Initial Steps in Methanobactin Biosynthesis: Substrate Binding by the Mixed-Valent Diiron Enzyme MbnBC.

The MbnBC enzyme complex converts cysteine residues in a peptide substrate, MbnA, to oxazolone/thioamide groups during the biosynthesis of copper chelator methanobactin (Mbn). MbnBC belongs to the mixed-valent diiron oxygenase (MVDO) family, of which members use an Fe(II)Fe(III) cofactor to react with dioxygen for substrate modification. Several crystal structures of the inactive Fe(III)Fe(III) form of MbnBC alone and in complex with MbnA have been reported, but a mechanistic understanding requires determination of the oxidation states of the crystallographically observed Fe ions in the catalytically active Fe(II)Fe(III) state, along with the site of MbnA binding. Here, we have used electron nuclear double resonance (ENDOR) spectroscopy to determine such structural and electronic properties of the active site, in particular, the mode of substrate binding to the MV state, information not accessible by X-ray crystallography alone. The oxidation states of the two Fe ions were determined by 15N ENDOR analysis. The presence and locations of both bridging and terminal exogenous solvent ligands were determined using 1H and 2H ENDOR. In addition, 2H ENDOR using an isotopically labeled MbnA substrate indicates that MbnA binds to the Fe(III) ion of the cluster via the sulfur atom of its N-terminal modifiable cysteine residue, with displacement of a coordinated solvent ligand as shown by complementary 1H ENDOR. These results, which underscore the utility of ENDOR in studying MVDOs, provide a molecular picture of the initial steps in Mbn biosynthesis.

Glutathione S-transferase directly metabolizes imidacloprid in the whitefly, Bemisia tabaci.

The whitefly Bemisia tabaci poses a significant threat to various crops and ornamental plants and causes severe damage to the agricultural industry. Over the past few decades, B. tabaci has developed resistance to several pesticides, including imidacloprid. Therefore, elucidating the mechanism that leads to insecticide detoxification is very important for controlling B. tabaci and managing whitefly resistance to neonicotinoid insecticides. Among insect detoxification enzymes, glutathione S-transferase (GST) is an important phase II detoxification enzyme that helps detoxify exogenous toxic substances. In this study, we cloned the BtGSTz1 gene and observed that its expression level was greater in imidacloprid-resistant populations than sensitive populations of B. tabaci. By silencing BtGSTz1 via RNA interference, we found a significant increase in the mortality of imidacloprid-resistant B. tabaci. Additionally, prokaryotic expression and in vitro metabolism studies revealed that the recombinant BtGSTz1 protein could metabolize 36.36% of the total imidacloprid, providing direct evidence that BtGSTz1 plays a crucial role in the detoxification of imidacloprid. Overall, our study elucidated the role of GSTs in physiological activities related to insecticide resistance, which helps clarify the resistance mechanisms conferred by GSTs and provides useful insights for sustainable integrated pest management.

Time-series analysis of rhenium(I) organometallic covalent binding to a model protein for drug development.

Metal-based complexes with their unique chemical properties, including multiple oxidation states, radio-nuclear capabilities and various coordination geometries yield value as potential pharmaceuticals. Understanding the interactions between metals and biological systems will prove key for site-specific coordination of new metal-based lead compounds. This study merges the concepts of target coordination with fragment-based drug methodologies, supported by varying the anomalous scattering of rhenium along with infrared spectroscopy, and has identified rhenium metal sites bound covalently with two amino acid types within the model protein. A time-based series of lysozyme-rhenium-imidazole (HEWL-Re-Imi) crystals was analysed systematically over a span of 38 weeks. The main rhenium covalent coordination is observed at His15, Asp101 and Asp119. Weak (i.e. noncovalent) interactions are observed at other aspartic, asparagine, proline, tyrosine and tryptophan side chains. Detailed bond distance comparisons, including precision estimates, are reported, utilizing the diffraction precision index supplemented with small-molecule data from the Cambridge Structural Database. Key findings include changes in the protein structure induced at the rhenium metal binding site, not observed in similar metal-free structures. The binding sites are typically found along the solvent-channel-accessible protein surface. The three primary covalent metal binding sites are consistent throughout the time series, whereas binding to neighbouring amino acid residues changes through the time series. Co-crystallization was used, consistently yielding crystals four days after setup. After crystal formation, soaking of the compound into the crystal over 38 weeks is continued and explains these structural adjustments. It is the covalent bond stability at the three sites, their proximity to the solvent channel and the movement of residues to accommodate the metal that are important, and may prove useful for future radiopharmaceutical development including target modification.

