Evernic acid

Chemotype variations among lichen ecotypes of Umbilicaria aprina as revealed by LC-ESI-MS/MS: a survey of antioxidant phenolics.[Pubmed:32661964]

Environ Sci Pollut Res Int. 2020 Nov;27(32):40296-40308.

In the present study, we characterized the phytochemical properties, which were specifically associated with phenolic compounds and antioxidant activities in six distinct ecotypes of Umbilicaria aprina Nyl. from Iran (including Kivarestan, Mishan, Takht-e Nader, Tochal, Sabalan, and Sahand) to detect diversities within the species. Total phenolic concentration (TPC) and radical scavenging capacities of U. aprina ecotypes were evaluated. Moreover, qualitative differences between chemical profiles were surveyed using liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Relatively moderate TPCs (Kivarestan = 36.12 +/- 2.1, Mishan = 41.59 +/- 2.2, Takht-e Nader = 31.85 +/- 1.3, Tochal = 37.55 +/- 2.3, Sabalan = 28.91 +/- 2.5, and Sahand = 31.59 +/- 2.2) were observed for ecotypes, but a very strong correlation (r = -0/842) was obtained between TPCs and IC50 values. Based on the results of LC-ESI-MS/MS, the following chemical substances were identified: orsellinic acid (1), lecanoric acid (2), Evernic acid (3), gyrophoric acid (4), umbilicaric acid (5), hiascic acid (6), stictic acid (7) methyl hiascic acid (8), and an unknown substance (9). The MS/MS fragmentation scheme for each substance was determined and proposed. Wide discrepancies were observed in the chemical profiles of lichen ecotypes, which may corroborate the influence of ecological locality conditions, for example, altitude and slope aspects on secondary metabolism of lichen species U. aprina. The north-facing and east-facing ecotypes (Sabalan and Mishan, respectively) lacked depsidones (stictic acid) mainly because they receive the least direct radiation. Mishan ecotype, as the only east-facing ecotype, showed the most different chemical profile.

Lichens in Genus Parmelia: An Overview and their Application.[Pubmed:32250223]

Curr Pharm Biotechnol. 2020;21(13):1289-1297.

Parmelia that belongs to the Parmeliaceae Family is a foliose lichen combined with one or two groups of fungi in Phylum Ascomycota or Basidiomycota and algae, which might be green algae or blue-green algae (cyanobacteria). It is generally called "Stone Flower," "Charila," "Pattharphool," or "Shilaaapushpa" in India. Lichen can be generally found growing on walls, old trees and spread largely across India, especially in the mountain area. It is a source of edible organisms for people residing in some regions of Nepal and it is also cultivated in hillsides of Kashmir. It has been found that lichen contains a lot of distinctive chemical compounds such as Evernic acid, lecanoric acid, lobaric acid, norstictic acid, physodic acid, and salazinic acid. Some species of this lichen are recommended traditionally for controlling diseases such as boils, bronchitis, inflammations, excessive salivation, toothache, vomiting, etc. It has also applied as an indicator for biomonitoring, astringent, carminative, demulcent, bitter, resolvent, emollient, laxative, sporofic, sedative, diuretic and considered for treating sores, bronchitis, excessive salivation, vomiting, tooth-ache, boils and inflammations. It has been utilized for preparing traditional food and acts as a bioindicator for air pollution and radiation. It shows antibacterial, antioxidant, antimycobacterial and antifungal activities, including haemolytic, anaesthetic, spasmolytic and antispasmodic and antitumour activities. It also has several unique phytoconstituents that could be in charge of different therapeutic activities, but the majority of them are still unexplored. The review mainly focuses on various facets, such as common names, synonyms, traditional uses, botanical descriptions, and pharmacological activities of seven species of Parmelia.

Structure and Chemical Analysis of Major Specialized Metabolites Produced by the Lichen Evernia prunastri.[Pubmed:31701649]

Chem Biodivers. 2020 Jan;17(1):e1900465.

We performed comparative profiling of four specialized metabolites in the lichen Evernia prunastri, collected at three different geographic locations, California and Maine, USA, and Yoshkar Ola, Mari El, Russia. Among the compounds produced at high concentrations that were identified in all three specimens, Evernic acid, usnic acid, lecanoric acid and chloroatranorin, Evernic acid was the most abundant. Two depsidones, salazinic acid and physodic acid, were detected in the Yoshkar-Ola collection only. The crystalline structure of Evernic acid (2-hydroxy-4-[(2-hydroxy-4-methoxy-6-methylbenzoyl)oxy]-6-methylbenzoate) (hmb) revealed two crystallographically and conformationally distinct hmb anions, along with two monovalent sodium atoms. One hmb moiety contained an exotetradentate binding mode to sodium, whereas the other exhibited an exohexadentate binding mode to sodium. Embedded edge-sharing {Na2 O8 }n sodium-oxygen chains connected the hmb anions into the full three-dimensional crystal structure of the title compound. The crystal used for single-crystal X-ray diffraction exhibited non-merohedral twinning. The data suggest the importance of the acetyl-polymalonyl pathway products to processes of maintaining integrity of the lichen holobiont community.

