This review explores the antioxidant properties of oak (Quercus sp.) extracts and their potential application in preventing oxidative rancidity in food products. Oxidative rancidity negatively impacts food quality, causing changes in color, odor, and flavor and reducing the shelf life of products. The use of natural antioxidants from plant sources, such as oak extracts, has gained increasing interest due to potential health concerns associated with synthetic antioxidants. Oak extracts contain various antioxidant compounds, including phenolic acids, flavonoids, and tannins, which contribute to their antioxidative capacity. This review discusses the chemical composition of oak extracts, their antioxidative activity in different food systems, and the safety and potential challenges related to their application in food preservation. The potential benefits and limitations of using oak extracts as an alternative to synthetic antioxidants are highlighted, and future research directions to optimize their application and determine their safety for human consumption are suggested.

Antibiotic resistance is a serious global threat, and the misuse of antibiotics is considered its main cause. It is characterized by the expression of bacterial defense mechanisms, e.g., β-lactamases, expulsion pumps, and biofilm development. Acinetobacter baumannii and Pseudomonas aeruginosa are antibiotic-resistant species that cause high morbidity and mortality. Several alternatives are proposed to defeat antibiotic resistance, including antimicrobial peptides, bacteriophages, and plant compounds. Terpenes from different plant essential oils have proven antimicrobial action against pathogenic bacteria, and evidence is being generated about their effect against antibiotic-resistant species. That is the case for oregano essential oil (Lippia graveolens), whose antibacterial effect is widely attributed to carvacrol, its main component; however, minor constituents could have an important contribution. The analyzed evidence reveals that most antibacterial evaluations have been performed on single species; however, it is necessary to analyze their activity against multispecies systems. Hence, another alternative is using plant compounds to inactivate hydrolytic enzymes and biofilms to potentiate antibiotics’ effects. Despite the promising results of plant terpenes, more extensive and deep mechanistic studies are needed involving antibiotic-resistant multispecies to understand their full potential against this problem.

This research focuses on assessing the synergistic effects of Mexican oregano (Lippia graveolens) essential oil or carvacrol when combined with the antibiotic imipenem, aiming to reduce the pathogenic viability and virulence of Acinetobacter baumannii and Pseudomonas aeruginosa. The study highlighted the synergistic effect of combining L. graveolens essential oil or carvacrol with imipenem, significantly reducing the required doses for inhibiting bacterial growth. The combination treatments drastically lowered the necessary imipenem doses, highlighting a potent enhancement in efficacy against A. baumannii and P. aeruginosa. For example, the minimum inhibitory concentrations (MIC) for the essential oil/imipenem combinations were notably low, at 0.03/0.000023 mg/mL for A. baumannii and 0.0073/0.000023 mg/mL for P. aeruginosa. Similarly, the combinations significantly inhibited biofilm formation at lower concentrations than when the components were used individually, demonstrating the strategic advantage of this approach in combating antibiotic resistance. For OXA-51, imipenem showed a relatively stable interaction during 30 ns of dynamic simulation of their interaction, indicating changes (10 ns, suggesting potential instability. With IMP-1, imipenem also displayed very stable interactions during 38 ns and demonstrated notable movement and positioning changes within the active site, indicating a more dynamic interaction. In contrast, carvacrol and thymol maintained their position within the active site only ~20 and ~15 ns, respectively. These results highlight the effectiveness of combining L. graveolens essential oil and carvacrol with imipenem in tackling the difficult-to-treat pathogens A. baumannii and P. aeruginosa.

Pseudomonas fluorescens is a major psychrotrophic bacterium responsible for spoilage in refrigerated foods, particularly dairy products, where deterioration is driven by biofilm formation, quorum sensing (QS) regulation, and the secretion of thermostable lipases. Conventional control strategies reduce bacterial loads but often fail to prevent enzymatic spoilage. Plant-derived phenolic compounds have been widely reported as QS inhibitors and lipase modulators in various biological systems; however, evidence specifically addressing their effects on P. fluorescens regulatory networks and bacterial lipases remains limited. This review critically examines current knowledge on QS-mediated biofilm formation and lipase production in P. fluorescens and analyzes the reported inhibitory activity of phenolic compounds, with emphasis on oak (Quercus spp.)-derived metabolites. While flavonoids and phenolic acids such as quercetin, gallic acid, and p-coumaric acid have demonstrated QS inhibition and antilipolytic activity in other Pseudomonas species and pancreatic models, direct mechanistic validation in P. fluorescens lipases is scarce. Moreover, most studies rely on crude plant extracts without comprehensive metabolomic characterization, and the potential contribution of additional oak metabolites, including terpenoids, remains largely unexplored. Identifying these gaps is essential for advancing toward integrative approaches that combine enzymology, molecular modeling, and validation in food-relevant systems.

Pseudomonas fluorescens forms biofilms on food-contact surfaces, contributing to persistent contamination in food-processing environments. Plant-derived extracts rich in phenolic compounds offer promising alternatives for controlling bacterial colonization due to their antimicrobial and antibiofilm properties. This study evaluated the antibacterial and antibiofilm activities of Quercus chihuahuensis leaf extract and selected phenolic constituents, alongside effects on quorum-sensing (QS)-associated phenotypes. Previous LC-MS profiling of the leaf extract reported relative abundances of 31.81% for p-coumaric acid, 13.66% for quercetin, and 3.04% for vanillic acid. Minimum inhibitory (MIC), bactericidal (MBC), and biofilm inhibitory (MBIC) concentrations were determined. Bacterial attachment and biofilm development were assessed on AISI 304 stainless steel as a model food-contact surface, while violacein production and swarming motility were evaluated in Chromobacterium violaceum; swarming was also assessed in P. fluorescens. The extract exhibited MIC, MBIC, and MBC values of 5, 7, and 22 mg/mL, respectively. At 5 mg/mL, it reduced attached-cell counts by 2.34 log CFU/cm²; final planktonic counts remained above the initial inoculum reference, with no statistically significant difference detected relative to the untreated control. This concentration was below the MBC but equaled the MIC, so growth-independent activity cannot be inferred. Among the individual phenolics, p-coumaric acid produced the greatest reduction in attachment. The extract and phenolic acids reduced violacein production, while the extract and p-coumaric acid significantly inhibited swarming motility in both bacterial species, with both effects observed at concentrations below their MICs. These findings demonstrate antibiofilm activity against P. fluorescens on stainless steel and alterations in QS-associated phenotypes.