Microbial-based metabolites associated with degradation of imidacloprid and its impact on stress-responsive proteins.

Imidacloprid (IMD), a neonicotinoid insecticide, is intensively used in agricultural fields for effective protection against aphids, cane beetles, thrips, stink bugs, locusts, etc., is causing serious environmental concerns. In recent years, seed treatment with Imidacloprid is being practiced mainly to prevent sucking insect pests. In India, due to the increase in application of this insecticide residue has been proven to have an impact on the quality of soil and water. In view of this, the current investigation is focussed on sustainable approach to minimize the residual effect of IMD in agricultural fields. The present study reveals a most promising imidacloprid resistant bacterium Lysinibacillus fusiformis IMD-Bio5 strain isolated from insecticide-contaminated soil. The isolated bacterial strain upon tested for its biodegradation potential on mineral salt medium (MSM) showed a significant survival growth at 150 g/L of IMD achieved after 3 days, whereas immobilized cells on MSM amended with 200 g/L of IMD as the sole carbon source provided degradation of 188 and 180 g/L of IMD in silica beads and sponge matrices, respectively. The liquid chromatography mass spectrometry was performed to test the metabolite responsive for IMD biodegradation potential of L. fusiformis IMD-Bio5 which showed the induced activity of the metabolite 6-Chloronicotinic acid. Furthermore, as compared to the untreated control, the Lysinibacillus fusiformis IMD-Bio5 protein profile revealed a range of patterns showing the expression of stress enzymes. Thus, results provided a most effective bacterium enabling the removal of IMD-like hazardous contaminants from the environment, which contributes to better agricultural production and soil quality, while long-term environmental advantages are restored.

Sulconazole induces pyroptosis promoted by interferon-γ in monocyte/macrophage lineage cells.

Imidazole derivatives are commonly used as antifungal agents. Here, we aimed to investigate the functions of imidazole derivatives on macrophage lineage cells. We assessed the expression levels of inflammatory cytokines in mouse monocyte/macrophage lineage (RAW264.7) cells. All six imidazole derivatives examined, namely ketoconazole, sulconazole, isoconazole, luliconazole, clotrimazole, and bifonazole, reduced the expression levels of inflammatory cytokines, such as interleukin (IL)-6 and tumor necrosis factor-α, after induction by lipopolysaccharide (LPS) in RAW264.7 cells. These imidazole derivatives also induced cell death in RAW264.7 cells, regardless of the presence or absence of LPS. Since the cell death was characteristic in morphology, we investigated the mode of the cell death. An imidazole derivative, sulconazole, induced gasdermin D degradation together with caspase-11 activation, namely, pyroptosis in RAW264.7 cells and peritoneal macrophages. Furthermore, priming with interferon-γ promoted sulconazole-induced pyroptosis in RAW264.7 cells and macrophages and reduced the secretion of the inflammatory cytokine, IL-1ß, from sulconazole-treated macrophages. Our results suggest that imidazole derivatives suppress inflammation by inducing macrophage pyroptosis, highlighting their modulatory potential for inflammatory diseases.

Interference in Macrophage Balance (M1/M2): The Mechanism of Action Responsible for the Anti-Inflammatory Effect of a Fluorophenyl-Substituted Imidazole.

