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<big>''[[Melastoma]]'' L.</big>
__NOTOC__
:Protologue: Sp. pl. 1: 389 (1753); Gen. pl. ed.5: 184 (1754).
:Family: Melastomataceae
:Chromosome number: ''x''= 9-12;''M. malabathricum'': 2''n''= 24 (also polyploids and aneuploids)
== Major species ==
*''Melastoma malabathricum'' L., *''M. sanguineum'' Sims.
== Vernacular names ==
''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 ''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 ==
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 ID<sub>50</sub>values between 2.0 and 5.1μM1 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 IC<sub>50</sub>values around 30-130μM130 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 ==
== 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 ==
== 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.
* 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 ==
<div style="column-count:3;-moz-column-count:3;-webkit-column-count:3">
*[[Melastoma malabathricum (PROSEA)|''Melastoma malabathricum'']]
*[[Melastoma sanguineum (PROSEA)|''Melastoma sanguineum'']]
</div>
== Authors ==
*J.L.C.H. van Valkenburg & N. Bunyapraphatsara
[[Category:Medicinal plants (PROSEA)]]
[[Category:PROSEA]]
