Chemistry of glycol nucleic acid (GNA): Synthesis, photophysical characterization and insight into the biological activity of phenanthrenyl GNA constituents.

The knowledge pertaining to the chemistry and biological activity of glycol nucleic acid (GNA) components, like nucleosides and nucleotides, is still very limited. Herein we report on the preparation of the uracil nucleoside (1) and nucleotide ester GNA (2). The compounds are functionalised with a luminescent phenanthrenyl group. In DMSO, 1 and 2 are brightly fluorescent, with emission maxima at 390 nm, nanosecond decay times (0.6 and 0.75 ns, respectively), and quantum yields of ca. 0.2. In the solid phase, they show excimeric emission, with maxima at 495 nm (1) and 432 nm (2), and decay times of 3.7 ns (1) and 2.9 ns (2). The anticancer activity of the GNA components, as well as gemcitabine hydrochloride, used as a reference drug, were examined in vitro against human cancer HeLa and Ishikawa cells, as well as against normal L929 cells, using a battery of biochemical assays. Furthermore, biodistribution imaging studies were carried out in HeLa cells, with luminescence confocal microscopy, which showed that the compounds localized mainly in the lipophilic cellular compartments. Nucleoside (1) and nucleotide ester (2) features two different anticancer activity profiles. At 24 h of treatment, the nucleoside acts mainly as a toxin and induces necrosis in HeLa cells, whereas the nucleotide ester exhibits pro-apoptotic activity. At longer treatment times (72 h), the nucleoside and the reference, gemcitabine hydrochloride, featured almost identical signs of anticancer activity, such as S-phase cell cycle arrest, proliferation inhibition, and apoptosis induction. In view of this data, one can hypothesize that despite the structural differences, the newly obtained phenanthrenyl GNA nucleoside (1) and gemcitabine may share a common mechanism of anticancer activity in HeLa cancer cells. The GNA components were also examined as antiplasmodial agents against Plasmodium falciparum, in vitro. Nucleoside (1) was found to be more potent than nucleotide (2), displaying activity in the low micromolar range. Furthermore, both phenanthrene derivatives were found to display resistance indices at least 9-fold lower than chloroquine diphosphate (CQDP).

The Effect of Photoperiod on Necrosis Development, Photosynthetic Efficiency and 'Green Islands' Formation in Brassica juncea Infected with Alternaria brassicicola.

The main goal of growing plants under various photoperiods is to optimize photosynthesis for using the effect of day length that often acts on plants in combination with biotic and/or abiotic stresses. In this study, Brassica juncea plants were grown under four different day-length regimes, namely., 8 h day/16 h night, 12 h day/12 h night, 16 h day/8 h night, and continuous light, and were infected with a necrotrophic fungus Alternaria brassicicola. The development of necroses on B. juncea leaves was strongly influenced by leaf position and day length. The largest necroses were formed on plants grown under a 16 h day/8 h night photoperiod at 72 h post-inoculation (hpi). The implemented day-length regimes had a great impact on leaf morphology in response to A. brassicicola infection. They also influenced the chlorophyll and carotenoid contents and photosynthesis efficiency. Both the 1st (the oldest) and 3rd infected leaves showed significantly higher minimal fluorescence (F0) compared to the control leaves. Significantly lower values of other investigated chlorophyll a fluorescence parameters, e.g., maximum quantum yield of photosystem II (Fv/Fm) and non-photochemical quenching (NPQ), were observed in both infected leaves compared to the control, especially at 72 hpi. The oldest infected leaf, of approximately 30% of the B. juncea plants, grown under long-day and continuous light conditions showed a 'green island' phenotype in the form of a green ring surrounding an area of necrosis at 48 hpi. This phenomenon was also reflected in changes in the chloroplast's ultrastructure and accelerated senescence (yellowing) in the form of expanding chlorosis. Further research should investigate the mechanism and physiological aspects of 'green islands' formation in this pathosystem.

Metal Homeostasis and Gas Exchange Dynamics in Pisum sativum L. Exposed to Cerium Oxide Nanoparticles.

