Rhododendron campanulatum D. Don.
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stems and bark cause hypotension in cats and inhibit intestinal movements in rabbits. The acetone and chloroform extracts and a resinous fraction from the alcoholic extract of leaves depress respiration. The petroleum ether extract decreases the rate of heartbeat and contraction in isolated heart of frog.
An alcoholic (50%) extract of the flowers lowered blood pressure in dogs and albino rats.
Cyanidin-3-galactoside and cyanidin-3-arbinoside are present in the pigments of flowers. The leaves of var. nilgiricum and var. cinnamonum contain ursolic acid, friedelin, epifriedelanol, quercetin. A triterpenoid, campanulin, has been isolated from the leaves of var. nilagaricum.
Rhododendron barbatum
Wall. ex G. Don.
Family Ericaceae.
Habitat The Himalayas from
Kumaon to Bhutan, extending to Assam.
English Giantblood Rhododendron.
Folk Chimal (Nepal), Kurbak, Guraans.
Action Respiratory depressant, emetic, toxic.
The leaves and flowers gave andromedotoxin which resembles tertiary amine veratrum alkaloids, particularly protoveratrine, in pharmacological action. Intravenous administration of andromedotoxin to dogs
resulted in 20—40% reduction in blood pressure. It also closely resembles protoveratrine in its stimulating effect on the barostatic-pressor-reflexmechanism, respiratory effects and emetic action. It produces reflex vasodepressor responses in intact animals; in debuffered dogs, it produced vasopressor responses. It also produced, both direct and indirect, positive ionotropic effects, the latter being more pronounced.
The leaves contain ursolic acid, alpha- amyrin, epi-friedelinol, campanulin and hyperoside. Chloroform extract of the leaves and shoots showed a depressant action. The honey from flowers is poisonous; contains andromedotoxin.
Rhododendron campanulatum
D. Don.
Synonym R. aeruginosum Hk. f. Family Ericaceae.
Habitat Throughout the Himalayas at altitudes of 2,400—5,200 m.
