# Metabolic Profiling of _Conyza sumatrensis_ ([PERSON].) [PERSON] from Lugazi, Uganda
## 3 Results and Discussion
### Pharmacological Investigations (Antimicrobial Activity)  
In our GC-MS analysis, we detected, amongst others, \(\alpha\)-pinene and D-limonene, which are known for their antimicrobial properties [50]. As a first indicator of the bioactivity of the extracts, we conducted antimicrobial assays against the three different representative microorganisms. _Bacillus subtilis_ DSM109511 was used as an indicator for activity against Gram-positive bacteria along with _Escherichia coli_ DSM498 and _Pseudomonas fluorescens_ DSM289 as indicators for activity against Gram-negative bacteria. The genus _Pseudomonas_ is known for its nonsusceptibility against a variety of antibiotics and is thus of particular clinical interest. The use of these strains allows a comprehensive evaluation of the antimicrobial activity of the extracts against both Gram-positive and Gram-negative bacteria, as they exhibit different properties. For the assays, 0.5 mg (50 mg/mL) of the extracts was applied to agar plates inoculated with the target microorganisms. The inhibition zones (IZ), which indicate the extent to which the growth of the microorganisms was suppressed, were measured and recorded (see Table 4). The minimal inhibition concentration (MIC) is described as the minimal concentration of the extract that inhibits cell growth. The MICs were determined in a range between 5 and 0.156 mg/mL extract. The results of the antimicrobial assays revealed a notable distinction between the ethanolic and aqueous extracts and demonstrated antimicrobial activity of the ethanolic extracts while the aqueous extracts showed no impact (see Figure S7). Ethanolic extracts exhibited significant antimicrobial activity against all tested microorganisms, as evidenced by the formation of clear inhibition zones. The mean inhibition zone diameters for the ethanolic extracts ranged from seven to nine millimeters (including 5 mm of the filter disc), depending on the microorganism. The minimal inhibition concentration (MIC) was determined as 0.313 mg/mL for the ethanolic extracts against _E. coli_ and 5 mg/mL for _B. subtilis_ (see Figures S8 and S9). The aqueous extracts showed no inhibitory effects on the growth of _E. coli_ or _B. subtilis_. These findings suggest that the active antimicrobial compounds within the plant extracts might be more effectively solubilized in ethanol, highlighting the importance of solvent selection in the extraction process. Further chemical analysis, accompanied by purification steps improving the bioactivity of the extracts, is warranted to identify the specific bioactive constituents responsible for the observed antimicrobial activity. These \begin{table}
\begin{tabular}{l l l l l l} \hline \hline  & **Positive Control** & \multicolumn{2}{c}{**Ethanoic Extracts**} & \multicolumn{2}{c}{**Aqueous Extracts**} \\ \hline  & \(\varnothing\)IZ & \(\varnothing\)IZ & MIC & \(\varnothing\)IZ & MIC \\ \hline _E. coli_ & 20 mm (gent) & 7 mm & 0.313 mg/mL & - & - \\ _B. subtilis_ & 14 mm (ery) & 9 mm & \(>\)2.5 mg/mL & - & - \\ _P. fluorescens_ & 17 mm (gent) & 9 mm & 0.078 mg/mL & - & - \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Antimicrobial testing of ethanolic and aqueous extracts. Diameter of the zones of inhibition (IZ), including the filter disc of 5 mm. The extracts were tested against _E. coli_, _B. subtilis_, and _P. fluorescens_ in a concentration of 50 mg/mL. MICs were determined using extract concentrations ranging from 0.156 to 5 mg/mL. As positive controls, gentamycin (gent) for _E. coli_ and _P. fluorescens_ and erythromycin (ery) for _B. subtilis_ were used in a concentration of 10 \(\mu\)g/mL. differences underscore the potential of specific plant extracts as natural antimicrobial agents and highlight the need for further investigation into their active compounds and mechanisms of action. To fully understand the biological variety of the phytochemical composition, additional replicate analyses are necessary. These can include samples from various geographical locations or parts of the plant.