Therapeutic orchids: traditional uses and recent advances--an overview.

Natural phenanthrenes and their biological activity.

The terpenoids are a class of natural products with biological activity. The number of isoprene units from which they are biogenetically composed is used for their classification. The diterpenes are another group from which several compounds with high biological activity have been produced. The most studied plant families are Asteraceae and Labiatae, as well as Conifers, which are the main sources of diterpenes. The lack of, or insufficient, chromatographic data (RI, Rt) as well as of reference compounds for most labdanes is the main reason for their absence from the chemical fingerprints of plantextracts. Also their use as chemotaxonomic markers within the species in which they occur is limited. The configuration at the C-13 carbon atom has been investigated, especially in the case of manoyl oxide, as well as the various isomers, the ratio of which determines antimicrobial activity. A variety of biological activities have been encountered in labdane diterpenes such as antibacterial, antifungal, antiprotozoal, enzyme inducing, anti-inflammatory activities and modulation of immune cell functions. More recent studies have shown that labdane exhibits significant cytotoxic and cytostatic effects against leukemic cell lines of human origin and interferes with the biochemical pathways of apoptosis and the cell cycle phases, as well as with the expression of several protooncogenes such as c-myc and bcl-2 . This report underlines the role of these compounds, not only as toolsfor the study of the biochemistry and regulation of biochemical and metabolic pathways of mammalian cellular systems, but also as potential pharmacological agents in the fight against diseases such as cancer and heart disorders.

Labdane-type diterpenes: Chemistry and biological activity

In the present study, four nutrient media viz., Murashige and Skoog (MS), Phytamax (PM), Mitra et al. (M) and Knudson ‘C’ (KC), were evaluated for seed germination and early protocorm development in Cymbidium aloifolium (L.) Sw., a medicinally important orchid of Bangladesh. Besides, effect of peptone, activated charcoal, plant growth regulators viz., 6-benzylaminopurine (1.0–2.0 mg/L) and 2,4-dichlorophenoxy acetic acid (1.0–2.0 mg/L), and light and dark conditions were also studied. Varied response in terms of per cent seed germination was observed in different media. Mitra et al. medium supplemented with 2.0 g/L activated charcoal (AC) showed 100% seed germination and effective for induction of significantly large size protocorms (1.64 mm in dia.). Protocorms turned necrotic under dark condition. Within two weeks of culture spherules emerged out due to cracking of the seed coat. The spherules developed into protocorms with a leaf primordium at apical portion after 3-4 weeks and gradually produced complete seedlings. A strong and stout root system was induced in in vitro seedlings upon transfer to half strength PM and M media fortified with 0.5 mg/L indole-3-acetic acid (IAA). Well-rooted seedlings were transferred to a green house with 95% survival. Based upon cost analysis it was suggested that Mitra et al. medium supplemented with AC (2.0 g/L) was more effective and economic for high frequency germination of seeds and seedlings development. IAA (0.5 mg/L) in Mitra et al. medium was suitable for development of stout root system which helped in high survival of seedlings under greenhouse condition.

Cost effective protocol for in vitro mass propagation of Cymbidium aloifolium (L.) Sw.– a medicinally important orchid

High altitude problems like hypoxia, acute mountain sickness, high altitude cerebral edema, pulmonary edema, insomnia, tiredness, lethargy, lack of appetite, body pain, dementia, and depression may occur when a person or a soldier residing in a lower altitude ascends to high-altitude areas. These problems arise due to low atmospheric pressure, severe cold, high intensity of solar radiation, high wind velocity, and very high fluctuation of day and night temperatures in these regions. These problems may escalate rapidly and may sometimes become life-threatening. Shilajit is a herbomineral drug which is pale-brown to blackish-brown, is composed of a gummy exudate that oozes from the rocks of the Himalayas in the summer months. It contains humus, organic plant materials, and fulvic acid as the main carrier molecules. It actively takes part in the transportation of nutrients into deep tissues and helps to overcome tiredness, lethargy, and chronic fatigue. Shilajit improves the ability to handle high altitudinal stresses and stimulates the immune system. Thus, Shilajit can be given as a supplement to people ascending to high-altitude areas so that it can act as a "health rejuvenator" and help to overcome high-altitude related problems.

Amarendra Patra

Papers

Cymbinodin-A, a phenanthraquinone from Cymbidium aloifolium.

The structure and stereochemistry of phlogantholide-A, a diterpene from Phlogacanthus thyrsiflorus

Phloganthoside—a diterpene lactone glucoside from Phlogacanthus thyrsiflorus

Cymbinodin-b, a phenanthraquinone from cymbidium aloifolium

Traditional medicine : proceedings of an International Seminar, November 7-9, 1992, Hotel Taj Bengal, Calcutta, India