Traditionally, the treatment of inflammatory conditions has focused on the inhibition of inflammatory mediator production; however, many conditions are refractory to this classical approach. Recently, an alternative has been presented by researchers to solve this problem: The immunomodulation of cells closely related to inflammation. Hence, macrophages, a critical key in both innate and acquired immunity, have been presented as an alternative target for the development of new medicines. In this work, we tested the fluorophenyl-imidazole for its anti-inflammatory activity and possible immunomodulatory effect on RAW 264.7 macrophages. We also evaluated the anti-inflammatory effect of the compound, and the macrophage repolarization to M2 was confirmed by the ability of the compound to reduce the M1 markers TNF-α, IL-6, MCP-1, IL-12p70, IFN-γ, and TLR4, the high levels of p65 phosphorylated, iNOS and COX-2 mRNA expression, and the fact that the compound was not able to induce the production of M1 markers when used in macrophages without lipopolysaccharide (LPS) stimulation. Moreover, fluorophenyl-imidazole had the ability to increase the M2 markers IL-4, IL-13, CD206, apoptosis and phagocytosis levels, arginase-1, and FIZZ-1 mRNA expression before LPS stimulation. Similarly, it was also able to induce the production of these same M2 markers in macrophages without being induced with LPS. These results reinforce the affirmation that the fluorophenyl-imidazole has an important anti-inflammatory effect and demonstrates that this effect is due to immunomodulatory activity, having the ability to trigger a repolarization of macrophages from M1 to M2a. These facts suggest that this molecule could be used as an alternative scaffold for the development of a new medicine to treat inflammatory conditions, where the anti-inflammatory and proregenerative properties of M2a macrophages are desired.

Design, Synthesis, and Evaluation of New 1H-Benzo[d]imidazole Based PqsR Inhibitors as Adjuvant Therapy for Pseudomonas aeruginosa Infections.

Pseudomonas aeruginosa is one of the top priority pathogens that requires immediate attention according to the World Health Organisation (WHO). Due to the alarming shortage of novel antimicrobials, targeting quorum sensing (QS), a bacterial cell to cell signaling system controlling virulence, has emerged as a promising approach as an antibiotic adjuvant therapy. Interference with the pqs system, one of three QS systems in P. aeruginosa, results in reduction of bacterial virulence gene expression and biofilm maturation. Herein, we report a hit to lead process to fine-tune the potency of our previously reported inhibitor 1 (IC50 3.2 µM in P. aeruginosa PAO1-L), which led to the discovery of 2-(4-(3-((6-chloro-1-isopropyl-1H-benzo[d]imidazol-2-yl)amino)-2-hydroxypropoxy)phenyl)acetonitrile (6f) as a potent PqsR antagonist. Compound 6f inhibited the PqsR-controlled PpqsA-lux transcriptional reporter fusion in P. aeruginosa at low submicromolar concentrations. Moreover, 6f showed improved efficacy against P. aeruginosa CF isolates with significant inhibition of pyocyanin, 2-alkyl-4(1H)-quinolones production.

Insight into the Long-Lasting Control Efficacy of Neonicotinoid Imidacloprid against Wheat Aphids during the Entire Growth Period.

Understanding the mechanism of long-lasting control efficacy of pesticides is important for developing sustainable high-efficacy pesticides, decreasing pesticide-use frequency and environmental input. This study investigates the long-term control mechanism of imidacloprid against wheat aphids under seed treatment. The concentrations of imidacloprid and its metabolites were 2.2-69.6 times lower than their individual LC50 after 238 days of treatment, and the control efficacy was still higher than 94.6%. The mixed bioactivity tests demonstrated that the insecticidal activity of the mixture of imidacloprid and its bioactive metabolites was approximately 1.5-189.7 times greater than that of a single compound against wheat aphids. The concentrations of imidacloprid, 5-hydroxy imidacloprid, and imidacloprid olefin in top flag leaves were 0.022, 0.084, and 0.034 mg/kg, respectively, during the aphid flourishing period, which were higher than the LC50 of the mixture (0.011 mg/kg), therefore providing long-lasting control efficacy. The study provides a first insight into the synergistic effects between a pesticide and its bioactive metabolites in ensuring long-term control performance.

