Rumex (PROSEA Medicinal plants)

Plant Resources of South-East Asia
Introduction

List of species

Rumex L.

Protologue: Sp. pl. 1: 333 (1753); Gen. pl. ed. 5: 156 (1754).

Family: Polygonaceae

Chromosome number: x= 10, 20; R. acetosa: 2n= 14, 15; R. crispus: 2n= 60;R. maritimus, R. patientia: 2n= 40

Major species

Rumex acetosa L.,
R. crispus L.

Vernacular names

Sorrel, dock (En)
Oseille, surelle (Fr)
Indonesia: daun suring, surengan.

Origin and geographic distribution

Rumex consists of about 200 species originating from the northern temperate regions, now distributed worldwide, sometimes cultivated. In South-East Asia, wild plants are mostly escapes from cultivation.

Uses

The rhizomes and roots of many Rumex species, especially R. acetosa and R. crispus, but also R. dentatus L., R. maritimus and R. wallichii, are generally used for medicinal purposes in South-East Asia and India, internally as a laxative, and externally applied on swellings and against ringworm (Tinea sp.). The leaves are used for this latter purpose as well.

In Indonesia and Indo-China, the rhizomes of R. crispus are used as a mild purgative and astringent, and a decoction of the roots is prescribed for intermittent fevers and chronic bronchitis. In China, the rhizomes are also used as tonic and febrifuge. In Vietnam, the dried rhizomes and leaves, in decoction, are used for treatment of tuberculosis, hepatitis, arthritis, diabetes, scabies, haemorrhoids, anaemia and leucorrhoea. In the Philippines, China and Japan, sun-dried rhizomes are used for treatment of chronic bronchitis, ringworm, and haemorrhoids. In Brazil and Cuba, a decoction of the rhizome was formerly taken as an astringent tonic, depurative and laxative. In Cuba this was used especially for people with skin eruptions. The mashed rhizome is applied externally to lymphatic or glandular swellings. In Europe and the United States, the rhizome has been much used in the treatment of syphilis, tuberculosis and rheumatism. They are now mainly taken, like the rhizomes of R. acetosa, as a tonic, haematic, and for acute and chronic inflammation of the nasal passages and respiratory tract. Fatal acute oxalate poisoning after eating large amounts of R. crispus leaves was observed in humans and sheep. Mucus membrane irritation, accompanied by vomiting, is possible following intake of the fresh rhizome, due to its anthrone content.

In Vietnam, the dried roots of R. wallichii are used for treatment of constipation, yellow skin, ringworm, acne, scabies and swellings. The bruised leaves are applied on ringworm and sprains. In India and Vietnam, the seeds of R. maritimus are used as an aphrodisiac and the leaves for the treatment of burns, swellings and ringworm.

In Haiti, a decoction of the root of R. patientia is applied to skin diseases, and taken internally as a tonic, astringent and depurative.

In Malesia, the leaves and petioles of several Rumex species are sometimes eaten raw as a salad or cooked as a rather sour vegetable.

The roots of R. crispus are sometimes used for tanning.

Production and international trade

Whole plants and roots of Rumex are only used on a local scale, and sold in markets and medicine stores.

Properties

R. crispus is known to contain several anthraquinone derivatives, e.g. oxymethyl-anthraquinone (0.2%) and emodin (0.1%) in the roots, and rumicin, physcion, chrysophanol, emodin, aloe-emodin, rhein and their glucosides, in the above-ground parts. Anthraquinone-containing drugs are well-known laxatives. In the colon, bacteria hydrolyse the glycosides and reduce the liberated anthraquinones to anthrones, which act directly on the large intestine to stimulate peristalsis.

The plant also contains 7-11% oxalic acid; fatal acute oxalate poisoning in sheep occurred within 40 hours after having eaten the plants. Clinical signs of poisoning were excess salivation, tremors, ataxia and recumbency. Other signs were hypocalcaemia, azotaemia, perirenal oedema, tubular degeneration.

R. acetosa also contains anthraquinones both in the roots and leaves: physcion, emodin, aloe-emodin, rhein and their glucosides. In addition, an extract showed strong antitumour activity in female ICR mice implanted with Sarcoma 180 solid tumour. The extract depressed aniline hydroxylase, aminopyrinedemethylase activities, prolonged the duration of pentobarbital-induced narcosis, and significantly enhanced the phagocytic activity and complement activity. Also, a water extract of the aerial parts exhibited antifungal activity.

R. nepalensis contains chrysophanic acid. An aqueous and ethanol extract of the leaves showed antihistaminic, anticholinergic and/or antibradykinin activity on rabbit skin in vivo.

The aqueous extract of the leaves of R. patientia was found to possess anti-inflammatory activity in rats in carrageenan, histamine, dextrane, or serotonine formaldehyde-induced oedema tests, as well as in cotton-pellet granuloma and Kabak tests. Acute toxicity studies revealed that the extract was non-toxic up to a dose of 3 mg/kg given orally.

R. wallichii contains anthraquinone glucosides. The aqueous extract of the root significantly increased the tonus of isolated intestines of frog and rabbit.

