Highly efficient site-specific protein modification using tyrosinase from Streptomyces avermitilis: Structural insight.

Tyrosinase-mediated protein conjugation has recently drawn attention as a site-specific protein modification tool under mild conditions. However, the tyrosinases reported to date act only on extremely exposed tyrosine residues, which limits where the target tyrosine can be located. Herein, we report a tyrosinase from Streptomyces avermitilis (SaTYR), that exhibits a much higher activity against tyrosine residues on the protein surface than other tyrosinases. We determined the crystal structure of SaTYR and revealed that the enzyme has a relatively flat and shallow substrate-binding pocket to accommodate a protein substrate. We demonstrated SaTYR-mediated fluorescence dye tagging and PEGylation of a surface tyrosine residue that was unreacted by other tyrosinases with an approximately 95.2 % conjugation yield in 1 h. We also present a structural rationale that considers the steric hindrance from adjacent residues and surrounding structures along with the extent of solvent exposure of residues, as necessary when determining the optimal positions for introducing target tyrosine residues in SaTYR-mediated protein modification. The study demonstrated that the novel tyrosinase, SaTYR, extends the scope of tyrosinase-mediated protein modification, and we propose that site-specific tyrosine conjugation using SaTYR is a promising strategy for protein bioconjugation in various applications.

Single-Walled Carbon Nanotube-Guided Topical Skin Delivery of Tyrosinase to Prevent Photoinduced Damage.

When the skin is exposed to ultraviolet radiation (UV), it leads to the degradation of the extracellular matrix (ECM) and results in inflammation. Subsequently, melanocytes are triggered to induce tyrosinase-mediated melanin synthesis, protecting the skin. Here, we introduce a proactive approach to protect the skin from photodamage via the topical delivery of Streptomyces avermitilis-derived tyrosinase (SaTy) using single-walled carbon nanotube (SWNT). Utilizing a reverse electrodialysis (RED) battery, we facilitated the delivery of SaTy-SWNT complexes up to depths of approximately 300 µm, as analyzed by using confocal Raman microscopy. When applied to ex vivo porcine skin and in vivo albino mouse skin, SaTy-SWNT synthesized melanin, resulting in 4-fold greater UV/vis absorption at 475 nm than in mice without SaTy-SWNT. The synthesized melanin efficiently absorbed UV light and alleviated skin inflammation. In addition, the densification of dermal collagen, achieved through SaTy-mediated cross-linking, reduced photoinduced wrinkles by 66.3% in the affected area. Our findings suggest that SWNT-mediated topical protein delivery holds promise in tissue engineering applications.

Effect of NaCl Pretreatment on the Relationship between the Color Characteristics and Taste of Cirsium setidens Processed Using a Micro-Oil-Sprayed Thermal Air Technique.

Cirsium setidens is commonly used as a food ingredient, and it is typically stored and distributed in a dried form to prolong its shelf life. In a previous study, a micro-oil-sprayed thermal air (MOTA) technique was developed, which effectively enhanced the rehydration properties and improved the color characteristics of Cirsium setidens after processing. Here, we investigated the relationship between the color characteristics and taste of MOTA-processed C. setidens and the effect of NaCl pretreatment, prior to processing, on the final quality of dried C. setidens. NaCl pretreatment, whether combined with the MOTA technique or not, showed improved color characteristics, in which MOTA-and NaCl+ MOTA-processed C. setidens manifested equal color characteristics. In contrast, NaCl + MOTA-processed C. setidens resulted in significantly higher values of sourness and saltiness than MOTA-processed C. setidens when the taste of the rehydrated C. setidens was examined using an electronic tongue (Astree II; Alpha MOS, Toulouse, France). Pearson correlation coefficient analysis showed that sourness and saltness were negatively correlated with Hunter a* values and positively correlated with Hunter L* and Hunter b* values, indicating that the color characteristics of dried and rehydrated C. setidens could be indicators of taste. Furthermore, the amounts of total phenol and chlorophyll were better preserved in C. setidens processed by the MOTA technique with NaCl than by the MOTA technique alone. Our data revealed that the color characteristics of dried plants are associated with the taste of processed C. setidens, and that the MOTA technique with NaCl pretreatment is a useful method for preserving health-promoting compounds during processing.

