An Extensive Pharmacological Evaluation of New Anti-Cancer Triterpenoid (Nummularic Acid) from Ipomoea batatas through In Vitro,In Silico,and In Vivo Studies

Prostate cancer (PCa) is the most common cancer in men, accounting for approximately 10% of all new cases in the United States. Plant-derived bioactive compounds, such as pentacyclic triterpenoids (PTs), have the ability to inhibit PCa cell proliferation. We isolated and characterized nummularic acid (NA), a potent PT, as a major chemical constituent of Ipomoea batatas, a medicinal food plant used in ethnomedicine for centuries. In the current study, in vitro antiproliferative potential against PCa cells (DU145 and PC3) via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay; Western blot protein expression analysis; absorption, distribution, metabolism, excretion (ADME); pharmacokinetic prediction studies; and bisphenol A (BPA)-induced prostate inhibition in Sprague Dawley rats were conducted to gauge the anti-cancer ability of NA. Significant (p < 0.05 and p < 0.01) time- and dose-dependent reductions in proliferation of PCa cells, reduced migration, invasion, and increased apoptotic cell population were recorded after NA treatment (3–50 µM). After 72 h of treatment, NA displayed significant IC₅₀ of 21.18 ± 3.43 µM against DU145 and 24.21 ± 3.38 µM against PC3 cells in comparison to the controls cabazitaxel (9.56 ± 1.45 µM and 12.78 ± 2.67 µM) and doxorubicin (10.98 ± 2.71 µM and 15.97 ± 2.77 µM). Further deep mechanistic studies reveal that NA treatment considerably increased the cleavage of caspases and downstream PARP, upregulated BAX and P53, and downregulated BCL-2 and NF-κB, inducing apoptosis in PCa cells. Pharmacokinetic and ADME characterization indicate that NA has a favorable physicochemical nature, with high gastrointestinal absorption, low blood–brain barrier permeability, no hepatotoxicity, and cytochrome inhibition. BPA-induced perturbations of prostate glands in Sprague Dawley rats show a potential increase (0.478 ± 0.28 g) in prostate weight compared to the control (0.385 ± 0.13 g). Multi-dose treatment with NA (10 mg/kg) significantly reduced the prostate size (0.409 ± 0.21 g) in comparison to the control. NA-treated groups exhibited substantial restoration of hematological and histological parameters, reinstatement of serum hormones, and suppression of inflammatory markers. This multifaceted analysis suggests that NA, as a novel small molecule with a strong pharmacokinetic and pharmacological profile, has the potential to induce apoptosis and death in PCa cells.     

The effect of ferulic acid ethyl ester on leptin-induced proliferation and migration of aortic smooth muscle cells

Leptin is a peptide hormone, which has a central role in the regulation of body weight; it also exerts many potentially atherogenic effects. Ferulic acid ethyl ester (FAEE) has been approved for antioxidant properties. The aim of this study was to investigate whether FAEE can inhibit the atherogenic effects of leptin and the possible molecular mechanism of its action. Both of cell proliferation and migration were measured when the aortic smooth muscle cell (A10 cell) treated with leptin and/or FAEE. Phosphorylated p44/42MAPK, cell cycle-regulatory protein (for example, cyclin D1, p21, p27), β-catenin and matrix metalloproteinase-9 (MMP-9) proteins levels were also measured. Results demonstrated that leptin (10, 100 ng ml⁻¹) significantly increased the proliferation of cells and the phosphorylation of p44/42MAPK in A10 cells. The proliferative effect of leptin was significantly reduced by the pretreatment of U0126 (0.5 μM), a MEK inhibitor, in A10 cells. Meanwhile, leptin significantly increased the protein expression of cyclin D1, p21, β-catenin and decreased the expression of p27 in A10 cells. In addition, leptin (10 ng ml⁻¹) significantly increased the migration of A10 cells and the expression of MMP-9 protein. Above effects of leptin were significantly reduced by the pretreatment of FAEE (1 and 10 μM) in A10 cells. In conclusion, FAEE exerts multiple effects on leptin-induced cell proliferation and migration, including the inhibition of p44/42MAPK phosphorylation, cell cycle-regulatory proteins and MMP-9, thereby suggesting that FAEE may be a possible therapeutic approach to the inhibition of obese vascular disease.     

Geissospermiculatine,a New Alkaloid from Geissospermum reticulatum Bark

A new alkaloid, geissospermiculatine was characterized in Geissospermum reticulatum A. H. Gentry bark (Apocynaceae). Here, following a simplified isolation protocol, the structure of the alkaloid was elucidated through GC-MS, LC-MS/MS, 1D, and 2D NMR (COSY, ROESY, HSQC, HMBC, ¹H-¹⁵N HMBC). Cytotoxic properties were evaluated in vitro on malignant THP-1 cells, and the results demonstrated that the cytotoxicity of the alkaloid (30  μg/mL) was comparable with staurosporine (10  μM). Additionally, the toxicity was tested on zebrafish (Danio rerio) embryos in vivo by monitoring their development (0–72 h); toxicity was not evident at 30  μg/mL.     

