Potential of tara (Caesalpinia spinosa) gallotannins and hydrolysates as natural antibacterial compounds

Gallotannins obtained from tara pod extracts (EE) and from the products of acid hydrolysis for 4 and 9 h (HE-4 and HE-9) were characterised for their composition, antioxidant activity, antimicrobial activity (AA) and minimum inhibitory concentration (MIC). Results of AA and MIC showed that EE exerted the highest inhibitory activity against Staphylococcus aureus, followed by Pseudomonas fluorescens; and among these bacteria, the antibacterial potency was enhanced after EE hydrolysis only against S. aureus. The lowest minimum inhibitory concentration (MIC) value (0.13 mg gallic acid equivalent (GAE)/ml) was exerted by HE-4 against S. aureus. These results indicate that tara gallotannins have the potential to inhibit pathogenic bacteria with potential application in foods as antimicrobials and their AA can be enhanced by acid hydrolysis.