1375

12(2): Medicinal and poisonous plants 2

Wedelia Jacq.

Enum. syst. pl. Carib. 8: 28 (1760).

COMPOSITAE

x = unknown; Wedelia biflora: 2n = 30; Wedelia chinensis: 2n = 50

Major species Wedelia biflora (L.) DC., Wedelia chinensis (Osbeck) Merr.

Wedelia is a large tropical and subtropical genus of 50—70 species, with probably about 15 species in South-East Asia.

In South-East Asia and India, Wedelia is commonly used for medicinal purposes, e.g. as a diuretic and anti-inflammatory. When prepared as a tea, the fresh roots and leaves of Wedelia biflora are especially known for their diuretic qualities, but the flower heads are a violent purgative, and old stems and leaves are toxic and can cause horses and goats to vomit and even die. Furthermore, the fresh or cooked roots of Wedelia biflora are used as a stomachic, a febrifuge, an emmenagogue, for checking vaginal discharges and as a cure against a tight chest and dizziness caused by eating poisonous fish and crab. The leaves, prepared as a tea, are an antiperiodic in malaria, and a cure for haematuria, stomach-ache, and in Thailand for headaches. Fresh leaves are used for dressing ulcers and abscesses, and in Malaysia also as a poultice for varicose veins and insect bites. The juice of the leaves mixed with cow's milk is given as a tonic after childbirth. Mixed with ginger, it is used against flatulence.
W. chinensis has analgesic, antipyretic, anti-inflammatory and antimicrobial properties and is commonly used in the treatment of abscesses, arthritis, mammary infections and odontitis. The leaves are considered tonic, alterative, and useful in coughs, headaches and skin diseases. The fruit and flower heads, as well as the leaves, are used in decoction as a purgative and emetic, and in uterine haemorrhage. In Indo-China, the herb is applied as a decoction against abdominal swellings and against hepatitis. In China, the plant is also used to treat diphtheria and haemorrhoids. In Fiji, the leaves are soaked in coconut oil and the oil is used to massage sprained or bruised limbs. A decoction of the leaves is applied to treat bacillary dysentery, infective hepatitis, haemorrhoids, bladder infections, swollen testicles and diarrhoea. The bark is used with coconut milk to treat fish poisoning.
In India, the juice of Wedelia chinensis is also used for tattooing, the colour produced being a deep indelible blue-black. The root is pounded and used as a black dye with salts of iron. In the Philippines and in India, the leaves are used for dyeing grey hair and against baldness.
Two Wedelia species are cultivated as ornamentals: Wedelia trilobata Hitchc. (introduced from South Africa) under lane trees in Singapore, and Wedelia urticifolia (Blume) DC. var. scaberrima DC. is known as a garden plant in Thailand. According to Rumphius, Wedelia moluccana (Blume) DC. has the same medicinal uses as Wedelia biflora.

In Indo-China, Wedelia chinensis is sold dry at markets by herbalists.

The methylene chloride extract of the dried leaves of Wedelia biflora contains, in addition to protein and a high fibre content, the flavonoids 3,3'-di-O-methylquercetin, 3',7-di-O-methylquercetin and 2,7-dihydroxy-3(3'-methoxy-4'-hydroxy)-5-methoxy-isoflavone and also veratrylidenehydrazide and rhamnazine. The first two compounds exhibit antifungal activity against Rhizoctonia grandis, and the second compound also possesses antifeedant activity against the cotton boll-weevil (Anthonomus grandis). 24-Ethylcoprostanone and ent-kauradienoic acid (a diterpene) are present in all above-ground parts of Wedelia biflora and also show antifeedant activity against the cotton boll-weevil, while the kaurane-type diterpene 16-methylkaur-15-en-19-oic acid and grandifloric acid show antifungal activity against Pythium ultimum and Rhizoctonia solani. An aqueous extract of the plant is toxic to American cockroaches. Wedelia chinensis leaves are known to contain around 0.05% wedelolactone (5,6-dihydroxy-2(2,6-dihydroxy-4-methoxyphenyl)benzofuran-3-carboxylic acid lactone), which is analogous in structure to coumestrol, a well-known phyto-oestrogen found in many Leguminosae (e.g. Medicago sativa L., Melilotus spp. or Trifolium spp.). Wedelolactone shows marked and selective inhibitory activity against 5-lipoxygenase, a key enzyme system involved in inflammatory reactions. The leaves also contain isoflavonoids, and melissic- and lignoceric acid, stigmasterol, stigmasteryl glucoside, (—)-kaur-16-en-19-oic acid and a mixture of three kaurenoid esters have been isolated from the whole dried plants.
The crude aqueous extract shows significant protection of the liver against the hepatotoxins CCl₄ and acetaminophen in mice, and D-(+)-galactosamine in rats. An alcoholic extract of the whole plant has a protective activity against CCl₄-induced liver injury in vivo. More detailed investigations in vitro reveal very marked antihepatotoxic activity of (—)-kaur-16-en-19-oic acid and the esters in assays with liver cells damaged by CCl₄ and D-(+)-galactosamine. Lignoceric acid shows activity against CCl₄-induced damage, and stigmasterol and its glucoside give some protection against both types of damage.
Further pharmacological effects include a significant healing effect of an aqueous extract of the leaves on open or sutured wounds in rats. An alcoholic extract increases bile flow in rats, which suggests a stimulation of liver secretory capacity. It has been observerd that growth of Ehrlich's ascites carcinoma is inhibited by a 5% ethanolic extract of the plant. The minimum lethal dose of the alcoholic extract was > 200 mg/kg orally in mice.
The aqueous extract of the leaves of Wedelia chinensis has an allelopathic effect on seedling growth of radish, mung bean, cucumber and rice, on the germination of rice, and on the germination and seedling growth of Althernanthera philoxeroides Griseb. and Eragrostis cilianensis Vignolo.

