Hydroxy3methoxybenzaldehyde

Fig. 55. Gastrodia elata Bl.

Acriopsis javanica Reinw. is an epiphyte orchid that grows in Burma, Malaysia, Indonesia, the Philippines, and Papua New Guinea. The pseudobulbs are 5 X 1.5 cm and develop thick roots. Each pseudobulb produces three leaves, which are linear and 25 cm X 9 mm. The influorescences are 60 long and branched panicles. The flowers are 7 mm long and pale purple (Fig. 56).

Malays drink a decoction of the whole plant that is used to reduce fever. In Indonesia, the juice expressed from the pseudobulbs is used to assuage earache, and a paste of the pseudobulb is applied externally to lower blood pressure and reduce fever. The pharmacological potential of this plant is unexplored. Is the antipyretic and analgesic property of Acriopsis javanica linked to a dopaminergic effect?

Bulbophyllum vaginatum Reich. f. is an epiphytic orchid that grows in Thailand, Indonesia, and Malaysia. The stems are 3 mm in diameter. The petiole is 2 X 6 mm, swollen, and deeply channeled. The blade is elliptic, thick, spongy, and 8 X 3 cm. The flowers are arranged in clusters of 12-15 pale yellow, 5-cm-long flowers with elongated corollas (Fig. 57).

Fig. 56. Acriopsis javanica. From Flora of Malaya. Geographical localization: S. Salat on Endau river, Johore. Rocky upper reaches, epiphyte.

In Malaysia, the juice expressed from the plant is warmed and instilled in the ear to mitigate earache. The pharmacological potential of this orchid is unexplored. Note that an interesting development in Bulbophyllum species, and Orchidaceae in general, is the search for dopaminergic phenanthrene. Orchidaceae are well known to elaborate bibenzyls, phenanthrenes, and 9,10-dihydrophenanthrenes. Such compounds are found in Bulbophyllum vaginatum Reichb., such as 4,6 dimethoxyphenanthrene-2,3,7-triol and 3,4',5-trihydroxy-3'-methoxybibenzyl (61). An example of a phenan-threnic dopaminergic agent is dihydrexidine, which is a dopamine D1 receptor agonist (62).

Fig. 57. Bulbophyllum vaginatum. From Flora of the Malay Peninsula. Geographical localization: Rantau Panjang, Selangor. 10/30/1930. Field collector: Symington, No: 24330.
Calanthe Society

Fig. 58. Calanthe triplicate. From Sarawak No 892. Royal Geographical Society, 1977-1978. Mulu Expedition. Field collectors: G. Argent, D Coppins, C. Jermy, 4/5/1978. Geographical localization: Gunong Mulu National Park. 4th Division, Baram District. Hidden Valley (Camp 6). 4° 0.5' North-114° 53' East. In lowland alluvial rainforest under towering limestone.

Fig. 58. Calanthe triplicate. From Sarawak No 892. Royal Geographical Society, 1977-1978. Mulu Expedition. Field collectors: G. Argent, D Coppins, C. Jermy, 4/5/1978. Geographical localization: Gunong Mulu National Park. 4th Division, Baram District. Hidden Valley (Camp 6). 4° 0.5' North-114° 53' East. In lowland alluvial rainforest under towering limestone.

Calanthe triplicata (Villem.) Ames (Calanthe veratrifolia R. Br.), or Christmas orchid, is a large terrestrial orchid that grows in Southeast Asia, Papua New Guinea, and Australia. Each pseudobulb develops three or four large pleated leaves, which are 40 X 9 - 50 X 18 cm. The roots are 1.5 cm long and 2 mm in diameter. The influorescence is 50 cm long with numerous 1-cm-long white flowers densely packed in a spike. The flowers show white with green rostrellum and yellow spots at base of labellum, which is forked (Fig. 58). In Indonesia, the roots are used to treat diarrhea and a paste is applied to swollen parts. A paste of flowers is inserted in the hollow of painful caries. A significant advance in the pharmacology of Calanthes species has been provided by the work of Yoshikawa et al. Using bioassay-guided fractionation, they isolated calanthoside, glu-coindican, calaliukiuenoside, and calaphenanthrenol from Calanthe discolor Lindl. and Calanthe liukiuensis, which showed an activating effect on skin blood flow and hair restoring activities (63). The dopaminergic and central property of this orchid is unexplored.

Fig. 59. Calanthe vestita Lindl. Flora of Malay Peninsula. Forest Department. Geographical localization: Batu Caves, Selangor. 12/26/1932. Field collector: E.J. Strugnel.

Calanthe vestita Lindl. is a terrestrial orchid that grows in Thailand, Burma, Cambodia, Laos, Vietnam, Malaysia, Sumatra, Java, Borneo, and Celebes. The leaves are 25 X 5 cm. The petiole is 5 cm long. The influorescence is 40 cm long. The flowers are white (Fig. 59). In Cambodia, Laos, and Vietnam, a paste of bulbs is applied to painful bones. The pharmacological properties of this plant are currently unknown.

Dendrobium crumenatum Sw., or pigeon orchid, is an epiphyte orchid that grows in India, China, the Philippines, and Malaysia. The stem is 4 mm in diameter and the bulbs are 2-3 cm around. The leaves are 7 X 1.3 cm, linear, and fleshy. The petiole is 4 X 1 mm. The flowers are white (Fig. 60).

Fig. 60. Dendrobium crumenatum I.

The dopaminergic potential of the Dendrobium species is, to date, open for exploration. An interesting feature of the Dendrobium species is their ability to elaborate sesquiter-pene alkaloids, the chemical structure of which resembles the one of strychnine. One such alkaloid is dendrobine, which is widespread in the genus. Kudo et al. noted that dendrobine, isolated from Dendrobium nobile, exhibits a strychnine-like presynaptic inhibition in frog spinal cord (64).

Dendrobine at a dose of 3 X 10~5 M reduced the dorsal root potential and reflex. It provoked a mild hyperpolarization in both dorsal and ventral roots of frog isolated spinal cord. It affected the p-alanine- and taurine-induced depolarization of primary afferent terminals and reversibly blocked the presynaptic inhibition caused by antidromic conditioning stimulation of the ventral root potential induced by repetitive antidromic stimulation of ventral root and lowered maximum. It would be interesting to learn whether further research of the Dendrobium species discloses any alkaloid interfering with the glycinergic system, an aspect discussed under the following heading.

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