# Isothiocyanates: An Overview of Their Antimicrobial Activity against Human Infections
## 4 Isothiocyanates Antimicrobial Properties against Human Pathogens
### Salmonella Enterica  
_Salmonella_ are Gram-negative, flagellar and optionally anaerobic bacilli belonging to the Enterobacteriaceae family. All medically important _Salmonella_ are included in the _S. enterica_ species and are divided into typhoidal _Salmonella_ serotypes and non-typhoidal _Salmonella_ serotypes [85]. The main studies carried out to evaluate the antimicrobial properties of ITCs against _S. enterica_ species were referred to the total extracts or oil and not to the isolated or synthetic ITCs. The following studies evaluated the antimicrobial effect of different extracts from three species of _Moringa_ plant [59; 65; 67] (_Moringa oleifera_, _Moringa peregrina_ (Forssk) and _Moringa stenopetala_) and of the oil obtained from _Salvadora persica_[52]. The authors investigated the part of the plant that showed the most effective antibacterial activity and the most useful extraction method to obtain a phyto-compound able to exert the greatest antimicrobial property against sensible and resistant _S. enterica_ strains. The antimicrobial properties of aqueous, methanol and chloroform extracts of _Moringa oleifera_ leaves, bark and roots against _S. enterica_ were recently investigated [65]. The results indicated that the bark chloroform extract showed the highest antimicrobial activity against _S. enterica_ reference strain compared to the other extracts (IZ \(>\) 20 mm) [65]. Moreover, _n_-hexane extracts of _Moringa oleifera_ and _Moringa stenopetala_ seed showed antimicrobial activity against _S. enterica_[67]. Regarding to the _S. enterica_ strains with resistant phenotype, [PERSON] et al. [59] investigated the antimicrobial potential of _Moringa peregrina_ (Forssk) seed extracts against 35 _S. enterica_ clinical isolates with resistant phenotype. Specifically four of them were characterized for MDR phenotypes resulting insensible to fluoroquinolones that are currently used as the last defense therapy against non-tynoid _S. enterica_ infection.The study was performed comparing the antimicrobial properties of the extracts of _M. peregrina_ seeds obtained using _n_-hexane or _n_-butanol or water. Results indicated that the aqueous seed extract of _M. peregrina_ showed an excellent inhibitory effect (MIC ranging from 109.37 to 437.5 mg/mL based on the different clones tested) against resistant isolates including strains with MDR phenotype. Moreover it was the most effective extract compared to _n_-hexane and _n_-butanol extracts [59]. In order to evaluate the bacterial ultrastructural changes induced by the aqueous extract of _M. peregrina_ seed the authors compared treated and non-treated bacteria (used as negative control) by scanning and transmission electron microscopy (STEM). Electron micrographs showed that treatment with the aqueous extract induced a modification of the bacterial surface with formation of holes in some parts of the cell wall. This outcome advanced with a time-dependent manner with a progressive structural disorganization of the cytoplasm and the appearance of wavy membranes. The cell wall was finally disrupted and leakage of cellular components was observed, with subsequent cell death [59]. Although the antimicrobial effect was shown observing electron micrographs the mechanism behind the mode of action is still unknown. Finally [PERSON] et al., suggested that BITC--the main component of _Salvadora persica_ root oil--displayed antimicrobial effects against _S. enterica_. The authors mainly characterized the essential oil obtained from _Salvadora persica_ root indicating that the oil contained 73.8% of BITC and 26.2% of benzyl cyanide and then tested its antimicrobial effect against _S. enterica_ ATCC14028 ser. _Typhimuriumium_[52]. Results indicated that oil rich in BITC exhibited high antibacterial activity in a dose-dependent manner against _S. enterica_ ATCC14028 ser. _Typhimuriumium_. Specifically 0.02% of oil extract was sufficient to significantly reduce _S. enterica_ CFU counts and 0.1% of the oil extract was able to completely abrogate _S. enterica_ growth.