Haberlea rhodopensis: pharmaceutical and medical potential as a food additive

Chemical Profiling, Antiproliferative and Antimigratory Capacity of Haberlea rhodopensis Extracts in an In Vitro Platform of Various Human Cancer Cell Lines

Haberlea rhodopensis is a Balkan endemic plant that belongs to the Gesneriaceae family, and is believed to have medicinal use and health-promoting properties. This study aimed to (i) prepare aqueous (HAE) and ethanolic (HEE) extracts from the leaves of H. rhodopensis from in vitro propagated plants, (ii) screen for their potential antiproliferative and antimigratory activities, and (iii) chemically characterize both HAE and HEE by identifying compounds which may contribute to their observed bioactivity thereby further supporting their potential use in biomedical applications. The antiproliferative activity of both extracts was assessed against six human cancer cell lines by employing the sulforhodamine-B (SRB) assay. HEE was found to be more potent in inhibiting cancer cell growth as compared to HAE. Therefore, HEE's antimigratory effects were further studied in hepatocellular carcinoma (HepG2) and non-small cell lung adenocarcinoma (A459) cell lines as they were among the most sensitive ones to its antiproliferative activity. HEE was found to exert significant antimigratory concentration-dependent effects in both cell lines assessed with the wound healing assay. Chemical characterization by UPLC-MS/MS analysis identified that HEE contains higher levels of flavonoids, phenolic compounds, pigments (chlorophyll-/-b, lycopene, and β-carotene), monoterpenoids, and condensed tannins compared to HAE, while HAE, contains higher levels of soluble protein and sugars. Furthermore, HEE demonstrated remarkable antioxidant activity evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH^●), 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS^●+) and ferric reducing/antioxidant power (FRAP) assays. We have obtained comprehensive results highlighting the potential of HEE as a source of bioactive compounds with anticancer properties. Future studies should aim at identifying the chemical constituents responsible for the bioactivities observed, and focus on investigating HEE's effects, in in vivo preclinical cancer models.

Myconoside Affects the Viability of Polarized Epithelial MDCKII Cell Line by Interacting with the Plasma Membrane and the Apical Junctional Complexes

The phenyl glycoside myconoside, extracted from Balkan endemic Haberlea rhodopensis, has a positive effect on human health, but the exact molecular mechanism of its action is still unknown. The cell membrane and its associated junctional complex are the first targets of exogenous compound action. We aimed to study the effect of myconoside on membrane organization and cytoskeleton components involved in the maintenance of cell polarity in the MDCKII cell line. By fluorescent spectroscopy and microscopy, we found that at low concentrations, myconoside increases the cell viability by enhancing membrane lipid order and adherent junctions. The opposite effect is observed in high myconoside doses. We hypothesized that the cell morphological and physicochemical changes of the analyzed cell compartments are directly related to cell viability and cell apical-basal polarity. Our finding contributes to a better understanding of the beneficial application of phytochemical myconoside in pharmacology and medicine.

Myconoside interacts with the plasma membranes and the actin cytoskeleton and provokes cytotoxicity in human lung adenocarcinoma A549 cells

Studies have been carried out on the effects of the phenyl glycoside myconoside, extracted from the relict, Balkan endemic resurrection plant Haberlea rhodopensis on the plasma membrane structural organization and the actin cytoskeleton. Because the plasma membrane is the first target of exogenous bioactive compounds, we focused our attention on the influence of myconoside on the membrane lipid order and actin cytoskeleton in human lung adenocarcinoma A549 cells, using fluorescent spectroscopy and microscopy techniques. We found that low myconoside concentration (5 μg/ml) did not change cell viability but was able to increase plasma membrane lipid order of the treated cells. Higher myconoside concentration (20 μg/ml) inhibited cell viability by decreasing plasma membrane lipid order and impairing actin cytoskeleton. We hypothesize that the observed changes in the plasma membrane structural organization and the actin cytoskeleton are functionally connected to cell viability. Biomimetic membranes were used to demonstrate that myconoside is able to reorganize the membrane lipids by changing the fraction of sphingomyelin-cholesterol enriched domains. Thus, we propose a putative mechanism of action of myconoside on A549 cells plasma membrane lipids as well as on actin filaments in order to explain its cytotoxic effect at high myconoside concentration.

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

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.