Nanometric-Mapping and In Situ Quantification of Site-specific Photoredox Activities on 2D Nanoplates.

Defective layered bismuth oxychloride (BiOCl) exhibits excellent photocatalytic activities in water purification and environmental remediation. Herein, in situ single-molecule fluorescence microscopy is used to spatially resolve the photocatalytic heterogeneity and quantify the photoredox activities on individual structural features of BiOCl. The BiOCl nanoplates with respective dominant {001} and {010} facets (BOC-001 and BOC-010) are fabricated through tuning the pH of the solution. The corner position of BOC-001 exhibits the highest photo-oxidation turnover rate of 262.7 ± 30.8 s-1 µm-2, which is 2.1 and 65.7 times of those of edges and basal planes, respectively. A similar trend is also observed on BOC-010, which can be explained by the heterogeneous distribution of defects at each structure. Besides, BOC-001 shows a higher photoredox activity than BOC-010 at corners and edges. This can be attributed to the superior charge separation ability, active high-index facets of BOC-001, and its co-exposure of anisotropic facets steering the charge flow. Therefore, this work provides an effective strategy to understand the facet-dependent properties of single-crystalline materials at nanometer resolution. The quantification of site-specific photoredox activities on BiOCl nanoplates sheds more light on the design and optimization of 2D materials at the single-molecule level.

Gas-phase solvent-free complexation of phenolic acids in cyclodextrins: A mass spectrometric study.

Phenolic acids are phytochemicals commonly existing in plants that are also beneficial to the human body after consumption. As additives in the food industry, phenolic acids typically need stabilization by encapsulation. We have been studying cyclodextrins as potential encapsulating agents, elucidating the structure and energetics of the complexes they form with phenolic acids. To highlight the role of the solvent in these interactions and to investigate the possible component ratios available to these complexes, we first carried out gas-phase studies monitored through mass spectrometry that allowed us to work in solvent-free conditions. In addition to detecting the products of these complexation equilibria qualitatively, we were also able to find conditions to quantitative determine the relative binding affinities associated with these processes. As well as on the unusual complex stoichiometry observed in the gas phase for a series of phenolic acids with α-CD, ß-CD, and γ-CD. We propose an explanation of these uncommon stoichiometries through solvation effects involving the cyclodextrin host as the solvating species. We also report on the observed trends in the measured relative affinities of these interactions.

Structure and properties of acidic polysaccharides isolated from Massa Medicata Fermentata: Neuroprotective and antioxidant activity.

Massa Medicata Fermentata (MMF) is a fermented food with therapeutic effects. Previous studies suggested that after stir-frying, the uronic acid content in MMF crude polysaccharides increases, and the pH value decreases, which is caused by the change in acidic polysaccharides. However, the detailed physicochemical properties and structure-activity correlation of the acidic polysaccharides in MMF have not been fully explored. In this study, two acidic polysaccharides (SMMFAP and CMMFAP) were isolated from the MMF and its stir-fried product, respectively. Their structural characteristics and bioactivities were comparatively studied, and the structure-activity correlation was examined. Our findings revealed that the SMMFAP had a higher average Mw and higher Gal and Man content than the CMMFAP. Both the SMMFAP and CMMFAP were mainly composed of Xyl, Man, and Gal residues, whereas the CMMFAP had fewer linkage types. Additionally, the CMMFAP exhibited stronger neuroprotective activity than the SMMFAP owing to its higher content of 1,6-linked-Galp, while the SMMFAP exhibited better antioxidant activity, which might be related to its higher average Mw. Our findings suggest that acidic polysaccharides may be the active substances that cause differences in effectiveness between the sheng and chao MMF. Furthermore, the research qualified the SMMFAP and CMMFAP with different potential applications.

Qualitative structure-activity relationships of aryl isoprenoid derivatives as biorational juvenoids - reweighing.

