Nature of light-absorbing pigments from Brazilian lichens identified by Raman spectroscopy

Fernandes, Rafaella F.; Porto, Arthur B.; Flores, Leonã S.; Maia, Lenize F.; Corrêa, Charlane C.; Spielmann, Adriano S.; Edwards, Howell G. M.; Oliveira, Luiz Fernando Cappa de

doi:10.1016/j.vibspec.2018.08.007

Cited by 7 publications

(4 citation statements)

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“…Usnic acid (UA) is a phenolic compound with a dibenzofuran structure occurring in the form of two enantiomers ( Figure 1 ) [ 1 ] in several lichen genera ( Alectoria , Cladonia , Evernia , Lecanora , Parmelia , Ramalina , Usnea , and Xanthoparmelia ) as a yellow cortical pigment [ 2 , 3 , 4 , 5 , 6 ]. Nowadays, it is the most extensively investigated lichen secondary metabolite.…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays, it is the most extensively investigated lichen secondary metabolite. Its numerous biological activities have been proved, e.g., antiprotozoal, anti-inflammatory, antimicrobial, antiviral, analgesic, insecticidal [ 7 ], antitumor, antipyretic, antiproliferative, antioxidant [ 8 ], photoprotective [ 6 ], cytoprotective, gastroprotective, and immunostimulatory properties [ 9 , 10 ]. Considering the above-mentioned activities, UA has found application in cosmetology, agriculture, the pharmaceutical industry, and dentistry [ 3 ].…”

Section: Introductionmentioning

confidence: 99%

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Methodological Aspects of Green Extraction of Usnic Acid Using Natural Deep Eutectic Solvents

et al. 2023

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Usnic acid (UA) is a compound with multiple biological activities that make it useful in various industries, e.g., pharmaceutical, cosmetic, dentistry, and agricultural sectors. Lichens are the primary source of UA, which is primarily extracted using acetone. This study aimed to investigate the solubility of UA in numerous natural deep eutectic solvents (NADESs) and use a mixture of thymol and camphor as a NADES in the optimization of the UA extraction process with the design of experiments method. For numerical optimization, the following parameters were employed in the experiment to confirm the model: a camphor-to-thymol ratio of 0.3, a liquid-to-solid ratio of 60, and a time of 30 min. The obtained experimental results aligned well with the predicted values, with the mean experimental value falling within the confidence interval, exhibiting deviations between 11.93 and 14.96. By employing this model, we were able to optimize the extraction procedure, facilitating the isolation of approximately 91% of the total UA content through a single extraction, whereas a single acetone extraction yielded only 78.4% of UA.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Methodological Aspects of Green Extraction of Usnic Acid Using Natural Deep Eutectic Solvents

et al. 2023

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“…was collected from the understory of a boreal forest on the outskirts of Syktyvkar, Komi Republic, Russia. From the literature, the main lichen substances in these species have been reported to be calycin and pulvinic acid for Crocodia aurata [15]; salizanic and stictic acid for Parmotrema perlata [16]; usnic acid for Ramalina celastri and Usnea undulata [17,18]; and fumarprotocetraric acid for Cladonia coniocraea and Cetraria islandica [19,20].…”

Section: Lichen Materialsmentioning

confidence: 99%

A Role for Secondary Metabolites in Desiccation Tolerance in Lichens

Ndhlovu,

Minibayeva,

Beckett

2024

Microbiology Research

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In lichens, secondary metabolites have been shown to protect against biotic stresses such as pathogen attacks and grazing, and abiotic stresses such as ultraviolet (UV) and high photosynthetically active radiation (PAR). Lichen secondary metabolites are known to have strong antioxidant activity, and while theoretically they may have roles in tolerance to other abiotic stresses, these roles remain largely unclear. Here, we used the acetone rinsing method to harmlessly remove most of the secondary metabolites from the thalli of six lichen species. This enabled us to compare the effects of desiccation on thalli with and without the presence of secondary metabolites. Results showed that in general, the presence of lichen substances reduces the effects of desiccation stress. For all species, substances significantly improved the photosystem two (PSII) activity of the photobiont during either desiccation or rehydration. In the mycobiont, in four of the six species, the presence of substances reduced membrane damage, which was assessed by measuring ion leakage during rehydration following desiccation. However, in one species, secondary metabolites had no effect, while in another the presence of substances increased membrane damage. Nevertheless, it seems clear that in addition to their more established roles in protecting lichens against pathogen attacks and grazing, lichen substances can also play a role in aiding desiccation tolerance.

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“…Their positional isomers with the rings connected by [3,2-b] type fusion are called iDPPs [25] or isoDPPs [26] . Parent isoDPP (Ar = phenyl, X=NH), just as its π-isoelectronic analogue, i. e. the lichen compound pulvinic dilactone (X=O) [27] , does not fluoresce even in solution, due to the low-lying symmetry-forbidden ππ* state. [25] The same reason probably causes very weak solution fluorescence of thieno[3,2-b]thiophene 2,5-diones (Ar=Th, X=S).…”

Section: Introductionmentioning

confidence: 99%

Four Slip‐Stacked Arrangements, Three Types of Photophysics: Crystal Structure and Solid‐State Fluorescence of 3,6‐Diaryl Substituted Furo[3,4‐c]furanone Polymorphs and Regioisomers

et al. 2023

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Six symmetrical 3,6‐diaryl (aryl=phenyl, 2‐, 3‐ and 4‐tolyl, 2,4‐ and 3,5‐xylyl) substituted furo[3,4‐c]furanones (DFF) were synthesized. The computational analysis, based on density functional theory, found eight possible centrosymmetrical slipped π‐stack arrangements, formed according to electron repulsion minimization principle, as for previously reported for π‐isoelectronic diketopyrrolopyrroles (DPP). One of these slipped stack arrangements was found to form infinite columns in the crystals of a new polymorph of parent phenyl derivative (with centre‐to‐centre distance CC=6.975 Å), other three types of stacks were found for 3‐tolyl (CC=6.153 Å), 4‐tolyl (CC=3.849 Å) and 2,4‐xylyl (CC=4.856 Å) derivatives by single crystal X‐ray diffractometry. All six derivatives show intense solution fluorescence in blue/green region, with a maximum driven entirely by a number and position of methyl substituents on phenyl rings. On the other hand, the solid‐state fluorescence from yellow over orange to red is observed only for four derivatives and its presence/absence, spectral position and vibronic structure is driven exclusively by the slips in π‐stacks (with interplanar distance always less than 3.5 Å) of almost planar DFF molecules, resulting in J‐type emission, H‐type excimer‐like emission and H‐type quenching.

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Nature of light-absorbing pigments from Brazilian lichens identified by Raman spectroscopy

Cited by 7 publications

References 50 publications

Methodological Aspects of Green Extraction of Usnic Acid Using Natural Deep Eutectic Solvents

Methodological Aspects of Green Extraction of Usnic Acid Using Natural Deep Eutectic Solvents

A Role for Secondary Metabolites in Desiccation Tolerance in Lichens

Four Slip‐Stacked Arrangements, Three Types of Photophysics: Crystal Structure and Solid‐State Fluorescence of 3,6‐Diaryl Substituted Furo[3,4‐c]furanone Polymorphs and Regioisomers

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