1279

12(2): Medicinal and poisonous plants 2

Rourea Aublet

Hist. pl. Guiane: 467 (1775).

CONNARACEAE

x = unknown; Rourea minor: 2n = 28

Major species Rourea mimosoides (Vahl) Planch., Rourea minor (Gaertner) Alston.

Rourea comprises about 40—70 species and is found in both the New World and Old World tropics.

In South-East Asia, various parts of Rourea mimosoides and Rourea 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 Rourea fulgens Planch. (synonym Santaloides fulgens O. Kuntze) and Rourea 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 Rourea rugosa is given for constipation. A poultice of the leaves of Rourea 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 Rourea acutipetala Miq. (synonyms Roureopsis acutipetala (Kurz) Leenh., Taeniochlaena acutipetala Kurz) are used as an application for lumbago.
In India, roots and twigs of Rourea 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 Rourea 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.

Rourea is only used on a local scale.

Aqueous extracts of leaves and stems of Rourea 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 Rourea obliquifoliolata show strong antibacterial activity against a range of enteropathogens (e.g MICs 31.25 µg/ml for Vibrio cholerae and Shigella dysenteriae) in vitro. The aqueous extract also acted weakly against Entamoeba hystolytica with an MIC value of 500 µg/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 Rourea 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 Rourea 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 Rourea minor, n-hentriacontane, leucopelargonidine and rapanone were isolated.

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.

Rourea mimosoides and Rourea 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.

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. Rourea acutipetala, Rourea emarginata), and section Santaloides (e.g. Rourea fulgens, Rourea mimosoides, Rourea minor, Rourea rugosa). Within the population of the species complex Rourea 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.

Rourea is found in both primary and secondary forest, with a preference for forest edges and margins. Most species are confined to lowland habitats.

Rourea is propagated by seed.

Leaves, bark and roots of Rourea are collected whenever the need arises.

Leaves of Rourea are used either fresh or dried; roots, bark and stem parts are either used directly or stored for some time.

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.

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. Rourea 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.

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.

J.L.C.H. van Valkenburg

Rourea mimosoides
Rourea minor

van Valkenburg, J.L.C.H., 2001. Rourea Aublet. 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:
Rourea mimosoides
Rourea minor