Juvenoids are juvenile hormone (JH) mimetics, with specific structural features and defined molecular size that disrupt the target insect development. Juvenoid activity (= JH-type activity) of various isoprenoid-based derivatives as insecticidal candidates of the insect growth disruptors (IGDs) type were rated against the house fly, Musca domestica L. The epoxidized decenyl and nonenyl phenyl ether derivatives have more active compounds than those of both parent alkoxidized or olefinic structures. The highest juvenoid potency was shown by 3,4-methylenedioxyphenyl ethers of 8,9-epoxy-5,9-dimethy1-3,8-decadiene. Qualitative structure-activity relationships are offered to relate the chemical structure criteria to observed juvenoid-related activity. Differences in activity among the reported isoprenoid-based derivatives were qualitatively rationalized. This study advances understanding of the structural qualifications and activity determinants of isoprenoid juvenoids, which is important for the development of new filth flies eco-friendly insecticides. Supplementary Information: The online version contains supplementary material available at 10.1007/s42690-023-01025-3.

Heparan sulfate analogues regulate tumor-derived exosome formation that attenuates exosome functions in tumor processes.

Heparan sulfate (HS) is involved in many biological activities, including the biogenesis and uptake of exosomes, which are related to the occurrence and development of tumors. This study investigated the role of HS analogues (heparin, low molecular weight heparin, and 6-O-desulfated heparin) in modulating exosome secretion, composition and functions. Exosomes derived from B16F10 cells exposed to different HS analogues were isolated and characterized by TEM, western blotting and Nanosight analyses. The number, size and protein cargo of exosomes secreted by HS analogues-induced B16F10 cells were detected. The findings indicated the reduced tumor-derived exosome secretion and protein cargo as reflected by lower levels of CD63, TSG101, heparinase and IL-6 in exosomes derived from heparin-induced B16F10 cells as compared with 6-O-desulfated heparin-induced tumor cells. Further functional assays demonstrated that exosomes from tumor cells exposed to heparin weakened tumor proliferation, migration and invasion most significantly among various exosomes derived from B16F10 cells treated with different HS analogues. Moreover, the sulfate group at 6-O position of heparan sulfate has been proved to play an important role in tumor-derived exosome formation and functions. This study suggested a vital view to develop more specific and efficient HS-based strategies in cancer treatment for targeting tumor-derived exosomes.

Phase Coexistence and Structural Dynamics of Redox Metal Catalysts Revealed by Operando TEM.

Metal catalysts play an important role in industrial redox reactions. Although extensively studied, the state of these catalysts under operating conditions is largely unknown, and assignments of active sites remain speculative. Herein, an operando transmission electron microscopy study is presented, which interrelates the structural dynamics of redox metal catalysts to their activity. Using hydrogen oxidation on copper as an elementary redox reaction, it is revealed how the interaction between metal and the surrounding gas phase induces complex structural transformations and drives the system from a thermodynamic equilibrium toward a state controlled by the chemical dynamics. Direct imaging combined with the simultaneous detection of catalytic activity provides unparalleled structure-activity insights that identify distinct mechanisms for water formation and reveal the means by which the system self-adjusts to changes of the gas-phase chemical potential. Density functional theory calculations show that surface phase transitions are driven by chemical dynamics even when the system is far from a thermodynamic phase boundary. In a bottom-up approach, the dynamic behavior observed here for an elementary reaction is finally extended to more relevant redox reactions and other metal catalysts, which underlines the importance of chemical dynamics for the formation and constant re-generation of transient active sites during catalysis.

Design and Synthesis of Novel Podophyllotoxins Hybrids and the Effects of Different Functional Groups on Cytotoxicity.

Development of novel anticancer therapeutic candidates is one of the key challenges in medicinal chemistry. Podophyllotoxin and its derivatives, as a potent cytotoxic agent, have been at the center of extensive chemical amendment and pharmacological investigation. Herein, a new series of podophyllotoxin-N-sulfonyl amidine hybrids (4a-4v, 5a-5f) were synthesized by a CuAAC/ring-opening procedure. All the synthesized podophyllotoxins derivatives were evaluated for in vitro cytotoxic activity against a panel of human lung (A-549) cancer cell lines. Different substituents', or functional groups' antiproliferative activities were discussed. The -CF3 group performed best (IC50: 1.65 µM) and exhibited more potent activity than etoposide. Furthermore, molecular docking and dynamics studies were also conducted for active compounds and the results were in good agreement with the observed IC50 values.