Practical prediction model of the clinical response to programmed death-ligand 1 inhibitors in advanced gastric cancer

The identification of predictive biomarkers or models is necessary for the selection of patients who might benefit the most from immunotherapy. Seven histological features (signet ring cell [SRC], fibrous stroma, myxoid stroma, tumor-infiltrating lymphocytes [TILs], necrosis, tertiary lymphoid follicles, and ulceration) detected in surgically resected tissues (N = 44) were used to train a model. The presence of SRC became an optimal decision parameter for pathology alone (AUC = 0.78). Analysis of differentially expressed genes (DEGs) for the prediction of genomic markers showed that C-X-C motif chemokine ligand 11 (CXCL11) was high in responders (P < 0.001). Immunohistochemistry (IHC) was performed to verify its potential as a biomarker. IHC revealed that the expression of CXCL11 was associated with responsiveness (P = 0.003). The response prediction model was trained by integrating the results of the analysis of pathological factors and RNA sequencing (RNA-seq). When trained with the C5.0 decision tree model, the categorical level of the expression of CXCL11, a single variable, was shown to be the best model (AUC = 0.812). The AUC of the model trained with the random forest was 0.944. Survival analysis revealed that the C5.0-trained model (log-rank P = 0.01 for progression-free survival [PFS]; log-rank P = 0.012 for overall survival [OS]) and the random forest-trained model (log-rank P < 0.001 for PFS; log-rank P = 0.001 for OS) predicted prognosis more accurately than the PD-L1 test (log-rank P = 0.031 for PFS; log-rank P = 0.107 for OS).Subject terms: Predictive markers, Predictive markers, Translational research, Predictive medicine     

Neuraminidase Inhibitor of Garcinia atroviridis L. Fruits and Leaves Using Partial Purification and Molecular Characterization

Neuraminidase (NA) is an enzyme that prevents virions from aggregating within the host cell and promotes cell-to-cell spread by cleaving glycosidic linkages to sialic acid. The best-known neuraminidase is the viral neuraminidase, which present in the influenza virus. Thus, the development of anti-influenza drugs that inhibit NA has emerged as an important and intriguing approach in the treatment of influenza. Garcinia atroviridis L. (GA) dried fruits (GAF) are used commercially as seasoning and in beverages. The main objective of this study was to identify a new potential neuraminidase inhibitor from GA. A bioassay-guided fractionation method was applied to obtain the bioactive compounds leading to the identification of garcinia acid and naringenin. In an enzyme inhibition study, garcinia acid demonstrated the highest activity when compared to naringenin. Garcinia acid had the highest activity, with an IC₅₀ of 17.34–17.53 µg/mL or 91.22–92.21 µM against Clostridium perfringens-NA, and 56.71–57.85 µg/mL or 298.32–304.31 µM against H1N1-NA. Based on molecular docking results, garcinia acid interacted with the triad arginine residues (Arg118, Arg292, and Arg371) of the viral neuraminidase, implying that this compound has the potential to act as a NA enzyme inhibitor.     

Inhibitory Effect of Salvia miltiorrhiza Extract and Its Active Components on Cervical Intraepithelial Neoplastic Cells

The effective treatment of cervical intraepithelial neoplasia (CIN) can prevent cervical cancer. Salvia miltiorrhiza is a medicinal and health-promoting plant. To identify a potential treatment for CIN, the effect of S. miltiorrhiza extract and its active components on immortalized cervical epithelial cells was studied in vitro. The H8 cell was used as a CIN model. We found that S. miltiorrhiza extract effectively inhibited H8 cells through the CCK8 method. An HPLC–MS analysis revealed that S. miltiorrhiza extract contained salvianolic acid H, salvianolic acid A, salvianolic acid B, monomethyl lithospermate, 9‴-methyl lithospermate B, and 9‴-methyl lithospermate B/isomer. Salvianolic acid A had the best inhibitory effect on H8 cells with an IC₅₀ value of 5.74 ± 0.63 μM. We also found that the combination of salvianolic acid A and oxysophoridine had a synergistic inhibitory effect on H8 cells at molar ratios of 4:1, 2:1, 1:1, 1:2, and 1:4, with salvianolic acid A/oxysophoridine = 1:2 having the best synergistic effect. Using Hoechst33342, flow cytometry, and Western blotting analysis, we found that the combination of salvianolic acid A and oxysophoridine can induce programmed apoptosis of H8 cells and block the cell cycle in the G2/M phase, which was correlated with decreased cyclinB1 and CDK1 protein levels. In conclusion, S. miltiorrhiza extract can inhibit the growth of H8 cells, and the combination of salvianolic acid A (its active component) and oxysophoridine has a synergistic inhibitory effect on H8 cells and may be a potential treatment for cervical intraepithelial neoplasia.     

Protective role of estrogen against excessive erythrocytosis in Monge’s disease

Monge’s disease (chronic mountain sickness (CMS)) is a maladaptive condition caused by chronic (years) exposure to high-altitude hypoxia. One of the defining features of CMS is excessive erythrocytosis with extremely high hematocrit levels. In the Andean population, CMS prevalence is vastly different between males and females, being rare in females. Furthermore, there is a sharp increase in CMS incidence in females after menopause. In this study, we assessed the role of sex hormones (testosterone, progesterone, and estrogen) in CMS and non-CMS cells using a well-characterized in vitro erythroid platform. While we found that there was a mild (nonsignificant) increase in RBC production with testosterone, we observed that estrogen, in physiologic concentrations, reduced sharply CD235a⁺ cells (glycophorin A; a marker of RBC), from 56% in the untreated CMS cells to 10% in the treated CMS cells, in a stage-specific and dose-responsive manner. At the molecular level, we determined that estrogen has a direct effect on GATA1, remarkably decreasing the messenger RNA (mRNA) and protein levels of GATA1 (p < 0.01) and its target genes (Alas2, BclxL, and Epor, p < 0.001). These changes result in a significant increase in apoptosis of erythroid cells. We also demonstrate that estrogen regulates erythropoiesis in CMS patients through estrogen beta signaling and that its inhibition can diminish the effects of estrogen by significantly increasing HIF1, VEGF, and GATA1 mRNA levels. Taken altogether, our results indicate that estrogen has a major impact on the regulation of erythropoiesis, particularly under chronic hypoxic conditions, and has the potential to treat blood diseases, such as high altitude severe erythrocytosis.Subject terms: Haematopoietic stem cells, Myeloproliferative disease     