Different Structures-Similar Effect: Do Substituted 5-(4-Methoxyphenyl)-1H-indoles and 5-(4-Methoxyphenyl)-1H-imidazoles Represent a Common Pharmacophore for Substrate Selective Inhibition of Linoleate Oxygenase Activity of ALOX15?

Mammalian 15-lipoxygenases (ALOX15) are lipid peroxidizing enzymes that exhibit variable functionality in different cancer and inflammation models. The pathophysiological role of linoleic acid- and arachidonic acid-derived ALOX15 metabolites rendered this enzyme a target for pharmacological research. Several indole and imidazole derivatives inhibit the catalytic activity of rabbit ALOX15 in a substrate-specific manner, but the molecular basis for this allosteric inhibition remains unclear. Here, we attempt to define a common pharmacophore, which is critical for this allosteric inhibition. We found that substituted imidazoles induce weaker inhibitory effects when compared with the indole derivatives. In silico docking studies and molecular dynamics simulations using a dimeric allosteric enzyme model, in which the inhibitor occupies the substrate-binding pocket of one monomer, whereas the substrate fatty acid is bound at the catalytic center of another monomer within the ALOX15 dimer, indicated that chemical modification of the core pharmacophore alters the enzyme-inhibitor interactions, inducing a reduced inhibitory potency. In our dimeric ALOX15 model, the structural differences induced by inhibitor binding are translated to the hydrophobic dimerization cluster and affect the structures of enzyme-substrate complexes. These data are of particular importance since substrate-specific inhibition may contribute to elucidation of the putative roles of ALOX15 metabolites derived from different polyunsaturated fatty acids in mammalian pathophysiology.

MDM2 Antagonist Nutlin-3 Stimulates Global DNA Hydroxymethylation by Enhancing p53-TET1 Signaling Axis.

DNA hydroxymethylation is involved in many biological processes, including nuclear reprogramming, embryonic development, and tumor suppression. In this study, we report that an anticancer agent, nutlin-3, selectively stimulates global DNA hydroxymethylation in TP53 wild-type cancer cells as manifested by the elevation of 5-hydroxymethylcytosine (5hmC) in genomic DNA. In contrast, nutlin 3 fails to enhance DNA hydroxymethylation in TP53-mutated cancer cells. Consistently, nutlin-3 as a MDM2 antagonist only activates wild-type but not mutated TP53. Furthermore, nutlin-3 does not alter the expression of TET1 but slightly reduces the expression of TET2 and TET3 proteins. These TET family proteins are responsible for converting 5-methylcytosine (5mC) to 5hmC. Interestingly, TET1 knockdown could significantly block the nutlin-3-induced DNA hydroxymethylation as well as TP53 and P21 activation. Immunoprecipitation analysis supports that p53 strongly interacts with TET1 proteins. These results suggest that nutlin-3 activates TP53 and promotes p53-TET1 interaction. As positive feedback, the p53-TET1 interaction further enhances p53 activation and promotes apoptosis. Collectively, we demonstrate that nutlin-3 stimulates DNA hydroxymethylation and apoptosis via a positive feedback mechanism.

Administration of necrostatin-1 ameliorates glucocorticoid-induced osteonecrosis of the femoral head in rats.

