets, drops, etc.)

• sennoside content or equivalent amount of herbal drug, where applicable

• indication for occasional constipation, recommended maximum duration of treatment and excluded groups (young children, pregnancy, etc.)

• warnings on possible side effects (cramps, diarrhoea, risk of prolonged use)

Troubleshooting

In use (laxative effect)

• no effect → dose too low, preparation incorrectly made, or herbal material of poor quality with low sennoside content

• marked abdominal cramps → dose too high, individual sensitivity, or presence of underlying conditions; reduce or stop use and seek medical advice

• intense diarrhoea → overdose; stop use, rehydrate, and monitor symptoms

In storage

• loss of efficacy over time → possible degradation of sennosides due to prolonged storage, light or heat; check production date and replace with fresher material

• darkening or stale odour → oxidised or degraded drug; replace with properly stored material

Main INCI functions (cosmetics)

In cosmetics, senna is not a major ingredient, but may appear as:

• a botanical extract in products with a “detox / purifying” concept

• a mild skin conditioning component due to its phenolic and flavonoid content

However, the main role of senna remains phytotherapeutic and medicinal, particularly as a stimulant laxative, rather than cosmetic.

Conclusion

Senna (Cassia angustifolia) is not a food plant but a pharmacologically active medicinal species. A modest-looking semi-arid shrub with compound leaves, yellow flowers and flat pods, it owes its importance to the dried leaves and fruits, rich in sennosides, which provide a strong stimulant laxative effect at low doses.

Used correctly, for short periods and under appropriate professional advice, senna is a useful tool for managing occasional constipation. Misuse or prolonged use, however, may lead to adverse effects — cramps, diarrhoea, electrolyte loss, and potential dependence on laxatives — making caution essential.

Overall, senna is a paradigmatic example of a powerful herbal remedy: morphologically unassuming but chemically very active, perfectly adapted to harsh environments, and capable of producing pronounced clinical effects in small, carefully controlled quantities. Its place is not on the plate, but firmly within herbal medicine and pharmacognosy.

Mini-glossary

• Anthracene glycosides / sennosides: active compounds in senna responsible for stimulant laxative action at colon level

• Stimulant laxative: agent that increases intestinal motility and secretions, accelerating transit

• Phytotherapy: rational use of medicinal plants or their extracts for health support or therapeutic purposes

• Skin conditioning: cosmetic function attributed to ingredients that help keep skin in good condition (softness, comfort, overall appearance)

Studies

Senna is used for both its antibacterial and laxative properties. 

The mechanism by which Senna acts as a laxative concerns the selective action on the nervous plexus of the intestinal smooth muscle which increases intestinal motility (1)

It is also used to treat skin diseases, helminthic and parasitic infections (2).

The seeds are soft, dicotyledonous and contain about 50% endosperm.

Worldwide, a major cause of morbidity and mortality is diabetes mellitus. This study provides evidence that extracts of radish (Raphanus sativus Linn) and Cassia angustifolia (Vahl.) improve metabolic abnormalities associated with diabetes and may delay the risk of complications due to chronic hyperglycemia. The beneficial effects of both extracts in diabetes seem to be attributed to the synergistic effects of its bioactive compounds such as flavonoids, saponins, and glycosides (3).

This study revealed extensive anthelmintic activity of both Cassia angustifolia and Cassia alata and Cassia occidentalis (4).

Senna Cassia angustifolia studies

Safety

Care should be taken not to ingest significant amounts of this plant as long-term use of Senna can lead to laxative dependence and liver damage (1)

Bibliografia_______________________________________________________________

(1) Haoudar A, Chekhlabi N, El Kettani C, Dini N. Acute Hepatitis and Pancytopenia in a Child With Chronic Abuse of Senna. Cureus. 2021 Jan 2;13(1):e12436. doi: 10.7759/cureus.12436.

