The overuse of antibiotics in human and veterinary medicine has contributed significantly to their persistent presence in the environment, creating conditions that promote the spread of antimicrobial resistance (AMR). In this context, innovative approaches that reduce antibiotic doses without compromising therapeutic efficacy are urgently needed. This review explores the emerging role of plant-derived secondary metabolites, particularly saponins, as bioactive excipients capable of enhancing antibiotic activity through synergistic mechanisms. By improving membrane permeability, inhibiting resistance pathways, and modulating host responses, these natural adjuvants may allow for lower antibiotic concentrations in clinical treatments, ultimately reducing pharmaceutical residues entering the environment. We discuss the potential of such combined therapies not only to mitigate the evolution and dissemination of AMR in natural microbial communities but also to provide more sustainable, biodegradable, and ecologically safer alternatives to synthetic formulation agents. Plant-derived compounds, inherently shaped by co-evolution with microbes, offer a dynamic and adaptive molecular diversity that may be less prone to long-term microbial resistance. In addition to reviewing current knowledge, this article highlights the environmental and public health implications of integrating phytochemical excipients into antibiotic regimens, and calls for further interdisciplinary efforts to evaluate their safety, efficacy, and role in shaping future antimicrobial stewardship.

With increasing bacterial resistance to antibiotics, novel strategies for protection against microbial infections are crucial. Emulsions enhance the solubility of natural antibacterial oils and their uptake, making them promising drug delivery systems. However, it is important to find the right emulsifier to ensure that the oil has the right dispersion and does not adversely affect its antibacterial properties. Hence, this study investigated emulsions created from three vegetable oils: moringa oil from Moringa oleifera seeds, inca inchi oil from Plukenetia volubilis seeds, and tamanu oil from the Calophyllum inophyllum fruit. Emulsions were formed using two natural emulsifiers, lecithin and casein, at concentrations of 2.5%, 5%, and 10% (w/w). The study assessed the oil and emulsions’ characteristics, including the zeta potential, creaming index, and particle size distribution. The antimicrobial properties of these oils and the most stable emulsions were examined. Gas chromatography was used to analyze the oil compositions. The potential antimicrobial properties of emulsions formulated with natural oils was proved. Particularly noteworthy were emulsions containing a 2.5% inca inchi or tamanu oil, stabilized with casein. The particle size ranged between 100 nm and 900 nm with the average size 300 nm. These emulsions also showed antibacterial activity against selected strains, and the strongest effect was observed for the system with inca inchi oil, which reduced S. epidermidis bacterial activity by more than 60%. Therefore, it can be expected that the completed research will allow the development of antibacterial systems based on inca inchi or tamanu oils for use in the food industry.

Bacterial infections remain a significant health concern, necessitating the continuous exploration of novel therapeutic strategies. Sapindus mukorossi extract, renowned for its bioactive saponins, presents a promising approach for combating bacterial pathogens. This study investigates the potential of S. mukorossi extract (SM) as a bioenhancer for the polymyxin B antibiotic (PMB) against four bacterial strains: Staphylococcus aureus (SA), Staphylococcus epidermidis (SE), Pseudomonas aeruginosa (PA), and Escherichia coli (EC). Research methods were used to determine the metabolic activity of the strains and the changes in their cell membrane permeability. Furthermore, advanced microscopic techniques (confocal and transmission electron microscopy) were used to confirm the viability and visualize morphological changes within selected strains. Obtained data were also correlated with the lipidomic and fatty acid methyl ester profiles of strains subjected to the described treatments. Results indicated that the conjugated treatment of bacterial cells with PMB and SM extract demonstrated an enhancement of bacterial total membrane permeability in comparison to the treatment with PMB alone. Notably, for the S. aureus strain, a significant decrease in viability was noted, which can be associated with the significant (in terms of statistical analysis) increase in cell membrane permeability for cells treated with SM and PMB, compared with samples treated with PMB alone. This was further conjoined and proven by the results of the FAME and lipidomic analyses. Specifically for S. aureus, an increase in branched fatty acids was detected in cells exposed to SM and SM + PMB. Additionally, the lipidomic analysis revealed notable membrane remodeling, characterized by an increase in lysyl-phosphatidylglycerol and diglucosyldiglyceride and a decrease in phosphatidylglycerol, in samples treated with SM and SM + PMB compared to the control group. This study underscores the potential of S. mukorossi extract as an enhancing agent to PMB in combination therapies against bacterial infections, paving the way for further investigations into its mechanistic insights and clinical applications.