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Results for “USNIC ACID”

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PubMed1999

Lichen metabolites. 2. Antiproliferative and cytotoxic activity of gyrophoric, usnic, and diffractaic acid on human keratinocyte growth.

The sensitivity of the human keratinocyte cell line HaCaT to several lichen metabolites isolated from Parmelia nepalensis and Parmelia tinctorum was evaluated. The tridepside gyrophoric acid (6), the dibenzofuran derivative (+)-usnic acid (1), and the didepside diffractaic acid (5) were potent antiproliferative agents and inhibited cell growth, with IC50 values of 1.7, 2.1, and 2.6 microM, respectively. Methyl beta-orcinolcarboxylate (2), ethyl hematommate (3), the didepside atranorin (4), and (+)-protolichesterinic acid (7) did not influence keratinocyte growth at concentrations of 5 microM. Keratinocytes were further tested for their susceptibility to the action of the potent antiproliferative agents on plasma membrane integrity. The release of lactate dehydrogenase activity into the culture medium was unchanged as compared to controls, documenting that the activity of gyrophoric acid (6), (+)-usnic acid (1), and diffractaic acid (5) was due to cytostatic rather than cytotoxic effects.

Anisoles↗

PubMed1980

Contact allergy to atranorin in lichens and perfumes.

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.

Adult↗

PubMed1995

[Effect of Cladonia alpestris on Trichomonas vaginalis in vitro].

In this paper, an experimental research is reported on the effect of water extract of Cladonia alpestris and S-(-) usnic acid on Trichomonas vaginalis in vitro. The results showed that both the water extract of Cladonia alpestris and S-(-)usnic acid exhibited a strong effect against Trichomonas vaginalis in vitro. As the time of action of the agents was prolonged, the mortality of Trichomonas vaginalis increased. For S-(-) usnic acid, 0.4 mg/ml was the lowest effective concentration against Trichomonas vaginalis in vitro. No remarkable differences were found in the effect of the S-(-)usnic acid and metronidazole at concentrations of 0.4 mg/ml and 0.6 mg/ml.

Animals↗

PubMed2002

Effects of ultraviolet radiation and PAR on the content of usnic and divaricatic acids in two arctic-alpine lichens.

The fruticose lichen Flavocetraria nivalis and the crustose lichen Ophioparma ventosa, both common in light-exposed arctic-alpine environments, were exposed to ultraviolet radiation (UVR) in growth chambers for 30 days. Treatment with visible light (PAR) served as control. Both species accumulate the UV-absorbing phenolic compound usnic acid in the upper cortex. The latter species also synthesises several UV-absorbing medullary compounds, among them divaricatic acid. The effects of treatment with UVR on the synthesis of these two compounds were investigated by analysing the compounds quantitatively by RP-HPLC. UV-exposed thallus tips of F. nivalis contained higher concentrations of usnic acid than those not grown under UVR. Both treatments had a positive effect on the synthesis of usnic acid in O. ventosa. An additional experiment with O. ventosa was performed by first storing samples in a low-light habitat for 1 year to obtain near-zero levels of phenolics, and thereby exposing the samples to UVR and PAR for 90 days. A rapid resynthesis of usnic acid was observed for both treatments. The amounts of divaricatic acid were highly variable in all groups, and were not correlated with usnic acid concentrations or treatments. A comparison of O. ventosa from three different habitat types showed that the highest usnic acid amounts were found in the habitat with the highest levels of solar radiation. Results indicate that the induction of usnic acid production by UVR depends on the species studied, and on how well acclimatised the lichen samples are to solar radiation before they are exposed to supplementary UVR. In lichens with an already well-developed internal screening capacity, like the population of F. nivalis, enhanced UVR need not induce further accumulation of usnic acid, but removal of UVR may induce a biodegradation of usnic acid. Results also indicate that PAR is just as important as UVR for triggering the resynthesis of usnic acid in shade-adapted lichens. Divaricatic acid seems to be of low importance for the UV-screening properties of O. ventosa.

