## 4 Conclusions  
The present study shows that the profiles of volatile compounds--triterpenoids, polyphenols, and phenolic acids--of samples of _I. paraguariensis_ and varieties of _I. aquifolium_ and _I. meserveae_ are qualitatively similar. The dominant components in the volatile profiles (HS-SPME-Arrow) of the European cultivars were limonene, linalool, and _p_-cymene. For triterpenoids, they were unsolic acid and oleanolic acid. In the profiles of polyphenols and phenolic acids, the dominant components were dicaffeoylquinic acids as well as chlorogenic acid and its isomers. A metabolome of about 180 proposed saponins is presented for _I. aquifolium_ and _I. meserveae_, enabling easy differentiation of samples. Fractions (terpenoids, saponins, polyphenols, and phenolic acids) of _I. aquifolium_ Silver Queen, as the plant material with the highest content of bioactive compounds, were subjected to biological tests. Selected extracts showed strong biological activity, indicating potential in preventing and treating colon cancer. Additionally, the _I. aquifolium_ extracts showed currently unpublished activity against HSV-1 and HAdV-5 viruses. In summary, European species of Ilex, i.e., _I. aquifolium_ and _I. meserveae_, are promising sources of fractions of antiviral and antiproliferative effects but more comprehensive in vivo model studies are required.  
**Supplementary Materials:** The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/molecules29133231/s1](https://www.mdpi.com/article/10.3390/molecules29133231/s1)]([https://www.mdpi.com/article/10.3390/molecules29133231/s1](https://www.mdpi.com/article/10.3390/molecules29133231/s1)), Table S1: Arroma profiles (HS-SPME-Arrow) of various _Ilex_ species; Table S2: List of triterpene saponins detected in the investigated _Ilex_ species, their retention times, proposed formulae, fragmentations, and relative concentrations; Figure S1: Hierarchical clustering of _Ilex_ taxons against their saponin constituents; Figure S2: Analysis of the effects of the tested extracts on the growth of L929 (A) and (B) NHDF cell lines using the SRB assay; Figure S3: Assessment of the cytotoxicity of the tested extracts against selected cancer lines: A549 (A), MCF7 (B), LoVo (C), and HT27 (D) using the SRB assay.  
**Author Contributions:** Conceptualization, N.P. and A.S.; methodology, N.P. and A.S.; software, N.P.; validation, N.P. and M.W.; formal analysis, N.P., M.W. and A.P.; investigation, N.P.; resources, N.P. and A.S.; data curation, N.P.; writing--original draft preparation, N.P.; writing--review and editing, N.P., M.W., B.B. and T.G.; visualization, N.P. and T.G.; supervision, A.S. and R.K.; project administration, N.P. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This article is part of a PhD dissertation titled \"Forgotten essential oil plants--analysis of composition and biological properties\" prepared during doctoral studies at the Wroclaw University of Environmental and Life Sciences. The APC/BPC is financed by Wroclaw University of Environmental and Life Sciences.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article/Supplementary Materials; further inquiries should be directed to the corresponding author.  
**Conflicts of Interest:** The authors declare no conflicts of interest.