Calcium ions tune the zinc-sequestering properties and antimicrobial activity of human S100A12

Human S100A12 is a host-defense protein expressed and released by neutrophils that contributes to innate immunity. Apo S100A12 is a 21 kDa antiparallel homodimer that harbors two Ca(ii)-binding EF-hand domains per subunit and exhibits two His₃Asp motifs for chelating transition metal ions at the homodimer interface. In this work, we present results from metal-binding studies and microbiology assays designed to ascertain whether Ca(ii) ions modulate the Zn(ii)-binding properties of S100A12 and further evaluate the antimicrobial properties of this protein. Our metal-depletion studies reveal that Ca(ii) ions enhance the ability of S100A12 to sequester Zn(ii) from microbial growth media. We report that human S100A12 has antifungal activity against Candida albicans, C. krusei, C. glabrata and C. tropicalis, all of which cause human disease. This antifungal activity is Ca(ii)-dependent and requires the His₃Asp metal-binding sites. We expand upon prior studies of the antibacterial activity of S100A12 and report Ca(ii)-dependent and strain-selective behavior. S100A12 exhibits in vitro growth inhibitory activity against Listeria monocytogenes. In contrast, S100A12 has negligible effect on the growth of Escherichia coli K-12 and Pseudomonas aeruginosa PAO1. Loss of functional ZnuABC, a high-affinity Zn(ii) import system, increases the susceptibility of E. coli and P. aeruginosa to S100A12, indicating that S100A12 deprives these mutant strains of Zn(ii). To evaluate the Zn(ii)-binding sites of S100A12 in solution, we present studies using Co(ii) as a spectroscopic probe and chromophoric small-molecule chelators in Zn(ii) competition titrations. We confirm that S100A12 binds Zn(ii) with a 2 : 1 stoichiometry, and our data indicate sub-nanomolar affinity binding. Taken together, these data support a model whereby S100A12 uses Ca(ii) ions to tune its Zn(ii)-chelating properties and antimicrobial activity.     

Attenuation of airway inflammation by simvastatin and the implications for asthma treatment: is the jury still out?

Although some studies have explained the immunomodulatory effects of statins, the exact mechanisms and the therapeutic significance of these molecules remain to be elucidated. This study not only evaluated the therapeutic potential and inhibitory mechanism of simvastatin in an ovalbumin (OVA)-specific asthma model in mice but also sought to clarify the future directions indicated by previous studies through a thorough review of the literature. BALB/c mice were sensitized to OVA and then administered three OVA challenges. On each challenge day, 40 mg kg⁻¹ simvastatin was injected before the challenge. The airway responsiveness, inflammatory cell composition, and cytokine levels in bronchoalveolar lavage (BAL) fluid were assessed after the final challenge, and the T cell composition and adhesion molecule expression in lung homogenates were determined. The administration of simvastatin decreased the airway responsiveness, the number of airway inflammatory cells, and the interleukin (IL)-4, IL-5 and IL-13 concentrations in BAL fluid compared with vehicle-treated mice (P<0.05). Histologically, the number of inflammatory cells and mucus-containing goblet cells in lung tissues also decreased in the simvastatin-treated mice. Flow cytometry showed that simvastatin treatment significantly reduced the percentage of pulmonary CD4⁺ cells and the CD4⁺/CD8⁺ T-cell ratio (P<0.05). Simvastatin treatment also decreased the expression of the vascular cell adhesion molecule 1 and intercellular adhesion molecule 1 proteins, as measured in homogenized lung tissues (P<0.05) and human epithelial cells. The reduction in the T cell influx as a result of the decreased expression of cell adhesion molecules is one of the mechanisms by which simvastatin attenuates airway responsiveness and allergic inflammation. Rigorous review of the literature together with our findings suggested that simvastatin should be further developed as a potential therapeutic strategy for allergic asthma.     

Illuminating anti-hydrozirconation: controlled geometric isomerization of an organometallic species

A general strategy to enable the formal anti-hydrozirconation of arylacetylenes is reported that merges cis-hydrometallation using the Schwartz Reagent (Cp₂ZrHCl) with a subsequent light-mediated geometric isomerization at λ = 400 nm. Mechanistic delineation of the contra-thermodynamic isomerization step indicates that a minor reaction product functions as an efficient in situ generated photocatalyst. Coupling of the E-vinyl zirconium species with an alkyne unit generates a conjugated diene: this has been leveraged as a selective energy transfer catalyst to enable E → Z isomerization of an organometallic species. Through an Umpolung metal–halogen exchange process (Cl, Br, I), synthetically useful vinyl halides can be generated (up to Z : E = 90 : 10). This enabling platform provides a strategy to access nucleophilic and electrophilic alkene fragments in both geometric forms from simple arylacetylenes.

