Table 1.

Studies illustrating the efficacy of plant-derived compounds and plant extracts in reducing toxin production in microbes with potential mechanism(s) of action.

Microbe	Toxin(s)	Plant Compounds with Anti-Toxin Activity	Potential Mechanism of Action/Target Site	Reference(s)
Gram positive bacteria
Clostridium sp.	TcdA, TcdB	Carvacrol, trans-cinnamaldehyde,	Down-regulation of toxin production genes, modulation of transcriptional repressor	[49]
	Botulinum neurotoxin	Toosendanin		[66,67]
Bacillus sp.	Labile enterotoxin	Carvacrol,	Modification of bacterial membranes.	[68,69,70,71]
	Anthrax lethal toxin	Celastrol, toosendanin	Inhibition of toxin entry to cell cytoplasm	[72,73]
Staphylococcus aureus	Hemolysin Enterotoxin A, B Toxic shock syndrome toxin	Essential oils from clove, cinnamon, oregano, Zataria multiflora, eugenol, 4-hydroxytyrosol	Reduced expression of toxin production genes, sea, seb, tst, hla	[53,74,75,76,77]
Listeria monocytogenes	Listeriolysin O (LLO)	trans-Cinnamaldehyde, carvacrol, thymol, eugenol, oil of bay, clove, nutmeg, thyme	Down-regulation of hly and prfA genes coding for toxin production and transcriptional regulator	[47,78,79]
Vibrio cholerae	Cholera toxin	Tea catechins, Dihydroisosteviol	Modulation of transmembrane regulators	[80,81]
		RG-tannin, apple phenols	Inhibition of ADP-ribosyltransferase activity	[82,83]
		Red chilli, sweet fennel, white pepper Red bayberry, thymol, carvacrol, eugenol	Modulation of toxin production genes ctxA, tcpA, toxT	[84,85,86,87]
Toxin producing E. coli	ETEC toxin	Extracts from Galla Chinensis and Berberis aristata, leanolic acid, ursolic acid, and betulinic acid, essential oil from Cymbopogon martini, C. winterianus and Psidium guajava	Inhibiting intestinal secretion of ETEC enterotoxins Blocking the binding of heat labile enterotoxin to GM1 Reducing toxin binding and toxin mediated cellular pathology	[88,89,90,91,92,93,94,95,96,97]
	Verotoxin	Extracts from Limonium californicum (Boiss.) A. Heller, Cupressus lustianica Miller, Salvia urica Epling and Jusiaea peruviana L., eugenol, catechin, epigallocatechin, cinnamon bark oil, cinnamaldehyde, Curtisia dentata extract carvacrol, thymol, beta-resorcylic acid, grape seed and pomace extracts	Decrease in toxin production Reducing the transcription of stx1 and stx2 genes Reducing the expression of globotriaosylceramide (Gb3) receptor by mimicking toxin receptors	[98,99,100,101,102,103,104,105,106,107,108,109]
Aspergillus ochraceus Penicillium verrucosum	Ochratoxin A	Oregano, mint, basil, sage, and coriander	Inhibiting fungal growth	[110]
Penicillium expansum	Patulin	Garlic, thyme, lavender oils, Azadirachta indica extracts.	Inhibiting fungal growth, mycelium formation and sporulation	[111,112]
Fusarium graminearum	Zearalenone	Cinnamon, clove, oregano, palmarosa, and lemongrass oils	An aromatic nucleus and phenolic OH group of plant compounds disrupting fungal cell membrane	[113]
	Deoxynivalenol	Clove		[113]
Fusarium proliferatum	Fumonisin B	Extracts from maize, garlic, and pea	Inhibiting primary and secondary metabolism of the fungal pathogens, decreasing biomass formation	[114]
Aspergillus flavus Aspergillus parasiticus	Aflatoxins	Clove, cinnamon, Zataria multiflora, carvacrol, trans-cinnamaldehyde	Down-regulation of aflatoxin production genes including aflc, ver1, nor1 and norA genes	[51,115,116,117]