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Antioxidant and cytoprotective potentials of Parmeliaceae lichens and identification of active compounds

3.2. Evaluation of antioxidant activity extracts exerted negligible antioxidant activity, such as
Cetraria aculeata and Cetrelia nigricans, whereas other
The chemoluminescence induced by the peroxyl species demonstrated higher potential for scavenging
radical generation, initiated by AAPH in ORAC assay, peroxyl radicals, such as Cetrelia braunsiana (3.21 µmol
decreased following the addition of several lichen extracts. TE/mg sample), Parmotrema saccatilobum (4.38 µmol
As shown in Table 3, there was a vast variation in ORAC TE/mg sample) and Usnea ghattensis (4.74 µmol TE/mg
values of the 29 lichen species studied; the higher the simple).
ORAC value, the better antioxidant activity. Some lichen

Table 3. ORAC values in µmol TE/mg sample (expressed as Mean ± SD) obtained for the 29 species.

Samples ORAC values

Bulbothrix meizospora 1.14 ± 0.11

Cetrelia braunsiana 3.21 ± 0.17

Cetrelia cetrarioides 0.13 ± 0.02

Cetrelia nigricans 0.03 ± 0.01

Cetrelia olivatorum 1.00 ± 0.04

Cetraria aculeata 0.01 ± 0.01

Cetraria canadensis 2.52 ± 0.17

Evernia prunastri 2.21 ± 0.19

Flavoparmelia citrinescens 0.24 ± 0.02

Flavoparmelia euplecta 0.62 ± 0.09
Flavoparmelia haysomii 1.40 ± 0.05
Flavoparmelia rutidota 0.15 ± 0.02
Hipotrachyna execta 1.67 ± 0.07
Myelochroa entothiochroa 0.60 ± 0.04
Myelochroa irrugans 0.52 ± 0.01
Parmelia saxathis 1.22 ± 0.23
Parmotrema abessicum 0.48 ± 0.24
Parmotrema austrosinense 0.46 ± 0.18
Parmotrema perlatum 0.25 ± 0.10
Parmotrema praeserediosum 0.23 ± 0.02
Parmotrema reticulatum 0.07 ± 0.02
Parmotrema saccatilobum 4.38 ± 0.18
Usnea arizonica 0.50 ± 0.04
Usnea aurantiacoatra 0.25 ± 0.02
Usnea contexta 0.20 ± 0.04
Usnea filipendula 1.67 ± 0.04
Usnea ghattensis 4.74 ± 0.09
Usnea sp 1.83 ± 0.05
Xantoparmelia coreana 0.71 ± 0.08

At this point, we selected the three species showing µg/ml and higher concentrations; however, from 10 µg/ml
higher antioxidant activity in ORAC assay (as highlighted of Ps and Ug cell viability appeared diminished.
above) for the following experiments.
Therefore, the concentrations of the extracts that
3.3. Cytoprotective activities compromised cell viability were discarded, and five/six
concentrations of each extract were chosen for assessing
3.3.a. A ssessment of cell viability and protection against their protection against oxidative stress and cellular
H2O2- induced cell death toxicity exerted by hydrogen peroxide. H2O2 decreased
cell viability to approximately 55% of control, but Cb
Nine different concentrations ranging from 0.25 to 100 0.25-0.5 µg/mL, Ps 0.25 µg/mL and Ug 0.25-0.5 µg/mL
µg/ml were tested for each extract in order to determine significantly reversed that effect and protected neurons
the effects of single extracts in the viability of SH-SY5Y viability. The concentrations displaying highest protection
cells through the MTT assay. Results obtained for the against H2O2 were then chosen for each extract (0.5 µg/ml
effects of Cb, Ps and Ug are shown in Figure 2, and for Cb and Ug and 0.25 µg/mL for Ps) and assayed in the
expressed as the percentage of cell viability, considering following experiments.
the optical density of untreated control cells as 100%
(triton X-100 5% was used as a negative control). A
significant cell viability loss was observed for Cb from 25

@Real Academia Nacional de Farmacia. Spain 169