PIDAZTA: Structurally Constrained Chelators for the Efficient Formation of Stable Gallium-68 Complexes at Physiological pH.

Two structurally constrained chelators based on a fused bicyclic scaffold, 4-amino-4-methylperhydro-pyrido[1,2-a][1,4]diazepin-N,N',N'-triacetic acids [(4R*,10aS*)-PIDAZTA (L1) and (4R*,10aR*)-PIDAZTA (L2)], were designed for the preparation of GaIII -based radiopharmaceuticals. The stereochemistry of the ligand scaffold has a deep impact on the properties of the complexes, with unexpected [Ga(L2)OH] species being superior in terms of both thermodynamic stability and inertness. This peculiar behavior was rationalized on the basis of molecular modeling and appears to be related to a better fit in size of GaIII into the cavity of L2. Fast and efficient formation of the GaIII chelates at room temperature was observed at pH values between 7 and 8, which enables 68 Ga radiolabeling under truly physiological conditions (pH 7.4).

Dithallium(III)-Containing 30-Tungsto-4-phosphate, [Tl2Na2(H2O)2(P2W15O56)2]16-: Synthesis, Structural Characterization, and Biological Studies.

Here we report on the synthesis and structural characterization of the dithallium(III)-containing 30-tungsto -4-phosphate [Tl2Na2(H2O)2{P2W15O56}2]16- (1) by a multitude of solid-state and solution techniques. Polyanion 1 comprises two octahedrally coordinated Tl3+ ions sandwiched between two trilacunary {P2W15} Wells-Dawson fragments and represents only the second structurally characterized, discrete thallium-containing polyoxometalate to date. The two outer positions of the central rhombus are occupied by sodium ions. The title polyanion is solution-stable as shown by 31P and 203/205Tl NMR. This was also supported by Tl NMR spectra simulations including several spin systems of isotopologues with half-spin nuclei (203Tl, 205Tl, 31P, 183W). 23Na NMR showed a time-averaged signal of the Na+ counter cations and the structurally bonded Na+ ions. 203/205Tl NMR spectra also showed a minor signal tentatively attributed to the trithallium-containing derivative [Tl3Na(H2O)2(P2W15O56)2]14-, which could also be identified in the solid state by single-crystal X-ray diffraction. The bioactivity of polyanion 1 was also tested against bacteria and Leishmania.

Equilibrium, Kinetic and Structural Properties of Gallium(III) and Some Divalent Metal Complexes Formed with the New DATAm and DATA5m Ligands.

The development of 68 Ge/68 Ga generators has made the positron-emitting 68 Ga isotope widely accessible and raised interest in new chelate complexes of Ga3+ . The hexadentate 1,4-di(acetate)-6-methyl[amino(methyl)acetate]perhydro-1,4-diazepane (DATAm ) ligand and its bifunctional analogue, 1,4-di(acetate)-6-pentanoic acid[amino(methyl)acetate]perhydro-1,4-diazepane (DATA5m ), rapidly form complexes with 68 Ga in high radiochemical yield. The stability constants of DATAm and DATA5m complexes formed with Ga3+ , Zn2+ , Cu2+ , Mn2+ and Ca2+ have been determined by using pH potentiometry, spectrophotometry (Cu2+ ) and 1 H and 71 Ga NMR spectroscopy (Ga3+ ). The stability constants of Ga(DATAm ) and Ga(DATA5m ) complexes are slightly higher than those of Ga(AAZTA). The species distribution calculations indicated the predominance of Ga(L)OH mixed-hydroxo complexes at physiological pH. The 1 H and 71 Ga NMR spectroscopy studies provided information about the coordinated functional groups of ligands and on the kinetics of exchange between the Ga(L) and Ga(L)OH complexes. The transmetalation reactions between the Ga(L) complexes and Cu2+ citrate (6

Cryptogamic Biomass in Pannonic Acidic Sand Steppes Subject to Changing Land-Use.

Cryptogams, often neglected in vegetation dynamics studies, compose a large part of biomass and contribute to the biodiversity of sandy grasslands. Since the work of Verseghy (1970s), their productivity has not been analyzed in Hungary. We studied the lichen and bryophyte dynamics (hereinafter called cryptogams) at two Eastern Hungarian dry sandy grassland sites. The sites of Corynephorus canescens and of Festuca vaginata dominance, respectively, belonging to the community Festuco vaginatae-Corynephoretum have been monitored. We aimed at (1) quantifying the diversity and biomass of the cryptogamic communities; (2) exploring the cryptogamic response to management changes; and (3) studying the effect of experimental management (fencing) on the cryptogamic assemblages. The sites have been compared in 2013 and 2018, respectively. Forty microplots per site per management have been analyzed in both years. Samples of lichens and bryophytes were hand-sorted, dried and then measured. Fencing has led to increased biomass of cryptogams within a few years. Lichens in general benefited comparatively more from exclosure than bryophytes. The increase in lichen biomass (especially that of Cladonia rangiformis) is clearly due to the over 10-year absence of grazing. The only lichen favored by moderate grazing is the legally protected C. magyarica. Short spells of low-intensity grazing can promote the species richness of cryptogams in the community.

