<i>IN VITRO</i>RADICAL-SCAVENGING ACTIVITY, TOXICITY AGAINST<i>A. salina</i>, AND NMR PROFILES OF EXTRACTS OF LICHENS COLLECTED FROM BRAZIL AND ANTARCTICA

Ravaglia, Luciana Marçal; Gonçalves, Kerolayne; Oyama, Nathália Mitsuko; Coelho, Roberta Gomes; Spielmann, Adriano Afonso; Honda, Nobuaki

doi:10.5935/0100-4042.20140159

Cited by 9 publications

(5 citation statements)

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“…, 9.92, and 13.61 for the O−H bonds at positions of 1, 10, 4, and 5-CH 2 -OH, respectively. The results are in good agreement with previous data 40. The calculated pK a values for compound 8 are 2.51 (COOH), 7.83 (O3−H), and 13.56 (O9−H); those for compound 6 are 3.00 (COOH), 6.87 (O1−H), and 10.12 (O4−H); those for compound 7 are 7.90 (O10−H) and 9.49 (O1−H) bonds, respectively, and that for compound 11 are 5.63 (Figure4).…”

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confidence: 93%

Theoretical Study on the Antioxidant Activity of Natural Depsidones

et al. 2020

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Depsidones are secondary metabolites in lichens with a range of potential health benefits. Among others, these compounds are believed to exhibit high hydroxyl radical and superoxide scavenging abilities, warranting a detailed investigation of their antioxidant properties. In this study, the radical scavenging activity of natural depsidones from Ramalina lichenized fungi was investigated in silico. Calculations of the thermodynamic parameters suggested that the main radical scavenging pathway follows the formal hydrogen transfer (FHT) mechanism; however, unexpectedly low rate constants were found in the CH3OO• scavenging reaction. Establishing that the depsidones are mostly ionized in an aqueous environment suggested that the single-electron transfer (SET) mechanism should not be ruled out. Consistently, depsidones were revealed to be excellent HO• and O2 •– scavengers in aqueous solutions (k = 4.60 × 105 – 8.60 × 109 M–1 s–1 and k = 2.60 × 108 – 8.30 × 109 M–1 s–1, respectively) following the sequential proton loss electron transfer (SPLET) mechanism. These results suggest that natural fungal depsidones are potent hydroxyl and superoxide radical scavengers in aqueous solutions.

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Theoretical Study on the Antioxidant Activity of Natural Depsidones

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“…Thus, Paudel et al [34], in the preliminary cytotoxicity study on Artemia salina L., showed that for 24 lichen species in Nepal, LC 50 was between 100 and 400 µg/mL. In another study, more recently, Ravaglia et al [37] evaluated the toxic potential on Artemia salina L. larvae for six species of lichens harvested from Brazil and Antarctica; LC 50 values between 151.0 and >600 µg/mL demonstrate that the tested extracts have a reduced toxicity on the Artemia salina L. larvae compared to that quantified in the present study (when LC 50 UBE = 164.92 µg/mL).…”

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confidence: 96%

Evaluation of the Cytotoxic Activity of the Usnea barbata (L.) F. H. Wigg Dry Extract

