Protocetraric acid

Unraveling the Pharmacological Potential of Lichen Extracts in the Context of Cancer and Inflammation With a Broad Screening Approach.[Pubmed:33013369]

Front Pharmacol. 2020 Sep 4;11:1322.

Lichen-forming fungi are symbiotic organisms that synthesize unique natural products with potential for new drug leads. Here, we explored the pharmacological activity of six lichen extracts (Evernia prunastri, Pseudevernia furfuracea, Umbilicaria pustulata, Umbilicaria crustulosa, Flavoparmelia caperata, Platismatia glauca) in the context of cancer and inflammation using a comprehensive set of 11 functional and biochemical in vitro screening assays. We assayed intracellular Ca(2+) levels and cell migration. For cancer, we measured tumor cell proliferation, cell cycle distribution and apoptosis, as well as the angiogenesis-associated proliferation of endothelial cells (ECs). Targeting inflammation, we assayed leukocyte adhesion onto ECs, EC adhesion molecule expression, as well as nitric oxide production and prostaglandin (PG)E2 synthesis in leukocytes. Remarkably, none of the lichen extracts showed any detrimental influence on the viability of ECs. We showed for the first time that extracts of F. caperata induce Ca(2+) signaling. Furthermore, extracts from E. prunastri, P. furfuracea, F. caperata, and P. glauca reduced cell migration. Interestingly, F. caperata extracts strongly decreased tumor cell survival. The proliferation of ECs was significantly reduced by E. prunastri, P. furfuracea, and F. caperata extracts. The extracts did not inhibit the activity of inflammatory processes in ECs. However, the pro-inflammatory activation of leukocytes was inhibited by extracts from E. prunastri, P. furfuracea, F. caperata, and P. glauca. After revealing the potential biological activities of lichen extracts by an array of screening tests, a correlation analysis was performed to evaluate particular roles of abundant lichen secondary metabolites, such as atranorin, physodic acid, and Protocetraric acid as well as usnic acid in various combinations. Overall, some of the lichen extracts tested in this study exhibit significant pharmacological activity in the context of inflammation and/or cancer, indicating that the group lichen-forming fungi includes promising members for further testing.

Morphology and secondary chemistry in species recognition of Parmelia omphalodes group - evidence from molecular data with notes on the ecological niche modelling and genetic variability of photobionts.[Pubmed:31866741]

MycoKeys. 2019 Dec 11;61:39-74.

To evaluate the importance of morphological and chemical characters used in the recognition of species within the Parmelia omphalodes group, we performed phylogenetic, morphological and chemical analyses of 335 specimens, of which 34 were used for molecular analyses. Phylogenetic analyses, based on ITS rDNA sequences, show that P. pinnatifida is distinct from P. omphalodes and the most important difference between those species is the development of pseudocyphellae. In P. pinnatifida, they are mostly marginal and form white rims along lobes margins, but laminal pseudocyphellae can develop in older parts of thalli and are predominantly connected with marginal pseudocyphellae. In contrast, in P. omphalodes laminal pseudocyphellae are common and are predominantly not connected to marginal pseudocyphellae. Chemical composition of secondary lichen metabolites in both analysed species is identical and therefore this feature is not diagnostic in species recognition. Few samples of P. discordans, species morphologically similar to P. omphalodes and P. pinnatifida, were also included in the analyses and they are nested within the clade of P. omphalodes, despite the different chemistry (Protocetraric acid present versus salazinic acid in P. omphalodes). All taxa of the P. omphalodes group occupy similar niches, but their potential distributions are wider than those currently known. The absence of specimens in some localities may be limited by the photobiont availability. Parmelia omphalodes and P. pinnatifida are moderately selective in photobiont choice as they form associations with at least two or three lineages of Trebouxia clade S. Parmelia pinnatifida, as well as P. discordans are associated with Trebouxia OTU S02 which seems to have a broad ecological amplitude. Other lineages of Trebouxia seem to be rarer, especially Trebouxia sp. OTU S04, which is sometimes present in P. pinnatifida. This study indicates the importance of extensive research including morphology, chemistry and analysis of molecular markers of both bionts in taxonomical studies of lichens.

Antibacterial activity of the lichens Usnea Florida and Flavoparmelia caperata (Parmeliaceae).[Pubmed:30676068]

Nat Prod Res. 2020 Dec;34(23):3358-3362.

