Melastoma (PROSEA)
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Introduction |
Melastoma L.
- Protologue: Sp. pl. 1: 389 (1753); Gen. pl. ed.5: 184 (1754).
- Family: Melastomataceae
- Chromosome number: x= 9-12; M. malabathricum: 2n= 24 (also polyploids and aneuploids)
Major species
- Melastoma malabathricum L.,
- M. sanguineum Sims.
Vernacular names
- Indonesia: senduduk
- Malaysia: sendudok (Peninsular).
Origin and geographic distribution
Melastoma comprises 22 species and is centered in South-East Asia, but extends to India, southern China, northern Australia and Oceania.
Uses
Melastoma is used throughout South-East Asia for its astringent properties. In Indonesia M. malabathricum is predominantly used whereas in Malaysia M. sanguineum is preferred. In Cambodia, the roots of M. sanguineum are further considered a stimulant and tonic. In the Moluccas, the pounded roots of a plant called "birurang merah" or "ligura banga", possibly M. cyanoides Sm. (synonyms Osbeckia annamanica Guill., Osbeckia papuana Cogn., Otanthera cyanoides (Sm.) Triana) or M. moluccana Blume (synonyms Otanthera moluccana (Blume) Blume, Otanthera nicobarensis Teijsm. & Blume, Otanthera novoguineensis Baker f.) are taken to prevent a miscarriage. The fruits are given to children to prevent bed-wetting. The roots, leaves, flowering tops or berries of several Melastoma from Indo-China e.g. M. dodecandrum Lour. (synonym Melastoma repens Desr.), M. saigonense (Kuntze) Merr. and M. septemnervium Lour. (synonym Melastoma candidum D. Don) are used in the same way as M. sanguineum in diarrhoea, leucorrhoea, and dysentery for their astringent properties.
The fruit of M. malabathricum yields a black or purple dye, the leaves and roots yield a pink dye. The ashes from the plant can be used as a dye mordant. The fruits of various Melastoma are eaten as a snack.
Production and international trade
Melastoma is only used at the local level and fresh or dried shoots or leaves are on sale in local markets.
Properties
In general, Melastoma species are rich in tannins of the hydrolysable type. Most of them are di- and trimers, with reported bactericidal and antiviral activities.
From the acetone extract of dried leaves of M. malabathricum, purchased from a market in Sukabumi (Indonesia), 14 tannins including malabathrins B, C and D, the dimers nobotanins B, G and H and the trimer nobotanin J, were isolated. Nobotanin B is reported active against human immunodeficiency virus (HIV) in vitro. Furthermore, M. malabathricum shows a broad spectrum antibacterial activity against gram positive bacteria, thereby supporting its use in cut, burn and wound treatment. It is further capable of suppressing established concentrations of Staphylococcus aureus, thereby supporting its use for abscesses, boils and swellings caused by infections.
A leaf extract of M. malabathricum showed a strong inhibition in the tetradecanoylphorbol acetate (TPA)-induced ear oedema test, at a dose of 2 mg per ear.
An extract of M. dodecandrum with 80% aqueous acetone (MDL) inhibited nitric oxide (NO) production by a murine macrophage-like cell line, RAW264.7, activated with lipopolysaccharide (LPS) and recombinant mouse interferon-gamma (IFN-gamma). The majority of the inhibitory activity was recovered in the 50% methanol extracts, which contained hydrolysable tannins. Among the latter, casuarinin, casuarictin, pedunclagin and nobotanin B exhibited strong inhibitory activities toward NO production, with ID50 values between 2.0 and 5.1 μM. Both MDL and the purified tannins significantly reduced the induction of the inducible nitric oxide synthase (iNOS) protein in the course of macrophage activation with LPS and IFN-gamma. In addition, the NO production by macrophages preactivated with LPS and IFN-gamma for 16 h was also inhibited by these tannins, with IC50 values around 30-130 μM, but not by MDL. These results suggest that MDL has the pharmacological ability to suppress NO production by activated macrophages and that the hydrolysable tannins have major inhibitory activities.
Three active principles were isolated from the leaves of M. septemnervium using the screening of hypotensive effects in the spontaneously hypertensive rat model (SHR). Intravenous injection of castalagin, procyanidin B-2, or helichrysoside into SHR lowered the mean blood pressure in a dose-dependent manner, with helichrysoside being the most potent compound. Plasma noradrenaline (NA) levels, both basal in SHR and elevated in normal rats through cold-stress stimulation, were attenuated by these compounds in a way which was not influenced by adrenalectomy. Decrease of NA release from sympathetic nerves was assumed to be responsible. Moreover, the hypertensive effect of various vasoconstrictors in anaesthetized rats was reduced by helichrysoside. The same results were also observed in castalagin or procyanidin B-2 treated animals. The results indicate that the three principles possess the ability to lower blood pressure through a decrease of sympathetic tone as well as due to direct vasodilatation in SHRs.
