Elucidating the Mode of Action of Hybrid Nanoparticles of Cu/Zn Against Copper-Tolerant Xanthomonas euvesicatoria.

The widespread presence of tolerance to copper in Xanthomonas species has resulted in the need to develop alternative approaches to control plant diseases caused by xanthomonads. In recent years, nanotechnological approaches have resulted in the identification of novel materials to control plant pathogens. With many metal-based nanomaterials having shown promise for disease control, an important question relates to the mode of action of these new materials. In this study, we used several approaches, such as scanning electron microscopy, propidium monoazide quantitative polymerase chain reaction, epifluorescence microscopy, and RNA sequencing to elucidate the mode of action of a Cu/Zn hybrid nanoparticle against copper-tolerant strains of Xanthomonas euvesicatoria. We demonstrate that Cu/Zn did not activate copper resistance genes (i.e., copA and copB) in the copper-tolerant bacterium but functioned by disrupting the bacterial cell structure and perturbing important biological processes such as cell respiration and chemical homeostasis.

The crucial role of silver(I)-salts as additives in C-H activation reactions: overall analysis of their versatility and applicability.

Transition-metal catalyzed C-H activation reactions have been proven to be useful methodologies for the assembly of synthetically meaningful molecules. This approach bears intrinsic peculiarities that are important to be studied and comprehended in order to achieve its best performance. One example is the use of additives for the in situ generation of catalytically active species. This strategy varies according to the type of additive and the nature of the pre-catalyst that is being used. Thus, silver(I)-salts have proven to play an important role, due to the resulting high reactivity derived from the pre-catalysts of the main transition metals used so far. While being powerful and versatile, the use of silver-based additives can raise concerns, since superstoichiometric amounts of silver(I)-salts are typically required. Therefore, it is crucial to first understand the role of silver(I) salts as additives, in order to wisely overcome this barrier and shift towards silver-free systems.

The Synthesis and Reactivity of Naphthoquinonynes.

The first systematic exploration of the synthesis and reactivity of naphthoquinonynes is described. Routes to two regioisomeric Kobayashi-type naphthoquinonyne precursors have been developed, and the reactivity of the ensuing 6,7- and 5,6-aryne intermediates has been investigated. Remarkably, these studies have revealed that a broad range of cycloadditions, nucleophile additions and difunctionalizations can be achieved while maintaining the integrity of the highly sensitive quinone unit. The methodologies offer a powerful diversity oriented approach to C6 and C7 functionalized naphthoquinones, which are typically challenging to access. From a reactivity viewpoint, the study is significant because it demonstrates that aryne-based functionalizations can be utilized strategically in the presence of highly reactive and directly competing functionality.

Novel Carbonaceous Adsorbents Prepared from Glycerin Waste and Dopamine for Gas Separation.

Glycerin, a low-valued waste from biodiesel production, and dopamine were used as precursors for adsorbent materials. The study is centered on the preparation and application of microporous activated carbon as adsorbent materials in the separation of ethane/ethylene and of gases that are natural gas or landfill gas components (ethane/methane and carbon dioxide/methane). The activated carbons were produced by the following sequence reactions: facile carbonization of a glycerin/dopamine mixture and chemical activation. Dopamine allowed the introduction of nitrogenated groups that improved the selectivity of the separations. The activating agent was KOH, but its mass ratio was kept lower than one to improve the sustainability of the final materials. The solids were characterized by N2 adsorption/desorption isotherms, SEM, FTIR spectroscopy, elemental analysis, and point of zero charges (pHPZC). The order for adsorption of the different adsorbates (in mmolg-1) on the most well performing material-Gdop0.75-is methane (2.5) < carbon dioxide (5.0) < ethylene (8.6) < ethane (8.9).

It Takes Two to Tango, Part II: Synthesis of A-Ring Functionalised Quinones Containing Two Redox-Active Centres with Antitumour Activities.

In 2021, our research group published the prominent anticancer activity achieved through the successful combination of two redox centres (ortho-quinone/para-quinone or quinone/selenium-containing triazole) through a copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. The combination of two naphthoquinoidal substrates towards a synergetic product was indicated, but not fully explored. Herein, we report the synthesis of 15 new quinone-based derivatives prepared from click chemistry reactions and their subsequent evaluation against nine cancer cell lines and the murine fibroblast line L929. Our strategy was based on the modification of the A-ring of para-naphthoquinones and subsequent conjugation with different ortho-quinoidal moieties. As anticipated, our study identified several compounds with IC50 values below 0.5 µM in tumour cell lines. Some of the compounds described here also exhibited an excellent selectivity index and low cytotoxicity on L929, the control cell line. The antitumour evaluation of the compounds separately and in their conjugated form proved that the activity is strongly enhanced in the derivatives containing two redox centres. Thus, our study confirms the efficiency of using A-ring functionalized para-quinones coupled with ortho-quinones to obtain a diverse range of two redox centre compounds with potential applications against cancer cell lines. Here as well, it literally takes two for an efficient tango!

