Antibacterial Activity and Mechanism of Action of Punicalagin against Staphylococcus aureus in vitro

Introduction: Punicalagin, the main active compound in pomegranate peel, has been reported to possess many properties, including antioxidant, antimicrobial, anti-proliferative, apoptotic, antiviral and immune-suppressive activities

Purpose: The aim of this study was to investigate the antibacterial effect of punicalagin against Staphylococcus aureus (S. aureus) and to elucidate its mechanism of action.

Methods: Inhibition zone diameter was measured using agar diffusion method. Agar dilution method was taken to determine the minimum inhibitory concentration (MIC). The effects of punicalagin on cell membrane of S. aureus were assessed by measuring potassium efflux, pH_in, scanning electron microscopy, and transmission electron microscopy.

Results: Punicalagin showed clearly antistaphylococcal effect. The inhibition zone diameter was 11.1 (± 0.4) mm in the presence of 1 mg/ml of punicalagin and the MIC was determined as 0.25 mg/ml. An increase of potassium efflux and pH_in was observed when cells were treated with punicalagin at 2 × MIC. Moreover, punicalagin induced significant morphological damage to the cell membrane.

Significance: The findings indicate that punicalagin has the potential to be developed as an alternative to control S. aureus and prevent the diseases associated with this microorganism.