Glucocorticoid (GC)-induced osteonecrosis of the femoral head (ONFH) is a serious complication of glucocorticoid treatment and is characterized by dysfunctional bone reconstruction at necrotic sites. Our previous study confirmed the protective potential of necrostatin-1, a selective blocker of necroptosis, in glucocorticoid-induced osteoporosis. In this study, rat models of GC-induced ONFH were established to evaluate the effects of necrostatin-1 on osteonecrotic changes and repair processes. Osteonecrosis was verified by histopathological staining. An analysis of trabecular bone architecture was performed to evaluate osteogenesis in the osteonecrotic zone. Then, necroptotic signaling molecules such as RIP1 and RIP3 were examined by immunohistochemistry. Histopathological observations indicated that necrostatin-1 administration reduced the incidence of osteonecrosis and the osteogenic response in subchondral areas. Additionally, bone histomorphometry demonstrated that necrostatin-1 intervention could restore bone reconstruction in the necrotic zone. The protective mechanism of necrostatin-1 was related to the inhibition of RIP1 and RIP3. Necrostatin-1 administration alleviated GC-induced ONFH in rats by attenuating the formation of necrotic lesions, recovering the function of osteogenesis, and suppressing glucocorticoid-induced osteocytic necroptosis by inhibiting the expression of RIP1 and RIP3.

Nutlin-3a-aa: Improving the Bioactivity of a p53/MDM2 Interaction Inhibitor by Introducing a Solvent-Exposed Methylene Group.

Nutlin-3a is a reversible inhibitor of the p53/MDM2 interaction. We have synthesized the derivative Nutlin-3a-aa bearing an additional exocyclic methylene group in the piperazinone moiety. Nutlin-3a-aa is more active than Nutlin-3a against purified wild-type MDM2, and is more effective at increasing p53 levels and releasing transcription of p53 target genes from MDM2-induced repression. X-ray analysis of wild-type MDM2-bound Nutlin-3a-aa indicated that the orientation of its modified piperazinone ring was altered in comparison to the piperazinone ring of MDM2-bound Nutlin-3a, with the exocyclic methylene group of Nutlin-3a-aa pointing away from the protein surface. Our data point to the introduction of exocyclic methylene groups as a useful approach by which to tailor the conformation of bioactive molecules for improved biological activity.

One-step metal affinity purification of recombinant hFGF19 without using tags.

Human fibroblast growth factor 19 (hFGF19) belongs to the endocrine FGF19 superfamily and is considered a potential agent to treat severe or relapsing nonalcoholic fatty liver disease. Numerous studies have confirmed the beneficial effects of this hormone on the related symptoms of the disease and attempts at producing recombinant proteins in various hosts are steadily proliferating. Recently, we reported that authentic hFGF19 can be solubly expressed through combining synonymous codon substitutions and co-expression with disulfide-bond isomerase (DsbC) in Escherichia coli. However, during purification, hFGF19 without the His-tag occasionally co-eluted with His-tagged DsbC when using metal affinity chromatography, thereby requiring auxiliary purification steps to achieve apparent homogeneity. This phenomenon provides evidence that hFGF19 specifically interacts with immobilized Ni2+, which can thus be used as an alternative tool for the purification of hFGF19. Consequently, we could simply and reproducibly purify hFGF19 from cell lysates by using Ni2+-immobilized metal affinity chromatography and stepwise gradient elution with imidazole.

In vitro metabolism of the new antifungal dapaconazole using liver microsomes.

Dapaconazole is a new antifungal imidazole that has been shown a high efficacy against several pathogenic fungi. This study aimed to investigate the interspecies variation in the in vitro metabolic profiles and in vivo hepatic clearance (CLH,in vivo) prediction of dapaconazole using liver microsomes from male Sprague Dawley rat, male Beagle dog and mixed gender human using a liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) method. In addition, the produced metabolites were identified by ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometer (UHPLC-QTOF-MS/MS). The microsomal protein concentration of 0.1 mg/mL and the incubation time of 10 min were employed for the kinetics determination, resulting in a sigmoidal kinetic profile for all species evaluated. The predicted CLH,in vivo was 6.5, 11.6 and 7.5 mL/min/kg for human, rat and dog, respectively. Furthermore, five metabolized products were identified. These findings provide preliminary information for understanding dapaconazole metabolism and the interspecies differences in catalytic behaviours, supporting the choice of a suitable laboratory animal for future pharmacokinetics and metabolism studies.

