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RHODODENDRON [满山红, MAN SHAN HONG]

Name : RhododendronR_catawbiense_opt

Chinese Name : 满山红

Latin Name : Folium Rhododendri daurici

Overview

This herb is the dried leaves and flowers of Rhododendron dauricum L, of the family Ericaceae. It is widely grown in the Jilin and Heilongjiang provinces, and Inner Mongolia of China, where it is harvested in summer and dried in the sun.

There are many rhododendrons found in China. The flowers were used as a sedative, for rheumatism, neuralgias, contractions, and bronchitis. The herb is used as an  antitussive and expectorant for chronic bronchitis and relieves asthma.

Use of Rhododendron TCM Properties

Acrid, bitter in taste, and slightly cold,it acts on the lung and spleen meridians.

Effects , Medicinal Uses, and Combinations

  1. Helps to relieve coughs and bronchitis: the herb is used as an effective antitussive and as an expectorant for chronic bronchitis.
  2. Relieves asthma and is also useful for  treating acute and chronic bronchial asthma in a decoction.

Dosage

In a decoction of 3  to 10 g, or 15 to 30 g if fresh rhododendron is used.

Precautions

People with a history of liver and heart ailments should not use this herb or use with caution, and avoid long-term use.

Side Effects and Toxicity

The  Chinese material medica reports that this plant is slightly toxic and it may cause symptoms of nausea, vomiting, dizziness, angina, sweating, and asthenia. After removing the volatile oil constituent, the plant does not cause these side effects. Long-term use or an overdose may cause liver damage.

Chemical Constituents

The leaves of the plant R. dauricum contain 0.3 to 0.5 percent of volatile oil. The chief ingredients responsible for antitussive and expectorant actions are hyperoside and isobyperin. From the leaf, active ingredients of hyperin, avicularin, azaleatin, and porial have been identified. Seven other flavones compounds (kaempferol, quercetin, myricetin, ferrerol, periol, hyperoside, and isohyperoside) were isolated. Germaerone, juniper camphor, menthol, alpha-eudesmol, beta-eudesmol, and  gamma-eudesmol have been isolated from the oil portion.

Pharmacological Findings

  1. A rhododendron decoction demonstrated noticeable antitussive action. The chief ingredient for the action is the flavones compound ferrerol. The antitussive properties of 160 mg of ferrerol were equivalent to 60 mg codeine in animal tests
  2. Expectorant action: the I:I rhododendron aqueous extract was given to rabbits and was a noticeable expectorant.
  3. Other effects: rhododendron is also antiasthmatic, cardiotonic, hypotensive, and antimicrobial.