Nigeria’s medicinal plants: Senna alata (Asunwon oyinbo)


Senna alata also known as Cassia alata belongs to the family Caesalpiniaceae. It is a soft-wooded shrub, growing up to 15 ft high with yellow flowers in stout dense erect racemes; and the fruits are black when ripe.

It is commonly known as candle bush, craw-craw plant, ringworm bush or ringworm plant. The Yoruba call it “Asunwon oyinbo.” Who does not know that Senna alata is traditionally used for treating skin blemishes? The first time I ever touched the plant in my life was when a friend plucked some leaves for me to be used because of pimples outbreak. Do you still remember I mentioned that I visited the medicinal plant gardens, Department of pharmacognosy,Obafemi Awolowo University, Ile-Ife, Osun State, last year? Senna alata was one of the plants shown to me that day. The flower of the plant stands erect like the male sexual organ and my guide reminded me of the doctrine of signatures (it states that herbs that resemble various parts of the body can be used to treat ailments of those parts of the body) Truly, the flower is used to treat low sperm count and erectile dysfunction traditionally!

The main medicinal uses of Senna alata are as a laxative or purgative and in the treatment of skin problems. Its active ingredients include the yellow chrysophanic acid. For laxative purposes, usually a decoction of the leaves is drunk. Skin problems treated with Senna alata include ringworm, impetigo, syphilis sores, psoriasis, herpes, chronic lichen planus, scabies, tinea infections, rash, eczema and itching. Skin problems are most often treated by applying leaf sap or by rubbing fresh leaves on the skin. Other ailments treated in tropical Africa with Senna alata include stomach pain during pregnancy, typhoid, diabetes, malaria, asthma, ringworms, tinea infections, scabies, blotch, herpes, and eczema, dysentery, haemorrhoids, blood in the urine (schistosomiasis, gonorrhoea), convulsions, oedema, jaundice, headache, hernia, one-sided weakness or paralysis.

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In veterinary medicine too, a range of skin problems in livestock is treated with leaf decoctions. Such decoctions are also used against external parasites such as mites and ticks.

The flower, root, leaves, seed and bark displayed diverse biological activities. These pharmacological activities include antimicrobial, antifungal, anticryptococcus, antibacterial, antitumor, anti-viral, anti-inflammatory, antidiabetic, antioxidant, dermatophytic, anti-convulsant, hepatoprotective,  antimalaria, anthelmintic, wound healing and antihelmintic activities and more. All these activities could be due to the array of secondary metabolites such as tannins, alkaloids, flavonoids, terpenes, anthraquinone, saponins, phenolics, cannabinoid alkaloids, 1,8-cineole, caryophyllene, limonene, α-selinene, β-caryophyllene, germacrene D, cinnamic acid, pyrazol-5-ol, methaqualone, isoquinoline, quinones, reducing sugars, steroids and volatile oils present in different parts of the plant. It also has arrays of bioactive chemical compounds. Some of the reported chemical constituents are phenolics (rhein, chrysaphanol, kaempferol, aloeemodin, and glycosides), anthraquinones (alatinone and alatonal), fatty acids (oleic, palmitic, and linoleic acids), steroids, and terpenoids (sitosterol, stigmasterol, and campesterol).

In India, leaf decoctions are used as an expectorant in bronchitis and dyspnoea. It is used as an astringent and mouthwash. Decoctions of the wood are used to treat liver problems, urticaria, rhinitis and loss of appetite caused by gastro-intestinal problems. The seeds are a source of gum. The young pods are eaten as a vegetable but only in small quantities. Toasted leaves are sometimes used as a coffee substitute. The bark is used as fish poison and for tanning leather. The roots and the bark are reported to be used for tattooing. Senna alata is widely appreciated as an ornamental plant and bee forage.

In northern Nigeria, the stem, leaf and root decoctions are used in treatment of wound, skin, respiratory tract infection, burns, diarrhoea and constipation. Also, in the south-western region, leaf decoction serves as an antidote to body and abdominal pain, stress and toothache. In Egypt, the leaf decoction was observed to be used as a bowel stimulant to stimulate peristaltic shrinkages and decrease water absorption from the colon in an attempt to prevent constipation. In Cameroon, the stem, bark and leaves were reported to be used as a remedy for gastroenteritis, hepatitis, ringworm and dermal infections.

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In Philippines, India and China, Senna alata’s stem, bark and leaf decoction were found to be effective in treating haemorrhoids, inguinal hernia, syphilis, intestinal parasitosis and diabetes. Currently, seeds and roots are used in regulating uterus disorder and worms. The leaves and flowers are typically used as antifungal agents and laxatives.  In China, the seeds are used in treating asthma and to improve vision. In Guatemala, Brazil and Guinea, the whole plant is used in the treatment of flu and malaria. The leaves are used in Sierra Leone to relieve abortion pain and facilitate baby delivery.

In China, India, Benin republic, Ghana, Nigeria and Togo, the whole plant is used as a curative for Diabetes mellitus.To treat ringworm and other fungal infections of the skin, the leaves are ground in a mortar to obtain a kind of “green cotton wool.” This is mixed with vegetable oil and rubbed on the affected area two or three times a day.

Crude leaf extracts have shown antibacterial activity against a range of bacteria (such as Dermatophilus congolensis which causes a serious skin condition in cattle), antifungal properties (such as against Pityriasis versicolor in humans) and also antitumour activity. The bark contains tannins. The petals contain anthraquinones, glycosides, steroids, tannins and volatile oil. Extracts of the petals have bactericidal activity against gram-positive bacteria but not against gram-negative bacteria. They are taken internally as a remedy for constipation and to purify the blood. The leaves are decocted with or without tripogandra serrulata and persea americana as a treatment for biliousness and hypertension.

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The plant can be applied as a tincture, poultice, powdered forms and then mixed with oil as an ointment. The sap can be spread over affected area. An infusion is used in the treatment of diarrhoea, tympanites, uterus problems and filaria worm expulsion. An infusion is used for remedying spleen conditions. The leaves, flowers and fruit are mixed in an infusion to treat stomach problems. The seed is laxative and anthelmintic. It is cooked and used as a remedy for intestinal worms. The plant has insecticidal properties. It is sometimes used as a colouring in tattooing.

Fresh leaves, flower and root of Senna alata were collected and mosquito larvae belonging to the genus anopheles were used for the purpose of a study titled, “Biolarvicidal control of malaria using solvent extracts of senna alata,” by Tariwari CN Angaye et al. This study investigated the biolarvicidal potential of the leaf and flower, using methanol and hexane extracts. Fortunately, both extracts of the plant demonstrated larvicidal activities with the leaf extract having higher mortality rate compared to the flower. In addition, the methanolic extract was more effective than the hexane extract. Notwithstanding, the larvicidal efficacy of Senna alata plant indicated that it can be recommended for the formulation of biolarvicide for the control of malaria. We have another plant that treats malaria! Why don’t you try Senna alata for all your skin troubles?

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