Dendrobium (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Dendrobium Sw.


Protologue: Nov. Act. Regiae Soc. Sci. Upsal., ser. 2(6): 82 (1799).
Family: Orchidaceae
Chromosome number: x= 19;D. crumenatum: 2n= 38,D. nobile: 2n= 38

Major species

Dendrobium crumenatum Sw., D. nobile Lindl.

Vernacular names

  • Indonesia: anggrek
  • Vietnam: hoàng thảo.

Origin and geographic distribution

Dendrobium is a large genus of 900-1400 species, distributed from India, throughout tropical Asia and Japan to Australia, New Zealand and Polynesia. Several species are used medicinally, but most of them are ornamentals.

Uses

In Peninsular Malaysia and Java, the heated pseudo-bulbs of the common Asian D. crumenatum (and similar species) are used for problems with infected ears, by squeezing the juice into it, while the ear is also poulticed with the crushed stems. A preparation of the leaves and flowers is also taken for cholera. In Peninsular Malaysia, the pounded leaves and fruits are applied on boils and pimples. The plant also enters into magic rituals, and is supposed to be very powerful in affections of the brain and nerves.


In Peninsular Malaysia, the Chinese import preparations of D. nobile , which is the most popular medicinally used Dendrobium in China. The stems are slightly sweetish and salty, and have a cooling effect. The whole plant is considered tonic, stomachic, sialagogue, and is prescribed in mild fever following illness, thirst from stress, dryness of mouth and throat, flatulence, anorexia, lumbago, impotence and amblyopia. In Vietnam, the plant is also used for tuberculosis. An infusion from the cut stems is applied for fever, excessive perspiration and weakness after illness, and also for sunstroke and thirst. It can be used interchangeably with D. pulchellum Roxb. and D. gratiossisimum Rchb.f. (synonyms D. boxallii Rchb.f. and D. bullerianum Batem.) from Indo-China, Thailand and India.

In eastern Malaysia and Indonesia the crushed and heated leaves of D. purpureum are used for poulticing infected nails (whitlow), for cooling and maturing. The stem and leaves of D. planibulbe Lindl. from Peninsular Malaysia are pounded and poulticed on skin infections in the neck. A decoction of the root of D. pachyphyllum (O. Kuntze) Bakh.f. (synonym D. pumilum Roxb.) is found from Burma (Myanmar) to Borneo and is used for dropsy. In northern Peninsular Malaysia the pounded leaves of D. subulatum Lindley are applied as a poultice on the forehead for headache. In Sabah, an infusion of the leaves of D. umbellatum Rchb.f. is taken to cure stomach-ache. In the Central Province of Papua New Guinea, the leaves of an unknown Dendrobium are chewed for cough.

The bright polished surface of the stems and pseudo-bulbs of several Dendrobium are used in the plaiting industry throughout South-East Asia. D. crumenatum and similar species are used in the straw-plaiting industry in the Philippines, where the stems are inserted for making a pattern in straw hats. In eastern Malaysia, D. faciferum J.J. Smith is similarly used and in Borneo and Sulawesi, D. utile J.J. Smith.

Production and international trade

Dendrobium is used as a medicinal plant on a local scale only. Most species enter international trade for their ornamental value.


Properties

The stems and pseudo-bulbs of D. nobile contain the alkaloids dendrobine, 3-hydroxy-2-oxodendrobine, dendroxine, dendramine (= 6-oxydendrobine) and 6-oxydendroxine. Biochemically, all are pseudo-alkaloids: the carbon skeleton of the molecule is derived from a sesquiterpene instead of an amino acid. As a purified compound, dendrobine was found to produce progressive paralysis of the peristaltic movement; it seems to act directly on the muscles, and also causes violent uterine contractions. For white mice, the lethal dose is 20 mg/kg, its action being very rapid, resulting in convulsions and paralysis. The effects of the alkaloids dendrobine and nobiline on the electrical activity, and on amino acid-induced depolarisation of primary afferent terminals, were tested in more detail on the frog isolated spinal cord and were compared with those of picrotoxinin and strychnine. Dendrobine caused a slight hyperpolarisation in both dorsal and ventral roots which was accompanied by the augmentation of the dorsal root potential and the ventral root potential and reflex. The amplitude of the dorsal root reflex however, was reduced significantly. It reversibly blocked the presynaptic inhibition caused by antidromic conditioning stimulation of the ventral root. These effects of dendrobine were qualitatively similar to those of strychnine but were somewhat different from those of picrotoxinin. Nobiline had no significant effect on either the root potentials or the reflexes.

