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Labrador-tea (Rhododendron tomentosum) and Arthritis / joint pain: evidence and sources
inferred from anti-inflammatory action
For educational purposes only, not medical advice. Always consult a qualified practitioner before using medicinal plants, especially alongside prescribed medication, during pregnancy, or for a serious condition.
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Rhododendron tomentosum (Ledum palustre) is an aromatic plant traditionally used for alleviating rheumatic complaints which makes it a potential candidate for a natural drug in rheumatoid arthritis (RA) treatment. However, the effects of plants' volatiles on apoptosis of synovial fibroblasts and infiltrating leucocytes of RA synovia, have not been reported. Volatile fraction of R. tomentosum is chemically variable and chemotypes of the plants need to be defined if the oil is to be used for therapeutic purposes. In the presented work, cluster analysis of literature data enabled to define 10 chemotypes of the plant. The volatile fractions of known composition were then tested for bioactivity using a RA-specific in vitro models. Essential oils of two wild types (γ-terpineol and palustrol/ledol type) and one in vitro chemotype (ledene oxide type) were obtained by hydrodistillation and their bioactivity was tested in two in vitro models: I - peripheral blood lymphocytes of healthy volunteers and II - synoviocytes and immune cells isolated from synovia of RA patients. The influence of oils on blood lymphocytes' proliferation and apoptosis rates of synovia-derived cells was determined by flow cytometry. Dose-dependent inhibitory effect of the serial dilutions of R. tomentosum oils on proliferation rates of blood lymphocytes was found. At 1:400 dilutions, all the tested oils increased the number of necrotic cells in synovial fibroblasts from RA synovia. Additionally, increased proportions of late apoptotic cells were observed in leucocyte populations subjected to oils at 1:400 dilution.
The anti-inflammatory activity of two extracts from the aerial parts of Ledum palustre has been reported. The volatile oil was obtained by supercritical fluid extraction (SFE) and the essential oil by hydrodistillation (HD). The oils were analysed by gas chromatography-mass spectrometry to monitor their composition. Both extracts shared as main compound (41.0-43.4%) ledol (23.3-26.7%) and ascaridole (15.1-4.5%). The anti-inflammatory activity was evaluated by the subcutaneous carrageenan injection-induced hind paw oedema. The treated animals received essential oil (SFE and HD), the reference group received ketoprofen or piroxicam and the control group received NaCl 0.9%. A statistical analysis was performed by the Student t-test. The results show that L. palustre essential oil enhanced a significant inhibition of oedema (50-73%) for HD oil and (52-80%) for SFE oil. These results were similar to those obtained with piroxicam (70%) and ketoprofen (55%).
4 sources supporting Labrador-tea for Arthritis / joint pain. Includes scientific publications, books, monographs and traditional-use references.
Mechanistic basis
This use is associated with the plant's anti-inflammatory action. Further evidence for that pharmacology:
Rhododendron subsect. Ledum is a distinct taxonomic subdivision within the genus Rhododendron , comprising a group of evergreen shrubs and small trees. This review will comprehensively analyse the phytochemical profiles and biological properties of the Rhododendron subsect. Ledum species subsect. Ledum consists of eight plant species indigenous to temperate and subarctic regions of the Northern Hemisphere, collectively known as Labrador tea. Recent investigations have concentrated on the phytochemical constituents of these plants due to limited data, emphasizing their evergreen nature and potential industrial significance. This review summarizes their major phytochemical constituents, including flavonoids, phenolic acids, and terpenoids, and discusses their potential biological activities, such as antioxidant, anti-inflammatory, antimicrobial, antitumor, hypoglycemic, hepatoprotective, neuroprotective, and cardioprotective effects. Traditional uses of these plant species align with scientific findings, emphasizing the significance of these plants in traditional medicine. However, despite promising results, gaps exist in our understanding of specific compounds' therapeutic effects, necessitating further research for comprehensive validation. This review serves as a valuable resource for researchers, identifying current knowledge, uncertainties, and emerging trends in the study of the Rhododendron subsect. Ledum species.