DFT and QTAIM based investigation on the structure and antioxidant behavior of lichen substances Atranorin, Evernic acid and Diffractaic acid.[Pubmed:30928870]

Comput Biol Chem. 2019 Jun;80:66-78.

In this study, the structural and antioxidant behavior of the three lichen-derived natural compounds such as atranorin (AT), Evernic acid (EV) and diffractaic acid (DF) has been investigated in the gas and water phase using both B3LYP and M06-2X functional level of density functional theory (DFT) with two different basis sets 6-31+G (d, p) and 6-311++G (d, p). The intramolecular H-bonds (IHB) strength, aromaticity and noncovalent interactions (NCI) have been computed with the help of the quantum theory of atoms in molecules (QTAIM). This calculation gives major structural characteristics that indirectly influence the antioxidant behavior of the investigated compounds. The spin density (SD) delocalization of the unpaired electron is found to be the main stabilizing factor of neutral and cationic radical species. The main mechanisms, recommended in the literature, for the antioxidant action of polyphenols as radical scavengers such as hydrogen atom transfer (HAT), single electron transfer followed by proton transfer (SET-PT), and sequential proton loss electron transfer (SPLET), were examined. The result shows that the HAT and SPLET mechanism are the most conceivable one for the antioxidant action of this class of compounds in gas and water phase respectively. Preference of SPLET over HAT in water phase is due to the significantly lower value of proton affinity (PA) compared to the bond dissociation enthalpy (BDE) value. This study reveals that O2-H3, O9-H26 and O4-H45 respectively are the most favored site of AT, EV and DF for homolytic as well as heterolytic OH bond breaking.

Simultaneous determination of usnic, diffractaic, evernic and barbatic acids in rat plasma by ultra-high-performance liquid chromatography-quadrupole exactive Orbitrap mass spectrometry and its application to pharmacokinetic studies.[Pubmed:29055065]

Biomed Chromatogr. 2018 Mar;32(3).

Usnea longissima Ach. (Usnea) is used in pharmaceuticals, food and cosmetics. Evernic acid (EA), barbatic acid (BA), diffractaic acid (DA) and usnic acid (UA) are the most typical ingredients in U. longissima and exert a wide variety of biological functions. The study aimed to develop a sensitive method for simultaneous analysis of EA, BA, DA and UA in rat plasma and was applied to pharmacokinetic studies after consumption of UA and ethanol extract from U. longissima (UE). The samples were separated on a BEH C18 column by gradient elution with 0.5% formic acid in water and in methanol. The relative molecular masses of analytes were obtained in full-scan range from 50.0 to 750.0 m/z under negative ionization mode by UPLC-Q-Exactive Orbitrap MS. All validation parameters, such as lower limit of quantitation, linearity, specificity, precision, accuracy, extraction recovery, matrix effect and stability, were within acceptable ranges and the method was appropriate for biological specimen analysis. The pharmacokinetic results indicated that the absolute bioavailabilities of UA after oral administration of UA and UE reached 69.2 and 146.9%, respectively. Compared with UA in UE, the relative bioavailability of DA, BA and EA reached 103.7, 10.4 and 0.7% after oral administration of UE.

Protective effects of lichen metabolites evernic and usnic acids against redox impairment-mediated cytotoxicity in central nervous system-like cells.[Pubmed:28450128]

Food Chem Toxicol. 2017 Jul;105:262-277.

Lichens species produce unique secondary metabolites that attract increasing pharmacological interest, including their redox modulatory activities. Current work evaluated for the first time the in vitro cytoprotective properties, based on the antioxidant activities, of the Parmeliaceae lichens Evernia prunastri and Usnea ghattensis and the mechanism of action of their major phenolic constituents: the evernic and usnic acids, respectively. In two models of central nervous system-like cells (U373-MG and SH-SY5Y cell lines), exogenous H2O2 induced oxidative stress-mediated cytotoxicity. We first assessed their radical scavenging capacities (ORAC and DPPH tests) and the phenolic content of the extracts. At the optimal concentrations, pretreatments with Evernic acid displayed significant protection against H2O2-induced cytotoxic damage in both models. It reversed the alterations in oxidative stress markers (including ROS generation, glutathione system and lipid peroxidation levels) and cellular apoptosis (caspase-3 activity). Such effects were in part mediated by a notable enhancement of the expression of intracellular phase-II antioxidant enzymes; a plausible involvement of the Nrf2 cytoprotective pathway is suggested. Usnic acid exerted similar effects, to some extent more moderate. Results suggest that lichen polyketides evernic and usnic acids merit further research as promising antioxidant candidates in the therapy of oxidative stress-related diseases, including the neurodegenerative disorders.

