Oxidative stress mediated by gyrophoric acid from the lichen Umbilicaria hirsuta affected apoptosis and stress/survival pathways in HeLa cells.

BACKGROUND: Lichens produce a huge diversity of bioactive compounds with several biological effects. Gyrophoric acid (GA) is found in high concentrations in the common lichen Umbilicaria hirsuta, however evidence for biological activity was limited to anti-proliferative activity described on several cancer cell lines. METHODS: We developed and validated a new protocol for GA isolation, resulting in a high yield of highly pure GA (validated by HPLC and NMR) in an easy and time saving manner. Anti-proliferative and pro-apoptotic activity, oxygen radicals formation and stress/survival proteins activity changes was study by flow cytometry. RESULTS: The highly purified GA showed anti-proliferative activity against HeLa (human cervix carcinoma) and other tumor cells. Moreover, GA threated cells showed a significant increase in caspase-3 activation followed by PARP cleavage, PS externalization and cell cycle changes mediated by oxidative stress. Production of oxygen radicals led to DNA damage and changes in stress/survival pathways activation. CONCLUSIONS: GA treatment on HeLa cells clearly indicates ROS production and apoptosis as form of occurred cell death. Moreover, DNA damage and changing activity of stress/survival proteins as p38MAPK, Erk1/2 and Akt mediated by GA treatment confirm pro-apoptotic potential. The pharmacological potential of U. hirsuta derived GA is discussed.

Ni tolerance and its distinguished amelioration by chelating agents is reflected in root radius of B. napus cultivars.

The negative effect of excess nickel (Ni) on plants is well investigated but there is only little information on its influence on root anatomy and a possible amelioration by chelating agents. In this study, we utilized light microscopy to observe anatomical changes in canola (Brassica napus) roots and investigated the element content by X-ray microanalysis. Ni-tolerant (Con-II) and Ni-sensitive cultivars (Oscar) were selected for this purpose. The plants were treated with 30 ppm NiSO4. Then, citric acid and ethylene-diamine-tetra-acetic acid (EDTA) (alone or in combination) were applied to observe the influence of chelating agents in metal stress amelioration. Ni treatment led to significant swelling of the roots in the Con-II variety as compared to the cultivar Oscar. Application of EDTA reduced the root radius of Con-II plants and this effect for Ni tolerance is discussed. According to X-ray microanalyses, Ni ions were more dispersed in the sensitive cultivar as indicated by metal adsorption to the cell wall. We investigate the hypothesis that an enhanced capacity of binding metals to the cell wall allows the plants to tolerate more heavy metals.

Lichen secondary metabolites affect growth of Physcomitrella patens by allelopathy.

Lichen secondary metabolites can function as allelochemicals and affect the development and growth of neighboring bryophytes, fungi, vascular plants, microorganisms, and even other lichens. Lichen overgrowth on bryophytes is frequently observed in nature even though mosses grow faster than lichens, but there is still little information on the interactions between lichens and bryophytes.In the present study, we used extracts from six lichen thalli containing secondary metabolites like usnic acid, protocetraric acid, atranorin, lecanoric acid, nortistic acid, and thamnolic acid. To observe the influence of these metabolites on bryophytes, the moss Physcomitrella patens was cultivated for 5 weeks under laboratory conditions and treated with lichen extracts. Toxicity of natural mixtures of secondary metabolites was tested at three selected doses (0.001, 0.01, and 0.1 %). When the mixture contained substantial amounts of usnic acid, we observed growth inhibition of protonemata and reduced development of gametophores. Significant differences in cell lengths and widths were also noticed. Furthermore, usnic acid had a strong effect on cell division in protonemata suggesting a strong impact on the early stages of bryophyte development by allelochemicals contained in the lichen secondary metabolites.Biological activities of lichen secondary metabolites were confirmed in several studies such as antiviral, antibacterial, antitumor, antiherbivore, antioxidant, antipyretic, and analgetic action or photoprotection. This work aimed to expand the knowledge on allelopathic effects on bryophyte growth.