A general strategy to enable the formal anti-hydrozirconation of arylacetylenes is reported that merges cis-hydrometallation using the Schwartz Reagent (Cp₂ZrHCl) with a subsequent light-mediated geometric isomerization at λ = 400 nm.

The venerable Schwartz reagent (Cp₂ZrHCl) is totemic in the field of hydrometallation,¹ where reactivity is dominated by syn-selective M–H addition across the π-bond.^2,3 This mechanistic foundation can be leveraged to generate well-defined organometallic coupling partners that are amenable to stereospecific functionalization. Utilizing terminal alkynes as readily available precursors,⁴ hydrozirconation constitutes a powerful strategy to generate E-configured vinyl nucleophiles that, through metal–halogen exchange, can be converted to vinyl electrophiles in a formal Umpolung process.⁵ Whilst this provides a versatile platform to access the electronic antipodes of the E-isomer, the mechanistic course of addition renders access to the corresponding Z-isomer conspicuously challenging. To reconcile the synthetic importance of this transformation with the intrinsic challenges associated with anti-hydrometallation and metallometallation,⁶ it was envisaged that a platform to facilitate geometric isomerization⁷ would be of value. Moreover, coupling this to a metal–halogen exchange would provide a simple Umpolung matrix to access both stereo-isomers from a common alkyne precursor (Fig. 1).Open in a separate windowFig. 1The stereochemical course of alkyne hydrometallation using the Schwartz reagent and an Umpolung platform to generate both stereo-isomers from a common alkyne precursor.Confidence in this conceptual blueprint stemmed from a report by Erker and co-workers, in which irradiating the vinyl zirconium species derived from phenyl acetylene (0.5 M in benzene) with a mercury lamp (Philips HPK 125 and Pyrex filter) induced geometric isomerization.⁸ Whilst Hg lamps present challenges in terms of safety, temperature regulation, cost and wavelength specificity, advances in LED technology mitigate all of these points. Therefore, a process of reaction development was initiated to generalize the anti-hydrozirconation of arylacetylenes. Crucial to the success of this venture was identifying the light-based activation mode that facilitates alkene isomerization. Specifically, it was necessary to determine whether this process was enabled by direct irradiation of the vinyl zirconium species, or if the E → Z directionality results from a subsequent selective energy transfer process involving a facilitator. Several accounts of the incipient vinyl zirconium species reacting with a second alkyne unit to generate a conjugated diene have been disclosed.^9,10 It was therefore posited that the minor by-product diene may be a crucial determinant in driving this isomerization (Fig. 2).Open in a separate windowFig. 2A working hypothesis for the light-mediated anti-hydrozirconation via selective energy transfer catalysis.To advance this working hypothesis and generalize the formal anti-hydrozirconation process, the reaction of Cp₂ZrHCl with 1-bromo-4-ethynylbenzene (A-1) in CH₂Cl₂ was investigated (‡ for full details). This generates a versatile electrophile for downstream synthetic applications. Gratifyingly, after only 15 minutes, a Z : E-composition of 50 : 50 was reached (entry 1) and, following treatment with NBS, the desired vinyl bromide (Z)-1 was obtained in 76% yield (isomeric mixture) over the two steps. Further increasing the irradiation by 15 minute increments (entries 2–4) revealed that the optimum reaction time for the isomerization is 45 minutes (74%, Z : E = 73 : 27, entry 3). Extending the reaction time to 60 minutes (entry 4, 54%) did not lead to an improvement in selectivity and this was further confirmed by irradiating the reaction mixture for 90 minutes (entry 5). In both cases, a notable drop in yield was observed and therefore the remainder of the study was performed using the conditions described in entry 3. Next, the influence of the irradiation wavelength on the isomerization process was examined (entries 6–11). From a starting wavelength of λ = 369 nm, which gave a Z : E-ratio of 27 : 73 (entry 6), a steady improvement was observed by increasing the wavelength to λ = 374 nm (Z : E = 44 : 56, entry 7) and λ = 383 nm (Z : E = 53 : 47, entry 8). The selectivity reached a plateau at λ = 400 nm, with higher wavelengths proving to be detrimental (Z : E = 60 : 40 at λ = 414 nm, entry 9; Z : E = 26 : 74 at λ = 435 nm, entry 10). It is interesting to note that at λ = 520 nm, Z-1 was not detected by ¹H NMR (entry 11).Reaction optimization^a

The arachidonic acid metabolite 11,12-epoxyeicosatrienoic acid alleviates pulmonary fibrosis

Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid that are rapidly metabolized into diols by soluble epoxide hydrolase (sEH). sEH inhibition has been shown to increase the biological activity of EETs, which are known to have anti-inflammatory properties. However, the role of EETs in pulmonary fibrosis remains unexplored. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) was used to analyze EETs in the lung tissues of patients with idiopathic pulmonary fibrosis (IPF, n = 29) and controls (n = 15), and the function of 11,12-EET was evaluated in in vitro and in vivo in pulmonary fibrosis models. EET levels in IPF lung tissues, including those of 8,9-EET, 11,12-EET, and 14,15-EET, were significantly lower than those in control tissues. The 11,12-EET/11,12-DHET ratio in human lung tissues also differentiated IPF from control tissues. 11,12-EET significantly decreased transforming growth factor (TGF)-β1-induced expression of α-smooth muscle actin (SMA) and collagen type-I in MRC-5 cells and primary fibroblasts from IPF patients. sEH-specific siRNA and 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU; sEH inhibitor) also decreased TGF-β1-induced expression of α-SMA and collagen type-I in fibroblasts. Moreover, 11,12-EET and TPPU decreased TGF-β1-induced p-Smad2/3 and extracellular-signal-regulated kinase (ERK) expression in primary fibroblasts from patients with IPF and fibronectin expression in Beas-2B cells. TPPU decreased the levels of hydroxyproline in the lungs of bleomycin-induced mice. 11,12-EET or sEH inhibitors could inhibit pulmonary fibrosis by regulating TGF-β1-induced profibrotic signaling, suggesting that 11,12-EET and the regulation of EETs could serve as potential therapeutic targets for IPF treatment.Subject terms: Respiratory tract diseases, Chronic inflammation     

Malformin-A1 (MA1) Sensitizes Chemoresistant Ovarian Cancer Cells to Cisplatin-Induced Apoptosis

High-grade epithelial ovarian cancer is a fatal disease in women frequently associated with drug resistance and poor outcomes. We previously demonstrated that a marine-derived compound MalforminA1 (MA1) was cytotoxic for the breast cancer cell line MCF-7. In this study, we aimed to examine the effect of MA1 on human ovarian cancer cells. The potential cytotoxicity of MA1was tested on cisplatin-sensitive (A2780S) and cisplatin-resistant (A2780CP) ovarian cancer cell lines using AlamarBlue assay, Hoechst dye, flow cytometry, Western blot, and RT-qPCR. MA1 had higher cytotoxic activity on A2780S (IC50 = 0.23 µM) and A2780CP (IC50 = 0.34 µM) cell lines when compared to cisplatin (IC50 = 31.4 µM and 76.9 µM, respectively). Flow cytometry analysis confirmed the cytotoxic effect of MA1. The synergistic effect of the two drugs was obvious, since only 13% of A2780S and 7% of A2780CP cells remained alive after 24 h of treatment with both MA1 and cisplatin. Moreover, we examined the expression of bcl2, p53, caspase3/9 genes at RNA and protein levels using RT-qPCR and Western blot, respectively, to figure out the cell death mechanism induced by MA1. A significant down-regulation in bcl2 and p53 genes was observed in treated cells compared to non-treated cells (p < 0.05), suggesting that MA1 may not follow the canonical pathway to induce apoptosis in ovarian cancer cell lines. MalforminA1 showed promising anticancer activity by inducing cytotoxicity in cisplatin-sensitive and cisplatin-resistant cancer cell lines. Interestingly, a synergistic effect was observed when MA1 was combined with cisplatin, leading to it overcoming its resistance to cisplatin.     

Figure-eight thermal hysteresis of aminomethylenehelicene oligomers with terminal C16 alkyl groups during hetero-double-helix formation

1 : 1 mixtures of aminomethylenehelicene (P)-tetramer and (M)-pentamer with terminal C₁₆ alkyl groups in fluorobenzene showed structural changes between hetero-double-helices B and C and random-coils 2A. Figure-eight thermal hysteresis appeared when the solution was cooled and heated at a constant rate and involved the crossing of cooling and heating curves in Δε/temperature profiles. This unusual thermal hysteresis emerged in the intermediate state between counterclockwise and clockwise thermal hystereses. This phenomenon arose from the competition between self-catalytic reactions to form B and C from 2A. Significant effects of terminal C₁₆ alkyl groups on the thermodynamic and kinetic phenomena are also described.

1 : 1 mixtures of aminomethylenehelicene (P)-tetramer and (M)-pentamer with terminal C₁₆ alkyl groups in fluorobenzene showed structural changes between hetero-double-helices B and C and random-coils 2A.     

Significant Inactivation of SARS-CoV-2 In Vitro by a Green Tea Catechin,a Catechin-Derivative,and Black Tea Galloylated Theaflavins

Potential effects of tea and its constituents on SARS-CoV-2 infection were assessed in vitro. Infectivity of SARS-CoV-2 was decreased to 1/100 to undetectable levels after a treatment with black tea, green tea, roasted green tea, or oolong tea for 1 min. An addition of (−) epigallocatechin gallate (EGCG) significantly inactivated SARS-CoV-2, while the same concentration of theasinensin A (TSA) and galloylated theaflavins including theaflavin 3,3′-di-O-gallate (TFDG) had more remarkable anti-viral activities. EGCG, TSA, and TFDG at 1 mM, 40 µM, and 60 µM, respectively, which are comparable to the concentrations of these compounds in tea beverages, significantly reduced infectivity of the virus, viral RNA replication in cells, and secondary virus production from the cells. EGCG, TSA, and TFDG significantly inhibited interaction between recombinant ACE2 and RBD of S protein. These results suggest potential usefulness of tea in prevention of person-to-person transmission of the novel coronavirus.     