Arctic Regions↗

PubMed1997

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

Three secondary metabolites isolated from Chilean lichens, (+) usnic acid, pannarine and 1'-chloropannarine, were tested against promastigotes forms of three strains of Leishmania ssp. Pannarine and 1'-chloropannarine exhibited in vitro activity at 50 micrograms/ml and (+) usnic acid at 25 micrograms/ml. BALB/c mice infected with Leishmania amazonensis were treated 4 weeks post-infection with (+) usnic acid by subcutaneous or oral routes for 15 days at 25 mg/kg or by five intralesional injections at interval of 4 days at 25 mg/kg of body weight. The reference drug, N-methylglucamine antimonate (Glucantime), was administered by subcutaneous injections (regimens of 28 mg of pentavalent antimony) for 15 days. The subcutaneous and oral treatments with (+) usnic did not produce any effect, but by intralesional administration we observed a significant effect that reduced by 43.34% the weight lesions and by 72.28% the parasites loads in infected footpads.

Animals↗

PubMed2005

Solubilization of poorly soluble lichen metabolites for biological testing on cell lines.

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.

Benzofurans↗

PubMed2005

Beta-orcinol depsidones from the lichen Usnea sp. from Sri Lanka.

Two beta-orcinol depsidone lactones, the methyl ethers of menegazziaic acid and stictic acid were isolated along with glyceryl trilinolate and usnic acid from an Usnea sp. new to Sri Lanka growing on rotting trees of Acacia decurrans. Usnic acid exhibited potent antitermite activity against a common pest of tea, Glyptotermes dilatatus, at low elevations.

Animals↗

PubMedDate not supplied

L-usnate-urease interactions: binding sites for polymerization.

L-usnic acid inactivates urease through a process which implicates the blockade of--SH groups in parallel to the formation of inactive polymers. Both L-alanine and L-proline partially reverses the inactivation and effectively diminishes the amount of highly polymerized protein. The amino acids also prevent the linkage of L-usnic acid on the sites of low affinity for the ligand, being then related to the sites of polymerization.

Alanine↗

PubMed2004

Cytotoxic activity of compounds from the lichen: Cladonia convoluta.

The depsidone 9'-( O-methyl)protocetraric acid was isolated from the lichen Cladonia convoluta (Lam.) Anders along with the known (-)-usnic acid and fumarprotocetraric acid. The complete structure of 9'-( O-methyl)protocetraric acid was elucidated using HSQC and HMBC spectral data. (-)-Usnic acid was the only compound to display a moderate cytotoxic activity on various cancer cell lines (IC (50) = 6, 12.1, 15.8, 17.8, 8.2 and 6.8 microg/mL on L1210, 3LL, DU145, MCF7, K-562 and U251, respectively). This compound was also shown to induce apoptosis of murine leukaemia L1210 cells in a dose- and time-dependent manner.

Animals↗

PubMed2004

Anti-proliferative lichen compounds with inhibitory activity on 12(S)-HETE production in human platelets.

Several lichen compounds, i.e. lobaric acid (1), a beta-orcinol depsidone from Stereocaulon alpinum L., (+)-protolichesterinic acid (2), an aliphatic alpha-methylene-gamma-lactone from Cetraria islandica Laur. (Parmeliaceae), (+)-usnic acid (3), a dibenzofuran from Cladonia arbuscula (Wallr.) Rabenh. (Cladoniaceae), parietin (4), an anthraquinone from Xanthoria elegans (Link) Th. Fr. (Calaplacaceae) and baeomycesic acid (5), a beta-orcinol depside isolated from Thamnolia vermicularis (Sw.) Schaer. var. subuliformis (Ehrh.) Schaer. were tested for inhibitory activity on platelet-type 12(S)-lipoxygenase using a cell-based in vitro system in human platelets. Lobaric acid (1) and (+)-protolichesterinic acid (2) proved to be pronounced inhibitors of platelet-type 12(S)-lipoxygenase, whereas baeomycesic acid (5) showed only weak activity (inhibitory activity at a concentration of 100 microg/ml: (1) 93.4+/-6.62%, (2) 98,5+/-1.19%, 5 14.7+/-2.76%). Usnic acid (3) and parietin (4) were not active at this concentration. 1 and 2 showed a clear dose-response relationship in the range of 3.33-100 microg/ml. According to the calculated IC50 values the highest inhibitory activity was observed for the depsidone 1 (IC50 = 28.5 microM) followed by 2 (IC50 = 77.0 microM). The activity of 1 was comparable to that of the flavone baicalein, which is known as a selective 12(S)-lipoxygenase inhibitor (IC50 = 24.6 microM).