Cerium dioxide nanoparticles are pollutants of emerging concern. They are rarely immobilized in the environment. This study extends our work on Pisum sativum L. as a model plant, cultivated worldwide, and is well suited for investigating additive interactions induced by nanoceria. Hydroponic cultivation, which prompts accurate plant growth control and three levels of CeO2 supplementation, were applied, namely, 100, 200, and 500 mg (Ce)/L. Phytotoxicity was estimated by fresh weights and photosynthesis parameters. Additionally, Ce, Cu, Zn, Mn, Fe, Ca, and Mg contents were analyzed by high-resolution continuum source atomic absorption and inductively coupled plasma optical emission techniques. Analysis of variance has proved that CeO2 nanoparticles affected metals uptake. In the roots, it decreased for Cu, Zn, Mn, Fe, and Mg, while a reversed process was observed for Ca. The latter is absorbed more intensively, but translocation to above-ground parts is hampered. At the same time, nanoparticulate CeO2 reduced Cu, Zn, Mn, Fe, and Ca accumulation in pea shoots. The lowest Ce concentration boosted the photosynthesis rate, while the remaining treatments did not induce significant changes. Plant growth stimulation was observed only for the 100 mg/L. To our knowledge, this is the first study that demonstrates the effect of nanoceria on photosynthesis-related parameters in peas.

Effects of exogenous compound sprays on cherry cracking: skin properties and gene expression.

BACKGROUND: Cherry fruit cracking is a costly problem for cherry growers. The effect of repeated sprayings (gibberellic acid - GA3 ; abscisic acid - ABA; salicylic acid - SA; glycine betaine - GB, and Ascophyllum nodosum - AN) combined with CaCl2 , on 'Sweetheart' cherry fruit-cracking characteristics was investigated. Cracking was quantified in terms of cracking incidence, crack morphology, confocal scanning laser microscopy, cuticular wax content, cell-wall modification, and cuticular wax gene expression. RESULTS: All spray treatments reduced cracking compared with an untreated control (H2 O), with fewer cheek cracks. The least cracking incidence was observed for ABA + CaCl2 - and GB + CaCl2 -treated fruits, indicating an added benefit compared to spraying with CaCl2 alone. In addition, GB + CaCl2 -treated fruits showed higher fruit diameter. ABA + CaCl2 and GB + CaCl2 sprays showed higher wax content and higher cuticle and epidermal thickness compared with the control, including increased expression of wax synthase (ABA + CaCl2 ) and expansin 1 (GB + CaCl2 ). CONCLUSION: In general, factors that improve the cuticle thickness appear to be important at the fruit-coloring stage. At the fruit-ripening stage, larger cell sizes of the epidermis, hypodermis, and parenchyma cells lower cracking incidence, indicating the importance of flexibility and elasticity of the epidermis. © 2020 Society of Chemical Industry.

Luminescent pyrenyl-GNA nucleosides: synthesis, photophysics and confocal microscopy studies in cancer HeLa cells.

Glycol nucleic acids (GNA) are synthetic genetic-like polymers with an acyclic three-carbon propylene glycol phosphodiester backbone. Here, synthesis, luminescence properties, circular dichroism (CD) spectra, and confocal microscopy speciation studies of (R,S) and (S,R) pyrenyl-GNA (pyr-GNA) nucleosides are reported in HeLa cells. Enantiomerically pure nucleosides were obtained by a Sharpless asymmetric dihydroxylation reaction followed by semi-preparative high-performance liquid chromatography (HPLC) separation using Amylose-2 as the chiral stationary phase. The enantiomeric relationship between stereoisomers was confirmed by CD spectra, and the absolute configurations were assigned based on experimental and theoretical CD spectra comparisons. The pyr-GNA nucleosides were not cytotoxic against human cervical (HeLa) cancer cells and thus were utilized as luminescent probes in the imaging of these cells with confocal microscopy. Cellular staining patterns were identical for both enantiomers in HeLa cells. Compounds showed no photocytotoxic effect and were localized in the lipid membranes of the mitochondria, in cellular vesicles and in other lipid cellular compartments. The overall distribution of the pyrene and pyrenyl-GNA nucleosides inside the living HeLa cells differed, since the former compound gives a more granular staining pattern and the latter a more diffuse one.

Adenosine Receptor Agonists Exhibit Anti-Platelet Effects and the Potential to Overcome Resistance to P2Y12 Receptor Antagonists.