Lithium achieves sequence selective ring-opening terpolymerisation (ROTERP) of ternary monomer mixtures

Heteroatom-containing degradable polymers have strong potential as sustainable replacements for petrochemically derived materials. However, to accelerate and broaden their uptake greater structural diversity and new synthetic methodologies are required. Here we report a sequence selective ring-opening terpolymerisation (ROTERP), in which three monomers (A, B, C) are selectively enchained into an (ABA′C)_n sequence by a simple lithium catalyst. Degradable poly(ester-alt-ester-alt-trithiocarbonate)s are obtained in a M_n range from 2.35 to 111.20 kDa which are not easily accessible via other polymerisation methodologies. The choice of alkali metal is key to achieve high activity and to control the terpolymer sequence. ROTERP is mechanistically compatible with ring-opening polymerisation (ROP) allowing switchable catalysis for blockpolymer synthesis. The ROTERP demonstrated in this study could be the first example of an entirely new family of sequence selective terpolymerisations.

A sequence selective ring-opening terpolymerisation of epoxides with CS₂ and phthalic thioanhydride yielding poly(ester-alt-ester-alt-trithiocarbonates) is reported.

Synthetic polymers are now more in demand than ever before and looking at their annually increasing production, a polymer free society is at best a vague memory rather than a vision for the future.¹ As most commodity polymers are based on chemically inert aliphatic –C–C– backbones, most polymer waste shows unappreciable degradation with respect to the polymer''s time in application.^2,3 In answer to the ever-increasing amount of plastic pollution, much effort focuses on the exploration of new heteroatom containing polymers which, because of their more polar bonds making up the backbone, are more susceptible to degradation via physical, chemical and biochemical pathways and even facilitate new chemical recycling methods.^4–8 Besides, there is also a constant demand for entirely new materials to enable technological innovation making new methodologies to synthesise heteroatom containing polymers necessary.Arguably one of the most popular methods to make such polymers is the ring-opening polymerisation (ROP) of a heterocycle A.^9–11 These polymerise under release of their associated ring strain energy to make polymers (A)_n such as poly(thio)ethers, poly(thio)ester and poly(thio)carbonates, only to name a few. Early on it has been realised that in some cases the ROP of three or four-membered heterocycles A can be coupled to the insertion of typically heteroallenes or cyclic anhydrides B to generate alternating copolymers (AB)_n.^12–14 The underlying requirements for (AB)_n polymerisations are a combination of kinetic factors, i.e. monomer A inserting orders of magnitude faster into the active catalyst growing chain-bond than monomer B, and chemoselectivities, i.e. insertion of monomer A resulting in type A active catalyst growing chain-bond that does not show appreciable reactivity with A but only with B (and vice versa). Prominent examples of this alternating (AB)_n ring-opening copolymerisation (ROCOP) include CO₂/epoxide ROCOP yielding polycarbonates and cyclic anhydride/epoxide ROCOP yielding polyesters.^15–17 Sulfur analogous are also accessible such as polythiocarbonate from CS₂/(epoxide or thiirane) and polythioesters from thioanhydride/(epoxide or thiirane) ROCOP.^18–31 Such sulfur rich polymers are attractive high-refractive index materials that can show improved crystallinity and degradability over their all-oxygen analogues and in some cases enable chemical polymer to monomer recycling.^32–39Most relevant to this study is a report by Werner and coworkers on lithium alkoxide catalysed CS₂/epoxide ROCOP yielding poly(monothio-alt-trithiocarbonate)s featuring R–O–C( S)–O–R and R–S–C( S)–S–R links (Fig. 1).^40,41 Such a polymer sequence is unexpected, as the formal product of alternating insertion would be a poly(dithiocarbonate) with R–O–C( S)–S–R links. Furthermore, the polymer shows an unusual “head-to-head-alt-tail-to-tail” selectivity meaning that the R–O–C( S)–O–R links sit adjacent to the tertiary CHR₃ positions of the ring opened epoxide (i.e. “head” position) and that the R–S–C( S)–S–R links sit adjacent to the secondary CH₂R₂ position of the ring opened epoxide (i.e. “tail” position). This sequence let the authors postulate a mechanism involving tail-selective epoxide ring-opening by a dithiocarbonate chain end which is formed by CS₂ insertion into an alkoxide intermediate. The resulting alkoxide intermediate was proposed to backbite into the adjacent dithiocarbonate link which after a rearrangement process resulted in an O/S exchange of the chain end. The rearrangement transforms the alkoxide into a thiolate chain end and the adjacent dithiocarbonate R–O–C( S)–S–R into a monothiocarbonate R–O–C( S)–O–R. CS₂ insertion of the thiolate generates a trithiocarbonate R–S–C( S)–S–R which after epoxide insertion regenerates the alkoxides. In contrast to alkoxides sitting adjacent to R–O–C( S)–S–R links, alkoxides next to R–S–C( S)–S–R links were not proposed to undergo backbiting and O/S exchange. Importantly the initial regioselectivity of the epoxide ring-opening was preserved throughout the rearrangement which explained the “head-to-head-alt-tail-to-tail” selectivity. Interestingly lithium appeared to be crucial as other alkali metal alkoxides failed to catalyse this ROCOP, while more sophisticated catalysts result in much more uncontrolled polymer sequences. Hence it appears that the Li controls which alkoxide intermediate precisely undergoes O/S exchange and to which degree this rearrangement occurs, but the reasons behind the special role of Li remains to be explored. Relatedly the ROCOP of thioanhydrides with epoxides has also been reported and similar exchange processes have been proposed as side reactions.