Effects of Oral Administration of Chitin Nanofiber on Plasma Metabolites and Gut Microorganisms

Interactive relationship between Trp metabolites and gut microbiota: The impact on human pathology of disease

Tryptophan (Trp), an α-amino acid, is the precursor of serotonin (5-hydroxytryptamine, 5-HT), which is involved in a variety of features of metabolic function and human nutrition. Evidence highlights the role of Trp metabolites (exclusively 5-HT) in the gastrointestinal (GI) tract; however, the mechanisms of action involved in the release of 5-HT in the GI tract are still unknown. Considering the fact that variations of 5-HT may facilitate the growth of certain GI disorders, gaining a better understanding of the function and release of 5-HT in the GI tract would be beneficial. Additionally, investigating Trp metabolism may clarify the relationship between Trp and gut microbiota. It is believed that other metabolites of Trp (mostly that of the kynurenine pathway) may play a significant role in controlling gut microbiota function. In this review, we have attempted to summarize the current research investigating the relationship of gut microbiota, Trp, and 5-HT metabolism (with particular attention paid to their metabolite type, as well as a discussion of the research methods used in each study). Taking together, regarding the role that Trp/5-HT plays in a range of physical and mental diseases, the gut bacterial types, as well as the related disorders, have been exclusively considered.

A systematic review on the effects of nanomaterials on gut microbiota

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Nanomaterials have been shown to affect gut microbiota (GM) both in vivo and in vitro.

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The effects have been shown to depend on size, dose, dose duration and functional groups.

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In general, more studies seem to indicate dose-dependent adverse effects of NMs towards GM.

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Standardized protocols are needed for characterization of NMs, dosing, and test systems (both in vitro and in vivo).

Some nanomaterials (NMs) have been shown to possess antimicrobial activity and cause GM dysbiosis. Since NMs are being used widely, a systematic assessment of the effects of NMs on GM is warranted. In this systematic review, a total of 46 in vivo and 22 in vitro studies were retrieved from databases and search engines including Science-Direct, Pubmed and Google scholar. Criteria for assessment of studies included use of in vitro or in vivo studies, characterization of NMs, use of single or multiple doses as well as consistency of results. GM dysbiosis has been studied most widely on TiO₂, Ag, Zn-based NMs. There was moderate evidence for GM dysbiosis caused by Zn- and Cu-based NMs, Cu-loaded chitosan NPs and Ag NMs, and anatase TiO₂ NPs, as well as low evidence for SWCNTs, nanocellulose, SiO₂, Se, nanoplastics, CeO_2, MoO₃ and graphene-based NMs. Most studies indicate adverse effects of NMs towards GM. However, more work is required to elucidate the differences on the reported effects of NM by type and sex of organisms, size, shape and surface properties of NMs as well as effects of exposure to mixtures of NMs. For consistency and better agreement among studies on GM dysbiosis, there is need for internationally agreed protocols on, inter alia, characterization of NMs, dosing (amounts, frequency and duration), use of sonication, test systems (both in vitro and in vivo), including oxygen levels for in vitro models.

Graphene oxide promoted chromium uptake by zebrafish embryos with multiple effects: Adsorption, bioenergetic flux and metabolism

The increasing production and application of graphene oxide (GO, a popular carbon nanomaterial), makes their release into aqueous environment inevitably. The capability of GO to enhance the toxicity of background contaminants has been widely concerned. However, the effect of GO on heavy metal accumulation in fish embryos remains unclear. Here, we show that GO-promoted chromium (Cr) uptake by zebrafish embryos with multiple effects. The adsorption accelerated the aggregation and settlement of Cr⁶⁺-adsorbed GO and decreased the Cr⁶⁺ concentration in the upper water, which enhanced the interaction of chorions and contaminants (Cr⁶⁺, GO and Cr⁶⁺-adsorbed GO). In the presence of GO, the Cr content in chorions and intra-chorion embryos was increased by four times and 57% respectively, compared to that of the single Cr⁶⁺ exposure. Furthermore, GO+Cr⁶⁺ increased the oxygen consumption rates, embryonic acid extrusion rates and ATP production, induced more serious oxidative stress, and disturbed amino acid metabolism, fatty acid metabolism and TCA cycle. These findings provide new insights into the effect of GO on heavy metal bioaccumulation and toxicity during embryogenesis.