Eclipta prostrata (L.) L. is said to possess properties similar to those of Wedelia chinensis, because of the presence of the coumestans wedelolactone and demethylwedelolactone, which are liver drugs. In India, Wedelia chinensis is supposed to be more active than Taraxacum officinale Weber ex F.H. Wigg. for diseases of the digestive tract and for liver obstructions.

Perennial herbs or subshrubs, scabrous to hirsute, with a camphor-like odour; stems creeping or climbing. Leaves opposite, simple, blade elliptical to ovate, entire or toothed, often with 3 pronounced basal veins; petiole present or leaf subsessile; stipules absent. Inflorescence consisting of 1—5 or more long-pedunculate heads, terminal and axillary; involucre 1-whorled, with a few smaller outer bracts, receptacle bracts strongly veined, obtuse, enfolding the achenes. Ligulate flowers 6—10, apex of corolla usually 2—3-toothed, yellow, corolla of tubular flowers 5-lobed, (greenish) yellow; anthers 5; style bifid. Fruit a thick, cuneiform achene, those of ligulate flowers 3-angled, of tubular flowers 4-angled; pappus consisting of 1—2 short hairs or absent, or crown-like, toothed or ringed, lower part glabrous.

Wedelia can be found flowering throughout the year, when sufficient water is available.

Wedelia belongs to the tribe Heliantheae, and is a large genus, in which only some partial revisions exist. Wedelia biflora has recently been renamed as Wollastonia biflora (L.) DC. but the status of other Wedelia species in Malesia is still unclear. It seems therefore appropriate to conserve the old name, until a revision of Wedelia and closely related genera is completed. The status of Wedelia moluccana (Blume) DC. and Wedelia prostrata Hemsl., for which medicinal uses are mentioned, will then hopefully be elucidated.

South-East Asian Wedelia species are common near the coast, also on sandy beaches, in plantations and waste places. They prefer sunny to lightly shaded localities.

Wedelia is propagated mainly by seed, but shoots can root quite easily as well.

Wedelia is very common near the seaside and can be picked whenever the need arises.

Wedelia can be used fresh or dried.

Both Wedelia species have a large area of distribution and do not seem to be at risk of genetic erosion. No germplasm collections are known to exist, except in botanical gardens.

Wedelia contains several compounds, e.g. flavonoids, diterpenes and wedelolactone, which have interesting pharmacological activities (antifungal, antifeedant, antihepatotoxic and anti-inflammatory), and therefore merits further research.

Council of Scientific and Industrial Research, 1976. The wealth of India: a dictionary of Indian raw materials & industrial products. Vol. 10. Publications and Information Directorate, New Delhi, India. pp. 567—568.
Fosberg, F.R. & Sachet, M.H., 1980. Systematic studies of Micronesian plants. Smithsonian Contributions to Botany 45: 1—40.
Lin, S.C., Lin, C.C., Lin, Y.H. & Shyuu, S.J., 1994. Hepatoprotective effects of Taiwan folk medicine: Wedelia chinensis on three hepatotoxin-induced hepatotoxicity models. American Journal of Chinese Medicine 22(2): 155—168.
Miles, D.H., Chittawong, V., Payne, A.M., Hedin, P.A. & Kokpol, U., 1990. Cotton boll weevil antifeedant activity and antifungal activity (Rhizoctonia solani and Pythium ultimum) of extracts of the stems of Wedelia biflora. Journal of Agricultural and Food Chemistry 38(7): 1591—1594.
Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha Publishing Co., Quezon City, the Philippines. pp. 1005—1006.
Yang, L.L., Yen, K.Y., Konno, C., Oshima, Y., Kiso, Y. & Hikino, H., 1986. Antihepatotoxic principles of Wedelia chinensis herbs. Planta Medica 6: 499—500.

G.H. Schmelzer

Wedelia biflora
Wedelia chinensis

Schmelzer, G.H., 2001. Wedelia Jacq.. In: van Valkenburg, J.L.C.H. and Bunyapraphatsara, N. (Editors): Plant Resources of South-East Asia No 12(2): Medicinal and poisonous plants 2. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea

The following species in this genus are important in this commodity group and are treated separatedly in this database:
Wedelia biflora
Wedelia chinensis