Sulphonated modification of polysaccharides from Pleurotus eryngii and Streptococcus thermophilus ASCC 1275 and antioxidant activities investigation using CCD and Caco-2 cell line models

Streptococcus thermophilus CNCM I-5570 lysate counteracts the aging process in human dermal fibroblast cells by neutralizing harmful free radicals and impacting antioxidant and anti-inflammatory pathways, thus restoring their physiological functions

Previous studies have highlighted the in vitro and in vivo anti-aging potential of Streptococcus thermophilus prompting us to investigate the biomolecular mechanisms underlying its effects. We evaluated the reparative ability of S. thermophilus lysate in a hydrogen peroxide (H2O2)-induced senescence model of human dermal fibroblasts (HDFs). Cell proliferation, cell number, and senescence level were evaluated by IncuCyte® Live Cell Imager system, trypan blue dye exclusion test and β-galactosidase activity, respectively. We analyzed p21, prolyl 4-hydroxylase A1, intracellular collagen I, nuclear factor E2-related factor 2 (Nrf2), nuclear factor kappa B (NF-κB) and heme oxygenase-1 expression through western blot. Extracellular levels of collagen I, interleukin-1β, and IL-6 were assessed by ELISA. The oxidative stress markers were assayed using standard methods. The direct antioxidant activity of probiotic was quantified using multiple techniques. The presence of antioxidant genes in probiotic was detected via PCR assay. Probiotic lysate exposure increased the proliferation rate, counteracted the aging by reducing β-galactosidase activity and p21 levels, promoted collagen I synthesis and neutralized oxidative stress by activating Nrf2. The probiotic lysate inhibited the NF-κB pathway with pro-inflammatory marker downregulation. Notably, we revealed that probiotic exhibited strong free radical scavenging ability, iron-chelating properties, and significant ferric reducing power in a concentration-dependent manner. We identified seven genes with antioxidant function in its genome. Our results show that S. thermophilus lysate is efficacious in suppressing the biomolecular events associated with H2O2-induced cellular aging, thus supporting the reparative action of S. thermophilus, helpful in treating skin aging.

A structure-functionality insight into the bioactivity of microbial polysaccharides toward biomedical applications: A review

Microbial polysaccharides (MPs) are biopolymers secreted by microorganisms such as bacteria and fungi during their metabolic processes. Compared to polysaccharides derived from plants and animals, MPs have advantages such as wide sources, high production efficiency, and less susceptibility to natural environmental influences. The most attractive feature of MPs lies in their diverse biological activities, such as antioxidative, anti-tumor, antibacterial, and immunomodulatory activities, which have demonstrated immense potential for applications in functional foods, cosmetics, and biomedicine. These bioactivities are precisely regulated by their sophisticated molecular structure. However, the mechanisms underlying this precise regulation are not yet fully understood and continue to evolve. This article presents a comprehensive review of the most representative species of MPs, including their fermentation and purification processes and their biomedical applications in recent years. In particular, this work presents an in-depth analysis into the structure-activity relationships of MPs across multiple molecular levels. Additionally, this review discusses the challenges and prospects of investigating the structure-activity relationships, providing valuable insights into the broad and high-value utilization of MPs.

The antioxidant and anti-apoptotic potential of Pleurotus eryngii extract and its chitosan-loaded nanoparticles against doxorubicin-induced testicular toxicity in male rats

This study was conducted to evaluate the protective role of Pleurotus eryngii extract (PE) and Pleurotus eryngii extract-loaded chitosan nanoparticles (PE-CSNP) against doxorubicin (DOX)-induced testicular toxicity in rats. Male rats were divided into six groups: control (DMSO/ethanol), PE (200 mg/kg PE), PE-CSNP (30 mg/kg PE-CSNP), DOX (10 mg/kg DOX, a single dose, i.p), DOX+PE (10 mg/kg DOX+200 mg/kg PE) and DOX+PE-CSNP (10 mg/kg DOX+30 mg/kg PE-CSNP). PE and PE-CSNP were administered by oral gavage every other day for 21 days. DOX-treated rats showed histopathological impairment compared with the control group. There was an increase in the apoptotic index, caspase 3 (CASP3), BCL2-associated X apoptosis regulator (BAX), dynamin-related protein 1 (DRP1) expression and total oxidative status (TOS) in the DOX group, while mitofusin-2 (MFN2), total antioxidative status (TAS) and serum testosterone levels of the DOX group reduced when compared with the other groups. PE and PE-CSNP treatments provided significant protection against DOX-induced oxidative stress by reducing TOS levels and increasing TAS levels. CASP3, BAX, apoptotic index and DRP1-MFN2 expressions were restored by PE and PE-CSNP. However, the PE-CSNP showed higher antioxidant and anti-apoptotic efficacy compared with PE. Thus, our results provide evidence that CSNP and PE could synergistically have a potent antioxidant and anti-apoptotic therapy against DOX-induced testicular damage in male rats.