Recent trends in the modification of polyphenolic compounds using hydroxylation and glycosylation.

Polyphenols are bioactive molecules that are used in therapeutics. Polyphenol hydroxylation and glycosylation have been shown to increase their bioavailability, solubility, bioactivity, and stability for use in various applications. Ortho-hydroxylation of polyphenols using tyrosinase allows high selectivity and yield without requiring a cofactor, while meta- and para-hydroxylation of polyphenols are mediated by site-specific hydroxylases and cytochrome P450s, although these processes are somewhat rare. O-glycosylation of polyphenols proceeds further after hydroxylation. The O-glycosylation reaction typically requires nucleotide diphosphate (NDP) sugar. However, amylosucrase (AS) has emerged as a promising enzyme for polyphenol glycosylation in large-scale production without requiring NDP-sugar. Overall, this review describes recent findings on the enzymatic mechanisms, enzyme engineering, and applications of enzymatic reactions.

Influence of Storage Temperature on Levels of Bioactive Compounds in Shiitake Mushrooms (Lentinula edodes).

Shiitake mushroom (Lentinula edodes) hold high nutritional and medicinal value as they contain an abundance of health-promoting compounds. However, the effect of long-term postharvest storage on the variation in the levels of health-promoting compounds has not been extensively studied. In this study, we investigated the changes in the levels of phenolic compounds, antioxidants, eritadenine, and ergothioneine in shiitake mushrooms stored at three different temperatures (1, 3, and 5 °C) for 4 weeks. Compared to mushrooms stored at lower temperatures, those stored at 5 °C exhibited a higher level of total phenolics in their pileus after 2 weeks of storage; however, storage at 5 °C also increased the deterioration of the fruiting body of these mushrooms. In mushrooms stored at all temperatures, the eritadenine content in the pilei tended to increase up to 2 weeks of storage. In contrast, the ergothioneine content in the pileus decreased during storage, with a significantly lower level detected in mushrooms stored at 5 °C for 4 weeks. Together, these results suggest that the mechanisms underlying the accumulation of phenolics and eritadenine may be related to mushroom deterioration during storage. Our findings indicate that the levels of health-promoting compounds in shiitake mushrooms are influenced by storage temperature, suggesting the potential to control adjustments of specific bioactive compounds by regulating storage conditions.

Leaves of Cedrela sinensis Attenuate Chronic Unpredictable Mild Stress-Induced Depression-like Behavior via Regulation of Hormonal and Inflammatory Imbalance.

This study aimed to evaluate the protective effects of ethyl acetate fraction from Cedrela sinensis (EFCS) against chronic unpredictable mild stress (CUMS)-induced behavioral dysfunction and stress response in C57BL/6 mice. The physiological compounds of EFCS were identified as rutin, isoquercitrin, ethyl gallate, quercitrin, kaempferol-3-O-rhamnoside, and ethyl digallate, using UPLC-Q-TOF/MSE. To evaluate the neuroprotective effect of EFCS, H2O2- and corticosterone-induced neuronal cell viability was conducted in human neuroblastoma MC-IXC cells. It was found that EFCS alleviated depression-like behavior by conducting the sucrose preference test (SPT), forced swimming test (FST), open field test (OFT), and tail suspension test (TST). EFCS inhibited mitochondrial dysfunction related to neuronal energy metabolism by regulating reactive oxygen species (ROS) levels, mitochondrial membrane potential (MMP), and ATP contents in brain tissue. In addition, the administration of EFCS regulated the stress hormones in serum. EFCS regulated stress-related indicators such as CRF, ACTH, CYP11B1, and BDNF. Moreover, EFCS downregulated the inflammatory responses and apoptosis proteins such as caspase-1, TNF-α, IL-1ß, p-JNK, BAX, and p-tau in brain tissues. These results suggest that EFCS might be a potential natural plant material that alleviates CUMS-induced behavior disorder by regulating inflammation in brain tissue against CUMS-induced depression.

Field Confirmation of (Z)-9-Heptacosene and (3Z,6Z,9Z)-Tricosatriene as Key Sex Pheromone Components of Korean Conogethes punctiferalis Guenée (Lepidoptera: Crambidae).

