Ipomoea (PROSEA Medicinal plants)

Plant Resources of South-East Asia
Introduction

Protologue: Sp. pl. 1: 159 (1753); Gen. pl. ed. 5: 76 (1754).

Family: Convolvulaceae

Chromosome number: x= 15; I. aquatica, I. carnea subsp.fistulosa, I. congesta, I. digitata, I. nil, I. obscura, I. pes-caprae, I. triloba: 2n= 30, I. pes-tigridis: 2n= 28, 30, I. purga: 2n= 24-28

Major species

Ipomoea digitata L.,
I. nil (L.) Roth,
I. pes-caprae (L.) R.Br.,
I. purga (Wender.) Hayne.

Vernacular names

Morning glory (En).
Liseron (Fr).

Origin and geographic distribution

Ipomoea comprises about 500 species, (600-700 species according to some authors) and occurs throughout tropical and subtropical regions of both hemispheres, mainly in America and Africa.

Uses

Several parts of Ipomoea species have purgative properties, and are also taken for dysentery or as a general tonic. In South-East Asia and India, the leaves or young tops of I. aculeata var. mollissima, I. batatas (L.) Lamk, I. carnea subsp. fistulosa and I. congesta are used for these purposes, and of I. nil and I. quamoclit L. the seeds. The taste of these seeds is at first sweetish, then acrid and disagreeable. The tubers of I. purga are used in the Old and New World alike as a purgative. In small doses, they are employed against gastritis, colitis and chronic dysentery. The roots of I. aquatica, I. digitata, I. pes-caprae and I. pes-tigridis L. are purgative, as are the seeds of I. digitata. The seeds are also a strong pesticide, killing earthworms, leeches, pig tapeworm and other intestinal parasites.

The crushed leaves of many Ipomoea, for instance of I. aculeata var. mollissima, I. aquatica, I. digitata, I. obscura, I. pes-caprae, I. pes-tigridis and the ornamental I. quamoclit are also widely applied on sores, boils, ulcers, piles, haemorrhoids, aphthae, swellings and wounds. In Peninsular Malaysia, the tubers of I. digitata and I. purga are used for this purpose.

In Indonesia, a decoction of the roots of I. aquatica is also used as an antidote against opium or arsenic poisoning or drinking of polluted water. Eating much I. aquatica has a nerve-calming effect in case of sleeplessness, stress, headache, general weakness and leucorrhoea. A decoction of the leaves is a remedy for cough. The buds, together with shoots of Heliotropium indicum L., are made into a paste to put on ringworm.

In India and the Philippines, the root of I. digitata is considered tonic, alterative, aphrodisiac, demulcent, lactagogue and cholagogue, and is useful in fever and bronchitis. The powdered root is given for diseases of spleen and liver, for menorrhagia, debility and fat accumulation. In China, the seeds are regarded as a diuretic, anthelmintic and deobstruant, and are prescribed for dropsy, constipation, to promote menstruation and cause abortion. In the West Indies, a weak leaf decoction is a remedy for asthma and rheumatism. It is also drunk daily in the last month of pregnancy to promote an easy delivery. A strong decoction is taken as an abortifacient. In Nigeria, the dried leaves are applied to burns.

In South-East Asia, Australia, India, Senegal, Brazil and Central America, the leaves of I. pes-caprae are considered astringent, alterative, tonic, and diuretic, and are used in an external application for rheumatism, dropsy and colic. In the Philippines, Papua New Guinea, Malaysia, Indo-China and India the seeds of I. pes-caprae are used as a remedy for stomach-ache and cramp. A decoction of the root is emollient and diminishes the irritation caused by bladder infections. In Nusakambangan Island, south of Central Java, and in Thailand, the juice from the stem is used to treat the sting of jellyfish and toadfish.

