Repeating Unit Research Articles

Structural characterization of the polysaccharides from Atractylodes chinensis (DC.) Koidz. and the protective effection against alcohol-induced intestinal injury in rats

A neutral polysaccharide, AP, with a weight-average molecular weight of 60.61 kDa, consisting mainly of arabinose and galactose, was isolated from the rhizomes of Atractylodes chinensis (DC.) Koidz. Methylation analyses and nuclear magnetic resonance spectroscopy indicated that the probable repeat unit of AP was →3,6)-α-D-Galp-(1→ residues and constituted the main chain, with a side chain of →5)-α-L-Araf-(1→ and terminal α-L-Araf attached to C-6 of the main chain. The protective activity and potential mechanisms of action of AP on the intestinal tract were investigated. AP improved intestinal oxidative stress injury and inflammatory responses by promoting the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signaling pathway and inhibiting the toll-like receptor 4/myeloid differentiation primary response protein 88/nuclear factor-kappa B signaling pathway, but also repaired colonic mucosal injury and reduced intestinal leakage of endotoxins by promoting expression of the tight-junction proteins zonula occludens-1 and occludin. AP improved ecological dysregulation of the intestinal microbiota and promoted the growth of the potentially beneficial bacteria Lactobacillus_taiwanensis, Limosilactobacillus_reuteri and Akkermansia_muciniphila. AP promoted intestinal health by increasing the production of potentially beneficial metabolites such as short-chain fatty acids, Indole-3-propionic acid, and N-Eicosapentaenoyl tryptophan through metabolism (amino acids, lipids, carbohydrates). These results suggest that AP is a promising prebiotic in attenuating alcohol-induced intestinal damage.

Length and Sequence-Selective Polymer Synthesis Templated by a Combination of Covalent and Noncovalent Base-Pairing Interactions.

Information can be encoded and stored in sequences of monomer units organized in linear synthetic polymers. Replication of sequence information is of fundamental importance in biology; however, it represents a challenge for synthetic polymer chemistry. A combination of covalent and noncovalent base pairs has been used to achieve high-fidelity templated synthesis of synthetic polymers that encode information as a sequence of different side-chain recognition units. Dialkyne building blocks were attached to the template by using ester base pairs, and diazide building blocks were attached to the template by using H-bond base pairs. Copper-catalyzed azide-alkyne cycloaddition reactions were used to zip up the copy strand on the template, and the resulting duplex was cleaved by hydrolyzing the covalent ester base pairs. By using recognition-encoded melamine oligomers with either three phosphine oxide or three 4-nitrophenol recognition units to form the noncovalent base pairs, exceptionally high affinities of the diazides for the template were achieved, allowing the templated polymerization step to be carried out at low concentrations, which promoted on-template intramolecular reactions relative to competing intermolecular processes. Two different templates, a 7-mer and an 11-mer, were used in the three-step reaction sequence to obtain the sequence-complementary copy strands with minimal amounts of side reaction.

Modeling of Chain Sequence Length and Distribution in Random Copolyesters.

The performances and properties of random copolyesters, including biodegradability, mechanical and thermal properties, transparency, etc., are highly influenced by their chain structures. However, obtaining detailed chain sequence information remains a significant challenge. This study introduces a mathematical model based on a probabilistic approach to determine the sequence length and distribution in random copolyesters. Two types of copolyesters, A1A1BB-A2A2BB, representing poly(butylene adipate-co-terephthalate) (PBAT), and A1A1B1B1-A2B2, using poly(butylene succinate-co-glycolic acid) (PBT-PGA) as an example, are the focus. The predicted sequence lengths of various copolyesters derived from the model are in good agreement with the values reported in the literature. The chain sequence distribution obtained from the model provides better insights into the unique properties of the copolyesters. It is observed that the incorporation of hydroxyl acid units into copolyester chains effectively reduces the sequence length without altering the copolymer composition, offering a strategic approach for enhancing degradation performance while maintaining mechanical properties of random copolyesters. The influence of the number-average sequence length becomes particularly significant when the copolymer composition ranges between 0.7 and 0.9, with a higher copolymer composition required for copolyesters containing hydroxyl acid monomer units. This model represents a powerful tool for researchers, enabling a deeper understanding of the relationship between copolymer composition and its structural characteristics in random copolyesters and facilitating the development of high-performance random copolyesters.