Pseudomonas californiensis sp. nov. and Pseudomonas quasicaspiana sp. nov., isolated from ornamental crops in California.

Five bacterial strains were isolated from symptomatic leaves of Achillea millefolium, Delphinium sp. and Hydrangea sp. in California. Colonies isolated on King's medium B (KMB) appeared white, mucoid and round, similar to Pseudomonas species. Phylogenetic analyses based on 16S rRNA, rpoB, rpoD and gyrB genes placed the bacteria into three distinct groups within Pseudomonas that were most closely related to Pseudomonas viridiflava, Pseudomonas cichorii or Pseudomonas caspiana. To further characterize the strains, phenotypic analyses and the following tests were performed: fatty acid methyl ester composition, LOPAT, fluorescence on KMB, Biolog assay, and transmission electron microscopy. Finally, whole genome sequencing of the strains was conducted, and the sequences were compared with reference genomes of Pseudomonas species based on average nucleotide identity (ANI). The first group, which consists of three strains isolated from delphinium, hydrangea and achillea, had 95.6-96.9 % pairwise ANI between each other; the second group consists of two strains isolated from delphinium that had 100 % pairwise ANI. Although comparisons of the two groups with publicly available genomes revealed closest relationships with P. viridiflava (91.6 %), P. caspiana (88.3 %) and P. asturiensis (86.7 %), ANI values were less than 95 % compared to all validly published pseudomonads. Combining genomic and phenotypic data, we conclude that these strains represent two new species and the names proposed are Pseudomonas quasicaspiana sp. nov. (type strain DSMZ 11 30 42T=LMG 32 434T) for the strains isolated from delphinium, achillea and hydrangea and Pseudomonas californiensis sp. nov. (DSMZ 11 30 43T=LMG 32 432T) for the two strains isolated from delphinium. The specific epithets quasicaspiana and californiensis were selected based on the close phylogenetic relationship of strains with P. caspiana and on the geographic location of isolation, respectively.

From a recombinant key antigen to an accurate, affordable serological test: Lessons learnt from COVID-19 for future pandemics.

Serological tests detect antibodies generated by infection or vaccination, and are indispensable tools along different phases of a pandemic, from early monitoring of pathogen spread up to seroepidemiological studies supporting immunization policies. This work discusses the development of an accurate and affordable COVID-19 antibody test, from production of a recombinant protein antigen up to test validation and economic analysis. We first developed a cost-effective, scalable technology to produce SARS-COV-2 spike protein and then used this antigen to develop an enzyme-linked immunosorbent assay (ELISA). A receiver operator characteristic (ROC) analysis allowed optimizing the cut-off and confirmed the high accuracy of the test: 98.6% specificity and 95% sensitivity for 11+ days after symptoms onset. We further showed that dried blood spots collected by finger pricking on simple test strips could replace conventional plasma/serum samples. A cost estimate was performed and revealed a final retail price in the range of one US dollar, reflecting the low cost of the ELISA test platform and the elimination of the need for venous blood sampling and refrigerated sample handling in clinical laboratories. The presented workflow can be completed in 4 months from first antigen expression to final test validation. It can be applied to other pathogens and in future pandemics, facilitating reliable and affordable seroepidemiological surveillance also in remote areas and in low-income countries.

Decoding Directing Groups and Their Pivotal Role in C-H Activation.