[Academic Detailing from the Viewpoint of Chemical Structural Formulas].

In order to implement academic detailing, it is extremely important to understand the pharmacological activity of drugs based on their chemical structures. To construct a database for academic detailing, a viewpoint for clinically utilizing the fundamental pharmacological features of a drug is required. These fundamental pharmacological features include chemical characteristics such as chemical structures, physical characteristics such as pharmaceutical formulations for efficient drug delivery to target organs, and a pharmacological viewpoint, which is a mechanism by which a drug is determined to be effective. In addition, in vivo kinetics are included in a drug's pharmacological features, i.e., a drug's excretion through urine and feces via the kidneys, its side effects due to differences in enzyme type when the drug is metabolized in the liver, as well as the capacity of the patient's current enzyme profile. This review describes academic detailing based on the chemical structure of drugs for breast cancer hormone therapy, as an example.

Operando X-ray absorption spectroscopy study of the Fischer-Tropsch reaction with a Co catalyst.

This article describes the setting up of a facility on the energy-scanning EXAFS beamline (BL-09) at RRCAT, Indore, India, for operando studies of structure-activity correlation during a catalytic reaction. The setup was tested by operando X-ray absorption spectroscopy (XAS) studies performed on a Co-based catalyst during the Fischer-Tropsch reaction to obtain information regarding structural changes in the catalyst during the reaction. Simultaneous gas chromatography (GC) measurements during the reaction facilitate monitoring of the product gases, which in turn gives information regarding the activity of the catalyst. The combination of XAS and GC techniques was used to correlate the structural changes with the activity of the catalyst at different reaction temperatures. The oxide catalyst was reduced to the metallic phase by heating at 400°C for 5 h under H2 at ambient pressure and subsequently the catalytic reaction was studied at four different temperatures of 240, 260, 280 and 320°C. The catalyst was studied for 10 h at 320°C and an attempt has been made to understand the process of its deactivation from the XANES and EXAFS results.

Immunomodulatory activity of heparan sulfate mimetics from Escherichia coli K5 capsular polysaccharide in vitro.

Escherichia coli K5 capsular polysaccharide (K5PS) has been used as starting material to synthesize heparan sulfate (HS) mimetics with various biological properties. This study determined the immunomodulatory activities of K5PS through the sulfation process. The immunomodulatory effects of sulfated K5 polysaccharide derivatives were evaluated in vitro on murine macrophages and lymphocytes. Results indicated that HS mimetics with high sulfation in the O-position stimulated cell proliferation of macrophages and lymphocytes, significantly enhanced cytokine secretion and upregulated the cytotoxicity of NK cells. This study suggests that high sulfation in O-position of HS is required for the immunomodulatory activities.

Structure analysis of a bioactive heteropolysaccharide from Schisandra chinensis (Turcz.) Baill.

Our previous study revealed that Schisandra polysaccharide (SCPP11) exerted excellent antitumor and immunomodulatory activities. In this investigation, the structure of SCPP11 was elucidated. The results indicated that SCPP11 has a backbone that is composed of 1,4-disubstituted-ß-gal, 1,4-disubstituted-α-glu,1,6-disubstituted-ß-man and 1,4,6-disubstituted-α-gal. The branches was composed of 1,4-disubstituted-α-glu and 1-substituted-ß-glu. The Mw and (r(g)(2))(z)(1/2) of the polymer molecules in 0.1 M NaCl were 1.793 × 10(4) Da and 11 nm, respectively. The exponent of (r(g)(2))(z)(1/2) versus Mw(0.39) suggested SCPP11 adopted a globular conformation with seldom random coil. Circular dichroism analysis revealed the presence of ordered structures in SCPP11. AFM and TEM further confirmed the agglomerated morphologies of SCPP11. In addition, it inferred the agglomerated conformation, branching structure and flexibility of chain are beneficial for exerting excellent activities. This information will be helpful in the recognition of biological systems for polysaccharides and the selection of active polysaccharide.