Development of a Water-Soluble Nanomicellar Formulation Loaded with Trans-Resveratrol Using Polyethylene Glycol Monostearate for the Treatment of Intracerebral Hemorrhage

Background/Objectives: Trans-resveratrol (Res) has been reported to possess many biological activities, including neuroprotective effects, owing to its anti-inflammatory and antioxidant properties. However, Res has very low water solubility, which limits its therapeutic application. In this work, we formulated water-soluble micellar formulations incorporating Res using polyethylene glycol monostearate (stPEG). Methods: These formulations (stPEG/Res) were developed using five types of stPEG containing 10, 25, 40, 55 and 140 PEG repeat units. The formulations were characterized for Res content, water solubility, particle size, zeta potential, precipitation, biodistribution, and efficacy against neuronal and motor dysfunction in intracerebral hemorrhage (ICH). Results: Intravenous administration of stPEG40/Res, which demonstrated particle size, water solubility, and biodistribution properties suitable for intravenous administration, suppressed neurological and motor dysfunction following in a collagenase-induced ICH mouse model. These effects were inhibited by zinc protoporphyrin-9, an inhibitor of the antioxidant enzyme heme oxygenase-1, suggesting that Res contributes to antioxidant enzyme expression and anti-inflammatory activity. Conclusions: The stPEG/Res micellar formulation developed in this study may offer a promising therapeutic approach for ICH treatment.

A Poly(2,7‐anthrylene) with peri‐Fused Porphyrin Edges

AbstractAnthracene has served as an important building block of conjugated polymers with the connecting positions playing a crucial role for the electronic structures. Herein, anthracene units have been coupled through their 2,7‐carbons to develop an unprecedented, conjugated polymer, namely, poly(2,7‐anthrylene) featuring additional peri‐fused porphyrin edges. The synthesis starts from a 2,7‐dibromo‐9‐nickel(II) porphyrinyl‐anthracene as the pivotal precursor. Polymerization is achieved by an AA‐type Yamamoto coupling, followed by a polymer‐analogous oxidative cyclodehydrogenation to obtain a peri‐fusion between porphyrin and anthracene moieties. Although further cyclodehydrogenation between the repeating units cannot be achieved in solution, the thermal treatment of the precursor polymer derived from 2,7‐dibromo‐9‐porphyrinyl‐anthracene on a metal surface realizes the full cyclodehydrogenation. The difference between solution and on‐surface reactivity can be rationalized by the larger dihedral angle between repeat units in solution, which is reduced under the pronounced interaction with the metal surface. The peri‐fusion in the title polymer gives rise to a narrow electronic band gap optical absorptions extending far into the near‐infrared region. Oligomeric models are synthesized as well to support the analyses of the electronic and photophysical properties.

High Charge Carrier Mobility in Porphyrin Nanoribbons

Polydisperse edge‐fused nickel(II) porphyrin nanoribbons have been synthesized by Yamamoto coupling followed by gold(III)‐mediated fusion, with average degrees of polymerization of up to 37 repeat units (length 31 nm). Time‐resolved optical‐pump terahertz spectroscopy measurements indicate that photo‐generated charge carriers have dc mobilities of up to 205 cm2 V–1 s–1 in these nanoribbons, exceeding the values previously reported for most other types of nanoribbon or π‐conjugated polymer.

High Charge Carrier Mobility in Porphyrin Nanoribbons.

Polydisperse edge-fused nickel(II) porphyrin nanoribbons have been synthesized by Yamamoto coupling followed by gold(III)-mediated fusion, with average degrees of polymerization of up to 37 repeat units (length 31 nm). Time-resolved optical-pump terahertz spectroscopy measurements indicate that photo-generated charge carriers have dc mobilities of up to 205 cm2 V-1 s-1 in these nanoribbons, exceeding the values previously reported for most other types of nanoribbon or π-conjugated polymer.

Total Syntheses of β‐ and γ‐Naphthocyclinones

AbstractAfter half a century from their isolation in 1974, we report the first total syntheses of β‐ and γ‐naphthocyclinones, two dimeric pyranonaphthoquinones featuring an unusual bicyclo[3.2.1]‐octadienone core. The syntheses were achieved with full stereochemical control and functional group management, relying on 1) enantioselective construction of the bicyclic core by Rh‐catalyzed enantioselective 1,4‐addition followed by thiolate‐mediated reductive cyclization, and 2) judicious design of a common chiral, non‐racemic monomer unit that is capable of divergence into the donor and acceptor units, and reunion to construct the bicyclo[3.2.1]octadienone core.

RAFT Polymerization for Advanced Morphological Control: From Individual Polymer Chains to Bulk Materials.