Large inter-individual variation in platelet response to endogenous agonists and pharmacological agents, including resistance to antiplatelet therapy, prompts a search for novel platelet inhibitors and development new antithrombotic strategies. The present in vitro study evaluates the beneficial effects of three adenosine receptor (AR) agonists (regadenoson, LUF 5835 and NECA), different in terms of their selectivity for platelet adenosine receptors, when used alone and in combination with P2Y12 inhibitors, such as cangrelor or prasugrel metabolite. The anti-platelet effects of AR agonists were evaluated in healthy subjects (in the whole group and after stratification of individuals into high- and low-responders to P2Y12 inhibitors), using whole blood techniques, under flow (thrombus formation) and static conditions (study of platelet activation and aggregation). Compared to P2Y12 antagonists, AR agonists were much less or not effective under static conditions, but demonstrated similar antiplatelet activity in flow. In most cases, AR agonists significantly enhanced the anti-platelet effect of P2Y12 antagonists, despite possessing different selectivity profiles and antiplatelet activities. Importantly, their inhibitory effects in combination with P2Y12 antagonists were similar in high- and low-responders to P2Y12 inhibitors. In conclusion, a combination of anti-platelet agents acting via the P1 and P2 purinergic receptors represents a promising alternative to existing antithrombotic therapy.

Acridine/Acridone-Carborane Conjugates as Strong DNA-Binding Agents with Anticancer Potential.

Synthesis of acridine derivatives that act as DNA-targeting anticancer agents is an evolving field and has resulted in the introduction of several drugs into clinical trials. Carboranes can be of importance in designing biologically active compounds due to their specific properties. Therefore, a series of novel acridine analogs modified with carborane clusters were synthesized. The DNA-binding ability of these analogs was evaluated on calf thymus DNA (ct-DNA). Results of these analyses showed that 9-[(1,7-dicarba-closo-dodecaborane-1-yl)propylamino]acridine (30) interacted strongly with ct-DNA, indicating its ability to intercalate into DNA, whereas 9-[(1,7-dicarba-closo-dodecaborane-1-yl)propanamido]acridine (29) changed the B-form of ct-DNA to the Z form. Compound 30 demonstrated cytotoxicity, was able to inhibit cell proliferation, arrest the cell cycle in the S phase in the HeLa cancer cell line, and induced the production of reactive oxygen species (ROS). In addition, it was specifically localized in lysosomes and was a weak inhibitor of Topo IIα.

Replacement of the phosphodiester backbone between canonical nucleosides with a dirhenium carbonyl "click" linker-a new class of luminescent organometallic dinucleoside phosphate mimics.

The first-in-class luminescent dinucleoside phosphate analogs with a [Re2(µ-Cl)2(CO)6(µ-pyridazine)] "click" linker as a replacement for the natural phosphate group are reported together with the synthesis of luminescent adenosine and thymidine derivatives having the [Re2(µ-Cl)2(CO)6(µ-pyridazine)] entity attached to positions 5' and 3', respectively. These compounds were synthesized by applying inverse-electron-demand Diels-Alder and copper(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition reactions in three or four steps. The obtained compounds exhibited orange emission (λPL ≈ 600 nm, ΦPL ≈ 0.10, and τ = 0.33-0.61 µs) and no toxicity (except for one nucleoside) to human HeLa cervical epithelioid and Ishikawa endometrial adenocarcinoma cancer cells in vitro. Furthermore, the compounds' ability to inhibit the growth of Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacterial strains was moderate and only observed at a high concentration of 100 µM. Confocal microscopy imaging revealed that the "dirhenium carbonyl" dinucleosides and nucleosides localized mainly in the membranous structures of HeLa cells and uniformly inside S. aureus and E. coli bacterial cells. An interesting finding was that some of the tested compounds were also found in the nuclei of HeLa cells.

Complexity of Brassica oleracea-Alternaria brassicicola Susceptible Interaction Reveals Downregulation of Photosynthesis at Ultrastructural, Transcriptional, and Physiological Levels.

Black spot disease, caused by Alternaria brassicicola in Brassica species, is one of the most devastating diseases all over the world, especially since there is no known fully resistant Brassica cultivar. In this study, the visualization of black spot disease development on Brassica oleracea var. capitata f. alba (white cabbage) leaves and subsequent ultrastructural, molecular and physiological investigations were conducted. Inter- and intracellular hyphae growth within leaf tissues led to the loss of host cell integrity and various levels of organelle disintegration. Severe symptoms of chloroplast damage included the degeneration of chloroplast envelope and grana, and the loss of electron denseness by stroma at the advanced stage of infection. Transcriptional profiling of infected leaves revealed that photosynthesis was the most negatively regulated biological process. However, in infected leaves, chlorophyll and carotenoid content did not decrease until 48 hpi, and several chlorophyll a fluorescence parameters, such as photosystem II quantum yield (Fv/Fm), non-photochemical quenching (NPQ), or plant vitality parameter (Rdf) decreased significantly at 24 and 48 hpi compared to control leaves. Our results indicate that the initial stages of interaction between B. oleracea and A. brassicicola are not uniform within an inoculation site and show a complexity of host responses and fungal attempts to overcome host cell defense mechanisms. The downregulation of photosynthesis at the early stage of this susceptible interaction suggests that it may be a part of a host defense strategy, or, alternatively, that chloroplasts are targets for the unknown virulence factor(s) of A. brassicicola. However, the observed decrease of photosynthetic efficiency at the later stages of infection is a result of the fungus-induced necrotic lesion expansion.

