Impact of Kefiran Exopolysaccharide Extraction on Its Applicability for Tissue Engineering and Regenerative Medicine

Nutritional Characteristics, Health Impact, and Applications of Kefir

A global epidemiological shift has been observed in recent decades, characterized by an increase in age-related disorders, notably non-communicable chronic diseases, such as type 2 diabetes mellitus, cardiovascular and neurodegenerative diseases, and cancer. An appreciable causal link between changes in the gut microbiota and the onset of these maladies has been recognized, offering an avenue for effective management. Kefir, a probiotic-enriched fermented food, has gained significance in this setting due to its promising resource for the development of functional or value-added food formulations and its ability to reshape gut microbial composition. This has led to increasing commercial interest worldwide as it presents a natural beverage replete with health-promoting microbes and several bioactive compounds. Given the substantial role of the gut microbiota in human health and the etiology of several diseases, we conducted a comprehensive synthesis covering a total of 33 investigations involving experimental animal models, aimed to elucidate the regulatory influence of bioactive compounds present in kefir on gut microbiota and their potential in promoting optimal health. This review underscores the outstanding nutritional properties of kefir as a central repository of bioactive compounds encompassing micronutrients and amino acids and delineates their regulatory effects at deficient, adequate, and supra-nutritional intakes on the gut microbiota and their broader physiological consequences. Furthermore, an investigation of putative mechanisms that govern the regulatory effects of kefir on the gut microbiota and its connections with various human diseases was discussed, along with potential applications in the food industry.

Evaluating the roughness dynamics of kefir biofilms grown on Amazon cupuaçu juice: a monofractal and multifractal approach

We conducted a comprehensive analysis of the surface microtexture of kefir biofilms grown on Theobroma grandiflorum Shum (cupuaçu) juice using atomic force microscopy. Our goal was to investigate the unique monofractal and multifractal spatial patterns of these biofilms to complement the existing limited literature. The biofilms were prepared dispersing four different concentrations of kefir grains in cupuaçu juice. Our morphological analysis showed that the surface of the obtained biofilms is essentially formed by the presence of cupuaçu fibers and microorganisms like lactobacilli and yeast. The topographic height-based parameter analysis reveals that there is a dependence between surface roughness and the concentration of kefir grains used. The strongly anisotropic well-centralized topographical height distribution of the biofilms also exhibited a quasi-symmetrical and platykurtic pattern. The biofilms exhibit comparable levels of spatial complexity, surface percolation and surface homogeneity, which can be attributed to their similar topographic uniformity. This aspect was further supported by the presence of similar multifractality in the biofilms, suggesting that despite their varying topographic roughness, their vertical growth dynamics follow a similar pattern. Our findings demonstrate that the surface roughness of kefir biofilms cultivated on cupuaçu juice is influenced by the concentration of kefir grains in the precursor solution. However, this dependence follows a consistent pattern across different concentrations. Graphical Abstract.

Novel Kefir Exopolysaccharides (KEPS) Mitigate Lipopolysaccharide (LPS)-Induced Systemic Inflammation in Luciferase Transgenic Mice through Inhibition of the NF-κB Pathway

A novel kefir exopolysaccharides (KEPS) derived from kefir grain fermentation were found to have a small molecular weight (12 kDa) compared to the traditionally high molecular weight (12,000 kDa) of kefiran (KE). KE has been shown to possess antioxidant, blood pressure-lowering, and immune-modulating effects. In this study, we characterized KEPS and KE and evaluated their anti-inflammatory properties in vitro using RAW264.7 macrophages. The main monosaccharide components were identified as glucose (98.1 ± 0.06%) in KEPS and galactose (45.36 ± 0.16%) and glucose (47.13 ± 0.06%) in KE, respectively. Both KEPS and KE significantly reduced IL-6 secretion in lipopolysaccharide (LPS)-stimulated macrophages. We further investigated their effects in LPS-induced systemic injury in male and female NF-κB-luciferase+/+ transgenic mice. Mice received oral KEPS (100 mg/kg) or KE (100 mg/kg) for seven days, followed by LPS or saline injection. KEPS and KE inhibited NF-κB signaling, as indicated by reduced luciferase expression and phosphorylated NF-κB levels. LPS-induced systemic injury increased luciferase signals, especially in the kidney, spleen, pancreas, lung, and gut tissues of female mice compared to male mice. Additionally, it upregulated inflammatory mediators in these organs. However, KEPS and KE effectively suppressed the expression of inflammatory mediators, including p-MAPK and IL-6. These findings demonstrate that KEPS can alleviate LPS-induced systemic damage by inhibiting NF-κB/MAPK signaling, suggesting their potential as a treatment for inflammatory disorders.

Development of Conjugated Kefiran-Chondroitin Sulphate Cryogels with Enhanced Properties for Biomedical Applications

Hydrogels based on natural polysaccharides can have unique properties and be tailored for several applications, which may be mainly limited by the fragile structure and weak mechanical properties of this type of system. We successfully prepared cryogels made of newly synthesized kefiran exopolysaccharide-chondroitin sulfate (CS) conjugate via carbodiimide-mediated coupling to overcome these drawbacks. The freeze-thawing procedure of cryogel preparation followed by lyophilization is a promising route to fabricate polymer-based scaffolds with countless and valuable biomedical applications. The novel graft macromolecular compound (kefiran-CS conjugate) was characterized through ¹H-NMR and FTIR spectroscopy-which confirmed the structure of the conjugate, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA)-which mirrored good thermal stability (degradation temperature of about 215 °C) and, finally, gel permeation chromatography-size exclusion chromatography (GPC-SEC)-which proved an increased molecular weight due to chemical coupling of kefiran with CS. At the same time, the corresponding cryogels physically crosslinked after the freeze-thawing procedure were investigated by scanning electron microscopy (SEM), Micro-CT, and dynamic rheology. The results revealed a prevalent contribution of elastic/storage component to the viscoelastic behavior of cryogels in swollen state, a micromorphology with micrometer-sized open pores fully interconnected, and high porosity (ca. 90%) observed for freeze-dried cryogels. Furthermore, the metabolic activity and proliferation of human adipose stem cells (hASCs), when cultured onto the developed kefiran-CS cryogel, was maintained at a satisfactory level over 72 h. Based on the results obtained, it can be inferred that the newly freeze-dried kefiran-CS cryogels possess a host of unique properties that render them highly suitable for use in tissue engineering, regenerative medicine, drug delivery, and other biomedical applications where robust mechanical properties and biocompatibility are crucial.