title: Redox characterization of usnic acid and its cytotoxic effect on human neuron-like cells (SH-SY5Y).
abstract: Usnic acid (UA) is the most common and abundant lichenic secondary metabolite with potential therapeutic application. Anti-inflammatory and antitumour properties have already been reported and UA-enriched extracts are widely used to treat several diseases in the folk medicine. First, we performed in silico evaluation of UA interactions with genes/proteins and important compounds for cellular redox balance and NO pathway. Then, we assessed UA redox properties against different reactive species (RS) generated in vitro, and evaluated its action on SH-SY5Y neuronal like cells upon hydrogen peroxide (H(2)O(2)), since no in vitro neurotoxicological data has been reported so far. Total reactive antioxidant potential index (TRAP) showed a significant antioxidant capacity of UA at the highest tested concentration; UA was also effective against hydroxyl radicals and reduced the formation of nitric oxide. In vitro, lipoperoxidation was enhanced by UA and changed the cellular viability at highest concentration of 20μg/mL for 1 and 4h, as well as 2 and 20μg/mL for 24h of treatment, according to MTT reduction assay. Moreover, UA did not display protective effects against H(2)O(2)-induced cell death in any case. Evaluation of intracellular RS production by the DCFH-based assay indicated that UA was able to induce changes in basal RS production at concentration of 20μg/mL for 1h and from 2ng/mL to 20μg/mL for 4 and 24h. In conclusion, UA could display variable redox-active properties, according to different system conditions and/or cellular environment. Moreover, our results suggest that potential neurotoxicological effects of UA should be further studied by additional approaches; for instance, in vivo and clinical studies.
authors.affiliation: Laboratory of Pharmaceutical Assays and Toxicity, Federal University of Sergipe (LeFT/UFS), São Cristóvão, SE, Brazil.
authors.forename: Thallita Kelly
authors.initials: TK
authors.lastname: Rabelo
authors.forename: Fares
authors.initials: F
authors.lastname: Zeidán-Chuliá
authors.forename: Laura Milán
authors.initials: LM
authors.lastname: Vasques
authors.forename: João Paulo Almeida
authors.initials: JP
authors.lastname: dos Santos
authors.forename: Ricardo Fagundes
authors.initials: RF
authors.lastname: da Rocha
authors.forename: Matheus Augusto de Bittencourt
authors.initials: MA
authors.lastname: Pasquali
authors.forename: José Luiz
authors.initials: JL
authors.lastname: Rybarczyk-Filho
authors.forename: Adriano Antunes Souza
authors.initials: AA
authors.lastname: Araújo
authors.forename: José Claudio Fonseca
authors.initials: JC
authors.lastname: Moreira
authors.forename: Daniel Pens
authors.initials: DP
authors.lastname: Gelain
mesh_terms: D001572:Benzofurans / Q000633:toxicity*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D017665:Hydroxyl Radical / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D010084:Oxidation-Reduction; D013482:Superoxide Dismutase / Q000378:metabolism; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D001572:Benzofurans; D017392:Thiobarbituric Acid Reactive Substances; C073339:usnic acid; D009569:Nitric Oxide; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D013482:Superoxide Dismutase