Synthesis, Structure Characterization, and Antioxidant and Antibacterial Activity Study of Iso-orientin-Zinc Complex

Study on the antidepressant activity of (2R,6R; 2S,6S)-Hydroxynorketamine (HNK) and its derivatives

OBJECTIVE

This study mainly explores (2R,6R; 2S,6S)-HNK and its compounds whether there are antidepressant effects.

METHODS

Four HNK compounds were obtained from 2-(Chlorophenyl) Cyclopentylmethanone. Forced swimming test, locomotor sensitization test, and conditioned location preference test were used to screen the antidepressant activity of the synthesized target compounds.

RESULTS

In the case of 10 mg HNK treatment, compared with saline, the immobile time of mice in the HNK group, I5 group and I6 group at 1 h and 7 days had statistical significance. In the case of 10 mg HNK treatment, compared with saline, the immobile time of compound C and D groups in the glass cylinder area was significantly different. In the locomotor sensitization test, the movement distance of compound C and D groups on day 15 and day 7 mice increased significantly compared with the first day. In the conditioned place preference experiment, compound C and compound D induced conditioned place preference in mice compared with the Veh group.

CONCLUSION

The results of the forced swimming test, locomotor sensitization test, and conditioned location preference test showed that compounds C and D may have certain anti-depressant activity. However, HNK exerts a rapid and significant antidepressant effect within 1 week, but the duration is short.

A trinuclear Zn (II) schiff base dicyanamide complex attenuates bacterial biofilm formation by ROS generation and membrane damage and exhibits anticancer activity

A trinuclear Zn (II) complex, [(ZnL{N(CN)2})2Zn], termed complex 1 has been synthesized by the reaction of an aqueous solution of sodium dicyanamide to the methanolic solution of Zn (CH3COO)2, 2H2O and corresponding Schiff base (H2L) which is derived from 1:2 condensation of 1, 4 butane diamine with 3-ethoxy salicylaldehyde. Complex 1 is characterized by elemental analysis, IR, UV and Single X-ray diffraction study. Drug resistance is a growing global public health concern that has prompted researchers to look into advanced alternative treatment modalities. In this context, complex 1 has shown promising antibacterial and antibiofilm efficacy against gram-positive Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus strains. Complex 1 attenuated Staphylococcal biofilm formation by reducing several virulence factors including the formation of extracellular polysaccharide matrix, slime, haemolysin, staphyloxanthin, auto-aggregation, cell surface hydrophobicity, and motility. Notably, complex 1 mechanistically potentiated Reactive Oxygen Species (ROS) generation within the bacterial cells, leading to the damage of bacterial cell membrane followed by DNA leakage and thereby impeding the growth of Staphylococcus aureus. Furthermore, complex 1 significantly exhibited anticancer activity by reducing the growth of prostate adenocarcinoma cells. It obstructed the migration of cancer cells by potentiating apoptosis and arresting the cell cycle at the G2/M phase. In summary, complex 1 could act as a potent candidate for the generation of novel antibacterial, antibiofilm as well as anticancer treatment regimens for the management of drug-resistant biofilm-mediated Staphylococcus aureus infection and lethal prostate malignancy.

Synthesis of bacterial cellulose nanofibers/Ag nanoparticles: Structure, characterization and antibacterial activity

