## 3 Results and Discussion
### Antioxidant Activity
ostreatus_ fruiting bodies showed significantly stronger scavenging potential compared to _P. erggii_ (5.41 \(\pm\) 0.33 \(\upmu\)moles/g and 4.38 \(\pm\) 0.06 \(\upmu\)moles/g, respectively). This finding is consistent with that of other authors who compared methanolic [32] or ethanolic [25] extracts obtained from these two _Pleurotus_ strains. The scavenging of DPPH radicals evidently depended on the part of the fruiting bodies from which the extracts were obtained. The stems of both white and brown _A. bisporus_ showed slightly higher antioxidant capacity compared to the caps. In the case of _P. erggii_ no statistical difference was observed. With regards to _L edodes_ and _P. ostreatus_, the caps exhibited significantly higher activities compared to the stems (almost twice and six times higher, respectively). Several previous reports have shown that mushrooms' caps, when compared to the stems, exhibit slightly higher DPPH scavenging potential [11; 36; 38]. However, this study has been unable to demonstrate that. It could be explained by the fact that the activity depends on many other factors including species, cultivation methods, time of harvest and finally, the methods of extraction [39]. DPPH scavenging activity calculated per one gram of the extracts is shown in Figure 5b. The most striking result to emerge from the data is that the extract from _P. ostreatus_ caps displayed exceptionally high potential (48.45 \(\pm\) 1.85 \(\upmu\)moles/g) compared to other species. Taking into account that the extraction yield of the _P. ostreatus_ caps was the lowest among the samples, this suggests that this extract contains the highest quantity of antioxidant compounds per gram. On the contrary, the lowest activity levels were exhibited by the _P. ostreatus_ stems (3.57 \(\pm\) 0.53 \(\upmu\)moles/g) followed by the _P. nameko_ stems (8.79 \(\pm\) 0.53 \(\upmu\)moles/g), _P. erggii_ stems and caps (10.85 \(\pm\) 0.08 \(\upmu\)moles/g and 11.53 \(\pm\) 0.95 \(\upmu\)moles/g, respectively), _L. edodes_ stems (16.34 \(\pm\) 0.84 \(\upmu\)moles/g) and finally, the caps of the white _A. bisporus_ (21.06 \(\pm\) 1.38 \(\upmu\)moles/g) and the brown _A. bisporus_ (21.52 \(\pm\) 1.28 \(\upmu\)moles/g). The antioxidant values calculated per one gram of dry extract were substantially higher in comparison to the values expressed per one gram of fruiting body. These values can be useful in determining the antioxidant properties of the product which could be potentially used as a food additive. Many authors point to a high correlation between the content of total phenolic compounds and the activity of antioxidants. As can be seen from Table 5, correlations between antioxidant activities and the content of antioxidant compounds were established. A very strong correlation was observed between total phenolics content and FRAP values, which is in accordance with previous findings [35]. Similarly, a strong correlation (0.83) was found between total phenolics content and DPPH. Much weaker correlations were observed between total flavonoids content and antioxidant assays. However, both antioxidant assays correlated well with one another (0.86). Figure 5: The scavenging of DPPH radicals by the extracts from caps, stems and whole fruiting bodies, expressed per fruiting body dry weight (**a**) and per extract dry weight (**b**); Abw—_A. bisporus_ (white), Abb—_A. bisporus_ (brown), Le—_L. eodes,_ Pr—_P. nameko,_ Pe—_P. eruggii,_ Po—_P. ostreatus_. Mean values (\(n=3\)) with different lowercase letters show significant differences among the parts of mushrooms belonging to the same species. Mean values with different capital letters indicate significant differences among the same parts belonging to various species (\(p<0.05\), Tukey’s test).