I. triloba L. is used in Peninsular Malaysia in a poultice against headache. In Java, the leaf juice of I. rumphii Miq., the identification of which is uncertain, is used against spots on the cornea and against bites from centipedes. The leaves are applied to wounds and ulcers, to ripen them. The plant is sometimes eaten as a vegetable, normally mixed with other herbs. In the Enga Province of Papua New Guinea, cuts or burns are treated with the juice from the heated tuber of I. batatas, which dries to a rubber-like gum that holds the skin together. The red-leaved variety is used with wild tobacco leaves to treat eye infections and alone to prevent sores on a baby’s skin. It is also taken for diabetes. The pounded leaves of the red-leaved variety are used to stupefy shrimp. In Milne Bay (Papua New Guinea) a decoction of the leaves is drunk against stomach-ache. In Peninsular Malaysia, the tuber is used to make a drink to allay thirst in fever. The finely crushed leaves are smeared on stiff joints and burns, and the stem is bound on stiff rheumatic joints.

In Indonesia, India and Africa, I. carnea subsp. fistulosa causes severe cases of poisoning in goats and sheep, the symptoms being staggering, weakness of hind legs, dyspnea, depression and pallor of the visible mucous membranes, and anaemia. The pollen is an important aero-allergen in India.

The shoots of I. aquatica are commonly eaten as a vegetable in South-East Asia, as aret he leaves of I. pes-caprae in Zanzibar. In Brazil the roots are eaten in case of famine, but they cause dizziness when used in excess. In Nigeria, the leaves of I. obscura are eaten in soup, and in Kenya as a vegetable.

Ipomoea is also an important genus for providing ornamentals, normally for the large flowers, such as I. purpurea (L.) Roth and I. tricolor Cav., but also I. digitata and I. carnea subsp. fistulosa. Some are also used as a hedge plant or green manure, such as I. aculeata var. mollissima in India, and I. digitata in Indonesia. Others are also used as fodder: I. digitata in Malesia and I. pes-tigridis in northern India and the Sahel. In China, the leaves of I. pes-caprae are given as a fodder to pigs, but if eaten by dairy cows, the milk is spoiled. In India, the seeds of I. digitata are used for coagulating milk.

In India, the leaves of I. aculeata var. mollissima are used as a substitute for soap to wash clothes. In Ambon (Indonesia), I. congesta is used for this purpose, and in Brazil, I. pes-caprae.

I. pes-caprae is an excellent sand binder, and is used for checking erosion and drifting of sand. The purple flowers mashed with a little chalk, give a bright green colour, which dries dark blue, like indigo. In Malawi, the long stems are made into ropes for hauling fishing nets, and in Gabon for skipping ropes. The pulped leaves are rubbed on fishing nets, to entice fish.

Production and international trade

The tubers of I. purga used to be dried and exported to Europe in considerable quantities, where they were used with carminatives such as ginger, cloves or other spices.

Properties

From the aerial parts of I. pes-caprae, 3 fatty acid glycosides, i.e. pescaprosides A, B and E were isolated, as well as organic acids such as behenic, melissic, butyric, succinic, betulinic, tartaric, fumaric, malic, citric and myristic acid, and flavonoids including hyperoside, isoquercitrin, isoquercitrin monoacetate and quercetin-3-galactoside. The leaves also contain damascenone, which is reported to be an antihistaminic agent in the literature. The root is starchy, and contains saponins.

An aqueous extract of the stems and leaves reversibly counteracts the spasmodic effects and dermatitis of the poison of jellyfish and Portuguese man-of-war. Possibly, the compoundsβ-damascenone and E-phytol are partly responsible for this effect, their effect being in the same range as papaverine. The extract was also tested for its antagonistic activity against histamine, acetylcholine, bradykinin and barium chloride on isolated guinea-pig ileum, and was found to inhibit the contractions induced by the spasmogens, probably by direct influence on the ileal smooth muscle. The extract was found to contain components which were shown to inhibit the synthesis of prostaglandins, e.g. 2-hydroxy-4,4,7-trimethyl-1(4H)-naphthalenone, (-)-mellein, eugenol and 4-vinylguaiacol. The combination of antispasmodic effects and prostaglandin synthesis inhibition of the extract may explain the use of I. pes-caprae leaves for treating jellyfish stings.

