Safety evaluation and lipid-lowering effects of food-grade biopolymer complexes (ε-polylysine-pectin) in mice fed a high-fat diet.

ε-Polylysine (ε-PL) is a potent cationic antimicrobial, but its application as a food additive is currently limited because it tends to precipitate with anionic species in food matrices. Previous research has shown that the formation of an electrostatic complex between cationic ε-PL and anionic pectin (P) improved the physical stability of ε-PL while maintaining its antimicrobial activity. However, the impact of complexation on the effects of ε-PL on health is currently unknown. A subchronic toxicity study was therefore carried out to determine the safety of ingested ε-PL-P complexes using high-fat diet-fed male and female mice. After a 13-week dietary treatment with P, ε-PL, or ε-PL-P complexes, no significant toxicological effects were observed on the survival, mean body weight, food consumption, and organ weights of the animals, suggesting that the complexes were safe for oral consumption. Interestingly, the ε-PL-P complexes were found to have several beneficial health effects: suppression of high-fat diet-induced elevation of serum aspartate aminotransferase and alanine aminotransferase activities, reduction in serum total triglyceride and cholesterol levels, and an increase in fecal excretion of triglycerides. These effects were much stronger in female mice than in male mice. Moreover, the lipid-lowering effects were observed only for the ε-PL-P complexes but not for ε-PL or P alone at the same doses. Overall, our results demonstrate the oral safety of ε-PL-P complexes and their gender-specific lipid-lowering effects in high-fat diet-fed mice, which provide an important basis for the utilization of ε-PL-P complexes in food systems as functional ingredients.

Food-grade cationic antimicrobial ε-polylysine transiently alters the gut microbial community and predicted metagenome function in CD-1 mice.

Diet is an important factor influencing the composition and function of the gut microbiome, but the effect of antimicrobial agents present within foods is currently not understood. In this study, we investigated the effect of the food-grade cationic antimicrobial ε-polylysine on the gut microbiome structure and predicted metagenomic function in a mouse model. The relative abundances of predominant phyla and genera, as well as the overall community structure, were perturbed in response to the incorporation of dietary ε-polylysine. Unexpectedly, this modification to the gut microbiome was experienced transiently and resolved to the initial basal composition at the final sampling point. In addition, a differential non-random assembly was observed in the microbiomes characterized from male and female co-housed animals, although their perturbation trajectories in response to diet remain consistent. In conclusion, antimicrobial ε-polylysine incorporated into food systems transiently alters gut microbial communities in mice, as well as their predicted function. This indicates a dynamic but resilient microbiome that adapts to microbial-active dietary components.

Impact of ε-polylysine and pectin on the potential gastrointestinal fate of emulsified lipids: In vitro mouth, stomach and small intestine model.

ε-Polylysine (ε-PL) is a broad-spectrum antimicrobial biopolymer, suitable for use in foods; however, some studies suggest that it may also inhibit lipid digestion. We therefore examined the effect of polylysine on the digestion of corn oil-in-water emulsions, using a simulated gastrointestinal tract (GIT) that included oral, gastric, and intestinal phases. Both mucin and polylysine had pronounced influences on the particle size, charge, and aggregation state throughout the GIT. However, surprisingly, we found that ε-polylysine did not have a significant impact on lipid digestion, either in the presence or absence of anionic mucin. However, it did form strong electrostatic complexes with mixed micelles, which could decrease the transport and absorption of lipids in the small intestine. These results have important implications for the incorporation of polylysine into food systems, particularly those containing lipophilic nutrients.

Impact of a food-grade cationic biopolymer (ε-polylysine) on the digestion of emulsified lipids: In vitro study.

ε-Polylysine (ε-PL) is a cationic biopolymer that may be used as a food ingredient because of its strong antimicrobial activity and potential to inhibit pancreatic lipase. We examined the effect of polylysine on the digestion of corn oil-in-water emulsions stabilized by either a natural anionic surfactant (quillaja saponin) or a synthetic non-ionic surfactant (Tween 20). Emulsions were prepared using high pressure homogenization (microfluidization) and then subjected to in vitro digestion in the absence or presence of polylysine at the maximum level allowed in foods by the FDA. Samples were characterized before and after in vitro digestion using electrophoresis, confocal microscopy, and static light scattering. The presence of polylysine decreased the hydrolytic activity of pancreatic lipase by around 53% and 28% in the Tween 20- and saponin-stabilized emulsions, respectively. The lipase-inhibiting properties of cationic polylysine were attributed to its electrostatic interaction with anionic components, such as bile salts, free fatty acids, and digestive enzymes. These results have important implications for the incorporation of polylysine into food systems, particularly those containing lipophilic nutrients.

Potential impact of biopolymers (ε-polylysine and/or pectin) on gastrointestinal fate of foods: In vitro study.

Food-grade biopolymers, such as proteins and polysaccharides, may impact the gastrointestinal fate of foods through various mechanisms. In this study, we examined the influence of ε-polylysine (an antimicrobial) and pectin (a thickening agent) on the behavior of a standard rodent diet (full-fat and fat-free) in a simulated gastrointestinal tract that included mouth, stomach, and small intestine phases. Powdered biopolymers were incorporated into the standard diet in either individual or complexed form. The presence of the biopolymers altered the microstructure and charge characteristics of the gastrointestinal contents. In particular, the presence of pectin appeared to increase the rate and extent of lipid digestion, which may have been due to its ability to inhibit protein aggregation. Our results do not support the hypothesis that polylysine inhibits lipid digestion, as has been reported previously. Overall, the results of this study may be useful for interpreting animal feeding studies of the influence of biopolymers on the gastrointestinal fate of foods.

Optimizing delivery systems for cationic biopolymers: competitive interactions of cationic polylysine with anionic κ-carrageenan and pectin.

Polylysine is a cationic biopolymer with a strong antimicrobial activity against a wide range of microorganisms, however, its functional performance is influenced by its interactions with anionic biopolymers. We examined the stability of polylysine-pectin complexes in the presence of carrageenan, and vice versa. Polylysine-pectin or polylysine-carrageenan complexes were formed at mass ratios of 1:0 to 1:32 (pH 3.5), and then micro-electrophoresis, turbidity, microscopy, and isothermal titration calorimetry (ITC) were used to characterise them. Solutions containing polylysine-pectin complexes were slightly turbid and relatively stable to aggregation at high mass ratios, whereas those containing polylysine-carrageenan complexes were turbid and unstable to aggregation and precipitation. Pectin did not strongly interact with polylysine-carrageenan complexes, whereas carrageenan displaced pectin from polylysine-pectin complexes, which was attributed to differences in electrostatic attraction between polylysine, carrageenan, and pectin. These results have important implications for the design of effective antimicrobial delivery systems for foods and beverages.