12-Hydroxy-5,8,10,14-eicosatetraenoic Acid↗

PubMed1995

Screening of tissue cultures and thalli of lichens and some of their active constituents for inhibition of tumor promoter-induced Epstein-Barr virus activation.

Inhibition of tumor promoter-induced Epstein-Barr virus (EBV) activation was screened using tissue culture and thallus extracts of lichens. Usnea longissima ACH. thallus and Cetraria ornata MULL. ARG. tissue culture showed strong inhibitory activity. We identified (+)-usnic acid (1), barbatic acid (2), diffractaic acid (3), 4-O-demethylbarbatic acid (4), and evernic acid (5) as inhibitors of EBV activation from the U. longissima thallus. Of these compounds, (+)-usnic acid exhibited the highest inhibitory activity (IC50 = 1.0 microM).

Anticarcinogenic Agents↗

PubMed1994

Analysis of Usnea fasciata crude extracts with antineoplastic activity.

Different fractions, isolated from the lichen Usnea fasciata, were analyzed by PC, TLC, and RP-HPLC. Analysis of the organic phases, mainly containing phenolics, revealed that usnic acid is the main product from secondary metabolites, whereas the polysaccharides isolichenin and raffinose are the most abundant water-soluble carbohydrates. Fractions containing usnic acid, as well as those containing isolichenin, showed moderate activity against sarcoma 180 and Ehrlich tumor cells. High antitumoral activity, near 90% inhibition, was found associated with the fraction containing raffinose.

Animals↗

PubMedDate not supplied

L-usnate-urease interactions: binding sites for the ligand.

L-usnic acid inactivates urease by formation of high molecular weight aggregates which can reached by a maximum of 880 000. L-cysteine partially reverses the inactivation of stimulating the appearance of active high molecular weight polymers. The existence of two class of binding points for L-usnic acid on the urease molecule is proposed, the first showing high affinity for the ligand, related with the loss of activity, and the second, of low affinity, related to polymerization process.

Benzofurans↗

PubMed1984

Purification and Properties of the Constitutive Arginase of Evernia prunastri.

Constitutive arginase (molecular weight 330,000) 920-fold purified from Evernia prunastri thallus, is activated by putrescine, l-ornithine, and agmatine with K(a) values of 2.7, 1.1, and 5.8 millimolar, respectively. Constitutive arginase is also activated by endogenous l-arginine, reaching its maximum activity at 16 hours of incubation on Tris-HCl (pH 9.15) with a subsequent decrease. Urea behaves as a mixed inhibitor of the enzyme with a K(i) value of 2.6 millimolar. Atranorin and evernic acid behave as in vitro activators of the enzyme; usnic acid does not have any significant effect as activator.

Journal Article↗

PubMed1999

Lichen metabolites. 1. Inhibitory action against leukotriene B4 biosynthesis by a non-redox mechanism.

Of several lichen metabolites isolated from Parmelia nepalensis and Parmelia tinctorum, the didepsides atranorin (4) and diffractaic acid (5), as well as (+)-protolichesterinic acid (7), inhibited LTB4 biosynthesis in polymorphonuclear leukocytes. Ethyl hematommate (3) and (+)-usnic acid (1) were only weak inhibitors, while methyl beta-orcinolcarboxylate (2) and gyrophoric acid (6) were inactive at concentrations up to 60 microM. Redox properties of the compounds were evaluated in terms of inhibition of nonenzymatic lipid peroxidation in model membranes, reactivity against the stable free radical 2,2-diphenyl-1-picrylhydrazyl, and deoxyribose degradation as a measure of hydroxyl-radical generation. The results revealed that lichen metabolites neither acted as antioxidants against the peroxidation process in model membranes nor did they scavenge or produce free radicals, suggesting that the inhibitory effects on LTB4 biosynthesis was due to specific enzyme interaction rather than a nonspecific redox mechanism.