Synthetic organic chemistry has witnessed a plethora of functionalization and defunctionalization strategies. In this regard, C-H functionalization has been at the forefront due to the multifarious applications in the development of simple to complex molecular architectures and holds a brilliant prospect in drug development and discovery. Despite been explored tremendously by chemists, this functionalization strategy still enjoys the employment of novel metal catalysts as well metal-free organic ligands. Moreover, the switch to photo- and electrochemistry has widened our understanding of the alternative pathways via which a reaction can proceed and these strategies have garnered prominence when applied to C-H activation. Synthetic chemists have been foraging for new directing groups and templates for the selective activation of C-H bonds from a myriad of carbon-hydrogen bonds in aromatic as well as aliphatic systems. As a matter of fact, by varying the templates and directing groups, scientists found the answer to the challenge of distal C-H bond activation which remained an obstacle for a very long time. These templates have been frequently harnessed for selectively activating C-H bonds of natural products, drugs, and macromolecules decorated with multiple C-H bonds. This itself was a challenge before the commencement of this field as functionalization of a site other than the targeted site could modify and hamper the biological activity of the pharmacophore. Total synthesis and pharmacophore development often faces the difficulty of superfluous reaction steps towards selective functionalization. This obstacle has been solved by late-stage functionalization simply by harnessing C-H bond activation. Moreover, green chemistry and metal-free reaction conditions have seen light in the past few decades due to the rising concern about environmental issues. Therefore, metal-free catalysts or the usage of non-toxic metals have been recently showcased in a number of elegant works. Also, research groups across the world are developing rational strategies for directing group free or non-directed protocols that are just guided by ligands. This review encapsulates the research works pertinent to C-H bond activation and discusses the science devoted to it at the fundamental level. This review gives the readers a broad understanding of how these strategies work, the execution of various metal catalysts, and directing groups. This not only helps a budding scientist towards the commencement of his/her research but also helps a matured mind searching out for selective functionalization. A detailed picture of this field and its progress with time has been portrayed in lucid scientific language with a motive to inculcate and educate scientific minds about this beautiful strategy with an overview of the most relevant and significant works of this era. The unique trait of this review is the detailed description and classification of various directing groups and their utility over a wide substrate scope. This allows an experimental chemist to understand the applicability of this domain and employ it over any targeted substrate.

The Different Facets of Metal-Catalyzed C-H Functionalization Involving Quinone Compounds.

Metal-catalysed C-H functionalization has emerged as a powerful platform for the derivatization of quinones, a class of compounds with wide-ranging applications. This review organises and discusses the evolution of this chemistry from early Fujiwara-Moritani reactions, through to modern directing-group assisted C-H functionalization processes, including C-H functionalization reactions directed by the quinone ring itself. Mechanistic details of these reactions are provided to afford insight into how the unique reactivity of quinoidal compounds has been leveraged in each example.

Imidazoles and Oxazoles from Lapachones and Phenanthrene-9,10-dione: A Journey through their Synthesis, Biological Studies, and Optical Applications.

Diverse structural frameworks are found in natural compounds and are well known for their chemical and biological properties; such compounds include the imidazoles and oxazoles. Researchers worldwide are continually working on the development of methods for synthesizing new molecules bearing these basic moiety and evaluating their properties and applications. To expand the knowledge related to azoles, this review summarizes important examples of imidazole and oxazole derivatives from 1,2-dicarbonyl compounds, such as lapachones and phenanthrene-9,10-diones, not only regarding their synthesis and biological applications but also their photophysical properties and uses. The data concerning the latter are particularly scarce in the literature, which leads to underestimation of the potential applications that can be envisaged for these compounds.

Removal and modification of directing groups used in metal-catalyzed C-H functionalization: the magical step of conversion into 'conventional' functional groups.

Over the past few decades, regioselective catalytic C-H functionalization has provided an attractive tool for unique retrosynthetic disconnections. The advancement of the directing group strategy in metal catalyzed synthetic transformation has contributed significantly to the incorporation of a wide range of functionalization reactions in both aromatic systems and aliphatic backbones. However, the extensive utilization of these methodologies depends on the ease of removal of the directing group to restore the free functional group. In this review, we have summarised the reported approaches for removing/modifying versatile directing groups.

Magnesium Oxide Nanomaterial, an Alternative for Commercial Copper Bactericides: Field-Scale Tomato Bacterial Spot Disease Management and Total and Bioavailable Metal Accumulation in Soil.