²³ Although not directly proven, this mechanism seemed reasonable and let us hypothesise that lithium catalysts could grant a general access to control the O/S exchange process in ROCOP and even in the polymerisation of ternary monomer mixtures. Furthermore, we reasoned that the two distinct chain ends formed via O/S exchange, i.e. alkoxide and thiolate (type A vide supra), could enable discrimination between two different type B monomers and enable sequence selective terpolymerisations. It should be noted that reports exist in which mixtures of A, B and C (e.g. epoxide A, cyclic anhydride B and CO₂ C) either yield random terpolymers, (AB)_n-ran-(AC)_m poly(esters-ran-carbonate), or block-terpolymers, (AB)_n-b-(AC)_m, polyester-b-polycarbonate. In this case the monomer sequence depends on catalyst selection and reaction conditions, but sequence selective terpolymers, e.g. (ABC)_n or (ABAC)_n, are unknown.^42–48 The hypothesis of O/S exchange here led us to discover a new type of polymerisation, sequence selective ring-opening terpolymerisation (ROTERP) that we report in this contribution. ROTERP produces poly(ester-alt-ester-alt-trithiocarbonates), i.e. (ABA′C)_n sequences, from a mixture of the monosubstituted epoxides propylene oxide (PO) or butylene oxide (BO) A, phthalic thioanhydride (PTA) B and CS₂ C, employing simple lithium salts as the catalyst. Furthermore, model reactions proof the previously postulated O/S rearrangement that enable ROTERP and elucidate the role of the lithium catalyst. Finally, we employed ROTERP in so-called switchable catalysis, in which the onset of ROTERP stops the occurrence of ROP, for the construction of blockpolymers.Open in a separate windowFig. 1(Top) CS₂/epoxide ROCOP and postulated mechanism involving a central O/S exchange reaction, (middle) phthalic thioanhydride (PTA)/epoxide ROCOP and (bottom) PTA/CS₂/epoxide ROTERP reported in this study. R = Me, Et; [R_n] = polymer chain.ROTERP of mixtures of PTA, PO and CS₂ at loadings typically employed in ROCOP catalysis with lithium hexamethyldisilazide (LiHDMS) or lithium benzyloxide (LiOBn) as the catalyst at loadings in the range of 1 eq. LiX : (6.25–500 eq.) PTA : (31.25–2500 eq.) PO : (62.5–5000 eq.) CS₂ yield polymeric materials in 95% selectivity at 80 °C (see 40,47 Spectroscopic analysis of the isolated polymer reveals surprisingly clean NMR spectra given the potential for statistical terpolymerisation of these three monomers. The ¹H NMR spectrum (Fig. 2) shows two main aryl resonances for a symmetrically substituted terephthalate unit from ring opened PTA (δ = 7.72 and 7.56 ppm) as well as one main resonance for the CHMe (δ = 5.42 ppm; head position of the ring-opened epoxide) and CH₂ (δ = 3.90–3.40 ppm; tail position of the ring opened epoxide) groups respectively stemming from the ring opened PO. Correspondingly the ¹³C{¹H} NMR spectrum (ESI Fig. S1^†) reveals the almost exclusive presence of trithiocarbonate R–S–C( S)–S–R (δ = 222.8 ppm) and arylester R–C( O)–O–R (δ ∼166.6 ppm) resonances (94–98%) alongside minor thioester R–C( O)–S–R (δ = 192.7 ppm) resonances (2–6%). ¹H and 2D NMR spectra (ESI Fig. S3^†) show that trithiocarbonate units are positioned adjacent to CH₂ groups while arylesters are connected to the tertiary CHMe groups. The spectra remain unchanged after multiple precipitations from DCM : MeOH or THF : pentane and DOSY NMR shows that all ¹H NMR resonances diffuse at the same rate confirming that these are part of the same species. Furthermore, no other type of thiocarbonate R–(O/S)–C( O/S)–(O/S)–R are part of the polymer. Linkage identity was further substantiated by the ATR-IR spectrum (ESI Fig. S5^†) of these polymers showing an arylester C O stretch at = 1716 cm⁻¹ as well as a thiocarbonate C S stretch at = 1062 cm⁻¹ (ESI Fig. S5^†). Accordingly, the polymers are obtained as yellow solids due the presence of the C S chromophore (λ_abs = 435 nm, ESI Fig. S6^†). MALDI-TOF analysis unfortunately only led to decomposition of the materials and no signals could be identified as previously reported for sulfur-rich polymers.^26,38 Nevertheless ¹H NMR allows some conclusions regarding the topology as both for LiHMDS or LiOBn initiation, resonances for the HMDS and OBn groups can be identified to be part of the purified polymers. Insertion of alkalimetal alkoxides and amides into CS₂ yielding alkali dithiocarbonates and dithiocarbamates have been previously reported.^40,79 This makes initiation via CS₂ insertion likely which defines one end of the polymer and hence indicates that chains are linear rather than cyclic. As ROTERP is followed by CS₂/epoxide coupling once all PTA is consumed (vide infra) we infer that chains are terminated by CS₂ because heteroallene insertion products are generally established to be the resting states of heteroallene/heterocycle coupling reactions.¹²Data showing PTA/CS₂/epoxide ROTERP under different conditions

A prochelator peptide designed to use heterometallic cooperativity to enhance metal ion affinity

A peptide has been designed so that its chelating affinity for one type of metal ion regulates its affinity for a second, different type of metal ion. The prochelator peptide (PCP), which is a fusion of motifs evocative of calcium loops and zinc fingers, forms a 1 : 2 Zn : peptide complex at pH 7.4 that increases its affinity for Zn²⁺ ∼3-fold in the presence of Tb³⁺ (log β₂ from 13.8 to 14.3), while the 1 : 1 luminescent complex with Tb³⁺ is brighter, longer lived, and 20-fold tighter in the presence of Zn²⁺ (log K from 6.2 to 7.5). This unique example of cooperative, heterometallic allostery in a biologically compatible construct suggests the possibility of designing conditionally active metal-binding agents that could respond to dynamic changes in cellular metal status.     