From the n-hexane fraction of a methanol extract of D. nobile , the compounds gigantol and moscatilin were isolated. Both compounds showed strong antimutagenic potential under the Ames test ( Salmonella typhimurium TA100 strain), by using well-known mutagens: furylfuramide and Trp-P-1f or gigantol, Trp-P-1 for moscatilin. In another test, the umu gene expression of the SOS response in S. typhimurium TA1535/pSK1002, gigantol displayed strong activity when using furylfuramide, Trp-P-1 and UV-radiation as mutagens. Additionally, moscatilin was also tested for its suppressive activity on these and other common mutagens e.g. 4-nitroquinoline-1-oxide, N-methyl-N'-nitro-N-nitrosoguanidine, benzo-α-pyrene and aflatoxin B(1). With all of the chemicals mentioned, moscatilin showed a dramatic reduction in their mutagenic potential.

Two phenanthrenes were isolated from the aerial parts of D. nobile , and were identified as 4,7-dihydroxy-2-methoxy-9,10-dihydrophenanthrene and denbinobin. These two compounds were found to be cytotoxic against A549 (human lung carcinoma), SK-OV-3 (human ovary adenocarcinoma), and HL-60 (human promyelocytic leukemia) cell lines in culture. The first compound also showed antitumour activity (increase of the life span) in mice, intraperitoneally implanted with 1 X 10-6cells of sarcoma 180.

Finally, several patients with chronic superficial gastritis were perfused in the stomach with 20 g of D. nobile to observe the variations in gastric acidity output, serum gastrin- and plasma somatostatin concentrations. The result showed a significant increase in both acidity output and serum gastrin concentrations. However, no significant change occurred in plasma somatostatin concentration.

Adulterations and substitutes

Other orchids such as Ephemerantha lonchophylla (Hook.f.) P.F. Hunt & Summerh. also yield denbinobin and gigantol.

Description

Epiphytic perennial herbs, with or without cane-type pseudo-bulbs, rhizomes present or absent; stems slender, hairy or not, coloured or not, internodes present in all parts or only basally, glabrous and shiny. Leaves 1-many, usually articulate, duplicative, ovate to linear, green or differently coloured. Inflorescence terminal or axillary, racemose or fascicled, with 1-numerous flowers. Flowers zygomorphic, showy or not, 1 sepal free, the lateral 2 joined at the base, usually subequal to petals, petals 3, lip entire or trilobed, joined to column foot at base, sometimes forming a spur or spur-like extension with lateral sepals; column-foot usually short; pollinia 4, in 2 pairs, waxy, sessile, without appendages like caudicles or viscidia, extrafloral nectaries present. Fruit a conical capsule, dehiscing by longitudinal slits, with many seeds; seeds minute.


Growth and development

Dendrobium grows best under permanent warm temperature conditions, and is usually pollinated by bees or ants. The seeds may be dispersed by wind. D. crumenatum can be found flowering throughout the year, but its main flowering period is between November-April in the humid tropics. Gregarious flowering follows 8-10 days after a temperature drop caused by heavy rainfall. The flowers are usually ephemeral.

Other botanical information

No general review of Dendrobium exists, and the large size of the genus makes it difficult to obtain a good overview. Detailed morphological investigations have shown that the name D. purpureum has been applied at various times to six distinct taxa: D. capituliflorum Rolfe, D. catillare Rchb.f., D. constrictum J.J. Smith, D. kraemeri Schltr., D. morrisonii Schltr. and D. purpureum . The name D. catillare has itself been misapplied to a species which is described under the new name D. taveuniense Dauncey & P.J. Cribb.

Ecology

Many Dendrobium species occur on trees in primary forest, either lowland, mountain or moss forests, in shady conditions, while other prefer more open lowland forest, with a short dry period. Dendrobium is found from sea-level up to 3000 m altitude.

Propagation and planting

Dendrobium is propagated vegetatively by division, by seed or by tissue culture. In vitro multiple shoot production was achieved using axillary buds that were excised from D. nobile and D. crumenatum and were cultured in vitro on four media (Vacin & Went, Knudson C, Murashige & Skoog and Morel) supplemented with 3 mg butyric acid (BA) plus 1 mg naphthalene acetic acid (NAA)/l. The Vacin & Went medium produced the largest number of shoots/culture. In the second experiment, buds were cultured on Vacin & Went medium supplemented with BA or kinetin with and without 1 mg NAA/l. The largest number of shoots/culture was obtained with 1 mg NAA/l plus 3-6 mg BA/l.