Recently, insufficient attractiveness of Conogethes punctiferalis Guenée adult males to sex pheromone, -(E)-10-hexadecenal and (Z)-10-hexadecenal, has been reported. To identify the other essential components of sex pheromone, male and female body extracts were analyzed. Two hydrocarbon components, (Z)-9-heptacosene (Z9-27:HC) and (3Z,6Z,9Z)-tricosatriene (Z3,Z6,Z9-23:HC), were identified from only female body extract. There was a significant difference in the electroantennogram (EAG) response of male antennae to Z3,Z6,Z9-23:HC and Z9-27:HC at all test concentrations compared to the response to the hexane control. In field attraction testing, the addition of Z9-27:HC and Z3,Z6,Z9-23:HC to binary aldehyde pheromones significantly increased trap catches of C. punctiferalis male adults. Based on the female and male body extract analysis and field attraction test, Z9-27:HC and Z3,Z6,Z9-23:HC were determined to be other essential sex pheromone components of the Korean C. punctiferalis population. No significant difference was observed in the number of male captures between the bucket trap and delta trap. Pheromone traps with a color close to yellow shade attracted more male adults than traps with a color close to blue shade.

Walnut Prevents Cognitive Impairment by Regulating the Synaptic and Mitochondrial Dysfunction via JNK Signaling and Apoptosis Pathway in High-Fat Diet-Induced C57BL/6 Mice.

This study was conducted to evaluate the protective effect of Juglans regia (walnut, Gimcheon 1ho cultivar, GC) on high-fat diet (HFD)-induced cognitive dysfunction in C57BL/6 mice. The main physiological compounds of GC were identified as pedunculagin/casuariin isomer, strictinin, tellimagrandin I, ellagic acid-O-pentoside, and ellagic acid were identified using UPLC Q-TOF/MS analysis. To evaluate the neuro-protective effect of GC, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), 2',7'-dichlorodihydrofluorecein diacetate (DCF-DA) analysis were conducted in H2O2 and high glucose-induced neuronal PC12 cells and hippocampal HT22 cells. GC presented significant cell viability and inhibition of reactive oxygen species (ROS) production. GC ameliorated behavioral and memory dysfunction through Y-maze, passive avoidance, and Morris water maze tests. In addition, GC reduced white adipose tissue (WAT), liver fat mass, and serum dyslipidemia. To assess the inhibitory effect of antioxidant system deficit, lipid peroxidation, ferric reducing antioxidant power (FRAP), and advanced glycation end products (AGEs) were conducted. Administration of GC protected the antioxidant damage against HFD-induced diabetic oxidative stress. To estimate the ameliorating effect of GC, acetylcholine (ACh) level, acetylcholinesterase (AChE) activity, and expression of AChE and choline acetyltransferase (ChAT) were conducted, and the supplements of GC suppressed the cholinergic system impairment. Furthermore, GC restored mitochondrial dysfunction by regulating the mitochondrial ROS production and mitochondrial membrane potential (MMP) levels in cerebral tissues. Finally, GC ameliorated cerebral damage by synergically regulating the protein expression of the JNK signaling and apoptosis pathway. These findings suggest that GC could provide a potential functional food source to improve diabetic cognitive deficits and neuronal impairments.

Synthesis of soluble melanin nanoparticles under acidic conditions using Burkholderia cepacia tyrosinase and their characterization.

Melanin nanoparticles (MNPs) used for biomedical applications are often synthesized via the chemical auto-oxidation of catecholic monomers such as dopamine and 3,4-dihydroxyphenylalanine (DOPA) under alkaline conditions. However, the synthetic method for the chemical synthesis of MNP (cMNP) is relatively straightforward and more robust to control their homogenous particle size and morphology than the corresponding enzymatic synthetic methods. In this study, we demonstrated that the simple enzymatic synthesis of MNPs (eMNPs) with homogenous and soluble (<20 nm diameter) properties is possible using dopamine and Burkholderia cepacia tyrosinase (BcTy) under acidic conditions (i.e., pH 3.0). BcTy was highly reactive under pH 5.0, where the natural and chemical oxidation of catechol is complex, and thus melanin was synthesized via the hydroxylation of phenolic substrates. The detailed chemical analysis and characterization of the physical properties of the eMNPs confirmed the higher preservation of the catechol and primary amine moieties in the monomer substrate such as dopamine under acidic conditions. The eMNPs showed enhanced antioxidant activity and conferred stickiness to the formed hydrogel compared to the chemical auto-oxidation method owing to the large number of hydroxyl groups remaining such as catechol and quinone moieties. Because of these advantages and characteristics, the synthesis of MNPs using BcTy under acidic conditions can open a new path for their biomedical applications.

