Rourea (PROSEA)
Introduction |
Rourea Aublet
- Protologue: Hist. pl. Guiane: 467 (1775).
- Family: Connaraceae
- Chromosome number: x = unknown;R. minor: 2n= 28
Major species
Rourea mimosoides (Vahl) Planch., R. minor (Gaertner) Alston.
Origin and geographic distribution
Rourea comprises about 40-70 species and is found in both the New World and Old World tropics.
Uses
In South-East Asia, various parts of R. mimosoides and R. minor are used for gastro-intestinal and urogenital disorders. They are generally considered tonic and in decoction are a well-known post partum medicine. In Indonesia, the soaked leaves of R. fulgens Planch. (synonym Santaloides fulgens O. Kuntze) and R. rugosa Planch. (synonym Santaloides rugosum (Planch.) O. Kuntze) are externally applied to the abdomen to soothe stomach-ache. In Peninsular Malaysia, a decoction of the roots of R. rugosa is given for constipation. A poultice of the leaves of R. emarginata (Jack) Jongkind (synonyms Roureopsis emarginata (Jack) Merr., Roureopsis pubinervis Planch.) is used in fevers, ague, and on any part of the body for aches. The boiled roots of R. acutipetala Miq. (synonyms Roureopsis acutipetala (Kurz) Leenh., Taeniochlaena acutipetala Kurz) are used as an application for lumbago.
In India, roots and twigs of R. minor are employed as a bitter tonic and prescribed for rheumatism, scurvy, diabetes and pulmonary complaints. The roots are also used as a mild aperient and in external applications for ulcers and skin complaints. In Africa, the seeds of several species are used as dog-poison. The roots of R. obliquifoliolata Gilg from Central Africa are taken finely ground as a cold infusion against diarrhoea and dysentery. The plant is also used for toothache and elephantiasis.
The flexible tough stems of several Rourea species are used for binding purposes.
Production and international trade
Rourea is only used on a local scale.
Properties
Aqueous extracts of leaves and stems of R. mimosoides from Sumatra showed some antimicrobial activity against gram-positive ( Staphylococcus aureus ) and gram-negative ( Escherichia coli ) bacteria in vitro. Methanol and aqueous extracts of roots of R. obliquifoliolata show strong antibacterial activity against a range of enteropathogens (e.g MICs 31.25μg/ml for Vibrio cholerae and Shigella dysenteriae ) in vitro. The aqueous extract also acted weakly against Entamoeba hystolytica with an MIC value of 500μg/ml after 72 and 144 hours’ incubation. A general phytochemical screening found that biological activity may well be attributed to the presence of tannins; this would support its traditional use as an antidiarrhoeal.
A decoction of the roots of R. minor in a small dose acts as an emetic. Larger doses are poisonous. The decoction mixed in the food of pigs and dogs kills them. A water extract has no decisive effects on dogs or guinea-pigs. The fruit is poisonous to dogs but has no effect on guinea-pigs. No information is available about the principle responsible for this activity. However, from the roots of R. orientalis Baill., an African species traditionally used as a dog-poison, a neurotoxic compound was isolated, which was identified as methionine sulphoximine. From the roots of Indian R. minor , n-hentriacontane, leucopelargonidine and rapanone were isolated.
Description
Lianas, shrubs or small trees; twigs often ending in a tendrilloid tip. Leaves alternate, imparipinnate, occasionally unifoliolate, leaflets opposite or subopposite, entire; stipules absent. Inflorescence axillary, paniculate or racemose, often together pseudo-terminal. Flowers bisexual, 4-5-merous, heterodistyllous, sweet-scented, sepals free or almost completely connate, imbricate in bud, usually accrescent, petals lanceolate, up to 2-3 times as long as sepals, stamens 10, in 2 whorls, carpels 5, free. Fruit an ovate to ellipsoid follicle, 1-2(-5) per flower, apex rounded to acute or beaked, orange to red, dehiscing by a ventral suture or more or less circumscissile at base, 1(-2) seeds per follicle. Seed subovoid to ellipsoid, testa partly or totally fleshy, this part yellow to red, or the seed enveloped by a fleshy arilloid, endosperm absent. Seedling with epigeal or hypogeal germination, first two leaves opposite.