Acetone extracts of the two common epiphytes lichens Usnea florida and Flavoparmelia caperata have been evaluated for their antimicrobial activities against Staphylococcus aureus, Candida albicans and Aspergillus brasiliensis. The dibenzofuran derivative (+)-usnic acid (1) was the main metabolite in these two species. Thamnolic (5), evernic (6), physodic (7) and 3-hydroxyphysodic acids (8) were isolated from U. florida, as well as 5,7-dihydroxy-6-methylphtalide (2) which was newly identified in this Genus. Protocetraric (3) and caperatic acids (4) and ergosterol peroxide (9) are usually biosynthezised by F. caperata. Antibacterial activity was determined for the four main compounds against Staphylococcus aureus using bioautography and broth dilution method. Minimal inhibitory concentrations of usnic acid, caperatic acid and Protocetraric acid were comprised between 7.25 and 12.5 microg/mL.

Lichen secondary metabolites affect growth of Physcomitrella patens by allelopathy.[Pubmed:27645140]

Protoplasma. 2017 May;254(3):1307-1315.

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.

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.

Protocetraric acid: an excellent broad spectrum compound from the lichen Usnea albopunctata against medically important microbes.[Pubmed:25174415]

Nat Prod Res. 2015;29(6):574-7.

The aim of this study was to investigate the antimicrobial property of the compounds present in the lichen Usnea albopunctata. Ethyl acetate extract of the lichen was purified by column chromatography to yield a major compound which was characterised by spectroscopic methods as Protocetraric acid. In this study, Protocetraric acid recorded significant broad spectrum antimicrobial property against medically important human pathogenic microbes. The prominent antibacterial activity was recorded against Salmonella typhi (0.5 mug/mL). Significant antifungal activity was recorded against Trichophyton rubrum (1 mug/mL), which is significantly better that the standard antifungal agent. Protocetraric acid is reported here for the first time from U. albopunctata. Thus the results of this study suggest that Protocetraric acid has significant antimicrobial activities and has a strong potential to be developed as an antimicrobial drug against pathogenic microbes.

Antitrypanosomal activity & docking studies of isolated constituents from the lichen Cetraria islandica: possibly multifunctional scaffolds.[Pubmed:24660683]

Curr Top Med Chem. 2014;14(8):1014-21.

Chemical investigation of the lichen Cetraria islandica has led to the isolation of four compounds identified as protolichesterinic acid, lichesterinic acid, Protocetraric acid and fumarProtocetraric acid. Their structures were characterized using their physical and spectroscopic data. Using an Alamarblue 96 well microplate assay, these compounds were tested to evaluate their trypanocidal activity against Trypanosoma brucei brucei. Protolichesterinic acid (MIC = 6.30 microM) and lichesterinic acid (MIC = 12.5 microM) showed very significant activity against the test organism. Docking studies (GRIP technique) of these molecules revealed their strong affinity towards possible targets of Trypanosoma brucei such as riboflavin kinase, sterol-14alpha-demethylase (CYP51), rohedsain and glutathione synthetase. Hydrophobicity played a significant role in their antitrypanosomal activity.

Comparative metabolite profiling and chemical study of Ramalina siliquosa complex using LC-ESI-MS/MS approach.[Pubmed:23489575]

Phytochemistry. 2013 May;89:114-24.

A chemical study of the lichen Ramalina siliquosa complex found in Brittany was conducted. Eight chemotypes were considered and their chemical composition was elucidated for the first time by LC-MS analysis. Ten main compounds were identified: conhypoProtocetraric acid (1), salazinic acid (2), peristictic acid (3), cryptostictic acid (4), Protocetraric acid (5), stictic acid (6), norstictic acid (7), hypoProtocetraric acid (8), 4-O-demethylbarbatic acid (9), (+)-usnic acid (10) and 22 minor compounds were reported. The MS/MS fragmentation patterns of each compound of R. siliquosa complex were determined and proposed.

Cytotoxic evaluation of phenolic compounds from lichens against melanoma cells.[Pubmed:23207680]

Chem Pharm Bull (Tokyo). 2013;61(2):176-83.