Persimmon Water Extract Suppresses Hepatic Lipotoxicity by Regulating Lipid Metabolites.

This study was performed to investigate the effects of persimmon (Diospyros kaki) on high-fat diet (HFD)-induced hepatic lipotoxicity. The compounds of persimmon water extract (PWE) were identified as gallic acid, glucogallin, 1-O-Galloyl-(2-O-acetyl)-glu, and trihydroxy-octadecadienoic acid. The PWE was ingested by C57BL/6 mice with an HFD for 8 weeks. The PWE improved glucose tolerance and suppressed weight gain by inhibiting increases in the weight of liver and adipose tissues. The results of serum biomarker analysis showed that PWE suppressed biomarkers such as liver injury and dyslipidemia. In ex vivo tests, reduction of oxidative stress and improvement of mitochondrial dysfunction were confirmed in the liver of PWE groups. In a molecular study, it was confirmed that PWE decreased lipid accumulation, insulin resistance, inflammation, and apoptosis in the liver. Finally, in a metabolite analysis of liver tissue using ultra-high performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS), it was confirmed that PWE has an effect on lipid metabolism. In particular, PWE reduced phosphatidylcholines (PCs) and lysophosphatidylcholines (lysoPCs). Notably, it is presumed that the reduction of lysoPCs and PCs in the PWE group is related to the improvement of liver dysfunction due to lipotoxicity.

Effect of Ethyl Acetate Fraction from Eucommia ulmoides Leaves on PM2.5-Induced Inflammation and Cognitive Dysfunction.

This study aimed to evaluate the protective effect of the ethyl acetate from Eucommia ulmoides leaves (EFEL) on PM2.5-induced cognitive impairment in BALB/c mice. EFEL improved PM2.5-induced cognitive decline by improving spontaneous alternative behavioral and long-term memory ability. EFEL increased ferric reducing activity power (FRAP) in serum. In addition, EFEL increased superoxide dismutase (SOD) and reduced glutathione (GSH) contents and inhibited the production of malondialdehyde (MDA) in lung and brain tissues. EFEL also restored the mitochondrial function by regulating reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP) level, and ATP level in lung and brain tissues. EFEL ameliorated the cholinergic system by regulating the acetylcholine (ACh) content and acetylcholinesterase (AChE) activity in the brain tissue and the expression of AChE and choline acetyltransferase (ChAT) in the whole brain and hippocampal tissues. EFEL reduced PM2.5-induced excessive expression of inflammatory protein related to the lung, whole brain, olfactory bulb, and hippocampus. Physiological compounds of EFEL were identified as 5-O-caffeolyquinic acid, rutin, quercetin, and quercetin glycosides. As a result, EFEL has anti-inflammation and anti-amnesic effect on PM2.5-induced cognitive impairment by regulating the inflammation and inhibiting the lung and brain tissue dysfunction, and its effect is considered to be due to the physiological compounds of EFEL.

Regioselective One-Pot Synthesis of Hydroxy-(S)-Equols Using Isoflavonoid Reductases and Monooxygenases and Evaluation of the Hydroxyequol Derivatives as Selective Estrogen Receptor Modulators and Antioxidants.