Near Infrared Phosphorescent Dinuclear Ir(III) Complex Exhibiting Unusually Slow Intersystem Crossing and Dual Emissive Behavior.

A dinuclear iridium(III) complex IrIr shows dual emission consisting of near infrared (NIR) phosphorescence (λmax = 714 nm, CH2Cl2, T = 300 K) and green fluorescence (λmax = 537 nm). The NIR emission stems from a triplet state (T1) localized on the ditopic bridging ligand (3LC). Because of the dinuclear molecular structure, the phosphorescence efficiency (ΦPL = 3.5%) is high compared to those of other known red/NIR-emitting iridium complexes. The weak fluorescence stems from the lowest excited singlet state (S1) of 1LC character. The occurrence of fluorescence is ascribed to relatively slow intersystem crossing (ISC) from state S1 (1LC) to the triplet manifold. The measured ISC rate corresponds to a time constant τISC of 2.1 ps, which is an order of magnitude longer than those usually found for iridium complexes. This slow ISC rate can be explained in terms of the LC character and large energy separation (0.57 eV) of the respective singlet and triplet excited states. IrIr is internalized by live HeLa cells as evidenced by confocal luminescence microscopy.

Ruthenium dendrimers against acute promyelocytic leukemia: in vitro studies on HL-60 cells.

Coordination of ruthenium arene fragments on carbosilane dendrimers' surface greatly increases their antitumor properties. Newly synthetized ruthenium dendrimers are water-soluble, monodisperse and stable. Since carbosilane dendrimers are good carriers of drugs and genes, the presence of ruthenium in their structure makes them promising candidates for new drug delivery systems with improved antitumor potential. Carbosilane ruthenium dendrimers are more toxic to cancer cells than normal cells. Results of several in vitro studies applied here indicate that carbosilane ruthenium dendrimers induce apoptosis in promyelocytic leukemia HL-60 cells.

Comparison of different microscopy approaches to quantification of inhibitory effect on thrombus formation under flow conditions by the example of adenosine receptor agonist HE-NECA.

INTRODUCTION: Thrombus formation in vitro in flow conditions and its visualization and quantification with the use of microscopy are widely utilized to evaluate activity of compounds with a potential antithrombotic activity. Visualization and quantification of thrombi can be performed with the use of wide-field or confocal microscopy. Acquiring reliable numerical data from wide-field microscopy images of objects which have a complex three-dimensional structure is strongly influenced by the methods used for image analysis. This can be a possible source of inaccuracy in assessment of antithrombotic activity of a tested substance. We aimed to verify how different approaches to the quantification of wide-field images can affect the evaluation of an antiplatelet effect of a tested substance. METHODS: We compared three algorithms of image analysis to evaluate an effect of 2-hexynyl-5'-ethylcarboxamidoadenosine (HE-NECA), a compound of a moderate antiplatelet activity on thrombus formation, and of abciximab - a potent antiplatelet compound. Also, we studied how the results obtained in a wide-field imaging correspond to those obtained by means of confocal imaging. RESULTS: Three algorithms for analysis of wide-field images showed antiplatelet effect of HE-NECA or abciximab. Absolute values of thrombus area and outcomes of the evaluation of inhibition efficacy of HE-NECA were significantly different between the algorithms. Analysis of volumes and heights of thrombi obtained by confocal imaging confirmed inhibitory effect of HE-NECA, but the evaluated levels of inhibition were significantly different from that obtained by wide-field imaging. DISCUSSION: We conclude that wide-field imaging provides reliable qualitative data on an inhibitory effect on thrombus formation, despite differences which can emerge from various approaches to image analysis. However, quantitative evaluation and comparison of the efficacy of inhibitors on the basis of total area occupied by thrombi obtained by wide-field microscopy should be made with caution. To obtain a reliable quantitative assessment of the effect of a tested compound on thrombus structure the use of confocal microscopy is inevitable.

Analysis of Triticum aestivum seedling response to the excess of zinc.

