## 4 Discussion
### Anticancer Activity  
The quantity and quality of the RM of medicinal plants can be modified based on the knowledge of the biology and ecology of the plant species and with the use of agricultural tools [7; 8; 9]. In field conditions, the chemical profile of _Arnica_ spp. can be determined via the propagule type during introduction [9], soil quality [7; 9], soil and foliar fertilization [3; 18], morphological features, and plant organs [23; 24], and may be responsible for the biological activity of plant material [23; 24; 25; 26; 27]. There are reports available in the literature on the apoptotic activity of mountain arrica extracts against melanoma WM-266-4 cells [4] and cytotoxic properties against colorectal cancer HCT-116 cells [43]. The present study has shown that the stage of plant development, the solvent type, and their interactions can modify the chemical composition of extracts and their antitumor activity against human carcinoma (HeLa), colon (HT29), and colon metastatic SW620 cell lines. Our earlier studies revealed that nitrogen fertilization, solvent type, and their interaction had an impact on apoptosis in the same cell lines, which confirms the relevance of research on the biological activity of extracts with the use of the abovementioned factors, including the more common use of water as an extractant [3]. The present research has indicated that the collection of flower heads during full flowering guarantees the production of RM, and their extracts have been characterized by the highest proapoptotic activity.  
_A. montana_ is a pharmacopeial plant species; therefore, extraction in the majority of studies is carried out with the method described in pharmacopeias [40], where ethanol is used as a solvent. Moreover, eluents such as 80% methanol [10; 44], 41% ethanol [34], and 95% ethanol [45] can be used during extraction. Recently, [PERSON] et al. [4] conducted research to achieve a high yield and content of active ingredients via supercritical CO\({}_{2}\) extraction. However, the use of water as an extractant has been investigated sporadically [3]. Hence, there is poor information of the biological activity of arrica water extracts and the importance of hydrophilic SMs. Moreover, the use of various eluents, including ethanol and water, gives the opportunity to demonstrate the proapoptotic activity of arrica extracts.  
In the literature, it has been suggested that the plant species variety and extractant polarity affect the extractability of flavonoids or polyphenols [45; 46]. In our study, the extracts were not comprehensively characterized chemically; hence, we are unable to explain the effect of particular molecules on the anticancer activity. Nevertheless, the strict dependence between the F content in the RM and the apoptosis level in all the studied lines suggested that these SMs may serve a crucial function in anticancer activity. Moreover, the highest impact of the extracts on apoptosis in the analyzed cell lines was visible when water was used as a solvent. It cannot be excluded that hydrophilic compounds, as in the case of other medicinal plants [32], may have an impact on biological activity. The _A. montana_ inflorescence is characterized by high concentrations of quercetin, and the antitumor activity of this metabolite has been presented many times [47; 48; 49; 50; 51]. Therefore,the role of this component and of other hydrophilic constituents in the biological activity of aqueous extracts is very probable. However, this requires further research, including the identification of SMs in mountain arnica extracts and observations of the biological model's response.