Control of the morphology of polymer systems is achieved through reversible-deactivation radical polymerization techniques such as Reversible Addition-Fragmentation chain Transfer (RAFT). Advanced RAFT techniques offer much more than just "living" polymerization - the RAFT toolkit now enables morphological control of polymer systems across many decades of length-scale. Morphological control is explored at the molecular-level in the context of syntheses where individual monomer unit insertion provides sequence-defined polymers (single unit monomer insertion, SUMI). By being able to define polymer architectures, the synthesis of bespoke shapes and sizes of nanostructures becomes possible by leveraging self-assembly (polymerization induced self-assembly, PISA). Finally, it is seen that macroscopic materials can be produced with nanoscale detail, based on phase-separated nanostructures (polymerization induced microphase separation, PIMS) and microscale detail based on 3D-printing technologies. RAFT control of morphology is seen to cross from molecular level to additive manufacturing length-scales, with complete morphological control over all length-scales.

Coarse-Grain Model of Ultrarigid Polymer Rods Comprising Bifunctionally Linked Peptide Bundlemers.

Computationally designed homotetrameric helical peptide bundles have been functionalized at their N-termini to achieve supramolecular polymers, wherein individual bundles ("bundlemers") are the monomeric units. Adjacent bundles are linked via two covalent cross-links. The polymers exhibit a range of conformational properties, including formation of rigid-rods with micrometer-scale persistence lengths. Herein, a coarse-grained model is used to illuminate how molecular features affect the rod-like behavior of the polymers. With increasing affinity between bundlemer ends, a sharp transition in the persistence length is observed. Doubly linked chains exhibit larger persistence lengths and more robust formation of rigid-rod structures than singly linked chains. Chain stiffness increases with decreasing temperatures. Increasing the length of the cross-linker results in more flexible chains. This model provides insights into how molecular features control the structural properties of chains comprising doubly linked rigid bundlemers.

Structure-aware annotation of leucine-rich repeat domains.

Protein domain annotation is typically done by predictive models such as HMMs trained on sequence motifs. However, sequence-based annotation methods are prone to error, particularly in calling domain boundaries and motifs within them. These methods are limited by a lack of structural information accessible to the model. With the advent of deep learning-based protein structure prediction, existing sequenced-based domain annotation methods can be improved by taking into account the geometry of protein structures. We develop dimensionality reduction methods to annotate repeat units of the Leucine Rich Repeat solenoid domain. The methods are able to correct mistakes made by existing machine learning-based annotation tools and enable the automated detection of hairpin loops and structural anomalies in the solenoid. The methods are applied to 127 predicted structures of LRR-containing intracellular innate immune proteins in the model plant Arabidopsis thaliana and validated against a benchmark dataset of 172 manually-annotated LRR domains.

Polymerization of six-membered propylene oxalate

Ring-opening polymerization (ROP) of the six-membered cyclic propylene oxalate was studied for the first time. The reaction proceeded with a high limiting conversion of about 96 % at 100 °C in the presence of tin(II) octoate. Linear macromolecules, Mw of 20–30 × 103, Ð ∼ 2, represented 86 % of the product, 4 % came from the equilibrium concentration of monomer, while the rest 10 % were cyclic oligomers consisting of 3–10 repeat units. ROP was accompanied by partial (about 30 %) conversion of the catalyst into the insoluble tin(II) oxalate in the course of polymer cross-linking reaction. The kinetics of polymerization obeyed first-order law, indicating typical for ROP constant number of active centers during the process. Polymerization without catalyst was 2000 times slower and also resulted in formation of polymer with Ð ∼ 2. Addition of benzyl alcohol to the polymerization mixture resulted in its inclusion into linear macromolecules and a decrease in their molecular weight. The results point to the possibility of synthesizing propylene oxalate block copolymers using macroinitiators with hydroxyl end groups.

The complete mitochondrial genome of Periphyllus koelreuteriae (Takahashi, 1919) (Hemiptera: Aphididae: Chaitophorinae)

We sequenced the complete mitochondrial genome of the aphid Periphyllus koelreuteriae. It is 16,828 bp long and includes 13 protein-coding genes (PCGs), 22 transfer RNA genes (tRNAs), two ribosome RNA genes (rRNAs), a control region, and a repeat region. The control region contains a 273-bp repeat motif repeated 2.3 times. The species-specific repeat region between trnE and trnF comprises two 340-bp repeat units. The maximum-likelihood tree based on all 37 mitochondrial genes indicated a close relationship between P. koelreuteriae and Periphyllus diacerivorus. This study provides a valuable mitogenomic resource for future research on Chaitophorinae phylogeny and P. koelreuteriae diversification.

