Bacillus coagulans and Clostridium butyricum synergistically alleviate depression in a chronic unpredictable mild stress mouse model through altering gut microbiota and prefrontal cortex gene expression.

Introduction: The prevalence of major depressive disorder (MDD) has gradually increased and has attracted widespread attention. The aim of this study was to investigate the effect of a probiotic compound consisting of Bacillus coagulans and Clostridium butyricum, on a mouse depression model. Methods: Mice were subjected to chronic unpredictable mild stress (CUMS) and then treated with the probiotics at different concentrations. And mice received behavior test such as forced swimming test and tail suspension test. After that, all mice were sacrificed and the samples were collected for analysis. Moreover, prefrontal cortex (PFC) gene expression and the gut microbiota among different groups were also analyzed. Results: Probiotics improved depressive-like behavior in CUMS mice, as indicated by decreased immobility time (p < 0.05) in the forced swimming test and tail suspension test. probiotics intervention also increased the level of 5-hydroxytryptamine (5-HT) in the prefrontal cortex and decreased the adrenocorticotropic hormone (ACTH) level in serum. In addition, by comparing the PFC gene expression among different groups, we found that the genes upregulated by probiotics were enriched in the PI3K-Akt signaling pathway in the prefrontal cortex. Moreover, we found that downregulated genes in prefrontal cortex of CUMS group such as Sfrp5 and Angpt2, which were correlated with depression, were reversed by the probiotics. Furthermore, the probiotics altered the structure of the gut microbiota, and reversed the reduction of cob(II)yrinate a,c-diamide biosynthesis I pathway in CUMS group. Several species like Bacteroides caecimuris and Parabacteroides distasoni, whose abundance was significantly decreased in the CUMS group but reversed after the probiotics intervention, showed significantly positive correlation with depression associated genes such as Tbxas1 and Cldn2. Discussion: These findings suggested that CUMS-induced depression-like behavior can be alleviated by the probiotics, possibly through alterations in the PFC gene expression and gut microbiota.

All-natural protein-polysaccharide conjugates with bead-on-a-string nanostructures as stabilizers of high internal phase emulsions for 3D printing.

The combination of proteins and polysaccharides creates an exceptional platform for stabilizing biphasic systems such as oil in water emulsions. In this paper, we propose the use of natural protein-polysaccharide conjugates (PPCs) extracted from shiitake mushroom roots to stabilize high internal phase emulsions (HIPEs). The PPCs had bead-on-a-string nanostructures with bead (300 nm in diameter) and string (50 nm in thickness) structures corresponding to proteins and polysaccharides, respectively. Having spaced compartments with favourable amphiphilic properties, the PPCs had a three-phase contact angle close to 90°, which were harnessed for the preparation of HIPEs with excellent long-term storage stability (30 d) and heat tolerance (90 °C). The HIPEs were amenable to three-dimensional printing, yielding different objects with strong self-standing and high structural resolution properties. This paper presents a good example of how these unique PPC structures can provide biphasic stabilization, HIPE preparation, and potential applications in food products.

Oxidative transformation of tunichromes - Model studies with 1,2-dehydro-N-acetyldopamine and N-acetylcysteine.

Tunichromes are 1,2-dehydrodopa containing bioactive peptidyl derivatives found in blood cells of several tunicates. They have been implicated in metal sequestering, tunic formation, wound healing and defense reaction. Earlier studies conducted on these compounds indicate their extreme liability, high reactivity and easy oxidative polymerization. Their reactions are also complicated by the presence of multiple dehydrodopyl units. Since they have been invoked in crosslinking and covalent binding, to understand the reactivities of these novel compounds, we have taken a simple model compound that possess the tunichrome reactive group viz., 1,2-dehydro-N-acetyldopamine (Dehydro NADA) and examined its reaction with N-acetylcysteine in presence of oxygen under both enzymatic and nonenzymatic conditions. Ultraviolet and visible spectral studies of reaction mixtures containing dehydro NADA and N-acetylcysteine in different molar ratios indicated the production of side chain and ring adducts of N-acetylcysteine to dehydro NADA. Liquid chromatography and mass spectral studies supported this contention and confirmed the production of several different products. Mass spectral analysis of these products show the potentials of dehydro NADA to form side chain adducts that can lead to polymeric products. This is the first report demonstrating the ability of dehydro dopyl units to form adducts and crosslinks with amino acid side chains.

Oxidative transformation of a tunichrome model compound provides new insight into the crosslinking and defense reaction of tunichromes.

Tunichromes, small oligopeptides with dehydrodopa units isolated from the blood cells of ascidians, have been implicated in the defense reactions, metal binding, wound repair, or tunic formation. Their instability and high reactivity has severely hampered the assessment of their biological role. Experiments conducted with the model compound, 1,2-dehydro-N-acetyldopamine, indicated that the instability of tunichromes is due to this basic structure. Exposure of this catecholamine derivative to even mild alkaline condition such as pH 7.5 causes rapid nonenzymatic oxidation. High performance liquid chromatography and mass spectrometry studies confirmed the production of dimeric and other oligomeric products in the reaction mixture. The nonenzymatic reaction seemed to proceed through the intermediary formation of semiquinone free radical and superoxide anion. Ultraviolet and visible spectral studies associated with the oxidation of tunichromes isolated from Ascidia nigra by tyrosinase indicated the probable formation of oligomeric tunichrome products. Attempts to monitor the polymerization reaction by mass spectrometry ended in vain. Tunichrome also exhibited instability in mild alkaline conditions generating superoxide anions. Based on these studies, a possible role for oxidative transformation of tunichrome in defense reaction, tunic formation and wound healing is proposed.

Mass spectrometric studies shed light on unusual oxidative transformations of 1,2-dehydro-N-acetyldopa.

RATIONALE: Lamellarins are a group of over 70 plus bioactive marine natural compounds possessing a 6,7-dihydroxycoumarin moiety. Although they appear to derive from 3,4-dihydroxyphenylalanine (dopa), practically nothing is known about the metabolic fate of these compounds. Biochemical considerations indicate that they could arise from a N-acetyl-1,2-dehydrodopa precursor through oxidative cyclization reaction. METHODS: To assess the above hypothesis, we synthesized N-acetyl-1,2-dehydrodopa and conducted oxidation studies with commercially available mushroom tyrosinase and evaluated the course of the reaction with reversed-phase liquid chromatography/mass spectrometry (LC/MS). RESULTS: Mushroom tyrosinase readily oxidized N-acetyl-1,2-dehydrodopa - not to the normally expected quinone - but to an unstable quinone methide isomer, which rapidly cyclized to produce the dihydroxycoumarin product, 3-aminoacetyl esculetin. Interestingly, 3-aminoacetyl esculetin was further oxidized to a second quinone methide derivative that exhibited an addition reaction with the parent dihydroxycoumarin generating dimeric and other oligomeric products in the reaction mixture. CONCLUSIONS: LC/MS analysis of the N-acetyl-1,2-dehydrodopa oxidation reaction reveals not only a possible novel oxidative cyclization route for the biosynthesis of coumarin-type dehydrodopa compounds in marine organisms, but also unusual oxidative transformations of dehydro dopa derivatives.