Polysaccharide from Boletus aereus ameliorates DSS-induced colitis in mice by regulating the MANF/MUC2 signaling and gut microbiota.

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions characterized by disruptions in the colonic mucus barrier and gut microbiota. In this study, a novel soluble polysaccharide obtained from Boletus aereus (BAP) through water extraction was examined for its structure. The protective effects of BAP on colitis were investigated using a DSS-induced mice model. BAP was found to promote the expression of intestinal mucosal and tight junction proteins, restore the compromised mucus barrier, and suppress the activation of inflammatory signaling. Moreover, BAP reshape the gut microbiota and had a positive impact on the composition of the gut microbiota by reducing inflammation-related microbes. Additionally, BAP decreased cytokine levels through the MANF-BATF2 signaling pathway. Correlation analysis revealed that MANF was negatively correlated with the DAI and the level of cytokines. Furthermore, the depletion of gut microbiota using antibiotic partially inhabited the effect of BAP on the activation of MANF and Muc2, indicating the role of gut microbiota in its protective effect against colitis. In conclusion, BAP had an obvious activation on MANF under gut inflammation. This provides new insights into the prospective use of BAP as a functional food to enhance intestinal health.

Anti-inflammatory activity of Boletus aereus polysaccharides: Involvement of digestion and gut microbiota fermentation.

Boletus aereus, an edible mushroom, has gained popularity as a medicinal and functional food. This study aimed to investigate the digestive characteristics of B. aereus polysaccharide (BAP) and its effects on gut microbiota. In vitro digestion results indicated partial degradation of BAP. Furthermore, the digested BAP displayed significantly enhanced antioxidant ability. The 16S rRNA sequencing data revealed that BAP positively influenced the abundance of Phascolarctobacterium, Prevotella, and Bifidobacterium in the gut microbiota. Additionally, BAP promoted the production of short-chain fatty acids (SCFAs). Metabolites of BAP utilized by the gut microbiota effectively reduced the concentration of TNF-α, IL-1ß, and NO in an LPS-stimulated RAW 264.7 cell inflammation model. Mantel tests demonstrated a strong correlation among fermentation indicators, gut microbiome composition, SCFAs, and inflammatory cytokines. Overall, this research revealed the underlying digestive and fermentation mechanisms of BAP and provided new insights into the usage of edible mushroom polysaccharides in functional food.

Spatio-temporal dynamics of the metabolome of climacteric fruit during ripening and post-harvest storage.

Fruit quality traits are determined to a large extent by their metabolome. The metabolite content of climacteric fruit changes drastically during ripening and post-harvest storage, and has been investigated extensively. However, the spatial distribution of metabolites and how it changes in time has received much less attention as fruit are usually considered as homogenous plant organs. Yet, spatio-temporal changes of starch, which is hydrolyzed during ripening, has been used for a long time as a ripening index. As vascular transport of water, and hence convective transport of metabolites, slows down in mature fruit and even stalls after detachment, spatio-temporal changes in their concentration are probably affected by diffusive transport of gaseous molecules that act as substrate (O2), inhibitor (CO2), or regulator (ethylene and NO) of the metabolic pathways that are active during climacteric ripening. In this review, we discuss such spatio-temporal changes of the metabolome and how they are affected by transport of metabolic gases and gaseous hormones. As there are currently no techniques available to measure the metabolite distribution repeatedly by non-destructive means, we introduce reaction-diffusion models as an in silico tool to compute it. We show how the different components of such a model can be integrated and used to better understand the role of spatio-temporal changes of the metabolome in ripening and post-harvest storage of climacteric fruit that is detached from the plant, and discuss future research needs.

Application of plasma-activated water in the food industry: A review of recent research developments.

Plasma-activated water (PAW) is liquid treated with plasma. This liquid develops a higher oxygen reduction potential, a lower pH, and conductivity due to the delivery of reactive species from plasma to water. In this article, we review the antimicrobial activity and other applications of PAW in various food products. We discuss the effects of PAW treatment parameters on microbial inactivation efficiency as well as the underlying mechanisms, pesticide dissipation and its degradation pathway, meat curing and strategies to improve the nitrite amount in PAW, enhancement of food functional characteristics, and seed germination and plant growth. Additionally, we highlight the effects of PAW on food quality attributes. We further introduce the synergistic interaction of PAW with other technologies. Finally, we provide an overview of future challenges that must be resolved in the application of PAW in the food industry.

Kinetic, spectroscopic, and molecular docking studies on the inhibition of membrane-bound polyphenol oxidase from Granny Smith apples (Malus domestica Borkh.).