Circulating Ligands of the Receptor for Advanced Glycation End Products and the Soluble Form of the Receptor Modulate Cardiovascular Cell Apoptosis in Diabetes

We determined whether plasma concentrations of the receptor for advanced glycation end products (RAGE) and the soluble (s) form of RAGE (sRAGE) in healthy individuals and patients with type 2 diabetes (T2D) modulate vascular remodeling. Healthy individuals and patients with T2D were divided into two age groups: young = <35 years old or middle-aged (36–64 years old) and stratified based on normal glucose tolerance (NGT), impaired (IGT), and T2D. Plasma titers of sRAGE, the RAGE ligands, AGEs, S100B, S100A1, S100A6, and the apoptotic marker Fas ligand Fas(L) were measured by enzyme-linked immunosorbent assay (ELISA). The apoptotic potential of the above RAGE ligands and sRAGE were assessed in cultured adult rat aortic smooth muscle cells (ASMC). In NGT individuals, aging increased the circulating levels of AGEs and S100B and decreased sRAGE, S100A1 and S100A6. Middle-aged patients with T2D presented higher levels of circulating S100B, AGEs and FasL, but lower levels of sRAGE, S100A1 and S100A6 than individuals with NGT or IGT. Treatment of ASMC with either AGEs or S100B at concentrations detected in T2D patients increased markers of inflammation and apoptosis. Responses attenuated by concomitant administration of sRAGE. In middle-aged patients with T2D, lower circulating plasma levels of sRAGE may limit decoy and exogenous trapping of deleterious pro-apoptotic/pro-inflammatory RAGE ligands AGEs and S100B, increasing the risk for diabetic complications.     

Morphological Transformation Reactions of Photocatalytic Metalloporphyrin-Containing Coordination Polymer Particles from Seed Structures

Coordination polymer particles have attracted a great deal of attention due to their characteristic properties and diverse applications in the fields of gas storage, catalysis, optics, sensing, electronics, photochemistry, and biology. Herein, we investigated shape transformation reactions of zinc 5, 10, 15, 20-tetra(4-pyridyl)-21 H, 23 H-porphine (ZnTPyP)-containing coordination polymer particles (ZnTPyP−CPPs) from seed structures by delicately controlling the Gibbs energy of the self-assembly system. We obtained a morphological transformation from 1 D short nanorods to 1 D long nanorods and 3 D nano-octahedral structures, and from 3 D nano-octahedral structures to 1 D nanorod structures. We illustrated a new method to design and synthesize metalloporphyrin-containing CPPs in a controllable manner. Furthermore, photocatalytic properties of ZnTPyP−CPPs were tested, showing good catalytic abilities towards the photodegradation of methylene blue (MB) under visible light illumination.     

Bis[pyrrolyl Ru(ii)] triads: a new class of photosensitizers for metal–organic photodynamic therapy

A new family of ten dinuclear Ru(ii) complexes based on the bis[pyrrolyl Ru(ii)] triad scaffold, where two Ru(bpy)₂ centers are separated by a variety of organic linkers, was prepared to evaluate the influence of the organic chromophore on the spectroscopic and in vitro photodynamic therapy (PDT) properties of the compounds. The bis[pyrrolyl Ru(ii)] triads absorbed strongly throughout the visible region, with several members having molar extinction coefficients (ε) ≥ 10⁴ at 600–620 nm and longer. Phosphorescence quantum yields (Φ_p) were generally less than 0.1% and in some cases undetectable. The singlet oxygen quantum yields (Φ_Δ) ranged from 5% to 77% and generally correlated with their photocytotoxicities toward human leukemia (HL-60) cells regardless of the wavelength of light used. Dark cytotoxicities varied ten-fold, with EC₅₀ values in the range of 10–100 μM and phototherapeutic indices (PIs) as large as 5400 and 260 with broadband visible (28 J cm^–2, 7.8 mW cm^–2) and 625 nm red (100 J cm^–2, 42 mW cm^–2) light, respectively. The bis[pyrrolyl Ru(ii)] triad with a pyrenyl linker (5h) was especially potent, with an EC₅₀ value of 1 nM and PI > 27 000 with visible light and subnanomolar activity with 625 nm light (100 J cm^–2, 28 mW cm^–2). The lead compound 5h was also tested in a tumor spheroid assay using the HL60 cell line and exhibited greater photocytotoxicity in this more resistant model (EC₅₀ = 60 nM and PI > 1200 with 625 nm light) despite a lower dark cytotoxicity. The in vitro PDT effects of 5h extended to bacteria, where submicromolar EC₅₀ values and PIs >300 against S. mutans and S. aureus were obtained with visible light. This activity was attenuated with 625 nm red light, but PIs were still near 50. The ligand-localized ³ππ* state contributed by the pyrenyl linker of 5h likely plays a key role in its phototoxic effects toward cancer cells and bacteria.