Background: Multi-drug-resistant bacteria such as Methicillin-Resistant Staphylococcus
aureus (MRSA) disseminate rapidly amongst patients in healthcare facilities and suppose an increasingly
important cause of community-associated infections and associated mortality. The development of
effective therapeutic options against resistant bacteria is a public health priority. Plant polyphenols are
structurally diverse compounds that have been used for centuries for medicinal purposes, including infections
treatment and possess, not only antimicrobial activity, but also antioxidant, anti-inflammatory
and anticancer activities among others. Based on the existing evidence on the polyphenols’ antibacterial
capacity, polyphenols may be postulated as an alternative or complementary therapy for infectious diseases.
Objective: To review the antimicrobial activity of plant polyphenols against Gram-positive bacteria, especially
against S. aureus and its resistant strains. Determine the main bacterial molecular targets of
polyphenols and their potential mechanism of action.
Methodology: The most relevant reports on plant polyphenols’ antibacterial activity and their putative
molecular targets were studied. We also performed virtual screening of thousand different polyphenols
against proteins involved in the peptidoglycan biosynthesis to find potential valuable bioactive compounds.
The bibliographic information used in this review was obtained from MEDLINE via PubMed.
Results: Several polyphenols: phenolic acids, flavonoids (especially flavonols), tannins, lignans, stilbenes
and combinations of these in botanical mixtures, have exhibited significant antibacterial activity
against resistant and non-resistant Gram-positive bacteria at low μg/mL range MIC values. Their
mechanism of action is quite diverse, targeting cell wall, lipid membrane, membrane receptors and ion
channels, bacteria metabolites and biofilm formation. Synergic effects were also demonstrated for some
combinations of polyphenols and antibiotics.
Conclusion: Plant polyphenols mean a promising source of antibacterial agents, either alone or in combination
with existing antibiotics, for the development of new antibiotic therapies.