## 4 Conclusions  
_T. vulgaris_ and _S. scardia_ extracts exhibit high levels of phenolics compounds and significant antioxidant activity, pointing to their potential application as antioxidant sources in the food industry. They may also be used for their therapeutic benefits in the treatment of certain diseases. Sideritis extracts contained more polyphenols and phenolic acids, whereas thyme extracts had a higher flavonoid content, which led to difference sin their antioxidant activity, as measured using DPPH and FRAP methods.  
We identified a significant correlation between antioxidant activity and total polyphenols content, pointing to phenolics as the main contributors to the antioxidative activity of the plants under study. Our study found also a strong positive correlation between AAS-FRAP SIEs and total polyphenols content/total phenolic acids content, whereas antioxidant activity (DPPH) does not show a correlation with the phenolic components of the extract. In contrast, THEs showed different correlations: antioxidant activity (DPPH) had a strong positive correlation with total phenolic acids content and a strong negative correlation with total flavonoids content, while antioxidant activity (FRAP) was strongly positively correlated with total polyphenols content and total phenolic acids content.  
Choosing the right solvent seems essential to ensure the efficient extraction of phenolic compounds, which are strongly associated with antioxidant activity. We have shown that the nature of the solvent affects the total polyphenols content, total flavonoids content, and antioxidant activity. EtOH-H\({}_{2}\)O (EtOH70%) extracts from _S. scardia_ and _T. vulgaris_ aerial parts are phenolics-rich, bioactive, safe, and environmentally friendly, making them valuable in the production of medicinal timetures and other plant-derived pharmaceuticals. Other extracts (ACT, MeOH, EtOAc) with strong antioxidant activity can be used as effective preservatives. The identification of phenolic acids in the tested extracts allows us to conclude that the type of solvent used for a specific raw material (sideritis/thyme) determines the presence of such acids in the extract. In the extracts tested, more phenolic acids were identified when MeOH and ACT were used as solvents (2-3) compared to EtOH-H\({}_{2}\)O and EtOAc (1). Chlorogenic acid was present in all sideritis extracts, while in most thyme extracts, caffe acid was present (exception: EtOH-H\({}_{2}\)O).  
The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/app15073842/s1](https://www.mdpi.com/article/10.3390/app15073842/s1)]([https://www.mdpi.com/article/10.3390/app15073842/s1](https://www.mdpi.com/article/10.3390/app15073842/s1)). Figure S1: Plant material prepared for biochemical analysis; Figure S2: HPLC chromatogram of free phenolic compounds from sideritis extracts; Figure S3: HPLC chromatogram of free phenolic compounds from thymi extracts.  
Conceptualization, M.W.-J., R.P. and R.N.-W.; methodology, M.W.-J. and R.P.; software, R.P. and R.N.-W.; validation, M.W.-J., R.P. and B.M.; formal analysis, M.W.-J. and R.N.-W.; investigation, M.W.-J., R.P. and B.M.; resources, R.N.-W.; data curation, R.P. and B.M.; writing--original draft preparation, R.N.-W. and M.W.-J.; writing--review and editing, R.N.-W., M.W.-J. and R.P.; visualization, R.P. and B.M.; supervision, R.N.-W. and M.W.-J.; project administration, R.N.-W. and R.P.; funding acquisition, R.N.-W. and M.W.-J. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
**Data Availability Statement:** The raw data supporting the conclusions of this article will be made available by the authors on request.  
**Conflicts of Interest:** The authors declare no conflicts of interest.