Preparation of newly identified polysaccharide from Pleurotus eryngii and its anti-inflammation activities potential

The anti-inflammatory effects of two newly identified Pleurotus eryngii polysaccharides (WPEP, NPEP) were determined in lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages in this study. Characterization analysis revealed that molecular weights of WPEP and NPEP were 167 and 274 kDa, and were mainly composed of glucose with β-type glycosidic linkages. WPEP and NPEP could significantly inhibit LPS-induced inflammatory responses by regulating the production of NO, Protaglandin E2 (PGE₂ ), Interleukin-1β (IL-1β), Tumor necrosis factor-α (TNF-α), and Interleukin-6 (IL-6). This was through the blocking of the activation of Mitogen-activated protein kinase (MAPK) pathway by inhibiting phosphorylation of p38, extracellular regulation of protein kinases 1/2, and stress-activated protein kinase/jun aminoterminal kinase. Moreover, WPEP and NPEP inhibited NF-κB signaling by reducing nuclear translocation and phosphorylation of p65. Overall, our results, for the first time identified two P. eryngii polysaccharides and demonstrated the related anti-inflammatory effects, which indicated the favorable potential of P. eryngii polysaccharide as specific functional foods. PRACTICAL APPLICATION: This study prepared and characterized newly identified Pleurotus eryngii water-soluble polysaccharide fractions and elucidated the nutritional benefits, mainly the immune response related to anti-inflammatory activities by utilizing lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Collectively, results of this study suggested that the P. eryngii polysaccharide fractions could be considered as potential candidates for exploration in the development of new immunomodulatory agent or functional supplementary foods.

Structural characterization of exopolysaccharide from Streptococcus thermophilus ASCC 1275

In this study, we purified and characterized exopolysaccharide (EPS) produced by a high-EPS-producing dairy starter bacterium, Streptococcus thermophilus ASCC 1275. Crude EPS was extracted from S. thermophilus ASCC 1275 and partially purified using dialysis. Further purification and fractionation of exopolysaccharide was conducted using HPLC on a Superose 6 column (Cytiva/Global Life Sciences Solutions, Marlborough, MA). Glycosyl composition analysis, linkage analysis along with 1-dimensional and 2-dimensional nuclear magnetic resonance spectroscopy were performed to deduce the structure of EPS. Three fractions (F) obtained from gel permeation chromatography were termed F1 (2.6%), F2 (45.8%), and F3 (51.6%) with average molecular weights of approximately 511, 40, and 5 kDa, respectively. Monosaccharide composition analysis revealed the dominance of glucose, galactose, and mannose in all 3 fractions. Major linkages observed in F3 were terminal galactopyranosyl (t-Gal), 3-linked glucopyranosyl (3-Glc), 3-linked galactofuranosyl (3-Galf), and 3,6-linked glucopyranosyl (3,6-Glc) and major linkages present in F2 were 4-Glc (48 mol%), followed by terminal mannopyranosyl (t-Man), 2- + 3-linked mannopyranosyl (2-Man+3-Man), and 2,6-linked mannopyranosyl (2,6-Man; total ∼28 mol%). The 1-dimensional and 2-dimensional nuclear magnetic resonance spectroscopy revealed that F2 comprised mannans linked by (1→2) linkages and F3 consisted of linear chains of α-d-glucopyranosyl (α-d-Glcp), β-d-glucopyranosyl (β-d-Glcp), and β-d-galactofuranosyl (β-d-Galf) connected by (1→3) linkages; branching was through (1→6) linkage in F3. A possible structure of EPS in F2 and F3 was proposed.

