Natural phenanthrenes and their biological activity.

Chemical constituents from Dendrobium densiflorum.

Orchids are nature's most extravagant group of flowering plants distributed throughout the world from tropics to high alpine. They exhibit incredible range of diversity in size, shape and color of their flowers. Though orchids are grown primarily as ornamentals, many are used as herbal medicines, food, and other have cultural value by different cultures and tribes in different parts of the world. Orchids have been used in many parts of the world in traditional healing system as well as in the treatment of a number of diseases since the ancient time. Though Orchidaceae is regarded as a largest family of plant kingdom, few studies have been done regarding their medicinal properties. Linking of the indigenous knowledge of medicinal orchids to modern research activities provides a new reliable approach, for the discovery of novel drugs much more effectively than with random collection. Many of these orchids face the extreme danger of extinction due to over-exploitation and habitat loss. Plant tissue culture could be one of the most suitable alternative tools to minimize the pressure on natural population of medicinal orchids and their sustainable utilization.

	 

	Key words: Medicinal, orchids, propagation, conservation, culture.

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Medicinal orchids and their uses: Tissue culture a potential alternative for conservation

Bi-bicyclic and bi-tricyclic compounds from Dendrobium thyrsiflorum.

Two new phenanthrenes (1 and 6) and four new dihydrophenanthrenes (2–5) were isolated from a methanolic extract of Dendrobium nobile stems, along with 13 known phenanthrenes and dihydrophenanthrenes (7–19). By spectroscopic analysis, the structures of compounds 1–6 were determined as 2,8-dihydroxy-3,4,7-trimethoxyphenanthrene (1), 3-hydroxy-2,4,7-trimethoxy-9,10-dihydrophenanthrene (2), 2,8-dihydroxy-3,4,7-trimethoxy-9,10-dihydrophenanthrene (3), 2-hydroxy-4,7-dimethoxy-9,10-dihydrophenanthrene (4), 2,2′-dihydroxy-3,3′,4,4′,7,7′-hexamethoxy-9,9′,10,10′-tetrahydro-1,1′-biphenanthrene (5), and 2,3,5-trihydroxy-4,9-dimethoxyphenanthrene (6), respectively. Antifibrotic activity of compounds 1–19 was evaluated employing HSC-T6, an immortalized rat hepatic stellate cell line, as an in vitro assay system by assessing cell proliferation.

P.L. Majumder

Papers

Pendulin, a polyoxygenated phenanthrene derivative from the orchid Cymbidium pendulum