Husbandry

Of the Dendrobium species treated here, D. crumenatum , D. nobile and D. purpureum are also cultivated as ornamentals in Europe.

In a test, small plants of D. nobile potted in sphagnum moss or hemlock bark received NPK-fertilizer in 10 different combinations for a period of 2 years. Growth and development were positively correlated to N application, but the highest N level had little effect on flowering. P deficiency suppressed growth, decreased the number of flowers and delayed flowering, whereas K did not have any significant effect at all. Plants in sphagnum moss grew more vigorously than in bark, but showed some root disturbance during the second season. Sprouting of basal axillary buds was promoted by low temperature treatment at 10°C for 16 hours and 20°C for 8 hours during a period of 30-50 days. The date of terminal leaf emergence was markedly advanced by high temperature treatment at 25°C for 40 days when the length of the pseudobulbs was about 5 mm. Maximum stem length was observed at 10-15°C in all cultivars.


Diseases and pests

Many different viruses (e.g. Dendrobium Mosaic Potyvirus, Cymbidium Mosaic Potexvirus), fungi and bacteria are known to attack Dendrobium , while cockroaches, scale insects, caterpillars, red spider mites and slugs can be serious pests, although they rarely eliminate the plants entirely. Young mistletoe ( Loranthus pentandrus L.) plants were found growing on the stems of D. crumenatum in the garden of the Botany Department of the National University of Singapore.

Harvesting

In Vietnam, D. nobile plants are harvested in the dry season.

Handling after harvest

In Vietnam, D. nobile is dried in the sun or in a stove, then cut into small pieces, humidified with alcohol and cooked in vapour before use.

Genetic resources and breeding

Some Dendrobium are widespread and common throughout South-East Asia, either naturally or as a result of cultivation, and do not seem to be at risk of genetic erosion. Some of them though have become extinct from the wild, because of overexploitation. Many Dendrobium have been brought into cultivation for ornamental purposes in hothouses in temperate climates, and gardens elsewhere, and a vast array of cultivars and hybrids have been developed. The Dendrobium species described here are widespread, and plant parts used for medicinal purposes are thus easily obtained.

Most commercial Dendrobium orchids grown in Hawaii are seed-propagated hybrids.

Prospects

Several compounds (dendrobine, gigantol, moscatilin) isolated from D. nobile display interesting pharmacological activities, which merit further research. Purified compounds such as these might have potential as biochemical tools in modern experimental pharmacological research. No information is available on the composition or pharmacological activities of the other Dendrobium , although their local medicinal use is similar to D. nobile , and it would certainly be interesting to obtain more information on their compounds and activity.

Literature

  • Backer, C.A. & Bakhuizen van den Brink Jr, R.C., 1968. Flora of Java. Vol. 3. Noordhoff, Groningen, Netherlands. pp. 344-374.
  • Burkill, I.H., 1966. A dictionary of the economic products of the Malay Peninsula. Revised reprint. Vol. 1. Ministry of Agriculture and Co-operatives, Kuala Lumpur, Malaysia. pp. 790-792.
  • Chen, S., Li, Y., Wu, Y., Zhuo, Z. & Sun, L., 1995. The effect of Dendrobium nobile Lindl. on gastric acid secretion, serum gastrin and plasma somatostatin concentration. Zhongguo Zhongyao Zazhi 20(3): 181-182. (in Chinese)
  • Lee, Y.H., Park, J.D., Baek, N.I., Kim, S.I. & Ahn, B.Z., 1995. In vitro and in vivo antitumoral phenanthrenes from the aerial parts of Dendrobium nobile. Planta Medica 61(2): 178-180.
  • Miyazawa, M., Shimamura, H., Nakamura, S.I. & Kameoka, H., 1997. Antimutagenic activity of gigantol from Dendrobium nobile. Journal of Agricultural and Food Chemistry 45(8): 2849-2853.
  • Miyazawa, M., Shimamura, H., Nakamura, S., Sugiura, W., Kosaka, H. & Kameoka, H., 1999. Moscatilin from Dendrobium nobile, a naturally occurring bibenzyl compound with potential antimutagenic activity. Journal of Agricultural and Food Chemistry 47(5): 2163-2167.

Authors

Diah Sulistiarini