Flavonoids as Potential Therapeutic Agents Against Gastrointestinal Pathogen Growth and Their Mechanisms of Action: A Comprehensive Review

The increasing prevalence of gastrointestinal infections, along with growing resistance to conventional antibiotics, has driven the search for alternative antibacterial agents including flavonoids, which are widely recognised for their antimicrobial properties. Flavonoids exhibit broad-spectrum antimicrobial activity against both Gram-positive and Gram-negative bacteria through multifactorial mechanisms, disrupting multiple bacterial cellular processes, including energy metabolism, membrane integrity, and protein synthesis. Several studies have highlighted the antimicrobial potential of flavonoids against gastrointestinal pathogens, with some evidence suggesting minimal disruption to beneficial intestinal microflora. Most investigations have primarily focused on in vitro assessments of antibacterial activity, with limited in vivo studies and insufficient therapeutic or clinical evaluation. Consequently, their efficacy in physiological systems and the underlying mechanisms of action remain inadequately understood. Studies should also examine the antimicrobial activity of flavonoids against a wider panel of gastrointestinal pathogens. Also, the panel of flavonoids previously evaluated for their antibacterial activity is relatively narrow and many compounds have been neglected to date. Multiple other flavonoids remain to be evaluated for antimicrobial activity against gastrointestinal pathogens. This review focuses on the antimicrobial activity of different classes of flavonoids against gastrointestinal pathogens. Additionally, we discuss the interaction of selected flavonoids with conventional antibiotics. Furthermore, their mechanisms of action (where known) are also discussed to focus attention on the use of this important class of molecules as antibiotic therapies.