We investigated the inhibitory effect and binding mechanism of four selected compounds (ascorbic acid, l-cysteine, glutathione, and citric acid) on membrane-bound polyphenol oxidases (mPPO) using spectroscopic and molecular docking techniques. Kinetic analysis demonstrated that these inhibitors reversibly inhibited the mPPO activity. Fluorescence spectroscopy revealed that the intrinsic fluorescence intensity of mPPO was quenched by inhibitors with a single class of the inhibition site on mPPO. Amino acid residues His 180, His 201, His 366, Cys 184, Glu 328, and Asn 333 were the important binding sites in the active center. These sites were identified using molecular docking techniques. Our findings suggested that the inhibitors were allosterically bound to the active center of mPPO through hydrogen bonds and ion contacts. This study provides new insights into the active site residues responsible for catalyzing mPPO and provides applicable information about the design of mPPO inhibitors.

Characterization of membrane-bound polyphenol oxidase from Granny Smith apple (Malus × domestica Borkh.).

Membrane-bound polyphenol oxidase (mPPO) from the Granny Smith apple was purified and characterized. The enzyme was purified by a factor of 20.53 with a recovery of 1.8%. The molecular weight of purified mPPO was determined to be 65 kDa by electrophoresis and nano-electrospray ionization mass spectrometry. mPPO exhibited its highest activity at a temperature of 35 °C and a pH of 7.0 and can be regarded as a diphenol oxidase. A low concentration of SDS (≤0.5 mM) enhanced the enzymatic activity, whereas mPPO was activated at high concentration EDTA (≥2 mM). The thermal transition temperature of mPPO was 76.98 °C. The circular dichroism spectrum showed that mPPO contains high α-helix content, the fluorescence spectroscopy indicated that the tryptophan residues of mPPO are partially buried. The particle size of mPPO was 5-10 nm with a complete structure. The structural characterization of mPPO provided better insights into the regions responsible for its activity.

Carotenogenesis and chromoplast development during ripening of yellow, orange and red colored Physalis fruit.

MAIN CONCLUSION: Formation of specific ultrastructural chromoplastidal elements during ripening of fruits of three different colored Physalis spp. is closely related to their distinct carotenoid profiles. The accumulation of color-determining carotenoids within the chromoplasts of ripening yellow, orange, and red fruit of Physalis pubescens L., Physalis peruviana L., and Physalis alkekengi L., respectively, was monitored by high-performance liquid chromatography/diode array detector/tandem mass spectrometry (HPLC-DAD-MS/MS) as well as light and transmission electron microscopy. Both yellow and orange fruit gradually accumulated mainly ß-carotene and lutein esters at variable levels, explaining their different colors at full ripeness. Upon commencing ß-carotene biosynthesis, large crystals appeared in their chromoplasts, while large filaments protruding from plastoglobules were characteristic elements of chromoplasts of orange fruit. In contrast to yellow and orange fruit, fully ripe red fruit contained almost no ß-carotene, but esters of both ß-cryptoxanthin and zeaxanthin at very high levels. Tubule bundles and unusual disc-like crystallites were predominant carotenoid-bearing elements in red fruit. Our study supports the earlier hypothesis that the predominant carotenoid type might shape the ultrastructural carotenoid deposition form, which is considered important for color, stability and bioavailability of the contained carotenoids.

Comparison of biochemical properties of membrane-bound and soluble polyphenol oxidase from Granny Smith apple (Malus × domestica Borkh.).

Polyphenol oxidase from Granny Smith apples was purified and characterized in both its soluble form (sPPO) and its membrane-bound form (mPPO). Both forms were purified by temperature-induced phase partitioning, precipitation with ammonium sulfate, and ion exchange chromatography. The specific activity of mPPO was 19.17 times that of sPPO. The optimum pH and temperature for both forms were 7.0 and 35 °C when catechol was the substrate. The Michaelis constant and maximum reaction rate for sPPO were 34.1 mM and 500 U/mL/min, whereas those for mPPO were 53 mM and 10,000 U/mL/min, respectively. The enzymes exhibited diphenolase activity, and their affinity was highest for catechol (sPPO) and 4-methylcatechol (mPPO). Inhibitors of sPPO and mPPO included ascorbic acid, glutathione, and l-cysteine. However, ethylenediaminetetraacetic acid increased the activity of mPPO. Purified sPPO was dimeric with a molecular weight of 31 kDa, whereas mPPO was monomeric with an estimated molecular weight of 65 kDa.