Reducing Virulence and Biofilm of Pseudomonas aeruginosa by Potential Quorum Sensing Inhibitor Carotenoid: Zeaxanthin.[Pubmed:28255686]

Microb Ecol. 2017 Aug;74(2):466-473.

Pseudomonas aeruginosa can regulate its virulence gene expressions by using a signal system called quorum sensing. It is known that inhibition of quorum sensing can block biofilm formation and leave the bacteria defenseless. Therefore, it is necessary to determine natural sources to obtain potential quorum sensing inhibitors. This study aims to investigate an alternative treatment approach by utilizing the carotenoid zeaxanthin to reduce the expressions of P. aeruginosa virulence factors through quorum sensing inhibition. The inhibition potential of zeaxanthin was determined by in silico screening from a library of 638 lichen metabolites. Fluorescent monitor strains were utilized for quorum sensing inhibitor screens, and quantitative reverse-transcriptase PCR assay was performed for evaluating gene expression. Results indicate that zeaxanthin is a better inhibitor than the lichen secondary metabolite Evernic acid, which was previously shown to be capable of inhibiting P. aeruginosa quorum sensing systems.

Lichen secondary metabolite evernic acid as potential quorum sensing inhibitor against Pseudomonas aeruginosa.[Pubmed:27465850]

World J Microbiol Biotechnol. 2016 Sep;32(9):150.

Cystic Fibrosis is a genetic disease and it affects the respiratory and digestive systems. Pseudomonas aeruginosa infections in Cystic Fibrosis are presented as the main cause for high mortality and morbidity rates. Pseudomonas aeruginosa populations can regulate their virulence gene expressions via the bacterial communication system: quorum sensing. Inhibition of quorum sensing by employing quorum sensing inhibitors can leave the bacteria vulnerable. Therefore, determining natural sources to obtain potential quorum sensing inhibitors is essential. Lichens have ethnobotanical value for their medicinal properties and it is possible that their secondary metabolites have quorum sensing inhibitor properties. This study aims to investigate an alternative treatment approach by utilizing lichen secondary metabolite Evernic acid to reduce the expressions of Pseudomonas aeruginosa virulence factors by inhibiting quorum sensing. For this purpose, fluorescent monitor strains were utilized for quorum sensing inhibitor screens and quantitative reverse-transcriptase PCR analyses were conducted for comparison. Results indicate that Evernic acid is capable of inhibiting Pseudomonas aeruginosa quorum sensing systems.

[Phenolic constituents from lichen Usnea longissima].[Pubmed:28895334]

Zhongguo Zhong Yao Za Zhi. 2016 May;41(10):1864-1869.

Sixteen compounds were isolated from lichen Usnea longissima using of various chromatographic techniques including silica gel, Sephadex LH-20, ODS, and semi-preparative HPLC. By spectroscopic data analyses, their structures were identified by as useanol(1), lecanorin(2), 3-hydroxy-5-methylphenyl 2-hydroxy-4-methoxy-6-methylbenzoate(3), lecanorin E(4), 3'-methylEvernic acid(5), Evernic acid(6), barbatinic acid(7), 3,7-dihydroxy-1,9-dimethyldibenzofuran(8), orcinol(9), O-methylorcinol(10), methyl orsellinate(11), methyl everninate(12), 2,5-dimethyl-1,3-benzenediol(13), 2-hydroxy-4-methoxy-3,6-dimethyl benzoic acid(14), ethyl everninate(15), and ethyl 2,4-dihydroxy-6-methylbenzoate(16). Compound 1 was obtained as a natural product for the first time, and 3,4, 8,10,12, and 13 were isolated from Usneaceae family for the first time. Compound 1, 8, and 13 showed significant anti-inflammatory activity against NO production in RAW 267.4 cells with IC(5)(0) values of 6.8, 3.9 and 4.8 mumol*L(-)(1), respectively, compared with the positive controls curcumin(IC(5)(0) 15.3 mumol*L(-)(1)) and indomethacin(IC(5)(0) 42.9 mumol*L(-)(1)).

