fumarprotocetraric-acid and atranorin

Three secondary metabolites of lichens - usnic acid, atranorin and fumarprotocetraric acid - were evaluated for their in vitro antibacterial and antibiofilm activities against three strains each of methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MRSA) from cystic fibrosis patients.. Antibacterial activity was assessed by broth microdilution, while antibiofilm activity was evaluated by spectrophotometry or viable count.. Usnic acid was significantly more active than atranorin against planktonic cells, while fumarprotocetraric acid exhibited no activity. Atranorin was the most effective in counteracting adhesion to polystyrene, although usnic acid was more active against MRSA. Usnic acid and atranorin showed comparable activity against biofilm formation, although atranorin was more active against MRSA. Usnic acid was significantly more active than atranorin against preformed biofilms.. Secondary metabolites of lichens may be considered to be 'lead compounds' for the development of novel molecules for the treatment of S. aureus infections in cystic fibrosis patients.

Topics: Anti-Bacterial Agents; Benzofurans; Biofilms; Biological Products; Colony Count, Microbial; Cystic Fibrosis; Fumarates; Humans; Hydroxybenzoates; Lichens; Methicillin-Resistant Staphylococcus aureus; Microbial Sensitivity Tests; Plant Extracts; Staphylococcal Infections

The depside atranorin and depsidone fumarprotocetraric acid, isolated from the lichens Stereocaulon alpinum and Cetraria islandica, respectively, were chosen as prototypes for poorly soluble natural compounds in an effort to facilitate testing in pharmacological models. Solubilizing agents previously identified as being non-toxic towards a malignant leukemic (K-562) cell line and suitable for testing of anti-proliferative activity of the dibenzofuran lichen metabolite (+)-usnic acid were used in solubilization studies of the depside and depsidone. Cyclodextrin derivatives were found to be most suitable for solubilizing the lichen compounds, the greatest rise in solubility being witnessed for fumarprotocetraric acid, increasing almost 300-fold from 0.03 mg/ml in water to 8.98 mg/ml in 10% 2-hydroxypropyl-beta-cyclodextrin (HPbetaCD). Subsequently, the lichen compounds, including (+)-usnic acid, were solubilized in 10% HPbetaCD and tested for effects on three malignant human cell lines; T-47D (breast), Panc-1 (pancreas) and PC-3 (prostate) in a standard proliferation assay. Atranorin and fumarprotocetraric acid did not exhibit anti-proliferative effects but usnic acid was active against all test cell lines with EC50 values of 4.3-8.2 microg/ml. The non-toxic solubilizing agents used in this study could prove useful for pharmacological testing of other poorly soluble natural products.

Topics: Benzofurans; Cell Line; Fumarates; Hydroxybenzoates; Lichens; Solubility; Thymidine

Atranorin, one of the most common lichen substances, gave positive patch test reactions in eight subjects (1%) in a routine series. These subjects also reacted to fumarprotocetraric acid and some of them to evernic acid. Stictic acid and usnic acid gave negative reactions. The lichen oak moss Evernia prunastri and an oak moss perfume gave positive reactions. Thin-layer chromatography and a spot test indicated that atranorin is present in oak moss perfumes which are made from oak moss and tree moss. Contact with oak moss perfumes and lichens in nature may cause atranorin allergy. None of the eight subjects had a history of light sensitivity or atopy and none had chronic facial eczema.

Topics: Adult; Dermatitis, Atopic; Dermatitis, Contact; Female; Fumarates; Humans; Hydroxybenzoates; Lichens; Male; Middle Aged; Patch Tests; Perfume