Copper (Cu) is the most extensively used bactericide worldwide in many agricultural production systems. However, intensive application of Cu bactericide have increased the selection pressure toward Cu-tolerant pathogens, including Xanthomonas perforans, the causal agent of tomato bacterial spot. However, alternatives for Cu bactericides are limited and have many drawbacks including plant damage and inconsistent effectiveness under field conditions. Also, potential ecological risk on nontarget organisms exposed to field runoff containing Cu is high. However, due to lack of alternatives for Cu, it is still widely used in tomato and other crops around the world in both conventional and organic production systems. In this study, a Cu-tolerant X. perforans strain GEV485, which can tolerate eight tested commercial Cu bactericides, was used in all the field trials to evaluate the efficacy of MgO nanomaterial. Four field experiments were conducted to evaluate the impact of intensive application of MgO nanomaterial on tomato bacterial spot disease severity, and one field experiment was conducted to study the impact of soil accumulation of total and bioavailable Cu, Mg, Mn, and Zn. In the first two field experiments, twice-weekly applications of 200 µg/mL MgO significantly reduced disease severity by 29-38% less in comparison to a conventional Cu bactericide Kocide 3000 and 19-30% less in comparison to the water control applied at the same frequency (p = 0.05). The disease severity on MgO twice-weekly was 12-32% less than Kocide 3000 + Mancozeb treatment. Single weekly applications of MgO had 13-19% higher disease severity than twice weekly application of MgO. In the second set of two field trials, twice-weekly applications of MgO at 1000 µg/mL significantly reduced disease severity by 32-40% in comparison to water control applied at the same frequency (p = 0.05). There was no negative yield impact in any of the trials. The third field experiment demonstrated that application of MgO did not result in significant accumulation of total and bioavailable Mg, Mn, Cu, or Zn in the root-associated soil and in soil farther away from the production bed compared to the water control. However, Cu bactericide contributed to significantly higher Mn, Cu, and Zn accumulation in the soil compared to water control (p = 0.05). This study demonstrates that MgO nanomaterial could be an alternative for Cu bactericide and have potential in reducing risks associated with development of tolerant strains and for reducing Cu load in the environment.

Ruthenium(II)- and Palladium(II)-catalyzed position-divergent CH oxygenations of arylated quinones: Identification of hydroxylated quinonoid compounds with potent trypanocidal activity.

A diversity-oriented synthesis of hydroxylated aryl-quinones via CH oxygenation reactions and their evaluation against Trypanosoma cruzi, the etiological agent of Chagas disease, was accomplished. With the use of ruthenium(II)- or palladium(II)-based catalysts, complementary regioselectivities were observed in the hydroxylation reactions and we have identified 9 compounds more potent than benznidazole (Bz) among these novel arylated and hydroxylated quinones. For instance, 5-hydroxy-2-[4-(trifluoromethyl)phenyl]-1,4-naphthoquinone (4h) with an IC50/24 h value of 22.8 µM is 4.5-fold more active than the state-of-the-art drug Bz. This article provides the first example of the application of CH activation for the position-selective hydroxylation of arylated quinones and the identification of these compounds as trypanocidal drug candidates.

On the application of 3d metals for C-H activation toward bioactive compounds: The key step for the synthesis of silver bullets.

Several valuable biologically active molecules can be obtained through C-H activation processes. However, the use of expensive and not readily accessible catalysts complicates the process of pharmacological application of these compounds. A plausible way to overcome this issue is developing and using cheaper, more accessible, and equally effective catalysts. First-row transition (3d) metals have shown to be important catalysts in this matter. This review summarizes the use of 3d metal catalysts in C-H activation processes to obtain potentially (or proved) biologically active compounds.

p53 reactivation with induction of massive apoptosis-1 (PRIMA-1) inhibits amyloid aggregation of mutant p53 in cancer cells.

p53 mutants can form amyloid-like structures that accumulate in cells. p53 reactivation with induction of massive apoptosis-1 (PRIMA-1) and its primary active metabolite, 2-methylene-3-quinuclidinone (MQ), can restore unfolded p53 mutants to a native conformation that induces apoptosis and activates several p53 target genes. However, whether PRIMA-1 can clear p53 aggregates is unclear. In this study, we investigated whether PRIMA-1 can restore aggregated mutant p53 to a native form. We observed that the p53 mutant protein is more sensitive to both PRIMA-1 and MQ aggregation inhibition than WT p53. The results of anti-amyloid oligomer antibody assays revealed that PRIMA-1 reverses mutant p53 aggregate accumulation in cancer cells. Size-exclusion chromatography of the lysates from mutant p53-containing breast cancer and ovarian cell lines confirmed that PRIMA-1 substantially decreases p53 aggregates. We also show that MDA-MB-231 cell lysates can "seed" aggregation of the central core domain of recombinant WT p53, corroborating the prion-like behavior of mutant p53. We also noted that this aggregation effect was inhibited by MQ and PRIMA-1. This study provides the first demonstration that PRIMA-1 can rescue amyloid-state p53 mutants, a strategy that could be further explored as a cancer treatment.

Ruthenium(II)-Catalyzed Double Annulation of Quinones: Step-Economical Access to Valuable Bioactive Compounds.

Double ruthenium(II)-catalyzed alkyne annulations of quinones were accomplished. Thus, a strategy is reported that provides step-economical access to valuable quinones with a wide range of applications. C-H/N-H activations for alkyne annulations of naphthoquinones provided challenging polycyclic quinoidal compounds by forming four new bonds in one step. The singular power of the thus-obtained compounds was reflected by their antileukemic activity.

