2936

12(3): Medicinal and poisonous plants 3

Tecoma stans (L.) Juss. ex Kunth

Humb., Bonpl. & Kunth, Nov. gen. sp. 3: 144 (1819).

BIGNONIACEAE

2n = 36

Bignonia stans L. (1763), Stenolobium stans (L.) Seem. (1862).

Yellow bells, trumpet bush (En). Indonesia: tetu lang (Timor), dufa dufa (Ternate). Malaysia: ai funan (Peninsular). Thailand: dok lakhon (northern), thong urai, soi thong (Bangkok). Vietnam: hu[yf]nh li[ee]n.

Tecoma stans is indigenous in the southern United States and Central America, but is widely cultivated as an ornamental in the tropics and subtropics worldwide. It has naturalized in several parts of South-East Asia and the Pacific, and locally become a cumbersome weed, hampering regeneration of the indigenous vegetation.

Tecoma stans is a well-known medicinal plant in Central America and official in e.g. the Mexican Pharmacopoeia. A decoction of the leaves is a popular diuretic, and taken to treat gastro-intestinal disorders. It is also credited with antidiabetic properties. A decoction of various plant parts is further taken as a general tonic and to treat gastritis. A decoction of the root is considered a strong diuretic and taken as a treatment for syphilis. In South-East Asia Tecoma stans is only planted as an ornamental.

Various parts of Tecoma stans are rich in alkaloids. Flavonoids have been found in the flowers, iridoids in the leaves. In a general screening for antimicrobial activity, a methanol extract of leaves was found to be effective against Candida albicans. In an experiment to substantiate the traditional use of Tecoma stans in Mexican folk medicine to control diabetes mellitus, an extract showed evident hypoglycaemic action in rabbits. Intravenous administration of a Tecoma stans infusion in dogs produced an early hyperglycaemic response and arterial hypotension followed by a slow decrease of the glucose blood values. Heart frequency was gradually increased after the first hour of drug administration and persisted for several hours. The effects observed on blood parameters seem to be related to hepatic glycogen metabolism, involving activation of glycogenolysis.

A much-branched shrub up to 4 m tall. Leaves opposite, (1—)3—7(—9)-foliolate; petiole and rachis slender; stipules absent; leaflets ovate-lanceolate, 3—10 cm x 1—4 cm, base acute, apex acuminate, irregularly serrate, slightly hirsute on midrib and in vein axils beneath, subsessile. Inflorescence an axillary or terminal, few-flowered raceme. Flowers bisexual, 5-merous, faintly scented; pedicel short, irregularly curved or twisted; calyx narrowly cylindrical-campanulate, 5—7 mm long, with subequal teeth, glabrous; corolla narrowly campanulate, 3.5—5 cm long, tube dorsiventrally compressed, lobes orbicular, subequal, bright yellow, with red stripes at the throat; stamens 4, in 2 unequal pairs, included, c. 6 mm long, sterile fifth stamen much reduced; ovary superior, narrowly cylindrical, 2-celled, lepidote, style filiform, glabrous, stigma flat. Fruit a linear, compressed capsule 10—25 cm x 0.5—0.8 cm, smooth, brown when ripe, tardily dehiscent, many-seeded. Seeds oblong, flat, c. 20 mm x 6 mm, with a membranous transparent wing on each end. Seedling with epigeal germination.
Tecoma stans flowers and fruits profusely throughout the year in South-East Asia. The flowers are frequently visited by humming birds and sunbirds.
Tecoma comprises 13 species and occurs naturally almost exclusively from the southern United States to Argentina, but 1 species is indigenous in southern Africa, which is sometimes considered to belong to a segregate genus Tecomaria.

In South-East Asia Tecoma stans can be found as a garden escape and naturalized from sea-level up to 1000 m altitude.

Tecoma stans is easily propagated by seed, suckers or cuttings.

In view of its large natural distribution, its popularity as a garden ornamental and its preference for anthropogenic habitats, Tecoma stans is not threatened by genetic erosion.

Little is known about the pharmacological activities of Tecoma stans. Further research is needed to evaluate the potential of the traditional medicinal uses, especially the use for the treatment of diabetes mellitus.

[247]Flora Malesiana (various editors), 1950—. Foundation Flora Malesiana. Rijksherbarium/Hortus Botanicus, Leiden, the Netherlands.
[576]Lozoya-Meckes, M. & Mellado-Campos, V., 1985. Is the Tecoma stans infusion an antidiabetic remedy? Journal of Ethnopharmacology 14(1): 1—9.
[646]Morton, J.F., 1981. Atlas of medicinal plants of Middle America. Bahamas to Yucatan. Charles C. Thomas, Springfield, Illinois, United States. 1420 pp.
[760]Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha Publishing Co., Quezon City, the Philippines. 1262 pp.
[797]Roman-Ramos, R., Flores-Saenz, J.L., Partida-Hernandez, G., Lara-Lemus, A. & Alarcon-Aguilar, F., 1991. Experimental study of the hypoglycemic effect of some antidiabetic plants. Archivos de Investigacion Medica 22(1): 87—93.

[94]Binutu, O.A. & Lajubutu, B.A., 1994. Antimicrobial potentials of some plant species of the Bignoniaceae family. African Journal of Medicine and Medical Sciences 23(3): 269—273.
[386]Huxley, A., Griffiths, M. & Levy, M., 1992. The new Royal Horticultural Society dictionary of gardening. 4 volumes. The MacMillan Press Ltd., London, United Kingdom. 3353 pp.

Mindarti Harapini

Harapini, M., 2003. Tecoma stans (L.) Juss. ex Kunth. In: Lemmens, R.H.M.J. and Bunyapraphatsara, N. (Editors): Plant Resources of South-East Asia No 12(3): Medicinal and poisonous plants 3. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea