# Potential Role of Plant Extracts and Phytochemicals Against Foodborne Pathogens
## 3 Plant Extracts and Phytochemicals against Bacteria Causing Foodborne Diseases  
### Campylobacter Species  
_Campylobacter jejuni_ is a Gram-negative, non-spore-forming and non-fermenting bacteria. It is one of the most common causes of foodborne diseases in the US and Europe. Humans are usually infected by the ingestion of contaminated food, milk, water or interaction with animals [35]. Globally, about 9.6 million people are infected by _C. jejuni_ annually [36]. For the treatment of _C. jejuni_ infection, tetracyclines and fluoroquinolones are the drugs of choice; however, these days they are associated with a high degree of antibiotic-resistance [37; 38]. Alternatively, phytochemicals can be utilized as they have the potential to combat foodborne diseases caused by _C. jejuni_. [PERSON] et al. reported the inhibitory activity of extracts of _Adenanthera pavonina_ L., _Moringa oleifera_ Lam. and _Annona squamous_ L. against _C. jejuni_[39]. In these plants, among the flavonoids, kaempfer, quercetin and rutin are present which possess strong antimicrobial properties [40]. _Manmaa africana_ Sabine is used traditionally for the treatment of infections, stomach pain and skin ailments in Africa [41]. A coumarin, mammea A/AA was isolated by [PERSON] et al. from _Manmaa africana_ and evaluated its activity against _C. jejuni_. It was found to be very potent with a minimum inhibitory concentration (MIC) value of 0.25 ug/mL [42]. [PERSON] et al. evaluated 28 plants against C. _jejuni_, out of which 21 were active. Of these 21 active plants, 4 plants including _Artemisia ludoviciana_ [PERSON], _Acacia farnesiana_ ([PERSON]) [PERSON]. _Opuntia ficus-indica_ ([PERSON] [PERSON] and _Cynara scolymus_ [PERSON] were most potent having minimal bactericidal concentration (MBC) values of 0.5, 0.3, 0.4 and 2 mg/mL, respectively. They also tested the anti-adherence activity of these 4 plants against _C. jejuni_, as adherence of the microbe to mucosal cells is important for its virulence. The results proved that extracts were able to inhibit the attachment of _C. jejuni_[32]. Another mechanism of _C. jejuni_ pathogenicity is cell lysis, entry into the host cell and production of a virulent cytotoxoxin, cytokal distending toxin (CDT) [43]. Extracts of _A. ludoviciana_ and _A. farnesiana_ were shown to prevent the production of CDT along with a decrease in cytoplasmic pH and cellular ATP concentration and damages the bacterial cell membrane [44]. Moreover, motility also contributes to the virulence of _C. jejuni_. The subinhibitory concentrations of natural compounds, i.e., carvacrol (0.002%), _trans_-cinnamaldehyde (0.01%) and eugenol 0.01%) prominently decrease the motility of _C. jejuni_. Furthermore, these natural compounds also reduce other virulence potentials of this pathogen [45]. Several researchers have reported the potential antibacterial activity of essential oils (EO) of various plants against _C. jejuni_ that are commonly used in the traditional system of medicine. These plants include _Syzygium aromaticum_ ([PERSON] [46; 47], _Citrus limon_ ([PERSON] and _Citrus bergamia_ [PERSON] [48], tea tree oil, Leptospermum oil [49], coriander (_Coriandrum sativum_ L.) [50], _Daucus carota_ L. [51], _Cuminum cynmium_ L. [52], garlic (_Allium sativum_ L.) [53], clove (_Syzygium aromaticum_), thymne (_Thimus vulgaris_ L.) [54], eucalyptus (_Eucalyptus globulus_ Labill. ), sage (_Salvia officinalis_ L.), rosemary (_Rosmarinus officinalis_ L.), juniper (_Juniperus communus_ L.), lavender (_Lavandula officinalis_ Chaix), _Myrtus communus_ L., _Laurus nobilis_ L., pine oil (_Pinus bruttia_) [55], _Juniperus excelsa_ M.Bieb. [56], _Inula helenium_ L [52], marigold (_Calendula officinalis_ L.), ginger (_Zingiber officinal_ L.), patchouli (_Pogostemon cablin_), gardenia (_Gardenia jasminoides_ ([PERSON]) Benth. ), cedarwood (_Cedrus atlantica_ (Endl.) [PERSON]), carrot seed (_Daucus carota_ L.), celery seed (_Apium graveelens_ L.), mugwort (_Artemisia vulgaris_ L.), spikenard (_Nardostachys jatamanis_ (D.Don) DC.