The aim of this study was to compare the characterization of bacterial cellulose nanofibers/Ag nanoparticles (BCNs/Ag nanoparticles) obtained by three different pretreatment methods of BCNs (no pretreatment, sodium hydroxide activation pretreatment and TEMPO-mediated oxidation pretreatment), which were recoded as N-BCNs/Ag nanoparticles, A-BCNs/Ag nanoparticles and O-BCNs/Ag nanoparticles, respectively. The results of scanning electron microscopy and transmission electron microscopy showed the prepared Ag nanoparticles by three different pretreatment methods were spherical and dispersed on the surface of BCNs, while the Ag nanoparticles in O-BCNs/Ag nanoparticles displayed the smallest diameter with a value of 20.25 nm and showed the most uniform dispersion on the surface of BCNs. The ICP-MS result showed O-BCNs/Ag nanoparticles had the highest content of Ag nanoparticles with a value of 2.98 wt%, followed by A-BCNs/Ag nanoparticles (1.53 wt%) and N-BCNs/Ag nanoparticles (0.84 wt%). The cytotoxicity assessment showed that the prepared BCNs/Ag nanoparticles were relatively safe. Furthermore, the O-BCNs/Ag nanoparticles had the best antioxidant and antibacterial activities as compared with the other two types of BCNs/Ag nanoparticles, where O-BCNs/Ag nanoparticles destroyed the structure of bacterial cell membranes to lead the leakage of intracellular components. This study showed that O-BCNs/Ag nanoparticles as antibacterial agents have great potential in food packaging.

Antibacterial Activity and Mechanism of Self-Assembly Spermidine-Capped Carbon Dots against Staphylococcus aureus

This paper investigated the antibacterial mechanism of spermidine-capped carbon dots (S-PCDs) against Staphylococcus aureus. The results showed that there were a large number of amino groups on the surface of S-PCDs and they had a high positive charge (+47.06 mV), which could be adsorbed on the negatively charged bacterial surface through electrostatic interaction and changed the permeability of the bacterial cell membrane. The extracellular protein and nucleic acid contents of S. aureus treated with S-PCDs were 5.4 and 1.2 times higher than those of the control group, respectively. The surface folds and defects of the bacterial cell membrane, and the leakage of cell contents were observed using SEM and TEM. The expression of metabolic oxidation regulatory genes dmpI, narJ and narK was upregulated and the intracellular ROS generation was induced, causing bacterial oxidative stress and eventually bacterial death. S-PCDs can effectively inhibit biofilm formation and had low cytotoxicity. The S-PCD treatment successfully inhibited microbial reproduction when pasteurized milk was stored at 25 °C and 4 °C. These results provide important insights into the antimicrobial mechanism of S-PCDs and lay the foundation for their application in the food field as a potentially novel bacteriostatic nanomaterial.

Synthesizing Carbon Quantum Dots via Hydrothermal Reaction to Produce Efficient Antibacterial and Antibiofilm Nanomaterials

This study aimed to synthesize antibacterial carbon quantum dots (SP-CDs) from polyethyleneimine and spermidine via hydrothermal reaction. It was revealed that SP-CDs, with small size (7.18 nm) and high positive charge (+31.15 mV), had good fluorescence properties and lots of amino groups on their surfaces. The inhibition effect of SP-CDs on Staphylococcus aureus was better than that towards Escherichia coli, and the SP-CDs also had an inhibitory effect on multi-drug-resistant E. coli. The mechanism of SP-CDs shows that the SP-CDs were adsorbed on the surface of the negatively charged cell membrane through electrostatic interaction. SP-CDs can cause changes in membrane permeability, resulting in a shift of the cell membrane from order to disorder and the decomposition of chemical components, followed by the leakage of cell contents, resulting in bacterial death. SP-CDs can also significantly inhibit biofilm formation, destroy mature biofilms and reduce the number of living cells. Moreover, SP-CDs had negligible antimicrobial resistance even after 18 generations of treatment. This study proves that SP-CDs effectively inhibit the proliferation of foodborne pathogens, providing new feasibility for the application of carbon-based nanomaterials in the food industry.

