# Antibacterial Activity of Crude Extract and Purified Acetogenins from _Amona muricata_ Seeds
## 3 Results and Discussion
### Antibacterial Assays of Crude Extract and Purified Acetogenins
The authors indicate that a final concentration of compounds is critical in antibacterial activity. However, the lowest bacterial reduction was obtained with CE and P-ACGs when evaluated against _E. coli_ (0.35-0.38 log CFU/mL), where there was no significant difference (_p_ < 0.05) between both samples. According to the results, P-ACGs are more effective than CE in Gram-positive and Gram-negative bacteria, but their antibacterial activity varies according to the microorganisms. Gram-negative bacteria possess an effective permeability barrier against hydrophobic antibacterial agents in their outer cell wall membrane, which do not effectively infiltrate the outer membrane of such bacteria. However, they can penetrate the outer membrane of specific mutants with a defective outer membrane or outer membrane damaged by chelators or polycationic compounds [16]. Sub-lethal injury is damage that leads to the inability of a microorganism to survive under stressful conditions and inhospitable environments without causing death. This lesion can be caused by structural (membrane permeability, cell wall disruption) or metabolic (functional components) factors [23; 43]. The most significant sublethal lesion occurred when strains of _L. monocytogenes_ (98.42%), _E. faecalis_ (96.14%), and _E. coli_ (57.78%) were treated with P-ACGs (Figure 4). A complete inhibition of _L. monocytogenes_ is described using P-ACGs [44], which agrees with the results obtained in this study. However, the CE showed an analogous activity to the P-ACGs on the _E. faecalis_ strain. This behavior is not unusual, since there are reports of the sensitivity of this microorganism to the components of _A. muricata_. In this regard, [PERSON] et al. [39] showed that a fraction of an extract from _A. muricata_ leaves had a 25% mortality rate on _E. faecalis_ after 30 min of exposure using a volume of 4.5 mL of the extract. Likewise, [PERSON] et al. [16] found a bacteriostatic effect of a methanol extract of _A. muricata_ leaves on the same strain. \begin{table}
\begin{tabular}{c c c} \hline \multirow{2}{*}{**Bacteria**} & \multicolumn{2}{c}{**Lethality (Log CFU/mL)**} \\ \cline{2-3}  & **Crude Extract** & **Purified Acetogenins** \\ \hline _Enterococcus faecalis_ & 1.07 \(\pm\) 0.06 \({}^{\text{aY}}\) & 1.27 \(\pm\) 0.10 \({}^{\text{cX}}\) \\ _Listeria monocytogenes_ & 0.96 \(\pm\) 0.01 \({}^{\text{bY}}\) & 1.81 \(\pm\) 0.08 \({}^{\text{aX}}\) \\ _Escherichia coli_ & 0.35 \(\pm\) 0.02 \({}^{\text{dX}}\) & 0.38 \(\pm\) 0.03 \({}^{\text{dX}}\) \\ \hline \end{tabular} Values are the average of three determinations \(\pm\) standard deviation (_n_ = 3). Lowercase letters different in each column suggest a statistically significant difference among each bacterial strain (\(\alpha\) = 0.05). Capital letters in each row suggest a statistically significant difference between samples (\(\alpha\) = 0.05).  
\end{table} 
Table 4: Lethal effect of crude extract and purified acetogenins on _Enterococcus faecalis, Listeria monocytogenes_, and _Escherichia coli_.