## 2 Materials and Methods
### Antibacterial Activity  
The antibacterial activity of the extracts was evaluated by determining the minimum inhibition concentration (MIC) values and the minimum bactericidal concentration (MBC) values of the extracts. The MIC was determined using the broth micro-dilution method as described in a previous study [27]. _Hypericum_ extracts (10 mg/mL starting concentration) were dissolved in DMSO (a final concentration of 4%), and 200 uL of each extract was transferred to a 96-well plate in order to achieve a 2-fold serial dilution with 100 uL  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**Taxon** & **Section** & **Collection Site** & **Collection Date** & **Latitude** & **Longitude** & **Elevation (m)** & **Habitat** & **Voucher Number** \\ \hline _H. cycladianum_ & _Drosocarpium_ & Andros Island & 12 May2019 & 37\({}^{\circ}\)54\({}^{\prime}\) & 24\({}^{\circ}\)52\({}^{\prime}\) & 30 & Phrygana & 12285 \\ _H. deblticum_ & _Adenospalum_ & Evvia Island & 14 June2019 & 38\({}^{\circ}\)53\({}^{\prime}\) & 23\({}^{\circ}\)52\({}^{\prime}\) & 1000 & Forest clearings & 12281 \\ _H. fragile_ & _Tarcincapium_ & Evvia Island & 15 June 2019 & 38\({}^{\circ}\)32\({}^{\prime}\) & 24\({}^{\circ}\)01\({}^{\prime}\) & 420 & Cliffs & 12283 \\ _H. polymorphic_ & _Olympia_ & Evvia Island & 14 June 2019 & 38\({}^{\circ}\)36\({}^{\prime}\) & 23\({}^{\circ}\)51\({}^{\prime}\) & 890 & Rocky slopes & 12288 \\ _H. perfolatum_ & _Drosocarpium_ & Mt. Parmon & 1 June 2019 & 37\({}^{\circ}\)15\({}^{\prime}\) & 22\({}^{\circ}\)39\({}^{\prime}\) & 1050 & Forest & 12282 \\ _H. perforatum_ & _Hypericum_ & Andros Island & 8 June 2019 & 37\({}^{\circ}\)50\({}^{\prime}\) & 24\({}^{\circ}\)53\({}^{\prime}\) & 560 & Rocky slopes & 12280 \\ _H. rameliacum_ & _Drosocarpium_ & Mt. Parmassos & 27 May 2019 & 38\({}^{\circ}\)33\({}^{\prime}\) & 22\({}^{\circ}\)34\({}^{\prime}\) & 1760 & Rocky slopes & 12286 \\ _subsp. apollins_ & _Hypericum_ & Evvia Island & 14 June 2019 & 38\({}^{\circ}\)36\({}^{\prime}\) & 23\({}^{\circ}\)51\({}^{\prime}\) & 910 & Wet places & 12287 \\ _H. vesiculosum_ & _Drosocarpium_ & Mt. Chelmos & 5 June 2022 & 38\({}^{\circ}\)05\({}^{\prime}\) & 22\({}^{\circ}\)10\({}^{\prime}\) & 910 & Woodland & 12284 \\ \hline \end{tabular}
\end{table}
Table 1: Collection data of the _Hypericum_ species examined.  
of Mueller Hinton Broth (MHB). Isolated cultures of _E. coli_ (NCTC 9001, Sigma Aldrich, Hamburg, Germany), _S. aureus_ (NCTC 6571, Sigma Aldrich, Germany), _E. faecalis_ (NCTC775, Sigma Aldrich, Hamburg, Germany), and _S. enteritidis_ (WDCM 00030, Sigma Aldrich, Hamburg, Germany)were prepared in MHB at a concentration of about 1 \(\times\) 10\({}^{6}\) cfu/mL. Onehundred microliters (100 uL) of each bacterial inoculum were added to each well of extract or control. Blank samples of each extract (without bacteria) were subjected to a 2-fold serial dilution with MHB (blank control). Controls with bacteria (100 uL) but no extract were used as growth controls. Also, a solvent control and a sterility control were used with MHB, with no bacteria and no extract, respectively. Ampicillin (0.516 mg/mL, Sigma Aldrich, Gillingham, UK) or Gentamycin (0.064 mg/mL, Molekula, Darlington, UK) were included as positive controls. After 18 h of incubation at 37 \({}^{\circ}\)C, 30 uL of 0.2 mg/mL p-iodonitrotetrazolium chloride (INT) (Sigma Aldrich, Gillingham, UK) was added to each plate, followed by incubation at 37 \({}^{\circ}\)C for 30 min. The absorbance of each plate was measured at 492 nm with a microplate reader (Sunrise, Tecan Trading Ltd., Zurich, Switzerland). The MIC of each extract was defined as the sample concentration that inhibited bacterial growth as compared with that of the blank control.The MBC of the extracts was also determined by subculturing 2 uL aliquots of the MIC assay preparations in 100 uL MHB and incubating for 24 h at 37 \({}^{\circ}\)C. The MBC was defined as the lowest concentration of each sample that did not exhibit a color change after the addition of INT, as described above.