Enhanced DNA nuclease activity of Momordica charantia lectin by biomimetic mineralization as hybrid copper phosphate nanoflowers and as zeolitic imidazole frameworks.

Biomimetic mineralization of enzymes for enhanced stability and activity is an important area of research due to its potential applications. Inorganic materials with enzymes coated and or embedded in them, viz., protein-inorganic hybrid nanomaterials with distinctive morphology and surface characteristics are promising candidates for exploring their elevated enzymatic activity. In this work, we have developed two different types of protein inorganic nanohybrid materials using a 120 kDa lectin purified from bitter gourd seeds (Momordica charantia lectin, MCL), and (i) copper phosphate nanoflowers to result in a protein - inorganic nano hybrid material CuPNF_MCL and (ii) encapsulating the protein in zeolitic imidazole framework, ZIF8_MCL. While CuPNF_MCL showed floral morphology, the ZIF8_MCL mostly showed hexapod morphology as noticed from the microscopy data. Both the nanomaterials showed a distinctive trend of decrease in size with increase in the protein concentration used during the preparation. The nanoflowers also showed an increase in the tightness of the packing of petals with increase in the protein concentration. Powder X-Ray diffraction studies confirmed the crystallinity of the inorganic frameworks. The Fourier Transform infrared spectroscopy studies coupled with confocal imaging of the fluorophore tagged MCL embedded hybrids confirmed the presence of the protein. The MCL protein was examined for its ability to cleave DNA, i.e., nuclease activity using pBR322, wherein the form I plasmid is completely transformed into the form II / III at 2 mg/mL concentration of the protein. However, both the hybrids showed a superior nuclease activity as compared to the protein, wherein the CuPNF_MCL showed a threefold greater nuclease activity as compared to the ZIF8_MCL. The greater nuclease activity of CuPNF_MCL is attributable to its mesoporous nature with higher pore size and pore volume as compared to that in case of ZIF8_MCL, which is microporous in nature. Thus, in this paper, we have purified a nuclease like lectin from bitter gourd seeds and improved its nuclease property by converting it into inorganic hybrid nanomaterial of two types wherein higher activity was observed in the material having better porosity and surface area characteristics.

Probing Alterations in MDM2 Catalytic Core Structure Effect of Garcinia Mangostana Derivatives: Insight from Molecular Dynamics Simulations.

The MDM2-p53 protein-protein interaction is a promising model for researchers to design, study, and discover new anticancer drugs. The design of therapeutically active compounds that can maintain or restore the binding of MDM2 to p53 has been found to limit the oncogenic activities of both. This led to the current development of a group of xanthone-core and cis-imidazoline analogs compounds, among which γ-Mangostin (GM), α-Mangostin (AM), and Nutlin exhibited their MDM2-p53 interaction inhibitory effects. Therefore, in this study, we seek to determine the mechanisms by which these compounds elicit MDM2-p53 interaction targeting. Unique to the binding of GM, AM, and Nutlin, from our findings, they share the same three active site residues Val76, Tyr50, and Gly41, which represent the top active side residues that contribute to high electrostatic energy. Consequently, the free binding energy contributed enormously to the binding of these compounds, which culminated in the high binding affinities of GM, AM, and Nutlin with high values. Furthermore, GM, AM, and Nutlin commonly interrupted the stable and compact conformation of MDM2 coupled with its active site, where Cα deviations were relatively high. We believe that our findings would assist in the design of more potent active anticancer drugs.

Adaptive exchange sustains cullin-RING ubiquitin ligase networks and proper licensing of DNA replication.

