Table 1.

Key examples of phytomolecules as potent antimicrobials, their bioactive constituents, and modes of action against pathogenic microbes (modified from Tiwari et al. [7]).

S. No.	Classification	Key Examples	Mechanism of Action	Reference
1.	Plant-derived compounds
	Phenolics	Thymol, Carvacrol	The hydroxyl group increases the Membrane disruption and Leakage of cellular contents	[60]
	Flavonoid compounds	Catechins	Antibacterial against Shigella, Vibrio, and Streptococcus mutans	[74,75]
	Hydroxylated phenols	Catechol and pyrogallol	Antibacterial against Corynebacterium xerosis, Pseudomonas putida, and P. pyocyanea, and antifungal (catechol) against Penicillium italicum and Fusarium oxysporum	[76]
	Polyphenol (3,5,4′-trihydroxystilbene)	Resveratrol	Antifungal against Plasmopara viticola, Sphaeropsis sapinea, and Pyricularia oryzae. In C. albicans, resveratrol penetrates the cell membrane and causes apoptosis. Antibacterial against M. tuberculosis, VRE, S. typhimurium, and MRSA	[77,78,79,80]
	Essential oil from Salvia fruticosa	----	Inhibition of Efflux pump in Staphylococcus epidermidis (clinical isolates)	[81]
	Quinones from Juglans and Plumbago	Juglone and plumbagin	Antibacterial against S. aureus by increasing membrane permeability and restricting the formation of cell wall	[82]
	Essential oil from Chenopodium ambrosioides	----	Efflux pump Tet(K) inhibition in S. aureus IS-58	[83]
	Alkaloid	Capsaicin	Efflux pump NorA inhibition in S. aureus SA-1199B	[84]
	Anthraquinone from Hypericum perforatum	Hypericin	Antimicrobial activity against methicillin-resistant and methicillin-sensitive Staphylococcus	[85]
	Alkaloid	Catharanthine	Efflux pump inhibition in P. aeruginosa	[86]
	Dimeric Phenylpropanoids from Styrax japonica	Lignans Styraxjaponoside C	Antifungal against C. albicans showing membrane-active mechanisms	[87]
	Flavonoid	Baicalein	S. aureus SA-1199B NorA efflux pump inhibition	[88]
	Triterpenoids	Ursolic acid and derivatives	inhibition of efflux pump AcrA/B, MacB, TolC and YojI in MDR E. coli (KG4)	[89]
2.	Plant by-products in food processing
	Green husks of walnuts	----	Antibacterial against B. subtilis, S. aureus and B. cereus	[90]
	Grape pomace	Phenolics	Growth is hampered in S. aureus, yeasts, and Salmonella sp.	[91]
	Bergamot peel, an essential oil by-product	Chlorogenic acid	Antibacterial against B. subtilis and food-borne E. coli, S. enterica	[70]
	Pomegranate fruit peel extracts	Phenolic constituents	Hampered growth in S. aureus, Y. enterocolitica, L. monocytogenes, etc.	[92]
	Pomegranate rind	Tannins	Antimicrobial against L. monocytogenes modify microbial cell membranes and impair cell homeostasis	[93]
	Coconut husk	Tannins and Phenolic constituents	In L. monocytogenes, and V. cholera, growth is hampered	[72]
	Olive juice powder and olive pomace	Phenolic compound (oleocanthal)	Antimicrobial against L. monocytogenes, S. aureus, and E. coli	[94]
3.	Animal-origin compounds
	Chitosan	Polycationic biopolymer compound	Antibacterial towards L. monocytogenes, B. cereus, S. aureus, and others	[64]
	Milk-derived substances (casein and whey proteins)	----	Antibacterial/antifungal against Helicobacter, Listeria, Salmonella, Staphylococcus, E. coli, yeasts, and filamentous fungi	[95]
	Lysozyme	Bacteriolytic enzyme	Lysozyme hydrolyzes the β-1, 4 linkages between N-acetylmuramic acid and N-acetylglucosamine in the peptidoglycan of the microbial cell wall	[64]
4.	Antimicrobials of bacterial origin
	Bacteriocin	Nisin	Growth is hampered in Gram-positive and spore-producing bacteria in food	[96]
	Reuterin	β-hydroxypropionaldehyde	Antimicrobial towards foodborne pathogens	[97]
5.	Antimicrobials from algae and mushrooms
	Phlorotannins from marine brown algae	----	Antimicrobial towards S. aureus, Salmonella spp., etc.	[98]
	Grifolin, and pleuromutilin from macrofungi	----	Antimicrobial activity against S. aureus, B. cereus, L. monocytogenes, E. coli	[99]
	Fatty acids, β-carotene-linoleic acid, flavonoids from Agaricus spp.	----	Antimicrobial towards Micrococcus luteus, B. cereus, etc.	[100]