Atranorin, lichexanthone, and the (+)-usnic, diffractaic, divaricatic, perlatolic, psoromic, protocetraric, and norstictic acids isolated from the lichens Parmotrema dilatatum (VAIN.) HALE, Usnea subcavata MOTYKA, Usnea sp., Ramalina sp., Cladina confusa (SANT.) FOLMM. & AHTI, Dirinaria aspera HASANEN, and Parmotrema lichexanthonicum ELIASARO & ADLER were evaluated against UACC-62 and B16-F10 melanoma cells and 3T3 normal cells. Sulforhodamine B assay revealed significant cytotoxic activity in protocetraric, divaricatic, and perlatolic acids on UACC-62 cells (50% growth inhibitory concentration (GI(50)) 0.52, 2.7, and 3.3 microg/mL, respectively). Divaricatic and perlatolic acids proved the most active on B16-F10 cells (GI(50) 4.4, 18.0 microg/mL, respectively) and the most cytotoxic to 3T3 normal cells. Diffractaic, usnic, norstictic, and psoromic acids were cytotoxic to UACC-62 cells in the 24.7 to 36.6 microg/mL range, as were protocetraric and diffractaic acids to B16-F10 cells (GI(50) 24.0, 25.4 microg/mL, respectively). Protocetraric acid was highly selective (selectivity index (SI*) 93.3) against UACC-62 cells, followed by norstictic, perlatolic, psoromic, and divaricatic acids, while norstictic and divaricatic acids were more selective against B16-F10 cells. The high SI* value obtained for Protocetraric acid on UACC-62 cells makes it a potential candidate for the study of melanomas in experimental models. Chemometric analysis was performed to evaluate the general behavior of the compounds against the cell lines tested.

Chemical composition of three Parmelia lichens and antioxidant, antimicrobial and cytotoxic activities of some their major metabolites.[Pubmed:22921748]

Phytomedicine. 2012 Oct 15;19(13):1166-72.

The aim of this study is to investigate chemical composition of acetone extracts of the lichens Parmelia caperata, P. saxatilis and P. sulcata and antioxidant, antimicrobial and anticancer activities of some their major metabolites. The phytochemical analysis of acetone extracts of three Parmelia lichens were determined by HPLC-UV method. The predominant phenolic compounds in these extracts were protocetraric and usnic acids (P. caperata) and depsidone salazinic acid (other two species). Besides these compounds, atranorin and chloroatranorin, were also detected in some of these extracts. Antioxidant activity of their isolated metabolites was evaluated by free radical scavenging, superoxide anion radical scavenging and reducing power. As a result of the study salazinic acid had stronger antioxidant activity than Protocetraric acid. The antimicrobial activity was estimated by determination of the minimal inhibitory concentration by the broth microdilution method. Both compounds were highly active with minimum inhibitory concentration values ranging from 0.015 to 1mg/ml. Anticancer activity was tested against FemX (human melanoma) and LS174 (human colon carcinoma) cell lines using MTT method. Salazinic acid and Protocetraric acid were found to be strong anticancer activity toward both cell lines with IC(50) values ranging from 35.67 to 60.18mug/ml. The present study shows that tested lichen compounds demonstrated a strong antioxidant, antimicrobial, and anticancer effects. That suggest that these lichens can be used as new sources of the natural antimicrobial agents, antioxidants and anticancer compounds.

Allelopathic and bioherbicidal potential of Cladonia verticillaris on the germination and growth of Lactuca sativa.[Pubmed:22835725]

Ecotoxicol Environ Saf. 2012 Oct;84:125-32.

Responses to germination and initial growth of Lactuca sativa (lettuce) submitted to organic extracts and purified compounds of Cladonia verticillaris ("salambaia") were analyzed in this work. The experiments were conducted in laboratory conditions using extracts and pure compounds at different concentrations. None of the assays showed any influence on the germination of L. sativa seeds using C. verticillaris extracts; however, modifications in leaf area and seedling hypocotyl and root development occurred. In the growth experiments, seedlings exposed to ether or acetone extract showed diminished hypocotyl growth in detriment to the root stimulus, compared to controls. Increases in extract concentrations led to the formation of abnormal seedlings. To determine the allelochemicals of C. verticillaris, its principal components, fumarprotocetraric and Protocetraric acids, were isolated and then analyzed by high performance liquid chromatography (HPLC). When the seedlings were exposed to the two acids separately, presented increased leaf area at all concentrations. In contrast, hypocotyl and root stimulus was observed only in the presence of Protocetraric acid at different concentrations. Fumarprotocetraric as well as Protocetraric acids, isolated and purified from C. verticillaris and Parmotrema dilatatum respectively, influenced the development of L. sativa seedlings at high concentrations, indicating a possible bioherbicide potential of these acids.

