Table 1.

Summary of the antimicrobial effects of some plant-derived terpenoids, alkaloids, and flavonoids.

	Compounds	Chemical Structures	Target Microorganisms	Antimicrobial Effects	Reference
Terpenoids	1,8-cineole		A. baumannii C. albicans MRSA strain E. coli	Cell membrane destruction	[22]
	cinnamaldehyde		S. typhimurium E. coli O157: H7 P. fluorescence B. thermophacta S. aureus	1. Cell membrane destruction 2. Anti-quorum sensing action 3. Inhibition of protein synthesis	[23,25,30,31]
	carvacrol		S. typhimurium E. coli O157: H7 P. fluorescence B. thermophacta S. aureus P. fluorescens KM121	1. Cell membrane destruction 2. Anti-quorum sensing action 3. Inhibition of nucleic acid synthesis 4. The synergistic effect 5. Inhibits cell movement and bacterial invasion	[23,26,27,29,32]
	thymol		S. typhimurium E. coli O157: H7 P. fluorescence B. thermophacta S. aureus P. fluorescens KM121	1. Cell membrane destruction 2. Anti-quorum sensing action 3. Inhibition of nucleic acid synthesis 4. The synergistic effect	[23,26,27,28,32]
	eugenol		S. typhimurium E. coli O157: H7 P. fluorescence B. thermophacta S. aureus	1. Cell membrane destruction 2. Inhibition of nucleic acid synthesis 3. The synergistic effect	[23,27,28,32]
	limonene		A. baumannii C. albicans MRSA strain E. coli	Cell membrane destruction	[23]
	oleanolic acid		E. coli S. aureus Enterococcus faecalis P. aeruginosa	Antibacterial	[33]
Alkaloids	piperine		S. aureus B. subtilis Salmonella sp. E. coli	Efflux pump inhibition	[34,35]
	reserpine		E. coli	Efflux pump inhibition	[36]
	berberine		E. coli Micrococcus luteus P. aeruginosa Prevotella intermedia Fusobacterium nucleatum MRSA strain	1. Efflux pump inhibition 2. DNA-intercalating 3. Growth inhibition	[37,38,39]
	L-ephedrine		Influenza A virus	DNA-intercalating	[40]
	D-pseudoephedrine		Influenza A virus	DNA-intercalating	[40]
	L-methylephedrine		Influenza A virus	DNA-intercalating	[40]
	chelerythrine		S. aureus MRSA strain ESBLs-SA	1. Nucleic acid synthesis and repair inhibition 2. Growth inhibition	[41]
	8-hydroxy quinoline		S. aureus H. influenza S. pneumoniae	Permeability change of membrane	[42,43]
	michellamine b		HIV	Protein activity inhibition	[44]
	sanguinarine		K. pneumoniae MRSA strain P. aeruginosa Streptococcus pyogenes	1. DNA-intercalating 2. Growth inhibition	[45,46]
	roemerine		S. aureus B. subtilis	1. Efflux pump inhibition 2. Permeability change of membrane	[47,48]
	dihydrochelerythrine		S. aureus MRSA strain	Growth inhibition	[49]
	evodiamine		M. tubercolosis	Peptidoglycan biosynthesis inhibitor	[50,51]
Flavonoids	hesperidin		S. aureus L. monocytogenes	Inhibit bacterial growth by modulating the expression of virulence factors	[52] [53]
	oroxylin a		B. subtilis S. aureus	/	[54]
	apigenin		S. aureus B. subtilis E. coli P. aeruginosa.	1. Inhibits peptidoglycan synthesis 2. Increases cell membrane permeability	[55]
	morin		E. coli	Inhibition of ATP synthetase	[56]
	silymarin		E. coli	Inhibition of ATP synthetase	[56]
	epigallocatechin gallate		S. maltophilia	Inhibits dihydrofolate reductase	[57]
	quercetin		P. aeruginosa	1. Inhibits viral polymerase and viral nucleic acid 2. Inhibits the formation of its biofilm	[58]
	galangin		S. aureus	1. Destroys the plasma membrane 2. Weakens the cell wall	[59]
	catechin		B. subtilis E. coli	Inhibits the bacterial DNA gyrase	[60] [61]
	baicalin		Salmonella spp. Staphylococcus spp.	Inhibits biofilm formation	[62] [63]
	phloretin		C. albicans	1. Inhibits the pathogenicity 2. Inhibits virulence factors	[64]
	silybin		MRSA strain	Inhibits the efflux pump	[65]