Description
- Erect or procumbent shrubs or small trees up to 10 m tall.
- Leaves opposite, simple, lanceolate to ovate, base acute, rounded to cordate, apex acute or acuminate, margin entire, 3-, 5-, 7- or 9-veined, almost glabrous, strigose or subvillose to villose; petiolate; stipules absent.
- Inflorescence terminal or in distal leaf axils, usually cymose, bracteolate.
- Flowers bisexual, 5(-8)-merous, diplostemonous; hypanthium campanulate, moderately to densely covered with scales, bristles or complex emergences; sepals triangular to lanceolate, deciduous; petals obovate; stamens normally dimorphic; ovary hemi-inferior, adnate to the hypanthium by 10 septa, 5-locular and apically bristly, many-seeded.
- Fruit a campanulate dry capsule, opening apically, or a fleshy capsule, splitting irregularly transversally or longitudinally, or an indehiscent berry.
- Seed minute, cochleate, embedded in the pulp.
- Seedling with epigeal germination; cotyledons leafy; hypocotyl elongated; leaves simple, opposite.
Growth and development
Pollination of Melastoma is by bees or bumble-bees. Dispersal of the seed is enhanced by frugivorous birds. Melastoma can be found flowering and fruiting throughout the year. In general Melastoma is not the first to colonize clearings; field observations suggest that germination is more successful in light shade, provided by grasses or sedges, with slightly increased relative humidity. Recent laboratory tests, however, indicate a preference for full daylight. As a weed in pineapple on peat soil M. malabathricum started flowering when 2 m tall and 5 months of age, and may grow up to 3 m in 2 years.
Other botanical information
The genus Othanthera, traditionally placed close to Melastoma because of its indehiscent fleshy fruits, isomorphic stamens and different inflorescences has been included here. Most important for species delimitation are the leaf and hypanthium indumentum. Character combinations and quantitative characters have to be used for species delimitation due to the variation of most vegetative and flower characters. In many species, especially M. malabathricum, morphological characters vary locally, which has resulted in the taxonomic recognition of numerous geographically restricted species here considered synonyms.
Ecology
Most Melastoma are pioneers with a high dispersal capacity. M. malabathricum can germinate and grow in fields of Imperata cylindrica (L.) Raeuschel and finally smother this grass.
Propagation and planting
Melastoma is propagated by seed. In a seedling trial in Malaysia seeds of M. sanguineum germinated in 25-50 days. Trials with various media for M. malabathricum in Singapore gave 65% germination within 10-15 days and up to 80% germination within 30 days.
Diseases and pests
M. malabathricum can be a serious weed in pastures, pineapple and other crops on peat soils. It is also a serious weed in oil palm, rubber and coconut. Locally it can be a weed in cassava, sugar cane, tea and upland rice.
Harvesting
Melastoma roots, shoots, leaves or fruits are harvested throughout the year, whenever the need arises.
Handling after harvest
In general leaves and roots are used fresh, but they may be dried and powdered for storage for later use.
Genetic resources and breeding
All Melastoma species treated here have a large area of distribution and are favoured by human disturbance. They do not seem to be at risk of genetic erosion.
Prospects
The tannins isolated from Melastoma show several in vitro, (e.g. antibacterial, antiviral, inhibition of NO production) and in vivo (antihypertensive) effects, which are very interesting. These effects merit further research in order to evaluate their possibilities in the future development of new lead-compounds or medicines.
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. 2 (I-Z) pp. 1462-1465.
- Cheng, J.T., Hsu, F.L. & Chen, H.F., 1993. Antihypertensive principles from the leaves of Melastoma candidum. Planta Medica 59(5): 405-407.
- Ishii, R., Saito, K., Horie, M., Shibano, T., Kitanaka, S. & Amano, F., 1999. Inhibitory effects of hydrolysable tannins from Melastoma dodecandrum Lour. on nitric oxide production by a murine macrophage-like cell line, RAW264.7, activated with lipopolysaccharide and interferon-gamma. Biological and Pharmaceutical Bulletin 22(6): 647-653.
- Meyer, K., 2001. Revision of the Southeast Asian genus Melastoma (Melastomataceae). Blumea 46(2): 351-398.
- Mustapha, N.M., Ali, R.M. & Shaari, K., 2000. Evaluation of anti-inflammatory activity of some Malaysian medicinal plants using the mouse ear oedema assay. Journal of Tropical Forest Products 6(1): 106-112.
- Yoshida, T., Nakata, F., Hosotani, K., Nitta, A. & Okuda, T., 1992. Dimeric hydrolysable tannins from Melastoma malabathricum. Phytochemistry 31(8): 2829-2833.
Selection of species
Authors
- J.L.C.H. van Valkenburg & N. Bunyapraphatsara
