The ancient Thracian endemic plant Haberlea rhodopensis Friv. and related species: A review

Abstract

Ethnopharmacological relevance: Haberlea rhodopensis (HR) use dates back to the Thracian and Roman periods. Bulgarians call it Orpheus flower and exploit its leaves for making tea and extracts with detoxifying, tonic, restorative and rejuvenating effects. HR was traditionally applied in wound healing and treatment of cattle diseases.

Aim of the study: The general aim of the review was to analyze the progress of phytochemical and pharmacological studies on HR, focusing on its radioprotective and immunomodulating effects.

Materials and methods: The main source material for the review was collected using several global search engines with the phrase: Haberlea rhodopensis, as well as Bulgarian books and dissertations.

Results: HR metabolite profile includes large amounts of free sugars, polyols, polysaccharides (PS), flavonoids, phenolic acids and carotenoids. The radioprotective effect of 70% ethanolic leaf extract (70HREE) is explained by preservation of lymphocytes, other blood cells and testicular tissue from aberration under γ-radiation via stimulation of antioxidant enzymes and neutralization of free radicals. The extract immunomodulating activity results from raised antibody response, stem and neutrophil cell count, complement system activation, anti-tumour and anti-inflammatory effects. The detoxifying, restorative, rejuvenating and wound healing plant properties known to ethnomedicine were supported by radioprotective and immunomodulating studies.

Conclusions: Metabolites of phenolic origin involved in HR resurrection are supposed to contribute to its radioprotective, immunomodulatory, anti-mutagenic and anti-aging effects. However, there is no chemical characterization of 70HREE in the investigations with humans and animals. Structure-activity relationship studies on HR immunomodulating and radioprotective compounds, and on their mode of action are required. They should include not only phenols but PS and other unexplored molecules. The metabolic activity of phagocytes, platelets and lymphocytes triggered by HR extracts has to be examined to elucidate their immunostimulatory potential. HR formulations can be tested in cosmetic, food and medical products as adjuvants to treat infectious, chronic inflammatory and tumour diseases, and especially in patients undergoing radiotherapy.

Keywords: 8-hydroxydehydrodunnione (PubChem CID: 132487931); 8-metoxylapachenol; Aggregatin D (PubChem CID: 46919399); Beta-sitosterol (PubChem CID: 222284); Endemic species; Haberlea rhodopensis; Herbal medicine; Hispidulin-8-C-(2-O-syringoyl)-β-Glcp; Hispidulin-8-C-(6-O-Acetyl-2-O-Syringoyl-β-Glcp); Hispidulin-8-C-(6-O-Acetyl-β-Glcp); Hispidulin-8-C-β-Galp; Immune system; Myconoside (PubChem CID: 10818823); Pectic polysaccharides; Radioprotection; Raffinose (PubChem CID: 439242); Resurrection plant; Sucrose (PubChem CID: 5988); Syringic acid (PubChem CID: 10742); Verbascoside (PubChem CID: 5281800).