Antimycobacterial activity of lichen substances.[Pubmed:19683421]

Phytomedicine. 2010 Apr;17(5):328-32.

We describe here the extraction and identification of several classes of phenolic compounds from the lichens Parmotrema dilatatum (Vain.) Hale, Parmotrema tinctorum (Nyl.) Hale, Pseudoparmelia sphaerospora (Nyl.) Hale and Usnea subcavata (Motyka) and determined their anti-tubercular activity. The depsides (atranorin, diffractaic and lecanoric acids), depsidones (protocetraric, salazinic, hypostictic and norstictic acids), xanthones (lichexanthone and secalonic acid), and usnic acid, as well seven orsellinic acid esters, five salazinic acid 8',9'-O-alkyl derivatives and four lichexanthone derivatives, were evaluated for their activity against Mycobacterium tuberculosis. Diffractaic acid was the most active compound (MIC value 15.6mug/ml, 41.6 microM), followed by norstictic acid (MIC value 62.5 microg/ml, 168 microM) and usnic acid (MIC value 62.5 microg/ml, 182 microM). Hypostictic acid (MIC value 94.0 microg/ml, 251 microM) and Protocetraric acid (MIC value 125 microg/ml, 334 microM) showed moderate inhibitory activity. The other compounds showed lower inhibitory activity on the growth of M. tuberculosis, varying from MIC values of 250 to 1370 microM.

Evaluation of the antimicrobial activity of the acetone extract of the lichen Ramalina farinacea and its (+)-usnic acid, norstictic acid, and protocetraric acid constituents.[Pubmed:18998406]

Z Naturforsch C J Biosci. 2004 May-Jun;59(5-6):384-8.

The acetone extract of the lichen Ramalina farinacea and its (+)-usnic acid constituent showed antimicrobial activity against Bacillus subtilis, Listeria monocytogenes, Proteus vulgaris, Staphylococcus aureus, Streptococcus faecalis, Yersinia enterocolitica, Candida albicans, and Candida glabrata. Norstictic acid was active against Aeromonas hydrophila as well as the above microorganisms except Yersinia enterocolitica. Protocetraric acid showed activity only against the tested yeasts Candida albicans and Candida glabrata. The MIC values of the extract as well as of the three substances were determined. No antifungal activity of the acetone extract has been observed against ten filamentous fungi.

Lichen substances affect metal adsorption in Hypogymnia physodes.[Pubmed:17136464]

J Chem Ecol. 2007 Jan;33(1):219-23.

Lichen substances are known to function as chelators of cations. We tested the hypothesis that lichen substances can control the uptake of toxic metals by adsorbing metal ions at cation exchange sites on cell walls. If true, this hypothesis would help to provide a mechanistic explanation for results of a recent study showing increased production of physodalic acid by thalli of the lichen Hypogymnia physodes transplanted to sites with heavy metal pollution. We treated cellulose filters known to mimic the cation exchange abilities of lichen thalli with four lichen substances produced by H. physodes (physodic acid, physodalic acid, Protocetraric acid, and atranorin). Treated filters were exposed to solutions containing seven cations (Ca(2+), Cu(2+), Fe(2+), Fe(3+), Mg(2+), Mn(2+), and Na(+)), and changes to the solution concentrations were measured. Physodalic acid was most effective at influencing metal adsorption, as it increased the adsorption of Fe(3+), but reduced the adsorption of Cu(2+), Mn(2+), and Na(+), and to a lesser extent, that of Ca(2+) and Mg(2+). Reduced Na(+) adsorption matches with the known tolerance of this species to NaCl. The results may indicate a possible general role of lichen substances in metal homeostasis and pollution tolerance.

Cytotoxic activity of compounds from the lichen: Cladonia convoluta.[Pubmed:15386197]

Planta Med. 2004 Sep;70(9):874-7.

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.