Antibacterial Activity of Ethanolic Extracts of Origanum majorana, Salvia officinalis, and Ribes nigrum Against Digestive Pathogens: Polyphenolic Composition and In Vitro Assessment

Digestive pathologies are commonly encountered in both human and veterinary medicine, frequently requiring antibiotic intervention. However, their extensive use has contributed to the global increase in antimicrobial resistance, posing a major public health challenge. With the emergence of multidrug-resistant bacteria, alternative antimicrobial strategies are urgently needed. This study assessed the total polyphenolic content and in vitro antimicrobial activity of ethanolic extracts from <i>Origanum majorana</i>, <i>Salvia officinalis</i>, and <i>Ribes nigrum</i> fruits against six digestive bacterial pathogens: <i>Escherichia coli</i>, <i>Salmonella enteritidis</i>, <i>Enterobacter cloacae</i>, <i>Yersinia enterocolitica</i>, <i>Listeria monocytogenes</i>, and <i>Enterococcus faecalis</i>. Antimicrobial activity was evaluated using agar well diffusion and minimum inhibitory concentration (MIC) assays. The total polyphenolic content of the extracts was 8509.457 μg/g for Salvia officinalis, 8140.996 μg/g for <i>Origanum majorana</i>, and 5776.616 μg/g for <i>Ribes nigrum</i>. <i>R. nigrum</i> showed the strongest antimicrobial effect (MIC 0.002 μg/μL; MBC 0.001 μg/μL) against <i>Y. enterocolitica</i>. <i>S. officinalis</i> had the highest efficacy against <i>E. faecalis</i>, while <i>O. majorana</i> was effective against both <i>Y. enterocolitica</i> and <i>E. faecalis</i>. All extracts showed bactericidal activity with MIC index values between 0.5 and 4. These findings suggest that these polyphenol-rich plant extracts may serve as promising natural antimicrobials or as adjuvants to conventional antibiotics.