A plant extract of I. pes-caprae exhibited furthermore significant inhibition of ADP-induced human platelet [14C]5-hydroxytryptamine release and platelet aggregation in vitro. The leaf extract also showed significant dose-dependent effects in the rat ear oedema test, while the methanol, ethyl acetate and aqueous extracts exhibited considerable antinociceptive activity against the writhing- and formalin tests in mice. Compounds responsible for this activity were initially identified as the triterpenes glochidone, betulinic acid andα- andβ-amyrin acetate.

The leaves of I. aquatica contain hentriacontane, β-sitosterol and its glycoside. A plant extract inhibited prostaglandin and leukotriene biosyntheses in vitro; N-trans- and N-cis feruloyltyramines were found to be responsible for this activity. Furthermore, the fresh aerial parts, intragastrically administered to rats at the dose of 3.4 g/kg body weight showed antihyperglycaemic activity.

The leaves of I. carnea subsp. fistulosa contain the polysaccharide ipomose, as well as jalapin, saponins and 3-dicaffeoylquinic acid esters. The water extract of the fresh leaves produced a positive inotropic effect on isolated frog heart in vitro, possibly by sodium extrusion or release of the intracellular calcium. It also causes haemolysis and a reduction in blood pressure, when administered intravenously. The ether extract affected the central nervous system, including the respiratory and cardiac regulatory centres. An ethanol extract, as well as succinylcholine as a reference, was tested in vitro on isolated preparations of the frog rectus abdominis muscle and the rabbit perfused heart as well as in vivo in chickens. Both the extract and succinylcholine contracted the frog rectus abdominis muscle, caused bradycardia of the rabbit heart, and produced spastic paralysis in chickens. The plant extract also shows moderate insecticidal, fungicidal, bactericidal and antiviral action, but also allelopathic activity against several crops and weeds. I. carnea subsp. fistulosa is toxic to goats and sheep. The signs of poisoning are loss of appetite, depression, weakness of hind limbs, dyspnoea, staggering and pallor of visible mucous membranes. It also shows a toxic effect on their livers and kidneys.

Some Ipomoea are known to contain alkaloids, e.g. the Mexican I. hardwegi Benth. contains ipalbidine, which has shown analgesic activity, and the seeds of I. obscura contain the indole alkaloids ipobscurine B and C.

Ipomeamaron, a phytoalexin of the furan-sesquiterpene type, was first found in the tubers of I. batatas, which were infected with fungi. Upon this infection, the concentration of ipomeamaron rose fast to a fungitoxic level of about 2%.

Adulterations and substitutes

In India, the rhizomes of Operculina turphetum (L.) S. Manso are often used as a substitute for tubers of I. purga, as a strong purgative.

Description

Herbs or shrubs, usually twining, sometimes prostrate, floating or erect.
Leaves alternate, simple, variable in size and shape, lobed or divided; petiolate.
Inflorescence mostly in axillary, 1-many-flowered cymes; peduncle present; bracts normally small, linear to triangular.
Flowers bisexual, regular, small to large; pedicel present; sepals 5, herbaceous or coriaceous, often unequal, often somewhat enlarged in fruit; corolla funnel-shaped or campanulate, 5-lobed, mid-petaline bands well defined by 2 distinct veins, mostly glabrous outside; stamens 5, inserted near the base of corolla tube, normally included, filaments often unequal in length, pollen spinulose; ovary 2(-4)-locular, with 4(-6) ovules; style 1, simple, filiform, normally included.
Fruit a globose or ovoid capsule, 4(-6)-valved, 4(-6)-seeded.
Seed glabrous or hairy.
Seedling with epigeal germination; cotyledons horseshoe-shaped or deeply divided into lobes or slips.

Growth and development

Ipomoea is sun-loving in general, and the species are known as honey-yielding plants. Many Ipomoea species are self-incompatible. The flowers of I. nil and I. triloba close before noon, those of I. aculeata var. mollissima and I. pes-tigridis open at night.