Design, Synthesis and Evaluation of a Series of Zinc(II) Complexes of Anthracene-Affixed Multifunctional Organic Assembly as Potential Antibacterial and Antibiofilm Agents against Methicillin-Resistant Staphylococcus aureus

A novel class of zinc(II)-based metal complexes, i.e., [Zn₂(acdp)(μ-Cl)]·2H₂O (1), [Zn₂(acdp)(μ-NO₃)]·2H₂O (2), and [Zn₂(acdp)(μ-O₂CCF₃)]·2H₂O (3) (Cl^- = chloride; NO₃^- = nitrate; CF₃CO₂^- = trifluoroacetate) of anthracene-affixed multifunctional organic assembly, H₃acdp (H₃acdp = N,N'-bis[anthracene-2-ylmethyl]-N,N'-bis[carboxymethyl]-1,3-diaminopropan-2-ol), have emerged as promising antibacterial and antibiofilm agents in the domain of medicinal chemistry. Accordingly, complexes 1-3 were synthesized by utilizing H₃acdp in combination with ZnCl₂, Zn(NO₃)₂·6H₂O, and Zn(CF₃CO₂)₂·H₂O respectively, in the presence of NaOH at ambient temperature. The complexation between H₃acdp and Zn²⁺ was delineated by a combined approach of spectrophotometric and spectrofluorometric titration studies. The stoichiometry of acdp^3-/Zn²⁺ in all three complexes is observed to be 1:2, as confirmed by spectrophotometric/spectrofluorometric titration data. Elemental analysis (C, H, N, Zn), molar conductance, FTIR, UV-vis, and thermoanalytical (TGA/DTA) data were effectively used to characterize these complexes. Besides, the structures of 1-3 were established by density functional theory (DFT) calculation using B3LYP/6-311G, specifying a self-assembled compact geometry with average Zn···Zn separation of 3.4629 Å. All three zinc complexes exhibited significantly high antibacterial and antibiofilm activity against methicillin-resistant Staphylococcus aureus (MRSA BAA1717). However, complex 1 showed a more recognizable activity than 2 and 3, with minimum inhibitory concentration (MIC) values of 200, 350, and 450 μg/mL, respectively. The antimicrobial activity was tested by employing the minimum inhibitory concentration (MIC) and time-kill assay. The crystal violet (CV) assay and microscopic study were performed to examine the antibiofilm activity. As observed, complexes 1-3 had an effect on the production of extracellular polymeric substance (EPS), biofilm cell-viability, and other virulence factors such as staphyloxanthin and hemolysin production, autoaggregation ability, and microbial cell-surface hydrophobicity. Reactive oxygen species (ROS) generated due to inhibition of staphyloxanthin production in response to 1-3 were also analyzed. Moreover, complexes 1-3 showed an ability to damage the bacterial cell membrane due to accumulation of ROS resulting in DNA leakage. In addition, complexes 1-3 displayed a synergistic/additive activity with a commercially available antibiotic drug, vancomycin, with enhanced antibacterial activity. On the whole, our investigation disclosed that complex 1 could be a promising drug lead and attract much attention to medicinal chemists compared to 2 and 3 from therapeutic aspects.

Hydroxyl-/Carboxyl-Rich Graphitic Carbon Nitride/Graphene Oxide Composites for Efficient Photodegradation of Reactive Red 195 and Antibacterial Applications

In this work, a protonated graphitic carbon nitride (P-g-C₃N₄)-coated graphene oxide (GO) composite (GO/P-g-C₃N₄) was prepared via wet-chemistry exfoliation, followed by a freeze-drying process. The GO/P-g-C₃N₄ composite was found to have an outstanding photodegradation performance effect on the reactive red 195 (RR195) dye and very strong antibacterial properties. Both the GO structure and the dispersed state of P-g-C₃N₄ were found to play a significant role in enhancing the photocatalytic activity of GO/P-g-C₃N₄. The GO/P-g-C₃N₄ obtained via freeze-drying retained a large number of oxygen-containing groups and showed higher catalytic activity and reusability than the reduced GO (rGO)/g-C₃N₄ obtained via thermal reduction. Characterization of the samples indicates that GO/P-g-C₃N₄ has a higher specific surface area and photocurrent density than rGO/g-C₃N₄; it is likely that these properties lead to the superior photocatalytic activity observed in GO/P-g-C₃N₄. Adsorption energy calculations indicate that O₂ can be readily adsorbed onto the GO surface, which results in stronger oxidizing superoxide anion radicals (^•O₂^-) and holes (h⁺); these active radicals can rapidly degrade RR195 dyes. Moreover, broad-spectrum antibacterial activity (demonstrated against Staphylococcus aureus and Escherichia coli) was observed in the case of the GO/P-g-C₃N₄ composite irradiated with visible light. This work offers new insights into the design of cost-effective g-C₃N₄-based photocatalysts for environmental remediation.