Several regiospecific enantiomers of hydroxy-(S)-equol (HE) were enzymatically synthesized from daidzein and genistein using consecutive reduction (four daidzein-to-equol-converting reductases) and oxidation (4-hydroxyphenylacetate 3-monooxygenase, HpaBC). Despite the natural occurrence of several HEs, most of them had not been studied owing to the lack of their preparation methods. Herein, the one-pot synthesis pathway of 6-hydroxyequol (6HE) was developed using HpaBC (EcHpaB) from Escherichia coli and (S)-equol-producing E. coli, previously developed by our group. Based on docking analysis of the substrate or products, a potential active site and several key residues for substrate binding were predicted to interpret the (S)-equol hydroxylation regioselectivity of EcHpaB. Through investigating mutations on the key residues, the T292A variant was verified to display specific mono-ortho-hydroxylation activity at C6 without further 3'-hydroxylation. In the consecutive oxidoreductive bioconversion using T292A, 0.95 mM 6HE could be synthesized from 1 mM daidzein, while 5HE and 3'HE were also prepared from genistein and 3'-hydroxydaidzein (3'HD or 3'-ODI), respectively. In the following efficacy tests, 3'HE and 6HE showed about 30∼200-fold higher EC50 than (S)-equol in both ERα and ERß, and they did not have significant SERM efficacy except 6HE showing 10% lower ß/α ratio response than that of 17ß-estradiol. In DPPH radical scavenging assay, 3'HE showed the highest antioxidative activity among the examined isoflavone derivatives: more than 40% higher than the well-known 3'HD. In conclusion, we demonstrated that HEs could be produced efficiently and regioselectively through the one-pot bioconversion platform and evaluated estrogenic and antioxidative activities of each HE regio-isomer for the first time.

Light-Triggered In Situ Biosynthesis of Artificial Melanin for Skin Protection.

Tyrosinase-mediated melanin synthesis is an essential biological process that can protect skin from UV radiation and radical species. This work reports on in situ biosynthesis of artificial melanin in native skin using photoactivatable tyrosinase (PaTy). The I41Y mutant of Streptomyces avermitilis tyrosinase (SaTy) shows enzymatic activity comparable to that of wild-type SaTy. This Y41 is replaced with photocleavable o-nitrobenzyl tyrosine (ONBY) using the introduction of amber codon and ONBY-tRNA synthetase/tRNA pairs. The ONBY efficiently blocks the active site and tyrosinase activity is rapidly recovered by the photo-cleavage of ONBY. The activated PaTy successfully oxidizes L-tyrosine and tyramine-conjugated hyaluronic acid (HA_T) to synthesize melanin particles and hydrogel, respectively. To produce artificial melanin in living tissues, PaTy is encapsulated into lipid nanoparticles as an artificial melanosome. Using liposomes containing PaTy (PaTy_Lip), PaTy is transdermally delivered into ex vivo porcine skin and in vivo mouse skin tissues, thus achieving the in situ biosynthesis of artificial melanin for skin tissue protection under UV irradiation. The results of this study demonstrate that this biomimetic system can recapitulate the biosynthetic analogs of naturally occurring melanin. It should therefore be considered to be a promising strategy for producing protective biological molecules within living systems for tissue protection.

Anti-Amnesic Effect of Synbiotic Supplementation Containing Corni fructus and Limosilactobacillus reuteri in DSS-Induced Colitis Mice.

This study was conducted to compare the synbiotic activity between Corni fructus (C. fructus) and Limosilactobacillus reuteri (L. reuteri) on dextran sulfate sodium (DSS)-induced colitis and cognitive dysfunction in C57BL/6 mice. C. fructus (as prebiotics, PRE), L. reuteri (as probiotics, PRO), and synbiotics (as a mixture of L. reuteri and C. fructus, SYN) were fed to mice for 3 weeks. Consumption of PRE, PRO, and SYN ameliorated colitis symptoms in body weight, large intestinal length, and serum albumin level. Moreover, SYN showed a synergistic effect on intestinal permeability and intestinal anti-inflammation response. Also, SYN significantly improved cognitive function as a result of measuring the Y-maze and passive avoidance tests in DSS-induced behavioral disorder mice. Especially, SYN also restored memory function by increasing the cholinergic system and reducing tau and amyloid ß pathology. In addition, PRE, PRO, and SYN ameliorated dysbiosis by regulating the gut microbiota and the concentration of short-chain fatty acids (SCFAs) in feces. The bioactive compounds of C. fructus were identified with quinic acid, morroniside, loganin, and cornuside, using ultra-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS2). In conclusion, synbiotic supplementation alleviated DSS-induced colitis and cognitive dysfunction by modulating gut microbiota, proinflammatory cytokines, and SCFAs production.

