## 5 Bioactivity of Secondary Metabolites in the _Leontopodium_ Taxa
### Antimicrobial Activity  
The usefulness of _Leontopodium_ sp. extracts for antimicrobial therapy has shown promising results since ancient times. Some of the antibacterial, antifungal or antiparasitic activities exhibited by representatives of the _Leontopodium_ genus are presented in Table 3. Fifteen antimicrobial compounds isolated from _L. alpinum_ and extracts obtained from roots and aerial parts were tested against bacterial and fungal pathogens [8]. The antimicrobial bioactivity of extracts seemed to depend on the type of solvents (ethanol, methanol, dichloromethane). Thus, the crude dichloromethane extracts exhibited significant growth inhibition on different strains of _Bacillus subtilis_, _Escherichia coli_, _Pseudomonas aeruginosa_, _Staphylococcus aureus_ and _Streptococcus pyogenes_, while methanol and methanol/water extracts exhibited only weak antimicrobial activity. Some of the isolated compounds from _L. alpinum_, such as different bisabolene sesquiterpenes and other tricyclic sesquiterpenes, showed significant antibacterial activity against _E. faccium_, _S. aureus_, _S. pneumoniae_ and _S. pyogenes_ strains, whereas other sesquiterpene esters and coumarin selectively inhibited the growth of _S. pyogenes_ and _S. pneumoniae_ strains [8]. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Bioactivity** & \
\begin{tabular}{c} **Taxon/Extract/Bioactive** \\ **Compound(s)** \\ \end{tabular} & **Experimental Model** & **Effects/Applied Tests** & **Ref.** \\ \hline \hline \multicolumn{4}{c}{_L. alpinum_} \\ - & extract: linoleic and & \multicolumn{2}{c}{Multiresistant strain} \\ \multicolumn{4}{c}{linolenic acids} & _Staphylococcus aureus_ DSM 1366 \\ \hline - & crude dichloromethane & \multicolumn{2}{c}{} \\ \multicolumn{4}{c}{extracts from aerial parts} & _B. subtilis._, _E. coli_, _P. aeruginosa_, & \\  & and roots: ester & _S. aureus_, and _S. pyogenes_ & \\  & sesquiterpene and & strains. & \\  & coumarin & & \\ \hline \multirow{4}{*}{
\begin{tabular}{c} Antibacterial \\ activity \\ \end{tabular} } & - & 15 compounds isolated & _E. faecalis_, _E. faccium_, and _S. aureus_ ATCC 25923 strains \\ \cline{2-4}  & & _E. faccium_, _S. aureus_, _S. aureus_, _S._ & \\  & tricyclic sesquiterpenes & _pneumonite_ and _S. pyogenes_ & \\  & strains & \\ \hline \multicolumn{4}{c}{_L. leontopodioides_} \\ - & ether and ethylacetate & _S. aureus_ & - & disc agar diffusion \\  & fractions & _E. coli_, _Salmonella_ sp. & assay & [92] \\  & n-butanol and water & & \\  & fractions & & \\ \hline \multicolumn{4}{c}{_L. longifolium_} \\ - & essential oil from aerial & _S. aureus_ strain & - & disc agar diffusion \\  & parts & & assay & [31] \\  & - & \(\alpha\)-bisabolol & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Antimicrobial activities of extracts and isolated compounds from different _Leontopodium_ taxa. Linolic and linolenic fatty acids had the most important antimicrobial effect, with an MIC of up to 4 mg/mL, showing activity even against the multiresistant _S. aureus_ strain DSM 13661 [8]. Another study using different types of _L. leontopodioides_ extracts indicated that the petroleum ether-soluble and ethyl acetate-soluble fractions of the alcoholic extract strongly inhibited _S. aureus_, while the n-butanol and water-soluble fractions had potent antibacterial activity against _E. coli_ and _Salmonella_ sp. [92]. A study reported the selective antibacterial activity of essential oil (sesquiterpeineol) from _L. longifolium_ against some bacterial strains, such as _S. aureus_ ATCC 6538, _E. coli_ ATCC 25922, _B. subtilis_ ATCC 6633 and _P. aeruginosa_ ATCC 27853, from a total of eight tested microorganisms [31]. The _S. aureus_ strain was the most sensitive to the essential oil, while _E. coli_ was the least inhibited. The extracts and isolated compounds obtained from _L. alpiumu_ were tested on _Candida albicans_ and _C. parapsilopsis_, _Aspergillus flavus_ and _A. fumigatus_; however, no antifungal activity was identified [8]. Moreover, the essential oil obtained from _L.