Novel flavonolignans from the roots of Indigofera stachyodes

Two pairs of new enantiomeric flavonolignans, ±stachyols A and B (±1 and ± 2), along with two novel isoflavanelignans, stachyols C and D (3 and 4) were isolated from the roots of Indigofera stachyodes. Their chemical structures and absolute configurations were determined using nuclear magnetic resonance and comparison of experimental and theoretical electronic circular dichroism (ECD) spectra, as well as quantum chemical calculations. Of those compounds, 1 and 2 represented the first examples of flavonolignans with 5-deoxyflavonoids adduct phenylpropanoids. Moreover, 3 and 4 possess an unprecedented skeleton with isoflavanes adduct phenylpropanoids. The antioxidant activity was evaluated for all compounds in terms of ABTS⁺ and DPPH bioassays. Compounds 3 and 4 exhibited significant radical-scavenging activity in the ABTS⁺ assay, with IC₅₀ values of 15.15 and 5.83 μM, respectively.

A Family of [Zn6] Complexes from the Carboxylate-Bridge-Supported Assembly of [Zn2] Building Units: Synthetic, Structural, Spectroscopic, and Systematic Biological Studies

The three discrete [Zn₆] complexes [Na₃Zn₆(cpdp)₃(μ-Bz)₃(CH₃OH)₆][ZnCl₄][ZnCl₃(H₂O)]·3CH₃OH·1.5H₂O (1), [Na₃Zn₆(cpdp)₃(μ-p-OBz)₃(CH₃OH)₆]·2H₂O (2), and [Na₃Zn₆(cpdp)₃(μ-p-NO₂Bz)₃(CH₃OH)₆]Cl₃·2H₂O (3), supported by the carboxylate-based multidentate ligand N,N'-bis[2-carboxybenzomethyl]-N,N'-bis[2-pyridylmethyl]-1,3-diaminopropan-2-ol (H₃cpdp), have been successfully synthesized and fully characterized (Bz = benzoate; p-OBz = dianion of p-hydroxybenzoic acid; p-NO₂Bz = p-nitrobenzoate). The complexes have been characterized by elemental analysis, FTIR, UV-vis, NMR spectroscopy, PXRD, and thermal analysis, including single-crystal X-ray crystallography of 1 and 2. The molecular architectures of 1-3 are built from the self-assembly of their corresponding [Zn₂] units, which are interconnected to the central [Na₃(CH₃OH)₆]³⁺ core by six endogenous benzoate groups, with each linking one Zn(II) and one Na(I) ion in a μ₂:η¹:η¹-syn-anti bidentate fashion. The composition of the (cpdp^3-)₃/(Zn²⁺)₆ complexes in 1-3 has been observed to be 1:2, on the basis of the UV-vis titration and NMR spectroscopic results, which is further supported by X-ray crystallography. Systematic biological studies performed with a mice model suggested possible antidiabetic efficacy as well as anticancer activities of the complexes. When complexes 1-3 were administered intraperitoneally in mice, 1 showed a lowering in the blood glucose level, overall maintenance of the pancreatic tissue mass, restriction of DNA damage in pancreatic cells, and retention of lipid droplet (LD) frequency, whereas 2 and 3 showed hepatic tissue mass consistency by inhibiting the DNA damage in hepatic cells, prior to the exposure to a potent diabetic inducer, alloxan (ALX). Similar trends of results were observed in inhibiting the generation of reactive oxygen species (ROS) in the pancreatic and hepatic cells, as examined by spectrofluorometric methods. Thus, 1 seems to be a better compound for overall diabetic management and control, whereas 2 and 3 seem to be promising compounds for designing chemopreventive drugs against hepatic carcinoma.