## 3 Results and Discussion
### Antimicrobial Activities of T. canadensis Seed and Cone EOs  
EOs from both cones and seeds of the _T. canadensis_ exhibited medium antimicrobial properties against _Staphylococcus aureus_ (ATCC 29213) (Table 3). The minimum inhibitory concentration (MIC) for the cone EO was found to be 1.95 \(\mu\)L/mL, surprisingly almost as low as for biological active volatiles--thymol. While for the seed EO, it was slightly higher at 3.91 \(\mu\)L/mL. The minimum bactericidal concentration (MBC), which is the lowest concentration required to kill the bacteria, was 13.02 \(\mu\)L/mL for the cone EO and 31.25 \(\mu\)L/mL for the seed EO. The MBC/MIC ratios for both EOs were 7 and 8, respectively, indicating their bacteriostatic properties rather than bactericidal. In comparison with the control antibiotic, gentamycin, a known antibiotic, showed bactericidal properties with an MIC of 0.31 \(\mu\)g/mL, an MBC of 0.61 \(\mu\)g/mL, and an MBC/MIC ratio of 2. The antimicrobial properties of _T. canadensis_ EOs against _S. aureus_ align with findings from other coniferous species, such as _A. concolor_[9], _P. pungens_, and _P. orientalis_[14], which also demonstrated mild antimicrobial activity. In _T. canadensis_, cone EO exhibited higher antimicrobial potency than seed EO, with lower MIC (1.95 \(\mu\)L/mL vs. 3.91 \(\mu\)L/mL) and MBC (13.02 \(\mu\)L/mL vs. 31.25 \(\mu\)L/mL) values, a trend consistent with the stronger antimicrobial effects observed in cone EO of _P. orientalis_[14]. However, both seed and cone EOs of _T. canadensis_ were less effective than the control antibiotic gentamycin.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Tested Substance** & **MIC 2 (\(\mu\)L/mL)** & **MBC 3 (\(\mu\)L/mL)** & **MBC/MIC 4** & **Properties** \\ \hline Cone EO & 1.95 \(\pm\) 0.00 A & 13.02 \(\pm\) 4.51 A & 7 & bacteriatic \\ Seed EO & 3.91 \(\pm\) 0.00 A & 31.25 \(\pm\) 0.00 A & 8 & bacteriatic \\ Thymol 1  & 1.90 \(\pm\) 0.00 B & 3.80 \(\pm\) 0.00 B & 2 & bactericidal \\ Gentamycin (\(\mu\)g/mL) & 0.31 \(\pm\) 0.00 B & 0.61 \(\pm\) 0.00 & 2 & bactericidal \\ \hline \hline \end{tabular}
\end{table}
Table 3: Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), MBC/MIC ratio and effectiveness of the analyzed substances against _Staphylococcus aureus_ ATCC 29213.  
Figure 2: Cytotoxic effects of _Tsuga canadensis_ seed and cone EOs on various cell lines. Viability of fibroblasts, keratinocytes, A375 melanoma cells, and C32 melanoma cells was assessed after treatment with different concentrations (0.012, 0.025, 0.05, 0.1, and 0.2 \(\mu\)L/mL) of _Tsuga_ seed (white bars) and cone (gray bars) EOs. Cell viability is expressed as a percentage of the control. IC\({}_{50}\) values for each cell line are provided in the table inset. Data are presented as mean \(\pm\) SEM. Asterisks (*) indicate statistically significant differences (\(p<0.05\)) compared to the control group.  
Furthermore, we assessed the antimicrobial activity of these EOs against _Escherichia coli_ (ATCC 8739) (Table 4). The MIC for the cone EO was found to be 7.81 uL/mL, while for the seed EO, it was slightly higher at 13.02 uL/mL. The MBC was 62.50 uL/mL for both the cone and seed EOs. The results exhibited that the cone EO had greater antibacterial activity against _E. coli_ than that isolated from seeds. The MBC/MIC ratios for both EOs were 8 and 5, respectively, again confirming their bacteriostatic nature rather than bactericidal properties. What is more, in comparison to the thymol and gentamicin sulfate (positive controls), the seed EO exhibited higher antibacterial activities than cone EO, but both EOs significantly lower than reference substances.