The effects of 50 and 300 mg L(-1) Zn(2+) (50 Zn and 300 Zn) were investigated in Triticum aestivum (cv. Zura) grown hydroponically for 7 days. Although wheat treated with 50 Zn took up relatively high amount of the metal (8,943 and 1,503 mg kg(-1) DW in roots and shoots, respectively), none of the morphological and cytological parameters were changed. After 300 Zn, the metal concentration increased to 32,205 and 5,553 mg kg(-1) DW in roots and shoots, respectively. It was connected with the depletion of shoot and root growth, their fresh and dry weight, water content and mitotic index of root meristematic cells. Microelement contents (Cu, Mn and Fe) after 50 Zn were changed only in roots, while 300 Zn disturbed ion balance in whole plants. The most evident ultrastructural alterations of root meristematic cells caused by both tested Zn(2+) doses included increased vacuolization, accumulation of granular deposits inside vacuoles and cell wall thickening. The effect of 300 Zn on root cell ultrastructure was greater that of 50 Zn. The majority of mitochondria had condensed matrix and swollen cristae, plastids contained plastoglobuli, nucleoli were ring-shaped, thinned down cytoplasm with lipid droplets and swollen endoplasmic reticulum cisternae appeared. In mesophyll cells, 50 Zn caused slight reorganization of chloroplast thylakoids and formation of condensed mitochondria. Three hundred Zn triggered more extensive, but not degenerative, changes: plasmolysis of some cells; chloroplasts with protrusions, changed thylakoid organisation and often large starch grains; irregular, condensed mitochondria. The results indicate that T. aestivum cv. Zura is relatively tolerant to Zn stress.

Silver nanoparticles: a mechanism of action on moulds.

Silver nanoparticles (AgNPs) are widely used in all branches of industry. However, their mechanisms of action towards moulds have not been studied yet. Thus we conducted this study in which we have used laser desorption/ionization time-of-flight mass spectrometry (LDI-ToF-MS) analysis to determine metabolomic changes, and microscopic analysis (transmission electron microscopy, fluorescent microscopy) to observe changes in mould cells. The AgNP treatment caused the downregulation of 162 (15 ppm) and 284 (62 ppm), and 19 (15 ppm) and 29 (62 ppm) metabolites of Aspergillus niger and Penicillium chrysogenum, respectively. All influenced features were below m/z 600 (mass-to-charge ratio). We have observed silver ions and their clusters (Ag, Ag2, and Ag3) accumulated in the mould mycelium. As well as, mono-silver ion adducts with nucleotide derivatives (Coenzyme A), amino acids (phenylglycine), peptides (LeuSerAlaLeuGlu) and lipids (fatty acids, diacylglycerophosphoglycerols, monoglicerides and glycerophospholipids). The ultrastructure analysis revealed many sever alterations due to the action of AgNPs, such us shortening and condensation of hyphae, ultrastructural reorganisation, cell plasmolysis, increased vacuolisation, numerous membranous structures, collapsed cytoplasm, accumulation of lipid material, condensed mitochondria, disintegration of organelles, nuclear deformation, condensation and fragmentation of chromatin, creation of apoptotic bodies, as well as a new inside cell wall in P. chrysogenum.

The effect of pre-incubation of Allium cepa L. roots in the ATH-rich extract on Pb uptake and localization.

The positive influence of anthocyanin (ATH) on toxic metal-treated plant material is well documented; however, it is still not explained if it is caused by changes in element absorption and distribution. Therefore, detailed analysis of the effect of the ATH-rich extract from red cabbage leaves on Pb uptake and localization at morphological, anatomical and ultrastructural level was the goal of this study. Two-day-old adventitious roots of Allium cepa L. (cv. Polanowska) were treated for 2 h with the aqueous solution of Pb(NO3)2 at the concentration of 100 µM with or without preliminary incubation in the anthocyanin-rich extract from Brassica oleracea L. var. capitata rubra leaves (250 µM, 3 h). The red cabbage extract did not change the total Pb uptake but it enhanced the translocation of accumulated metal from roots to shoots. Within the pretreated roots, more Pb was deposited in their basal part and definitely smaller amount of the metal was bound in the apoplast of the outer layers of cortex cells. The ultrastructural analysis (transmission electron microscopy and X-ray microanalysis) revealed that the ATH-rich extract lowered the number of Pb deposits in intracellular spaces, cell wall and cytoplasm of root meristematic cells as well as in such organelles important to cell metabolism as mitochondria, plastids and nucleus. The Pb deposits were preferably localised in those vacuoles where ATH also occurred. This sequestration of Pb in vacuoles is probably responsible for reduction of metal cytotoxicity and consequently could lead to better plant growth.