Animals↗

PubMed2002

Differential sensitivity of four Lobaria lichens to copper in vitro.

Treatment of Lobaria amplissima, Lobaria pulmonaria, Lobaria scrobiculata, and Lobaria virens with 0 to 500 microM CuSO4 for 0 to 120 min at 25.0 degrees C resulted in a time- and copper-concentration-dependent decrease in the thallus total potassium content and a release of K- from the thallus, indicating that copper damaged the cytoplasmic membrane of the fungal hyphae. Lobaria pulmonaria was the most sensitive species, L virens the most resistant to copper treatment. Lobaria amplissima and L. scrobiculata displayed intermediate sensitivity. Treatment with copper also resulted in a time-dependent increase in the thallus copper content. For all four Lobaria species, the thallus potassium content decreased linearly with increasing thallus copper content, suggesting that, as cupric ions bound to the thallus, they reach target sites in the membrane. Acetone extracts contained low concentrations of chlorophyll a, amino acids, polyols, and sugars, but detectable or considerable amounts of lichen substances, i.e.. constictic, norstictic, stictic, and usnic acids and scrobiculin. Titration of the extracts with copper and assay of free Cu2+ revealed the presence of copper-binding ligands, most probably corresponding to the lichen substances detected in the extracts. Acetone extracts of L. amplissima and L. virens bound small or very small amounts of Cu2+; binding was monophasic and probably involved scrobiculin. Acetone extracts of L. pulmonaria and L. scrobiculata bound high or intermediate amounts of copper; binding was polyphasic and probably involved the lichen acids detected in the extracts. It was concluded that, in the studied Lobaria species, acetone extracts containing lichen substances could bind, in vitro, considerable amounts of Cu2+, but this binding did not prevent membrane damage in the thallus. Several hypotheses are presented to explain these results.

Air Pollutants↗

PubMed2006

Indole rings in palladium(II) complexes. Dual mode of metal binding and aromatic ring stacking causing syn-anti isomerism.

In view of the interesting metal-binding properties of lichen substances and the indole ring as a potential ligand, we studied the Pd(II) complexes of indole-containing ligands, N-(indole-3-ethyl)-Delta(2,11)-enaminousnic acid (IEU) and 4-[2-(indol-3-yl)-ethylamino]pent-3-en-2-one (IEP) obtained by condensation of tryptamine with usnic acid and its model acetylacetone, respectively. Reactions of Pd(II) with IEU and IEP gave isomeric complexes resulting from coordination of the C3 atom of the indole ring in the 3H-indole form, Pd2(IEUH(-2))(2) (1 and 2) and Pd2(IEPH(-2))(2) (3 and 4) (IEUH(-2) and IEPH(-2) denote doubly deprotonated forms of IEU and IEP, respectively). Complexes 1-4 were determined, from the NMR and MS spectra, to have dimeric structures doubly bridged by the indole rings, which were stacked in different orientations. X-ray crystal structure analysis of 3 and 4 established that they are indole-bridged dimers of the [C,N,O]-donor palladacycles with the Pd(II) centers in a square-planar geometry formed by a CN(2)O donor set and are anti and syn isomers with respect to the bridging indole rings, respectively. On the basis of the spectral similarity with 4, 1 and 2 were concluded to be stereoisomers assuming the syn form with the same donor set. The results demonstrate the metal binding and stacking abilities of the indole ring and the stereoisomerism from the sp3 C3 atom formed upon coordination.

Crystallography, X-Ray↗

PubMed2000

Allergy to lichen acids in a fragrance.

A 48-year-old clerical officer with a recurrent facial eruption had positive patch test reactions to nickel, fragrance mix and lichen acid mix. On testing to individual ingredients of fragrance mix and lichen acid mix, she had 2+ reactions to oak moss, which is thought to be the main allergen in fragrance mix, and to usnic acid, which is one of a number of lichen acids comprising oak moss. Avoidance of fragrance use resulted in clearing of the eruption but, subsequently, an acute vesicular flare on her face and hands occurred after exposure to lichen on garden shrubs.

Allergens↗