Tissue factor mediates microvesicles shedding from MDA-MB-231 breast cancer cells.

Extracellular vesicles, such as microvesicles (MVs), were identified as important players in tumor progression and acquisition of an aggressive phenotype. Tissue factor (TF) is a transmembrane protein that initiates the blood coagulation cascade. In tumor cells, TF has been associated with aggressiveness and cancer progression. Previous studies demonstrate that TF is incorporated into MVs secreted by tumor cells; however, it is unknown whether TF is actively involved in the release of MVs. Here, we investigated the influence of TF expression on the release of MVs. TF silencing was achieved through CRISPR/Cas9 approaches in the human breast cancer cell line, MDA-MB-231. TF knockout in MDA-MB-231 cells efficiently reduced TF-dependent signaling and procoagulant activity. Remarkably, silencing of TF caused a significant decrease in the number of MVs released by MDA-MB-231 cells. We also observed an increase in actin-positive membrane projections in TF knockout cells and a reduction in RhoA expression when compared to TF-expressing cells. Treatment of MDA-MB-231 cells with the RhoA-ROCK signaling pathway inhibitor, fasudil, significantly reduced the release of MVs. Taken together, our results suggest a novel and relevant role for TF in tumor biology by playing an active role in the MVs secretion.

Combination of Aryl Diselenides/Hydrogen Peroxide and Carbon-Nanotube/Rhodium Nanohybrids for Naphthol Oxidation: An Efficient Route towards Trypanocidal Quinones.

This work reports a combination of aryl diselenides/hydrogen peroxide and carbon-nanotube (CNT)/rhodium nanohybrids (RhCNT) for naphthol oxidation towards the synthesis of 1,4-naphthoquinones and evaluation of their relevant trypanocidal activity. Under a combination of (PhSe)2 /H2 O2 in the presence of O2 in iPrOH/hexane, several benzenoid (A-ring)-substituted quinones were prepared in moderate to high yields. We also studied the contribution of RhCNT as co-catalyst in this process and, in some cases, yields were improved. This method provides an efficient and versatile alternative for preparing A-ring-modified naphthoquinonoid compounds with relevant biological profile.

Ligand-free method to produce the anti-angiogenic recombinant Galectin-3 carbohydrate recognition domain.

Galectin-3 (Gal3) is involved in many physiological processes related to tumor growth, such as promoting angiogenesis, cell migration/invasion, resistance to apoptosis and immune response modulation. Usually the overexpression of Gal3 is a poor prognostic marker for cancer patients. Recombinant Gal3 carbohydrate domain (Gal3C) has been proposed as a useful tool to inhibit angiogenesis. So far, all production protocols reported for Gal3C production have used proteolytic cleavage of full length Gal3 and/or affinity-based purification. This involves dialysis, a time consuming step used to eliminate the elution ligand, usually lactose. In this report, we describe an alternative method to produce human recombinant Gal3C in E. coli, purified with cationic exchange and size exclusion chromatography. The recombinant protein was characterized using circular dichroism and nuclear magnetic resonance, showing a beta sheet enriched well-folded globular structure. The average yield obtained was 26 mg/L of broth and the purity was above 99%. The anti-angiogenic activity was assessed in vitro and showed a reduction of 70% and 77% in endothelial cells tubule formation upon treatment with 10 and 20 µg/mL, respectively and also had no impact on cell viability. The method described here is more suitable for both laboratory and industrial production of the potential anti-tumor Gal3C.

Periodontal Evaluation in Noncarious Cervical Lesions Restored with Resin-modified Glass-Ionomer Cement and Resin Composite: A Randomised Controlled Study.

PURPOSE: To assess periodontal parameters of noncarious cervical lesions (NCCLs) restored with glass-ionomer cement (RM-GIC) and composite resin at baseline, three and six months. MATERIALS AND METHODS: Eighteen patients with bilateral lesions were included in the study. Lesions (1 mm in depth) were randomly restored with each type of restorative material. Probing depth (PD), relative gingival recession (rGR), relative clinical attachment level (rCAL), visible plaque index (VPI) and gingival bleeding index (GBI) were measured. RESULTS: No statistically significant differences were found when comparing within groups (p > 0.05). However, the intergroup analysis demonstrated a decrease in GR and rCAL gain for teeth restored with the resin-modified glass-ionomer cement (RM-GIC). CONCLUSION: Both materials behaved similarly when in close contact with periodontal tissues and did not influence periodontal parameters.