(2) Boonhok R, Sangkanu S, Norouzi R, Siyadatpanah A, Mirzaei F, Mitsuwan W, Charong N, Wisessombat S, Pereira ML, Rahmatullah M, Wilairatana P, Wiart C, Tabo HA, Dolma KG, Nissapatorn V. Amoebicidal activity of Cassia angustifolia extract and its effect on Acanthamoeba triangularis autophagy-related gene expression at the transcriptional level. Parasitology. 2021 May 10:1-9. doi: 10.1017/S0031182021000718.

Abstract. Cassia angustifolia Vahl. plant is used for many therapeutic purposes, for example, in people with constipation, skin diseases, including helminthic and parasitic infections. In our study, we demonstrated an amoebicidal activity of C. angustifolia extract against Acanthamoeba triangularis trophozoite at a micromolar level. Scanning electron microscopy (SEM) images displayed morphological changes in the Acanthamoeba trophozoite, which included the formation of pores in cell membrane and the membrane rupture. In addition to the amoebicidal activity, effects of the extract on surviving trophozoites were observed, which included cyst formation and vacuolization by a microscope and transcriptional expression of Acanthamoeba autophagy in response to the stress by quantitative polymerase chain reaction. Our data showed that the surviving trophozoites were not transformed into cysts and the trophozoite number with enlarged vacuole was not significantly different from that of untreated control. Molecular analysis data demonstrated that the mRNA expression of AcATG genes was slightly changed. Interestingly, AcATG16 decreased significantly at 12 h post treatment, which may indicate a transcriptional regulation by the extract or a balance of intracellular signalling pathways in response to the stress, whereas AcATG3 and AcATG8b remained unchanged. Altogether, these data reveal the anti-Acanthamoeba activity of C. angustifolia extract and the autophagic response in the surviving trophozoites under the plant extract pressure, along with data on the formation of cysts. These represent a promising plant for future drug development. However, further isolation and purification of an active compound and cytotoxicity against human cells are needed, including a study on the autophagic response at the protein level.

(3) Jani DK, Goswami S. Antidiabetic activity of Cassia angustifolia Vahl. and Raphanus sativus Linn. leaf extracts. J Tradit Complement Med. 2019 Mar 6;10(2):124-131. doi: 10.1016/j.jtcme.2019.03.002.

(4) Kundu S, Roy S, Lyndem LM. Broad spectrum anthelmintic potential of Cassia plants. Asian Pac J Trop Biomed. 2014 May;4(Suppl 1):S436-41. doi: 10.12980/APJTB.4.2014C1252. 

Abstract. Objective: To study the in vitro anthelmintic efficacy of Cassia alata (C. alata), Cassia angustifolia (C. angustifolia) and Cassia occidentalis (C. occidentalis). Methods: Crude ethanol extract from leaves of the three plants were prepared in rotary evaporator and different concentrations (10, 20 and 40 mg/mL) of leaf extracts were used for treatment on different representatives of helminthes (Heterakis gallinarum, Raillietina tetragona and Catatropis sp.) from domestic fowl (Gallus gallus domesticus). Loss of motility and death were monitored frequently. Results: C. alata showed early paralysis in all worms treated followed by C. angustifolia. C. occidentalis in combination with C. alata together caused early paralysis in all treated worms than the combination of C. alata with C. angustfolia. While Heterakis gallinarum in control survived for (81.33±2.07) h, treated worms lost their motility at (5.71±0.10) h, (6.60±0.86) h and (13.95±0.43) h with C. angustifolia, C. alata and C. occidentalis respectively at a concentration of 40 mg/mL which showed better efficacy than albendazole. Catatropis sp. survival period was (26.49±1.38) h in control, but with plant treatment, it lost its motility in just (0.57±0.08) h, (1.00±0.12) h and (1.47±0.40) h at 40 mg/mL concentration of C. alata, C. angustifolia and C. occidentalis respectively. Raillietina tetragona on the other hand became paralysed at (1.68±0.27) h, (2.95±0.29) h and (4.13±0.31) h with above concentrations treated with three plants respectively, however in control it survived up to (81.93±4.71) h.