Growth and development
R. mimosoides and R. minor flower and fruit throughout the year. The sweet-scented flowers are most likely pollinated by insects. Dispersal is probably effected by birds, in view of the conspicuous fruit with the contrasting pericarp and seed, (partly) covered by a fleshy yellow to orange arilloid.
Other botanical information
In a recent revision, Rourea has been divided into 5 sections. In South-East Asia 3 sections are present, i.e. section Rourea , section Roureopsis (e.g. R. acutipetala , R. emarginata ), and section Santaloides (e.g. R. fulgens , R. mimosoides , R. minor , R. rugosa ). Within the population of the species complex R. minor , certain local populations can be distinguished. However, when considering larger distributional areas, the distinguishing characters merge. A non-geographical variation in number and dimensions of leaflets and size of fruits can be observed. Rourea may well be confused with Sarcotheca ( Oxalidaceae ); synonyms linking the 2 genera abound. However, Rourea has a dry indehiscent fruit containing a seed covered in an arilloid, whereas Sarcotheca has a fleshy fruit and seed without an arilloid.
Ecology
Rourea is found in both primary and secondary forest, with a preference for forest edges and margins. Most species are confined to lowland habitats.
Propagation and planting
Rourea is propagated by seed.
Harvesting
Leaves, bark and roots of Rourea are collected whenever the need arises.
Handling after harvest
Leaves of Rourea are used either fresh or dried; roots, bark and stem parts are either used directly or stored for some time.
Genetic resources and breeding
The Rourea species treated here are widespread and common throughout South-East Asia. They are commonly encountered in disturbed habitats and do not seem to be at risk of genetic erosion. There are no known breeding programmes of Rourea .
Prospects
The use of tannin-containing extracts in the treatment of diarrhoea is quite well documented; the mechanism of action is believed to be the absorption of bacterial toxins. When extracts of e.g. R. obliquifoliolata also show antibacterial activity against enteropathogenic organisms, this could be an extra advantage. However, more research is needed to investigate the activity in vivo and the toxicological aspects in order to fully evaluate its potential use in (local) medicine.
Literature
- Burkill, I.H., 1966. A dictionary of the economic products of the Malay Peninsula. Revised reprint. Ministry of Agriculture and Co-operatives, Kuala Lumpur, Malaysia. Vol. 1 (A-H) pp. 656-666, Vol. 2 (I-Z) pp. 1950, 1984-1986, 2157.
- Grosvenor, P.W., Gothard, P.K., McWilliam, N.C., Supriono, A. & Gray, D.O., 1995. Medicinal plants from Riau Province, Sumatra, Indonesia. Part 1: uses. Journal of Ethnopharmacology 45: 75-95.
- Jongkind, C.C.H., 1989. Rourea Aublet. In: Breteler, F.J. (Editor): The Connaraceae, a taxonomic study with emphasis on Africa. Agricultural University Wageningen Papers 89-6. pp. 310-368.
- Leenhouts, P.W., 1958. Connaraceae. In: van Steenis, C.G.G.J. (Editor): Flora Malesiana. Series 1, Vol. 5(4). Noordhoff-Kolff N.V., Djakarta, Indonesia. pp. 495-541.
- Otshudi, A.L., Vercruysse, A. & Foriers, A., 2000. Contribution to the ethnobotanical, phytochemical and pharmacological studies of traditionally used medicinal plants in the treatment of dysentery and diarrhoea in Lomela area, Democratic Republic of Congo (DRC). Journal of Ethnopharmacology 71(3): 411-423.
- Quisumbing, E., 1978. Medicinal plants of the Philippines. Katha Publishing Co., Quezon City, the Philippines. pp. 356-358.
Authors
J.L.C.H. van Valkenburg