## 3 Results
### Color Evaluation  
The data obtained for the color parameters of _U. barbata_ fractions are displayed in Table 1. Significant differences (\(p<\) 0.05) between all samples were observed for all color parameters considered, supported by the images from Figure 1. The highest luminosity was observed for _cc_UB (70.29), while the _mc_UB fraction presented the lowest value (59.08). The samples containing the medulla-cortex (_d_UB and _mc_UB) exhibited a green nuance indicated by the negative values of the \(a^{*}\) parameter. In contrast, the positive values observed for _cc_UB suggested a red nuance. Both fractions and integral lichen showed a yellow nuance, as the positive values of the \(b^{*}\) parameter showed, the nuance being more pronounced in _cc_UB (13.92). Compared to the _cc_UB fraction, the _mc_UB sample showed a lower hue angle and chroma value.  
The green color is due to chlorophyll from the algal layer [22], and the yellow one to usnic acid, the most well-known phenolic secondary metabolite [38].  
Chlorophyll degradation significantly increases in prolonged sunlight and heavy metal exposure of lichens [39], and their color can be modified. Due to usnic acid's photoprotective effect, _Usnea_ species show a moderate level of photoinhibition [40]. [PERSON] et al. [41]  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Property** & _d_**UB** & _mc_UB** & _cc_UB** & \\ \hline \multicolumn{4}{c}{**Color Properties**} & \multicolumn{1}{c}{**F-Value**} \\ \hline \(L^{*}\) (adim.) & 63.02 \(\pm\) 0.11\({}^{\text{b}}\) & 59.08 \(\pm\) 0.15\({}^{\text{c}}\) & 70.29 \(\pm\) 0.13\({}^{\text{a}}\) & 5703.14 *** \\ \(a^{*}\) (adim.) & \(-\)1.29 \(\pm\) 0.02\({}^{\text{b}}\) & \(-\)1.83 \(\pm\) 0.03\({}^{\text{c}}\) & 2.12 \(\pm\) 0.17\({}^{\text{a}}\) & 1414.01 *** \\ \(b^{*}\) (adim.) & 13.60 \(\pm\) 0.02\({}^{\text{b}}\) & 12.52 \(\pm\) 0.04\({}^{\text{c}}\) & 13.92 \(\pm\) 0.05\({}^{\text{a}}\) & 1086.01 *** \\ \(h_{ab}\) (\({}^{\text{c}}\)) & 178.52 \(\pm\) 0.00\({}^{\text{c}}\) & 178.57 \(\pm\) 0.00\({}^{\text{b}}\) & 181.42 \(\pm\) 0.01\({}^{\text{a}}\) & 165,195.71 *** \\ \(C^{*}\) (adim.) & 13.66 \(\pm\) 0.02\({}^{\text{b}}\) & 12.65 \(\pm\) 0.05\({}^{\text{c}}\) & 14.08 \(\pm\) 0.04\({}^{\text{a}}\) & 1125.62 *** \\ \hline \hline \end{tabular} \(d\)UB—_d_U. _hrnta_ integral lichen, _mc_UB—medulla-cortex, _cc_UB—central cord, \(L^{*}\)—lightness, \(a^{*}\)—positive values describe red and negative, green nuance, \(b^{*}\)—positive values represent yellow and negative, blue nuance, \(h_{ab}\)—the angle, \(C^{*}\)—Chroma, adim.—_adimensional. Mean values followed by different superscript letters are significantly different, *** significant at \(p<0.001\).  
\end{table}
Table 1: Color evaluation of _U. harnta_ samples.  
Figure 5: SEM micrographs of _cc_UB, _mc_UB, and _d_UB as a fine powder (particle size \(\leq\) 180 \(\upmu\)m): _cc_UB (**a–c**); _mc_UB (**d–f**); _d_UB (**g–i**) with different magnifications: 1 k\(\times\) and scale bar = 20 \(\upmu\)m (**a,d,g**), 2 k\(\times\) and scale bar = 20 \(\upmu\)m (**b,e,h**), and 5 k\(\times\) and scale bar = 5 \(\upmu\)m (**c,f,i**).  
reported that _U. diffracta thalli_ change color chane from greyish-green to brownish-green through massive heavy metal accumulation due to chlorophyll breakdown.