Rationally Designed Eugenol-Based Chain Extender for Self-Healing Polyurethane Elastomers.

Bio-based polyurethane (PU) has recently drawn our attention due to the increasing interest in sustainability and the risks involved with petroleum depletion. Herein, bio-based self-healing PU with a novel polyol, i.e., eugenol glycol dimer (EGD), was synthesized and characterized for the first time. EGD was designed to have pairs of primary, secondary, and aromatic alcohols, which all are able to be involved in urethane bond formation and to show self-healing and antioxidant effects. EGD was incorporated into a mixture of the prepolymer of polyol (tetramethylene ether glycol) and 4,4'-methylene diphenyl diisocyanate to synthesize PU. EGD-PU showed excellent self-healing properties (99.84%), and it maintained its high self-healing property (84.71%) even after three repeated tests. This dramatic self-healing was induced through transcarbamoylation by the pendant hydroxyl groups of EGD-PU. The excellent antioxidant effect of EGD-PU was confirmed by 2,2-diphenyl-1-picrylhydrazyl analysis. Eugenol-based EGD is a promising polyol chain extender that is required in the production of bio-based, self-healing, and recyclable polyurethane; therefore, EGD-PU can be applied to bio-based self-healable films or coating materials as a substitute for petroleum-based PU.

Polyphenol-Hydroxylating Tyrosinase Activity under Acidic pH Enables Efficient Synthesis of Plant Catechols and Gallols.

Tyrosinase is generally known as a melanin-forming enzyme, facilitating monooxygenation of phenols, oxidation of catechols into quinones, and finally generating biological melanin. As a homologous form of tyrosinase in plants, plant polyphenol oxidases perform the same oxidation reactions specifically toward plant polyphenols. Recent studies reported synthetic strategies for large scale preparation of hydroxylated plant polyphenols, using bacterial tyrosinases rather than plant polyphenol oxidase or other monooxygenases, by leveraging its robust monophenolase activity and broad substrate specificity. Herein, we report a novel synthesis of functional plant polyphenols, especially quercetin and myricetin from kaempferol, using screened bacterial tyrosinases. The critical bottleneck of the biocatalysis was identified as instability of the catechol and gallol under neutral and basic conditions. To overcome such instability of the products, the tyrosinase reaction proceeded under acidic conditions. Under mild acidic conditions supplemented with reducing agents, a bacterial tyrosinase from Bacillus megaterium (BmTy) displayed efficient consecutive two-step monophenolase activities producing quercetin and myricetin from kaempferol. Furthermore, the broad substrate specificity of BmTy toward diverse polyphenols enabled us to achieve the first biosynthesis of tricetin and 3'-hydroxyeriodictyol from apigenin and naringenin, respectively. These results suggest that microbial tyrosinase is a useful biocatalyst to prepare plant polyphenolic catechols and gallols with high productivity, which were hardly achieved by using other monooxygenases such as cytochrome P450s.

Immature Persimmon Suppresses Amyloid Beta (Aß) Mediated Cognitive Dysfunction via Tau Pathology in ICR Mice.

This study confirmed the ameliorating effect of immature persimmon (Diospyros kaki) ethanolic extract (IPEE) on neuronal cytotoxicity in amyloid beta (Aß)1-42-induced ICR mice. The administration of IPEE ameliorated the cognitive dysfunction in Aß1-42-induced mice by improving the spatial working memory, the short-term and long-term memory functions. IPEE protected the cerebral cholinergic system, such as the acetylcholine (ACh) level and acetylcholinesterase (AChE) activity, and antioxidant system, such as the superoxide dismutase (SOD), reduced glutathione (GSH) and malondialdehyde (MDA) contents. In addition, mitochondrial dysfunction against Aß1-42-induced toxicity was reduced by regulating the reactive oxygen species (ROS), mitochondrial membrane potential and ATP contents. In addition, IPEE regulated the expression levels of tau signaling, such as TNF-α, p-JNK, p-Akt, p-GSK3ß, p-tau, p-NF-κB, BAX and caspase 3. Finally, gallic acid, ellagic acid and quercetin 3-O-(6″-acetyl-glucoside) were identified as the physiological compounds of IPEE using ultra-performance liquid chromatography ion mobility separation quadrupole time-of-flight/tandem mass spectrometry (UPLC IMS Q-TOF/MS2).

