Redox properties and cytoprotective actions of atranorin, a lichen secondary metabolite

Abstract

Atranorin (ATR) is a lichenic secondary metabolite with potential uses in pharmacology. Antinociceptive and antiinflammatory actions have been reported, and the use of atranorin-enriched lichen extracts in folk medicine is widespread. Nonetheless, very few data on ATR biological actions are available. Here, we evaluated free radical scavenging activities and antioxidant potential of ATR using various in vitro assays for scavenging activity against hydroxyl radicals, hydrogen peroxide, superoxide radicals, and nitric oxide. The total reactive antioxidant potential (TRAP) and total antioxidant reactivity (TAR) indexes and in vitro lipoperoxidation were also evaluated. Besides, we determined the cytoprotective effect of ATR on H(2)O(2)-challenged SH-SY5Y cells by the MTT assay. ATR exerts differential effects towards reactive species production, enhancing hydrogen peroxide and nitric oxide production and acting as a superoxide scavenger; no activity toward hydroxyl radical production/scavenging was observed. Besides, TRAP/TAR analysis indicated that atranorin acts as a general antioxidant, although it demonstrated to enhance peroxyl radical-induced lipoperoxidation in vitro. ATR was not cytotoxic, and also protected SH-SY5Y cells against H(2)O(2)-induced cell viability impairment. Our results suggest that ATR has a relevant redox-active action, acting as a pro-oxidant or antioxidant agent depending on the radical. Also, it will exert cytoprotective effects on cells under oxidative stress induced by H(2)O(2).

Chemical composition and bioactive properties of the lichen, <i>Pleurosticta acetabulum</i >

“…Also, total reactive antioxidant potential and total antioxidant reactivity analysis indicate that atranorin acts as a general antioxidant, although it appeared to enhance peroxyl radical-induced lipoperoxidation in vitro [16]. Similarly, strong antioxidant activities were found for salazinic, protocetraric, evernic and norstictic acids [4,5,17].…”

“…Kosanic et al and Melo et al found that atranorin exerts differential effects towards reactive species production, enhancing hydrogen peroxide and nitric oxide production and acting as a superoxide scavenger, and then the activity towards hydroxyl radical production scavenging was observed [16,17]. Also, total reactive antioxidant potential and total antioxidant reactivity analysis indicate that atranorin acts as a general antioxidant, although it appeared to enhance peroxyl radical-induced lipoperoxidation in vitro [16].…”

Anti-inflammatory and toxicity studies of atranorin extracted from Cladina kalbii Ahti in rodents

“…Co-incubation with ATR protects SH-SY5Y cells against the cytotoxic effects of H 2 O 2 . Nonetheless, all ATR concentrations reversed the effect of H 2 O 2 (Melo et al, 2011).…”

“…These results suggest that ATR has no cytotoxic effects at these concentrations. Melo et al (2011) reported an effect of ATR on SH-SY5Y cultures, a neuroblastoma-derived catecholaminergic cell line.…”

ASSESSMENT OF THE ANTIOXIDANT ACTIVITY AND PHYTOCHEMICAL ANALYSIS OF A LICHEN, EVERNIASTRUM CIRRHATUM (FR.) HALE ex. SIPMAN

“…[58] Similarly newer lichen specific compounds have gained priorities in recent antioxidant research. [59,60] Thus, the obtained results in this study suggested that the identified phytochemical compounds, both in phytochemical analyses and HPLC may be the main bioactive constituents which impart the lichen Everniastrum cirrhatum potent antioxidant potential since it is a valuable reservoir of bioactive compounds of substantial medicinal merit.…”