Cop9 signalosome (CSN) regulates the function of cullin-RING E3 ubiquitin ligases (CRLs) by deconjugating the ubiquitin-like protein NEDD8 from the cullin subunit. To understand the physiological impact of CSN function on the CRL network and cell proliferation, we combined quantitative mass spectrometry and genome-wide CRISPR interference (CRISPRi) and CRISPR activation (CRISPRa) screens to identify factors that modulate cell viability upon inhibition of CSN by the small molecule CSN5i-3. CRL components and regulators strongly modulated the antiproliferative effects of CSN5i-3, and in addition we found two pathways involved in genome integrity, SCFFBXO5-APC/C-GMNN and CUL4DTL-SETD8, that contribute substantially to the toxicity of CSN inhibition. Our data highlight the importance of CSN-mediated NEDD8 deconjugation and adaptive exchange of CRL substrate receptors in sustaining CRL function and suggest approaches for leveraging CSN inhibition for the treatment of cancer.

Therapeutic Potential of Ex Vivo Expanded γδ T Cells against Osteosarcoma Cells.

Immunotherapy is an attractive therapeutic strategy for the treatment of osteosarcoma (OS). The unique features of γδ T cells have made them popular for cancer immunotherapy. Here, we expanded γδ T cells using human peripheral blood mononuclear cells (PBMCs) and investigated their therapeutic potential against OS cells. PBMCs from healthy donors were cultured for 10 days with CON medium (unstimulated control); EX media, CON with recombinant human interleukin-2 (rhIL-2) and zoledronate; and EX28 media, CON with rhIL-2, zoledronate, and CD3/CD28 activator. The expanded γδ T cells were isolated by magnetic cell separation or fluorescence-activated cell sorting, cultured with two OS cell lines (KHOS/NP and MG-63) at various cell ratios with or without doxorubicin or ifosfamide, and analyzed for cytotoxicity and cytokine secretion. The number of CD3+γδTCR+Vγ9+ triple-positive γδ T cells and concentrations of IFN-γ and TNF-α were highest in the rhIL-2 (100 IU) and zoledronate (1 µM) supplemented culture conditions. The CD3/CD28 agonist did not show any additional effects on γδ T cell expansion. The expanded γδ T cells exhibited potent in vitro cytotoxicity against OS in a ratio- and time-dependent manner. The γδ T cells may enhance the effect of chemotherapeutic agents against OS and may be a new treatment strategy, including chemo-immunotherapy, for OS.

Synthesis and Characterization of Preacinetobactin and 5-Phenyl Preacinetobactin.

We report the first total synthesis of 5-phenyl preacinetobactin and its characterization. The route was developed for the synthesis of preacinetobactin, the siderophore critical to the Gram-negative pathogen A. baumannii. It leverages a C5-substituted benzaldehyde as a key starting material and should enable the synthesis of similar analogs. 5-Phenyl preacinetobactin binds iron in a manner analogous to the natural siderophore, but it did not rescue growth in a strain of A. baumannii unable to produce preacinetobactin.

Balenine, Imidazole Dipeptide Promotes Skeletal Muscle Regeneration by Regulating Phagocytosis Properties of Immune Cells.

Balenine is one of the endogenous imidazole dipeptides derived from marine products. It is composed of beta-alanine and 3-methyl-L-histidine, which exist mainly in the muscles of marine organisms. The physiological functions of dietary balenine are not well-known. In this study, we investigated whether the supplementation of dietary balenine was associated with muscle function in a cardiotoxin-indued muscle degeneration/regeneration model. Through morphological observation, we found that the supplementation of balenine-enriched extract promoted the regeneration stage. In addition, the expression of regeneration-related myogenic marker genes, such as paired box protein 7, MyoD1, myogenin, and Myh3, in a group of mice fed a balenine-enriched extract diet was higher than that in a group fed a normal diet. Moreover, the supplementation of balenine-enriched extract promoted the expression of anti-inflammatory cytokines as well as pro-inflammatory cytokines at the degeneration stage. Interestingly, phagocytic activity in the balenine group was significantly higher than that in the control group in vitro. These results suggest that balenine may promote the progress of muscle regeneration by increasing the phagocytic activity of macrophages.