Biopharmaceutical Potential of Two Ramalina Lichens and their Metabolites.[Pubmed:27033512]

Curr Pharm Biotechnol. 2016;17(7):651-8.

This paper studies the phytochemical analysis of the acetone extracts of the Ramalina fraxinea and Ramalina fastigiata lichens and the antioxidant, antimicrobial and antitumour activities of these species and their constituents. The phytochemical analysis of two Ramalina species was evaluated using HPLC-UV test. The depsides (Evernic acid, obtusatic acid, sekikaic acid and atranorin), depsidones (protocetraric acid) and dibenzofurane (usnic acid) were identified from these lichens. Antioxidant activity was evaluated by DPPH assay, reducing power assay and by measuring the amounts of total phenolics in extracts. Antimicrobial activity was tested towards five bacterial and 10 fungal species, using broth microdilution method to determine the minimum inhibitory concentration. Cytotoxic activity was tested using MTT method on the human epithelial carcinoma (Hela), human lung carcinoma (A549) and human colon carcinoma (LS174) cells. As a result of the study, tested samples showed strong free radical scavenging activity with I50 values within the range of 285.45-423.51 mug/mL. Absorbance for reducing power was found to be from 0.0043 to 0.1747. The total amount of phenol concentrations in extracts of Ramalina fraxinea and Ramalina fastigiata was 32.63 and 33.49 mug PE/mg, respectively. Methyl evernate showed the strongest antimicrobial properties with the least measured MIC value being 0.125 mg/mL. In addition, all samples exhibited strong anticancer activities against tested cells (I50 values were between 24.63 and 161.37 mug/mL). These results indicate that lichen appears to be a possible natural biopharmaceutical.

Optimisation and establishment of separation conditions of organic acids from Usnea longissima Ach. by pH-zone-refining counter-current chromatography: Discussion of the eluotropic sequence.[Pubmed:26686561]

J Chromatogr A. 2016 Jan 4;1427:96-101.

The major bioactive constituents of Usnea longissima Ach. are organic acids. However, few recent literatures involve the preparative separation of these organic acids. In the present study, pH zone-refining counter-current chromatography is used to separate organic acids from crude sample of U. longissima Ach. The crude extract was separated with the two-phase solvent system Pet-EtAc-MeOH-H2O (5:5:3:7, v/v) with 10mM TFA in organic stationary phase and different concentration of the eluter in aqueous mobile phase for the screening of the most suitable separation conditions. From the crude extract (1.2g), 74.0mg of orsellinic acid at 92.7% purity, 55.5mg of 4-O-methylorsellinic acid at 97.7% purity, 353.5mg of Evernic acid at 93.8% purity, 102.0mg of barbatic acid at 94.8% purity, 19.4 mg of diffractaic acid at 92.2% purity, and 44.9 mg of usnic acid at 95.7% purity were obtained using the selected conditions in which the concentration of TFA in stationary phase was 10mM and the concentration of NaOH in mobile phase was 10-20mM. The purities of the separated organic acids were measured by HPLC. And the data of electrospray ionization-liquid chromatography/mass spectrometry (ESI-LC/MS), (1)H NMR, and (13)C NMR were used for confirming chemical structures.

Clastogenic effect of atranorin, evernic acid, and usnic acid on human lymphocytes.[Pubmed:24868868]

Nat Prod Commun. 2014 Apr;9(4):503-4.

Three lichen secondary metabolites atranorin (1), Evernic acid (2), and usnic acid (3), were evaluated for their in vitro clastogenic and antiproliferative effects on human lymphocytes using the cytochalasin-B blocked micronucleus (CBMN) assay at concentrations of 2 microg/mL, 4 microg/mL and 6 microg/mL of final culture solution. The frequency of micronucleus (MN) was scored in binucleated cells, and cytokinesis-block proliferation index (CBPI) was calculated. Among the tested compounds, 3 exhibited the most prominent effect decreasing the frequency of MN in the range of 42.5% - 48.9%, that is about double of the positive control amifostin WR-2721 that reduces MN frequency for 22.0%. The effect of Evernic acid was approximately equal to action of amifostin (23.2% -32.9%). Atranorin at concentrations of 2 microg/mL and 4 microg/mL decreasing the frequency of MN only for 11.1% and 1.8%, while in concentration of 6 microg/mL increases the frequency of MN for 9.6 %. The comparable CBPI values of the investigated compounds and control suggested that they did not show a statistically significant inhibitory effect on lymphocyte cell proliferation at applied concentrations.