# Evaluation of _Sambucus nigra_ L. Biopotential as an Unused Natural Resource
## 3 Results and Discussion
### Biological Activity  
#### 3.2.1 Antioxidant Capability  
The antioxidant ability of extracts of fresh elderberry fruits was evaluated by using a variety of different in vitro assays: radical scavenging (ABTS\({}^{\star+}\), DPPH\({}^{\star}\) and \({}^{\star}\)NO), reducing power (FRAP and CUPRAC), total antioxidant activity (PM), and metal chelating (MC) assays. The results are presented in Table 3.  
The examined extracts have achieved excellent results in terms of antioxidant ability. The investigated radical scavenger activity ranged from 113.00 to 157.99 mg TE/g E for scavenging ABTS\({}^{\star+}\), while the values for the DPPH\({}^{\star}\) ranged from 53.20 to 76.28 mg TE/g E.  
The extracts obtained by MAE and 50% EtOH as solvent exhibited the highest scavenger activity, while UAE showed the lowest potential. Additionally, the activity of MAC was in the vicinity of MAE ability, which highlights that MAC is a competitive approach to MAE extraction. Considering water extracts, the dominant activity of MAE extracts was observed, while UAE and MAC have attained approximately similar activity. Neutralization of \({}^{\star}\)NO radicals may contribute to a better forecast of the in vivo biological potential of fresh elderberry fruit extracts [35]. The elderberry extracts have shown good potential to  
Figure 2: Principal component analysis of phenolic acids and flavonoids content in fresh fruits of elderberry extracts. (**a**) Distribution of variables on loadings plot; (**b**) distribution of elderberry extracts on scores plot. inhibit the \({}^{\bullet}\)NO radical, where 50% EtOH MAC and H\({}_{2}\)O MAE extracts were particularly active. Regarding the reduction power capacity, examined by FRAP and CUPRAC tests, the extracts achieved great activity and the same trend as a radical scavenger activity. The 50% EtOH UAE extract and H\({}_{2}\)O MAC extract exhibited the best chelating effect in the MC assay (58.88 and 27.64 mg EDTAE/g E, respectively). In the PM test, 50% EtOH and H\({}_{2}\)O MAC extracts (1.91 and 1.70 mmol TE/g E, respectively) have shown the best effect and expressed their domination to the extracts obtained by modern extraction techniques. LC-MS/MS analysis showed that elderberry fruits contain a significant amount of both phenolic and terpene compounds, and it could be assumed that the expressed antioxidant activity was the result of their activity. Regarding phytochemical composition and antioxidant activity relationship, the content of ruin was strongly correlated with potency of ABTS\({}^{\bullet+}\) scavenging, FRAP, and CUPRAC tests, and moderately in other antioxidant assays. Further, due to the high correlation between the amount of chlorogenic acid and antioxidant activity, it can be concluded that this compound, besides rutin, contributes to the overall notable antioxidant activity of extracts. Ursolic acid was in excellent correlation with the ability of the extracts to neutralize ABTS\({}^{\bullet+}\) and DPPH\({}^{\bullet}\) free radicals, as well as to chelating metal ions. A very good correlation of unsolic acid was achieved with reduction capacity and overall antioxidant potential of analyzed elderberry fruit extracts (Table S1, Supplementary Material). The antioxidant potential of fresh fruits of elderberry extracts in this investigation was compared to the antioxidant potential of elderflower extracts of the same plant species, which was collected at the same locality and obtained according to the same procedure [26]. 50% EtOH and H\({}_{2}\)O elderflowers extract realized the stronger antioxidant potential in radical scavenger, reducing power and MC assays, while elderberry extracts achieved slightly better activity than elderflowers using PM assay, but with small differences in the obtained values. Comparing the antioxidant potential of the investigated elderberry fruit extracts with the antioxidant capacity of the elderberry fruit extracts tested in the study [PERSON] et al.