Variant Analysis of the Ownership Structure of Land Intended for Single-family Housing

The most frequently preferred solution for the ownership structure of land for single-family housing in Poland is the structure of one cadastral plot – one single-family building. However, changing architectural concepts allow for the creation of single-family housing estates in systems consisting of atrial houses or T-type buildings, which have much more advantages than traditional terraced or semi-detached buildings. These advantages result from a different solution of building forms, which can be combined not only in rows, but also in variously shaped groups consisting of many houses. This provides greater possibilities for the free shaping of development plans for groups of houses, which in turn can be combined in various spatial arrangements while maintaining the required conditions of individual entrance, proper lighting of rooms and mutual distances. At the same time, it allows for more intensive use of the area. Despite the indicated advantages, in the light of the observed implementation practice, it seems problematic to locate buildings with separate ownership, used individually on a plot of land used jointly. The article analyzes the possibilities of legal solutions in the area of land and buildings that can be applied in such a solution. The strengths and weaknesses of each solution were assessed and their opportunities and threats were indicated. For the purposes of this research, four differently shaped groups of buildings consisting of T houses were selected. The results were presented in a SWOT analysis for the development variants adopted for the research using the T house as a repeatable residential unit. The article proposes four legal and neighborly solutions that enable and promote the construction of housing estates using highly intensive atrial development based on the T-house.

Comparative plastomes sheds light on phylogeny of Weigela.

Weigela Thunb. is a genus in the family Caprifoliaceae. All species in this genus have high ornamental and medicinal value. However, the genetic divergence between species and the phylogeny within Weigela is still unclear. Therefore, we sequenced and analyzed four plastomes from four different Weigela species to reveal the genetic divergence among species of this genus, and the phylogeny within Weigela. The four plastomes from Weigela ranged from 156,909 bp to 157,739 bp in size, and presented a typical circular quadripartite structure. Each complete plastome contained a pair of inverted repeat regions (23,592~24,957 bp), a larger single-copy (LSC) region (89,922~90,229 bp), and a small single-copy (SSC) region (17,668~20,429 bp). We identified three types of repeats, corresponding to 268 forward repeats, 128 palindromic repeats, and 867 tandem repeats, for a total of 1,263 long repeats. A total of 352 SSRs were identified from the four plastomes, and most of them were concentrated in the LSC region and the noncoding regions. Mononucleotide repeat units were the most frequently detected types of repeats, of which A/T repeat units were the most abundant. Three mutational hotspots (trnH-psbA, trnR-ndhF, and trnN-ndhF) were identified as candidate barcodes for Weigela species. Weigela belongs to Diervilloideae located at an early diverging position in the Caprifoliaceae. Within Weigela, W. japonica and W. floribunda were sister with W. subsessilis and W. florida. This study revealed the plastome structure and variation of four well-known Weigela species, and found three candidate barcodes for further study of four well-known Weigela species. In addition, the phylogenetic location of Weigela within the Caprifoliaceae was identified.

A Syndiotactic Polymer via Spontaneous Exoselective Single-Crystal-To-Single-Crystal Topochemical Diels-Alder Cycloaddition Reaction.

We designed and synthesized an amide-based monomer decorated with furan as the diene unit and maleimide as the dienophile unit at its termini. Single-crystal X-ray diffraction (SCXRD) analysis of its crystal revealed a head-to-tail arrangement of molecules with furan and maleimide groups of neighboring molecules proximally placed in an arrangement suitable for their topochemical Diels-Alder cycloaddition (TDAC) to form a linear polymer. The monomer underwent a spontaneous single-crystal-to-single-crystal (SCSC) polymerization at room temperature, yielding a linear polymer with oxa-bicyclic linkage. SCXRD analysis revealed that the cycloaddition occurred in an exoselective manner, and the absolute stereochemistry of the oxa-bicyclic linkage alternated in successive repeat units, leading to a syndiotactic linear polymer. The polymerization can be accelerated by heating the powder at 120 °C; the topochemical nature of the high-temperature reaction was established by time dependent differential scanning calorimetry (DSC), time-dependent powder X-ray diffraction (PXRD), and UV-visible spectroscopic analysis; the polymer was characterized using solid-state NMR spectroscopy and MALDI-TOF mass spectrometry.

Accurate prenatal diagnosis of facioscapulohumeral muscular dystrophy 1 using nanopore sequencing

BackgroundFacioscapulohumeral muscular dystrophy 1 (FSHD1) is an autosomal dominant muscular disorder mainly caused by the contraction and hypomethylation of the D4Z4 repeat array in chromosome 4q35. Prenatal diagnosis of FSHD1...

