Table 2.

Antistaphylococcal properties of flavonols, flavanols and phenolic acids.

Phenolic Compound	Proposed Mechanism of Action	Examined Strains	Synergism with Antibiotics	References
Flavolons
Galangin	a	S. aureus NCTC 6571	Penicillin G	[38,41]
Morin	b	S. aureus clinical strains	-	[42]
Quercetin	c	MRSA clinical strains	Rifampicin Ciprofloxacin	[43,44,45]
Kaempferol	c	MRSA clinical strains	Rifampicin Ciprofloxacin Fluoroquinolone	[43,44,45,46]
Flavanols and Derivatives
(−)-Epigallocatechin gallate	b,d	MRSA and MSSA clinical and standard strains	Oxacillin Ampicillin/Sulbactam Penicillin Imipenem Panipenem Meropenem Tetracyclin Oxytetracycline	[47,48,49,50,51,52,53]
(+)-catechin acyl derivatives	a	MRSA clinical strains	-	[40]
Epicatechin gallate	a,e	MRSA clinical strains	β-lactams Ampicillin Ampicillin/Sulbactam Cefazolin Cefepime Imipenem/Cilastatin	[4,37,54]
3-O-decyl-(+)-catechin	a	MRSA and MSSA clinical strains	-	[55]
(+)-catechin	e	MRSA clinical strains	Ampicillin Ampicillin/Sulbactam Cefazolin Cefepime Imipenem/Cilastatin	[4]
Catechin hydrate	nk	MRSA and MSSA clinical and standard strains	Clindamycin Erythromycin	[18]
Phenolic Acids and Derivatives
Ferulic acid	a	S. aureus ATCC 6538	-	[56]
Coumaric acid	a	S. aureus ATCC 6538	-	[56]
Chlorogenic acid	a	S. aureus ATCC 6538	-	[56]
Protocatechuic acid ethyl ester	nk	MRSA and MSSA clinical and standard strains	Clindamycin	[5]
Caffeic acid	a	MRSA and MSSA clinical and standard strains	Clindamycin Erythromycin Cefoxitin	[16,57,58,59]

a—interaction with a cytoplasmic membrane, b—influence on the staphylococcal virulence factors, c—inhibition of bacterial topoisomerases activity, d—direct action on the bacterial cell wall, e—inhibition of bacterial gene expression, nk—not known.