Other botanical information

Several authors have wrongly considered the Malesian specimens of I. nil conspecific with the North American I. hederacea (L.) Jacq.

Ecology

Most Ipomoea grow under everwet and seasonal climatic conditions, although some prefer regions with a pronounced dry monsoon, savanna and grasslands. The Ipomoea species of the beach can tolerate high temperatures, periodic drought, sea water spray, high pH and low soil nitrogen content.

Propagation and planting

Ipomoea is normally propagated by seed. The capsules float and can probably be dispersed by water or sea currents. When planted, stem cuttings are used, placed 60-100 cm apart. Whereas I. aquatica is propagated by seed and by cuttings, I. carnea subsp. fistulosa and I. digitata are normally propagated only by cuttings. I. pes-caprae can also be successfully propagated from nodal explants through Murashige and Skoog (MS) media, supplemented with either 2-isopentenyladenine or zeatin. Quite similarly, I. triloba can be propagated through protoplast, petiole or leaf explants, grown on MS media, supplemented with 3-indole acetic acid and 6-benzylaminopurine. I. purga is cultivated in Mexico, where seeds are scarified and sown in holes, and sticks are placed near the plants for support. The seeds are planted during the rainy season and harvested about 8 months later.

Diseases and pests

Several leaf-spot diseases caused by Alternaria sp. and Xanthomonas sp. are regularly found in Ipomoea. An important disease in I. aquatica is white rust, caused by Albugo candida. Important pests include the caterpillars Spodoptera litura and Diacrisia strigatula as well as several thrips and aphids all of which can cause serious damage. Ipomoea is also attacked by several nematodes, in particular Meloidogyne incognita and M. javanica, although tests with extracts of I. carnea subsp. fistulosa show high mortality of juveniles and adults of these pests.

Harvesting

The plant parts of many Ipomoea used are simply harvested from the wild whenever needed.

Yield

In Mexico, yield of fresh I. purga roots is 1.5-2.7 t/ha.

Handling after harvest

The roots of I. purga lose 75% of their weight by drying. After drying the roots are smoked before being sold.

Genetic resources and breeding

Germplasm collections containing I. batatas are found all over the world. Large Ipomoea germplasm collections are kept in Iquitos and Lima (Peru) and in Griffin (United States).

Prospects

Components of several Ipomoea species show pharmacological activities, e.g.β-damascenone (anti-spasmodic) and (-)-mellein and 4-vinylguaiacol (inhibition of prostaglandin synthesis). Since these activities are of interest for the development of future medicines, they merit further research in order to evaluate their possible potential.

Literature

Austin, D.F., 1977. Ipomoea carnea Jacq. vs. Ipomoea fistulosa Mart. ex Choisy. Taxon 26(2-3): 235-238.
Bachhav, K.V., Burande, M.D., Rangari, V.D. & Mehta, J.K., 1999. Effect of aqueous extract of Ipomoea carnea leaf on isolated frog and mouse heart. Indian Journal of Experimental Biology 37(11): 1080-1084.
De Souza, M.M., Madeira, A., Berti, C., Krogh, R., Yunes, R.A. & Cechinel Filho, V., 2000. Antinociceptive properties of the methanolic extract obtained from Ipomoea pes-caprae (L.) R.Br. Journal of Ethnopharmacology 69(1): 85-90.
Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha Publishing Co., Quezon City, the Philippines. pp. 757-763.
Rogers, K.L., Grice, I.D. & Griffiths, L.R., 2000. Inhibition of platelet aggregation and 5-HT release by extracts of Australian plants used traditionally as headache treatments. European Journal of Pharmaceutical Sciences 9(4): 355-363.
Van Oostroom, S.J., 1953. Ipomoea. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 4. Noordhoff-Kolff, Djakarta, Indonesia. pp. 458-488.

Selection of species

Authors

Anna L.H. Dibiyantoro & G.H. Schmelzer