Assessment of the in vitro toxicity of the disinfection byproduct 2,6-dichloro-1,4-benzoquinone and its transformed derivatives

An emerging class of unregulated disinfection byproducts, halobenzoquinones (HBQs), has gained recent interest following suggestions of enhanced toxicity compared to regulated disinfection byproducts. While the kinetics of HBQ hydrolysis in water have been well characterized, the stability of HBQs in cell culture media, a critical parameter when evaluating toxicity in vitro, has been overlooked. The objective of this study was: (1) to contrast the stability of a prevalent HBQ, 2,6-dichloro-1,4-benzoquinone (DCBQ), in cell culture media and water, and (2) to evaluate the cytotoxicity of parent and transformed DCBQ compounds as well as the ability of these compounds to generate intracellular reactive oxygen species (ROS) in normal human colon cells (CCD 841 CoN) and human liver cancer cells (HepG2). The half-life of DCBQ in cell media was found to be less than 40 min, compared to 7.2 h in water at pH 7. DCBQ induced a concentration-dependent decrease in cell viability and increase in ROS production in both cell lines. The parent DCBQ compound was found to induce significantly greater cytotoxicity compared to transformed DCBQ products. We demonstrate that the study design used by most published studies (i.e., extended exposure periods) has led to a potential underestimation of the cytotoxicity of HBQs by evaluating the toxicological profile primarily of transformed HBQs, rather than corresponding parent compounds. Future in vitro toxicological studies should account for HBQ stability in media to evaluate the acute cytotoxicity of parent HBQs.

Sulfonation of Lactobacillus plantarum WLPL04 exopolysaccharide amplifies its antioxidant activities in vitro and in a Caco-2 cell model

Exopolysaccharide (EPS) of Lactobacillus plantarum WLPL04 and its sulfated EPS were systematically investigated for their antioxidant activities and effects on protecting the oxidative damage of Caco-2 cells from H2O2. Exopolysaccharide was successfully sulfonated from purified EPS as confirmed by Fourier-transform infrared spectroscopy, and the degree of sulfonation was 0.30. Both EPS and sulfated EPS showed antioxidant activities in vitro determined by 1,1-diphenyl-2-picrylhydrazyl, superoxide, and hydroxyl radical scavenging tests, and those activities of sulfated EPS were significantly enhanced at 1,000 μg/mL. Cell viabilities of Caco-2 in the range of 1 to 100 μg/mL of EPS and sulfated EPS showed no significant difference. In H2O2-damaged Caco-2 cells models, EPS and sulfated EPS significantly inhibited the enhancement of reactive oxygen species and malondialdehyde levels, and sulfated EPS enhanced the effects by 40.86% and 61.11% when compared with the purified EPS at the same concentration of 100 μg/mL, respectively. For the activities of antioxidant-related enzymes (superoxide dismutase, catalase, and glutathione peroxidase) and expression of genes (SOD2, GPX2, MT1M) on Caco-2 cells, strong protection abilities against the oxidative stress were displayed from both EPS and sulfated EPS, and sulfated EPS exhibited significant enhancement as compared with either EPS or control groups. In summary, sulfonation is an effective strategy for improving the antioxidant activities of EPS from L. plantarum WLPL04 in vitro and on Caco-2 cells.

Cytoprotective effect of Streptococcus thermophilus against oxidative stress mediated by a novel peroxidase (EfeB)

Streptococcus thermophilus is one of the most important starter species used in the dairy industry and exhibits several beneficial properties for the hosts. However, knowledge of the mechanism of its beneficial effect is still limited. The objective of this study was to investigate the cytoprotective effect of S. thermophilus CGMCC 7.179 with a novel peroxidase (EfeB) against oxidative stress in human intestinal epithelial cells, HT-29. Previously, we identified EfeB in S. thermophilus CGMCC 7.179, which could provide protection when growing at aerobic conditions. Here, we found that, when exposed to 15 mM H₂O₂, the cell viability of the efeB mutant (ST1314) was much lower than that of strain CGMCC 7.179, and the 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity of strain ST1314 decreased by 15%. When co-incubated with HT-29 cells, strain CGMCC 7.179 stimulated the enhancement of the major antioxidant enzyme activities (superoxide dismutase, glutathione peroxidase, and catalase) in HT-29 cells under 2 mM H₂O₂-induced oxidative stress, whereas the active decrease of those antioxidant enzymes was observed in strain ST1314. In addition, the intracellular reactive oxygen species content in HT-29 cells co-incubated with strain CGMCC 7.179 was lower than that with strain ST1314 under the same oxidative stress. Furthermore, the protein content of nuclear factor erythroid 2-related factor 2 (Nrf2) in HT-29 cells following strain CGMCC 7.179 treatment was 1.4-fold higher than that with strain ST1314 treatment, and the increased transcription levels of Nrf2-related antioxidant enzyme genes were also observed in strain CGMCC 7.179 cells. All of these results demonstrated that S. thermophilus CGMCC 7.179 enhanced cellular antioxidant responses and endowed host cells with protective effects against oxidative stress mediated by the peroxidase EfeB.