Isoxanthohumol, a hop-derived flavonoid, alters the metabolomics profile of mouse feces

The aim of this study was to verify the effect of treatment with isoxanthohumol (IX) on the metabolomics profile of mouse feces to explore the host-intestinal bacterial interactions at the molecular level. The fecal contents of several amino acids in the high-fat diet (HFD) + 0.1% IX group (treated with IX mixed in diets for 12 weeks) were significantly lower than in the HFD group. The fecal contents of the secondary bile acid deoxycholic acid (DCA) in the HFD + 180 mg/kg IX group (orally treated with IX for 8 weeks) were significantly lower than in the HFD group; the values in the HFD group were higher than those in the normal diet (ND) group. Administration of IX changed the fecal metabolomics profile. For some metabolites, IX normalized HFD-induced fluctuations.

Preparation and evaluation of freeze dried surface-deacetylated chitin nanofiber/sacran pellets for use as an extended-release excipient

Pelleted preparations were formulated from sacran (Sac), an anionic, sulfated, carboxyl-containing polysaccharide, which is extracted from the Japanese indigenous cyanobacterium Aphanothece sacrum, and surface-deacetylated chitin nanofibers (SDACNF). The use of this material as an extended-release excipient for tetrahydrocurcumin (THC), a model drug that is used to treat wounds via its radical scavenging ability was examined. The THC used in the study was complexed with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), which increases its water solubility. The radical scavenging activity of the THC/HP-β-CD complex (molar ratio of 1:1) was significantly higher than the values for SDACNF or Sac alone. The rate of release of THC from the Sac/SDACNF pellets containing the THC/HP-β-CD complex decreased with increasing Sac content in the pellet, suggesting that Sac/SDACNF (1:1) and Sac alone pellets function as extended-release excipients for THC. The findings reported here indicate that this can be attributed to the ability of the Sac component to retain fluids, thus extending the effects of the drug. In view of the above experimental outcomes, i.e. wound healing efficacy, fluid absorption, retention and the extended drug release of the system indicates that this preparation, in the appropriate ratios, has the potential for use as a controlled-release drug in wound healing.

CE–MS-based metabolomics reveals the metabolic profile of maitake mushroom (Grifola frondosa) strains with different cultivation characteristics

Maitake mushroom (Grifola frondosa [Dicks.] Gray) is generally cultured using the sawdust of broadleaf trees. The maitake strain Gf433 has high production efficiency, with high-quality of fruiting bodies even when 30% of the birch sawdust on the basal substrate is replaced with conifer sawdust. We performed metabolome analysis to investigate the effect of different cultivation components on the metabolism of Gf433 and Mori52 by performing CE–MS on their fruiting bodies in different cultivation conditions to quantify the levels of amino acids, organic acids, and phosphorylated organic acids. We found that amino acid and organic acid content in Gf433 were not affected by the kind of sawdust. However, Gf433 contained more organic acids and less amino acids than Mori52, and Gf433 also contained more chitin compared with Mori52. We believe that these differences in the metabolome contents of the two strains are related to the high production efficiency of Gf433.

Protein/CaCO₃/Chitin Nanofiber Complex Prepared from Crab Shells by Simple Mechanical Treatment and Its Effect on Plant Growth

A protein/CaCO₃/chitin nanofiber complex was prepared from crab shells by a simple mechanical treatment with a high-pressure water-jet (HPWJ) system. The preparation process did not involve chemical treatments, such as removal of protein and calcium carbonate with sodium hydroxide and hydrochloric acid, respectively. Thus, it was economically and environmentally friendly. The nanofibers obtained had uniform width and dispersed homogeneously in water. Nanofibers were characterized in morphology, transparency, and viscosity. Results indicated that the shell was mostly disintegrated into nanofibers at above five cycles of the HPWJ system. The chemical structure of the nanofiber was maintained even after extensive mechanical treatments. Subsequently, the nanofiber complex was found to improve the growth of tomatoes in a hydroponics system, suggesting the mechanical treatments efficiently released minerals into the system. The homogeneous dispersion of the nanofiber complex enabled easier application as a fertilizer compared to the crab shell flakes.