Adulterations and substitutes

Anthraquinone(-glycosides) are also obtained from several other species, often in higher concentrations. These include Rheum palmatum L. roots, ripe pods of Senna and Cassia spp., Aloe leaves, and frangula (Rhamnus frangula L.) and cascara bark (Rhamnus purshianus DC.).

Description

Annual or perennial, variable herbs, usually with stout rhizomes or roots.
Leaves spirally arranged, the lower ones mostly in a rosette, sheathing at base, ocrea amplexicaul, blade linear, lanceolate, ovate, hastate or sagittate; petiole present.
Inflorescence a raceme or panicle, often elongate, composed of pseudo-clusters.
Flowers small, unisexual or bisexual, perianth segments 6, in 2 whorls of 3, the inner usually enlarged and mostly enclosing the fruit; stamens 6, in 2 whorls of 3, inserted at the base, anthers basifixed; ovary 3-carpellate, styles 3, outwardly deflexed or adnate to the marginal ribs, stigma penicillate or fimbriate.
Fruit a sharply trigonous nutlet, included in the enlarged inner perianth, brown, shiny.
Seedling with epigeal germination; cotyledons small, ellipsoid, apex pointed; first leaf ovate, base cuneate, apex acuminate.

Growth and development

Rumex flowers at the beginning of the rainy season, and fruits ripen 5-6 months later. Rumex is wind pollinated. Seed is dispersed by wind and will pass through digestive tracts of most birds and cattle, but are destroyed when fed to chickens.

Other botanical information

In Rumex, several subgenera are recognized, mainly based on gender of the flowers, the size of the inner perianth in fruit and the form of the leaves. There is no general botanical revision of the genus and therefore the status of lesser-known species remains unclear.

Ecology

Rumex occurs in the northern temperate regions and preferably in the tropical highlands. It is commonly found in humid localities along roadsides, ditches, irrigation canals, and rice fields, and can become a troublesome weed. It prefers sunny or lightly shaded, not too dry localities, and occurs from sea-level up to 500 m altitude. Some species though grow mainly in moist, cool climates, up to 2000-3000 m altitude.

Propagation and planting

Rumex is mainly propagated by seed, and after establishment, by division. Differences in size and in germination requirements are found in Rumex seeds borne on different parts of the plant, but are also caused by the stage of maturity of a plant and the year of production. Most seeds germinate readily under moist conditions. R. crispus may produce 60 000 seeds per plant per year.

Husbandry

Rumex can be cultivated in the tropics at higher altitudes in fertile soils. For optimal leaf production, the inflorescences should be removed. When cultivated under shade, the leaves become less sour. R. acetosa can be cultivated on the same site for 4 years. Rumex grown as a vegetable should be watered every day; for medicinal use, watering once a week is adequate.

Diseases and pests

The leaves of Rumex are often attacked by caterpillars. The larvae and adults of the Chrysomelid Gastrophysa atrocyanea were found to attack in particular weedy R. acetosa and R. crispus var. japonicus, causing a progressive decline of these populations in China.

Harvesting

In Vietnam, whole plants or the roots of Rumex are harvested all year round. The roots are collected preferably before flowering. Mature seeds are harvested at the end of the year.

Handling after harvest

Rumex plants are cleaned and the leaves are cut or just bunched for transport to the market. The roots are chopped and dried.

Genetic resources and breeding

As Rumex produces large amounts of seed, which germinate easily, it is unlikely that it will become rare. A large germplasm collection of Rumex is kept in Gatersleben (Germany).

Prospects

Anthraquinone-containing plants are well-known laxatives, widely used in medicine. The best known preparations, and those of first choice, are senna, frangula or cascara. Therefore, Rumex will probably remain only of local importance, since its anthraquinone content is lower. The potential for cultivating Rumex in the highlands of other South-East Asian countries needs further investigation.

Literature

Aggarwal, P.K., Kumar, L., Garg, S.K. & Mathur, V.S., 1986. Effect of Rumex nepalensis extracts on histamine, acetylcholine, carbachol, bradykinin, and PGs evoked skin reactions in rabbits. Annals of Allergy 56(2): 177-182.
Fleming, T. (Editor), 1998. PDR for herbal medicines. Medical Economics Company, Montvale, New Jersey, United States. pp. 1105-1107.
Le Tran Duc, 1997. Vietnamese medicinal plants: culture, harvesting, preparation, initial treatment. Agricultural Press, Hanoi, Vietnam. p. 645.
Panciera, R.J., Martin, T., Burrows, G.E., Taylor, D.S. & Rice, L.E., 1990. Acute oxalate poisoning attributable to ingestion of curly dock (Rumex crispus) in sheep. Journal of the American Veterinary Medical Association 196(12): 1981-1984.
Perry, L.M., 1980. Medicinal plants of East and Southeast Asia. Attributed properties and uses. MIT Press, Cambridge, Massachusetts, United States & London, United Kingdom. p. 322.
Suleyman, H., Demirezer, L.O., Kuruuzum, A., Banoglu, Z.N., Gocer, F., Ozbakir, G. & Gepdiremen, A., 1999. Antiinflammatory effect of the aqueous extract from Rumex patientia L. roots. Journal of Ethnopharmacology 65(2): 141-148.

Selection of species

Authors

Nguyen Thi Do