Bauhinia (PROSEA Medicinal plants)

Plant Resources of South-East Asia Introduction

List of species

Bauhinia L.

Protologue: Sp. pl. 1: 374 (1753); Gen. pl. ed. 5: 177 (1754).

Family: Leguminosae

Chromosome number: x= 13, 14; B. malabarica, B. purpurea, B. tomentosa, B. vahlii: 2n= 28, B. variegata: 2n= 28, 32

Origin and geographic distribution

Bauhinia is a pantropical genus of approximately 300 species. In all 69 species are recorded for South-East Asia.

Uses

Throughout South-East Asia various parts of numerous Bauhinia species are used in poulticing to reduce swelling and bruises, and to ripen ulcerations and boils. Decoctions of various plant parts are taken internally as a febrifugal, antidiarrhoeal and antidysenteric remedy. In the Philippines B. binata Blanco is used against blood spitting, bleeding in general and dysentery. In Sarawak a decoction of the root of B. kockiana Korth. is drunk to treat gonorrhoea and body pains resulting from sickness. In Ternate (Indonesia) mention is made of a decoction of the root of B. lingua DC. as a bath with febrifugal properties.

B. malabarica Roxb., known for its low-grade timber applications, is used in folk medicine as well. Pounded bark is applied in Timor for poulticing wounds. In the Philippines an infusion of fresh flowers or a decoction of the bark is known to be antidysenteric. The leaves are topically applied to the head in fevers accompanied by headaches. In India a decoction of the root bark is a common remedy for liver troubles. In Riau Province (Sumatra) leaves of an unidentified Bauhinia were rolled into cigarettes and the smoke inhaled to treat polyps in the nasal tract.

B. pullei Craib, known from Thailand and Cambodia, is used in traditional Thai medicine. A decoction or powder of the stem is applied as a detoxifying agent. The seeds are used as an anthelmintic, diaphoretic and antipyretic.The root juice of B. vahlii Wight & Arnott is applied to cuts and wounds in traditional Nepalese medicine. The root of B. viridescens Desv. is used in Vietnamese folk medicine to treat colitis.

The bright flowers of Bauhinia make them attractive ornamentals or roadside trees. B. purpurea apart from being an ornamental is well known as the source of Bauhinia purpurea agglutin (BPA), a lectin with an affinity to galactose and lactose, widely applied in biochemical, immunochemical and histochemical studies. The bark of Bauhinia is used to make rope and stems of smaller lianescent species are used for binding. Some Bauhinia species reputed for their fibre application are used medicinally as well. In Johor (Peninsular Malaysia) leaf juice of B. integrifolia Roxb. (synonyms: B. cummingiana (Benth.) Fern.-Vill., B. flammifera Ridley) is used for stomach disorders; in the Philippines a decoction of the roots is administered as a post-partum medicine and to treat coughs. In Java sap from the stem or dried and powdered leaves of B. scandens L. are taken as a cough medicine. The young leaves and flowers of various Bauhinia species are eaten as a side dish with rice, or used to flavour meat and fish. Leaves of some species are used as wrappers, for lining or even as plates. Sometimes the seeds are edible.

Properties

The bark of various Bauhinia species contains considerable amounts of tannin. Medicinal uses of bark can be largely attributed to the presence of these tannins. Flavonoids are a common feature of Bauhinia. B. malabarica, B. valhii and B. variegata contain quercetol glycosides in every organ, and kaempferol glycosides in the flowers.

A methanol extract of the roots of B. vahlii showed cytotoxicity against the Vero cell line at 100 μg/ml, and herpes simplex virus-1 (HSV-1) was inactivated at 25 μg/ml. Root extracts of B. malabarica showed moderate in-vitro antimalarial activity with EC₅₀ values of 0.9-18 μg/ml. Racemosol and demethylracemosol (stilbenes) isolated from the root extract exhibited cytotoxicity against KB (EC₅₀ at 15.0 μg/ml and 5.6 μg/ml, respectively) and BC (EC₅₀ at 6.1 μg/ml and 3.6 μg/ml, respectively) cell lines.

Administration of B. purpurea bark extract to female mice at 2.5 mg/kg body weight for 20 days significantly stimulated thyroid function without hepatotoxic effects. An ethanol extract of the leaves showed significant antidiarrhoeal effects in castor oil-induced diarrhoea and gastro-intestinal motility test models in rats.

Administration of a methanol extract of B. racemosa Lamk flower buds (at 2.0 g/kg body weight) had a significant anti-ulcerogenic effect on aspirin-induced gastric ulcers in rats.

In a general screening experiment an ethanol extract of B. variegata stem bark showed activity with respect to gross effect, hypothermia and antagonism of amphetamine hyperactivity. In another experiment crude organic and aqueous extracts of dried flowers and leaves showed antibacterial activity.

Botany

• Trees or shrubs, unarmed or with intrastipular spines or lianas usually with simple tendrils; branches terete or angular.
• Leaves alternate, simple, entire, 2-lobate or 2-foliolate; stipules various, deciduous or persistent, intrastipular trichomes variously developed.
• Inflorescence racemose, corymbose or paniculate, or flowers solitary.
• Flowers usually bisexual; hypanthium short-cupulate to long-tubular; calyx spathaceous or irregularly deeply divided into 2-5 lobes or shallowly 5-lobed or 5-dentate; petals (1-)5(-6), subequal to greatly unequal, white, various shades of red to purple or yellow; fertile stamens 0-10, staminodes often present; ovary superior, stiped, 1-celled.
• Fruit a flat suborbicular to elliptical, obovate or linear pod, woody or thin-valved, dehiscent or indehiscent.
• Seeds orbicular to elliptical; endosperm present or absent.
• Seedling with epigeal germination; cotyledons emergent; hypocotyl elongated.

Bauhinia can be found flowering and fruiting throughout the year, but some species have a distinct seasonality. Ectomycorrhizae are known to be present in some Bauhinia species.

B. malabarica differs from other South-East Asian Bauhinia particularly in being dioecious.

Ecology

Bauhinia is found in most types of vegetation ranging from evergreen lowland rain forest to mountain forest up to 2000(-3000) m altitude and savanna, scrub and dry deciduous forest to swamp forest, on various soils.

Management

Bauhinia can be propagated by seed, layering or grafting. Cuttings of semi-ripe wood with leaves removed will root in moist sand. Bauhinia should preferably be grown in full sun in fertile, moisture-retentive but well-drained soils.

Genetic resources

The Bauhinia species treated here generally have either a rather large natural distribution or are widely cultivated and do not seem to be seriously threatened by genetic erosion.

Prospects

Bauhinia species show cytotoxic and antimicrobial activity, that may partly support their traditional uses. The stimulatory effect on thyroid function without hepatotoxic effects of B. purpurea bark is very interesting. However, further research is needed to evaluate possible future applications.

Literature

28, 241, 247, 487, 670, 719, 883, 916.

Selection of species

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Authors

• J.W.A. Ridder-Numan