A Poly(2,7-anthrylene) with peri-Fused Porphyrin Edges.

Anthracene has served as an important building block of conjugated polymers with the connecting positions playing a crucial role for the electronic structures. Herein, anthracene units have been coupled through their 2,7-carbons to develop an unprecedented, conjugated polymer, namely, poly(2,7-anthrylene) featuring additional peri-fused porphyrin edges. The synthesis starts from a 2,7-dibromo-9-nickel(II) porphyrinyl-anthracene as the pivotal precursor. Polymerization is achieved by an AA-type Yamamoto coupling, followed by a polymer-analogous oxidative cyclodehydrogenation to obtain a peri-fusion between porphyrin and anthracene moieties. Although further cyclodehydrogenation between the repeating units cannot be achieved in solution, the thermal treatment of the precursor polymer derived from 2,7-dibromo-9-porphyrinyl-anthracene on a metal surface realizes the full cyclodehydrogenation. The difference between solution and on-surface reactivity can be rationalized by the larger dihedral angle between repeat units in solution, which is reduced under the pronounced interaction with the metal surface. The peri-fusion in the title polymer gives rise to a narrow electronic band gap optical absorptions extending far into the near-infrared region. Oligomeric models are synthesized as well to support the analyses of the electronic and photophysical properties.

Caffeic Acid Based Polyurethane Membrane Modified Screen-Printed Electrodes and Their Application for the Simultaneous Determination of Melatonin and Serotonin

Caffeic acid (CA) based polyurethane (PU) films were synthesized and characterized for the simultaneous determination of melatonin (MT) and serotonin (5-HT). The CA based PUs were synthesized using a polyol mixture of 4,4’-diisocyanodiphenylmethane (MPI), polyethylene glycol-200 (PEG), and CA. The PEG–CA monomer units in the polyol were varied in molar ratios of 99:1, 97:3, 95:5, and 90:10. The synthesized PUs were characterized by FTIR spectroscopy and thermal analysis. These CA based PU films were coated onto screen-printed carbon electrodes (SPCEs) with varying thicknesses and used for the simultaneous determination of MT and 5-HT. Electrochemical responses of MT and 5-HT were evaluated using differential pulse voltammetry. The limit of detection and correlation coefficient for MT were 280 µM and 0.9797, respectively, while for 5-HT, the detection was 150 µM with a correlation coefficient of 0.9690. The precision, expressed as the relative standard deviation was 2.633% for MT and 4.668% for 5-HT. These findings suggest that CA based PU-modified electrodes hold potential in medical and biomedical applications.

Preparation, identification and α-glucosidase inhibitory activity of a high-methoxyl HG-type pectin from Liangping pomelo (Citrus maxima cv. Liangpin Yu) peel.

The peel from Liangping pomelo (Citrus maxima cv. Liangpin Yu) is generally discarded as waste during post-harvest handling and process, resulting in environmental pollution and waste. Pectin is the major component in pomelo peels and yields significant economic advantages. Thus, developing pomelo peel pectin (PPs) might be a feasible strategy to reduce environmental pollution caused by pomelo peel. The optimized PPs yield was 156.5 ± 2.5 g kg-1 under the inoculum size of 100 mg g-1, liquid-solid ratio of 31 mL g-1, fermentation time of 64 h, and fermentation temperature of 39 °C. PPs-6Aa, a pectin fraction from PPs purified with DEAE-52 cellulose, Sephadex G-100 and Sephadex G-75 column chromatography, showed higher α-glucosidase inhibitory activity, with an IC50 of 0.12 ± 0.03 mg mL-1. It was a high-methoxyl HG-type pectin of 42.8 kDa, and its repeat unit was →4)-α-GalpA-6-OMe-(1→4)-α-GalpA-6-OMe-(1→. Additionally, its α-glucosidase inhibitory activity might be related to hydrogen bonds formed with Lys-156, Glu-277, His-280, Asp-307, Arg-315, Asn-350, Asp-352 and Glu-411, and to hydrophobic interactions formed with Ser-157, Tyr-158, Asp-233, Gln-239, Ser-240, Phe-303, Thr-306, Leu-313, Phe-314, Gln-353 and Arg-442. These findings provide structural and bioactivity information on pectin from Liangping pomelo peel, which could be beneficial for the development of functional foods and pharmaceuticals. © 2024 Society of Chemical Industry.