et al. 2020

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The secondary metabolites of lichens have proven to be promising sources of anticancer drugs; one of the most important of these is usnic acid, which is a phenolic compound with dibenzofuran structure that is responsible for the numerous biological actions of lichens of genus Usnea. As a result, in this study, we related to this phenolic secondary metabolite. The aim of the present study is the evaluation of the cytotoxic activity of Usnea barbata (L.) F. H. Wigg dry acetone extract (UBE). In advance, the usnic acid content was determined in various extracts of Usnea barbata (L.) F. H. Wigg: the liquid extracts were found in water, ethanol, acetone, and the dry acetone extract; the highest usnic acid quantity was found in the dry acetone extract. First, the cytotoxic action of UBE was assessed using Brine Shrimp Lethality (BSL) test; a significant lethal effect was obtained after 24 h of treatment at high used concentrations of UBE, and it was quantified by the high mortality rate of the Artemia salina (L.) larvae. Secondly, in vitro cytotoxicity of UBE was evaluated on human tongue squamous cells carcinoma, using CAL 27 (ATCC ® CRL-2095™) cell line. The most intense cytotoxic effect of UBE on CAL 27 cells was registered after 24 h; this response is directly proportional with the tested UBE concentrations. The obtained results have been reported regarding usnic acid content of UBE, and the data show that CAL 27 cells death was induced by apoptosis and high oxidative stress.Molecules 2020, 25, 1865 2 of 17 therapeutic tools for the total destruction of cancer cells with limited effects on normal cells [1]. It is known that carcinogenesis is a complex process, involving cellular and molecular alterations, mediated by endogenous and/or exogenous factors: oxidative DNA damage, chromosomal abnormalities, and oncogene activation are responsible for the development of cancer and may be induced by prolonged oxidative stress [2]. Thus, in cancer pathology, the reactive oxygen species (ROS) have dual role, confirmed by many studies: first, ROS are cytotoxic, having an important contribution in the etiology and progression of cancer [3]. At the same time, many antitumor agents can destroy the cancer cells through intense oxidative stress, generating ROS production in high quantities [4]. Increasing ROS levels through redox modulation could in the future be an effective strategy for the selective destruction of cancer cells (not normal cells) [5]; this method is called "oxidative therapy" [6], and it was developed by inducing cytotoxic oxidation as a stress factor in cancer cells in the treatment of cancer [7].One of the most invasive malignancies is the oral squamous cell carcinoma (OSCC), which is the most common cancer of oral cavity; it can affect any part of the oral cavity including lips, tongue, gums, buccal epithelium, and salivary glands [8]. Despite that, the oral cavity is easily accessible for the direct visual examination, and the mortality from oral cancer remains still high because in the early stages, the pat...

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“…The effects of UBDE were evaluated using Artemia sp. (also named brine shrimp) bio-tester organisms, BSL assay [ 31 ], used for the pre-screening of plant extracts cytotoxicity [ 32 ]. The BSL assay represents a significant step before modelling in pharmaceutical research [ 33 ].…”

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confidence: 99%

Antioxidant and Cytotoxic Activities of Usnea barbata (L.) F.H. Wigg. Dry Extracts in Different Solvents

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et al. 2021

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Lichens represent a significant source of antioxidants due to numerous metabolites that can reduce free radicals. Usnea barbata (L.) F.H. Wigg. has been recognized and used since ancient times for its therapeutic effects, some of which are based on its antioxidant properties. The present study aims to analyze the phytochemical profile and to evaluate the antioxidant and cytotoxic potential of this lichen species. Five dry extracts of U. barbata (UBDE) in different solvents (acetone, ethyl acetate, ethanol, methanol, water) were prepared by refluxing at Soxhlet to achieve these proposed objectives and to identify which solvent is the most effective for the extraction. The usnic acid content (UAC) was quantified by ultra-high performance liquid chromatography (UHPLC). The total polyphenols content (TPC) and tannins content (TC) were evaluated by spectrophotometry, and the total polysaccharides (PSC) were extracted by a gravimetric method. The 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) free radical method was used to assess the antioxidant activity (AA) and the Brine Shrimp Lethality (BSL) assay was the biotest for cytotoxic activity evaluation. The ethyl acetate extract had the highest usnic acid content, and acetone extract had the highest content of total polyphenols and tannins. The most significant antioxidant effect was reported to methanol extract, and all the extracts proved high cytotoxicity. The water extract has the lowest cytotoxicity because usnic acid is slightly soluble in this solvent, and it was not found at UHPLC analysis. All extracts recorded a moderate correlation between the content of usnic acid, polyphenols, tannins, and AA; furthermore, it has been observed that the cytotoxicity varies inversely with the antioxidant effect.

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IN VITRORADICAL-SCAVENGING ACTIVITY, TOXICITY AGAINSTA. salina, AND NMR PROFILES OF EXTRACTS OF LICHENS COLLECTED FROM BRAZIL AND ANTARCTICA

Abstract: 600 µg mL-1).]]>

Cited by 9 publications

References 1 publication

Theoretical Study on the Antioxidant Activity of Natural Depsidones

Theoretical Study on the Antioxidant Activity of Natural Depsidones

Evaluation of the Cytotoxic Activity of the Usnea barbata (L.) F. H. Wigg Dry Extract

Antioxidant and Cytotoxic Activities of Usnea barbata (L.) F.H. Wigg. Dry Extracts in Different Solvents

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