Antioxidant activity of grape seed (Vitis vinifera) extracts on peroxidation models in vitro

and Evernia prunastri are processed in the perfume industry, and some lichens are sensitive reagents for the evaluation of air pollution.

The significance of lichens and their metabolites.

A review of natural products with antileishmanial activity

Soleil et peau

Lichens are symbiotic organisms of fungi and algae or cyanobacteria. Lichen-forming fungi synthesize a great variety of secondary metabolites, many of which are unique. Developments in analytical techniques and experimental methods have resulted in the identification of about 1050 lichen substances (including those found in cultures). In addition to their role in lichen chemotaxonomy and systematics, lichen secondary compounds have several possible biological roles, including photoprotection against intense radiation, as well as allelochemical, antiviral, antitumor, antibacterial, antiherbivore, and antioxidant action. These compounds are also important factors in metal homeostasis and pollution tolerance of lichen thalli. Although our knowledge of the contribution of these extracellular products to the success of the lichen symbiosis has increased significantly in the last decades, their biotic and abiotic roles have not been entirely explored.

/pdf/current-results-on-biological-activities-of-lichen-secondary-43g6cbv6ir.pdf

Current Results on Biological Activities of Lichen Secondary Metabolites: a Review

Antioxidant activity of depsides and depsidones

Activity of compounds isolated from Chilean lichens against experimental cutaneous leishmaniasis.

Lichens produce a diversity of phenolic compounds, some of which efficiently absorb ultraviolet radiation, 8-Methoxypsoralen (8-MOP), commonly used in the treatment of psoriasis, binds irreversibly to proteins in the presence of ultraviolet radiation by a mechanism that is not well established. In this paper we demonstrate the photoprotector capacity of three phenolic compounds-pannarin, 1'chloropannarin and atranorin-through the inhibition of 8-MOP-human serum albumin (HSA) photobinding. The method measures the UV-filtering capacity of lichen compounds by means of a double-tube compartment (thus, solubility and interaction with the reaction medium is avoided). Photobinding was determined by measuring the radioactivity of mixtures containing 8-(methyl-3H) MOP and HSA irradiated at 360 and 310 nm in the presence of increasing concentrations of lichen phenolics. Pannarin, l'-chloropannarin and atranorin at a concentration of 10 mM and irradiated at 360 nm, inhibited photobinding to HSA by 40.4%, 31.7% and 20.1% respectively. Pannarin (10 mM) irradiated at 310 nm inhibited the photobinding by 35.2%. The participation of singlet oxygen and hydroxyl radicals was demonstrated in the photoreaction process.

Photoprotector capacity of lichen metabolites assessed through the inhibition of the 8-methoxypsoralen photobinding to protein.

En la especie liquenica Acarospora schleicheri, recolectada en gradientes altitudinales a 18o, 19o y 33o Lat. S, en zonas alpinas de Chile, se determinaron y compararon las concentraciones de acido rizocarpico. Se observaron incrementos significativos en la acumulacion del metabolito con la altura s.n.m. y el aumento en los niveles de radiacion UV-B en los gradientes seleccionados. Los resultados obtenidos sugieren que la sintesis de acido rizocarpico es inducida por la radiacion UV-B y que su presencia representa una adaptacion quimica frente a los elevados niveles de radiacion UV-B en los habitats de esta especie liquenica.

Effects of solar uv-b radiation in the accumulation of rhizocarpic acid in a lichen species from alpine zones of chile

The photostabilities of several quinolones have been determined using high performance thin layer chromatography. On irradiation with UVA (350 nm), the photostability decreases in the order: ciprofloxacin (CP)> norfloxacin (NF) > pipemidic acid (PA) > nalidixic acid (NA) > M-193324 > rosoxacin (RS) > oxolinic acid (OA). The photo- degradation process in all cases follows first-order kinetics. Furthermore, the quantum yield of fluorescence was determined for each quinolone; these values vary from 0.15 x 10 −2 to 5.15 x 10 −2 . The highest Φ f value corresponds to CP and NF. These results show that quinolones which possess a piperazine ring at the C-7 position (CP, NF, PA) are less photostable and more fluorescent.

Ernesto Fernández

Papers

Antioxidant activity of depsides and depsidones

Activity of compounds isolated from Chilean lichens against experimental cutaneous leishmaniasis.

Photoprotector capacity of lichen metabolites assessed through the inhibition of the 8-methoxypsoralen photobinding to protein.

Effects of solar uv-b radiation in the accumulation of rhizocarpic acid in a lichen species from alpine zones of chile

Comparative determination of photodegradation kinetics of quinolones