Novel enzymatic cross-linking-based hydrogel nanofilm caging system on pancreatic ß cell spheroid for long-term blood glucose regulation.

Pancreatic ß cell therapy for type 1 diabetes is limited by low cell survival rate owing to physical stress and aggressive host immune response. In this study, we demonstrate a multilayer hydrogel nanofilm caging strategy capable of protecting cells from high shear stress and reducing immune response by interfering cell-cell interaction. Hydrogel nanofilm is fabricated by monophenol-modified glycol chitosan and hyaluronic acid that cross-link each other to form a nanothin hydrogel film on the cell surface via tyrosinase-mediated reactions. Furthermore, hydrogel nanofilm formation was conducted on mouse ß cell spheroids for the islet transplantation application. The cytoprotective effect against physical stress and the immune protective effect were evaluated. Last, caged mouse ß cell spheroids were transplanted into the type 1 diabetes mouse model and successfully regulated its blood glucose level. Overall, our enzymatic cross-linking-based hydrogel nanofilm caging method will provide a new platform for clinical applications of cell-based therapies.

Ameliorative effect of persimmon (Diospyros kaki) in cognitively impaired diabetic mice.

The effects of ethanolic extract of Diospyros kaki (EED) on diabetic cognitive impairment were investigated in high-fat diet (HFD)-induced mouse. After HFD was fed to mouse for 16 weeks, EED was administrated to mouse for 4 weeks. EED reduced fasting blood glucose level and improved cognitive and behavioral dysfunction. EED improved serum biomarkers related to lipid and liver damage better than positive control (PC). In addition, EED ameliorated impaired cholinergic system, increased oxidative stress as well as mitochondrial dysfunction compared with HFD group. In the molecular study, EED downregulated the phosphorylation of c-Jun N-terminal kinase (p-JNK), which phosphorylates the serine residue of insulin receptor substrate-1 (IRS-1pSer). Finally, various physiological compounds such as tannin-based ingredients were identified using UPLC-QTOF/MS2 . These results suggest that EED can help improve cognitive impairment caused by HFD. PRACTICAL APPLICATIONS: Recently, cognitive impairment caused by type 2 diabetes mellitus (T2DM) has become a problem. T2DM, mainly derived from HFD, is characterized by hyperglycemia, which is associated with insulin resistance. In this study, EED not only improved hyperglycemia and insulin resistance, but also restored diabetes-related cognitive dysfunction in HFD-induced diabetic mice. Finally, the decrease in cholinergic and antioxidant systems related to cognitive impairment was recovered by consumption of EED via improvement of insulin signaling pathway. Therefore, this study suggests that persimmon (Diospyros kaki) containing diverse physiological compounds has potential and industrial value as a functional food material for cognitive improvement.

Matcha Improves Metabolic Imbalance-Induced Cognitive Dysfunction.

This study was conducted to assess the protective effect of extract of match (EM) on high-fat diet- (HFD-) induced cognitive deficits in male C57BL/6 mice. It was found that EM improved glucose tolerance status by measuring OGTT and IPGTT with HFD-induced mice. EM protected behavioral and memory dysfunction in Y-maze, passive avoidance, and Morris water maze tests. Consumption of EM reduced fat mass, dyslipidemia, and inflammation in adipose tissue. Also, EM ameliorated hepatic and cerebral antioxidant systems. EM improved the cerebral cholinergic system by regulating ACh contents and expression of AChE and ChAT. Also, EM restored mitochondrial function in liver and brain tissue. EM attenuated hepatic inflammatory effect, lipid synthesis, and cholesterol metabolism by regulating the protein expression of TNF-α, TNFR1, p-IRS-1, p-JNK, IL-1ß, iNOS, COX-2, HMGCR, PPARγ, and FAS. Finally, EM regulated cognitive function and neuroinflammation in the whole brain, hippocampus, and cerebral cortex by regulating the protein expression of p-JNK, p-Akt, p-tau, Aß, BDNF, IDE, COX-2, and IL-1ß. These findings suggest that EM might be a potential source of functional food to improve metabolic disorder-associated cognitive dysfunction.