Cryptogamic communities on flatroofs in the city of Debrecen (East Hungary).

Cryptogams of ten urban flatroofs, contrasting in their age and size, were studied between 2016 and 2018. Siliceous (bituminous felt, gravel, brick) and calcareous (concrete) substrata occurred at each site. Microclimate (T, RH) at two sites of contrasting shading was monitored from September 2016 to January 2017. Biomass of two differently aged, exposed flatroofs was sampled in October 2018. Taxa of Cladonia and Xanthoparmelia have been identified by spot tests and HPTLC. A total of 61 taxa (25 bryophytes, 36 lichens), mostly widespread synanthropic species, have been detected with an explicit difference of species composition between shaded and exposed sites. Floristically interesting species included acidophilous bryophytes (Hedwigia ciliata, Racomitrium canescens) and lichens (Xanthoparmelia conspersa, Stereocaulon tomentosum) of montane character. The most widespread lichen is Cladonia rei which accounted for a significant part of the biomass at selected sites. Species-area curves for bryophytes at exposed sites have become saturated at 100-150 m2. In contrast, saturation of lichen diversity has not been reached even at the largest sites. Flatroofs with traditional roofing techniques can harbour relatively diverse microhabitats and species-rich synanthropic vegetation. It is urgent to study these sites before renovation with modern roofing techniques eliminates them. Diversification of urban surroundings is possible in the future via application of various substrats in renovated and newly constructed roofs.

The long-term effect of removing the UV-protectant usnic acid from the thalli of the lichen Cladonia foliacea.

Terricolous lichens are abundant in semi-arid areas, where they are exposed to high irradiation. Photoprotection is essential for the algae as the photobiont provides the primer carbon source for both symbionts. The UV-protectant lichen metabolites and different quenching procedures of the alga ensure adequate photoprotection. Since the long-term effect of diminishing UV-protectant lichen metabolites is unknown, a major part of lichen secondary metabolites was removed from Cladonia foliacea thalli by acetone rinsing, and the lichens were then maintained under field conditions to investigate the effect on both symbionts for 3 years. Our aim was to determine if the decreased level of UV-protectant metabolites caused an elevated photoprotection in the algae and to reveal the dynamics of production of the metabolites. Photosynthetic activity and light protection were checked by chlorophyll a fluorescence kinetics measurements every 6 months. The concentrations of fumarprotocetraric and usnic acids were monitored by chromatographic methods. Our results proved that seasonality had a more pronounced effect than that of acetone treatment on the function of lichens over a long-term scale. Even after 3 years, the acetone-treated thalli contained half as much usnic acid as the control thalli, and the level of photoprotection remained unchanged in the algae. However, the amount of available humidity was a more critical limiting environmental factor than the amount of incoming irradiation affecting usnic acid production. The lichenicolous fungus Didymocyrtis cladoniicola became relatively more abundant in the acetone-treated samples than in the control samples, indicating a slight change caused by the treatment. Supplementary Information: The online version contains supplementary material available at 10.1007/s11557-022-01831-y.

Distribution Types of Lichens in Hungary That Indicate Changing Environmental Conditions.

Distribution data originating from earlier herbarium collections and recent biodiversity records form the basis of distribution analyses in lichen species with different ecological requirements, where the records allowed comparisons or showed clear trends. As the occurrences of lichens are strongly correlated to background environmental conditions (e.g., air pollution, global warming), confirmed by Wirth's ecological indicator values, the analysis of distribution types has a great value for bioindication and the establishment of current and future climatic and pollution situations. Five distribution types were introduced-presented by characteristic examples (13)-according to lichen distribution maps prepared in different periods of time (representing changing environmental conditions): (1) species of decreasing occurrences by time (e.g., Lobaria pulmonaria, Menegazzia terebrata, suboceanic, acidic pollution sensitive species), (2) species with no or few former records but with increasing occurrences in recent decades (e.g., Flavoparmelia soredians, Hyperphyscia adglutinata, Solenopsora candicans, sub-Mediterranean species), (3) species with increasing and then (from c. 2000) decreasing occurrences (e.g., Scoliciosporum chlorococcum, Straminella conizaeoides, acidofrequent species), (4) species with widely increasing occurrences in recent decades (e.g., Physcia aipolioides, Piccolia ochrophora, Xanthoria parietina, nitrofrequent species), and (5) species with rapidly increasing occurrences (e.g., Absconditella lignicola, Coenogonium pineti, Evernia divaricata, rapidly spreading species). The proposed distribution types of lichen species may be applied to wider regions (the European or the global level).

Current results on biological activities of lichen secondary metabolites: a review.

Lichens are symbiotic organisms of fungi and algae or cyanobacteria. Lichen-forming fungi synthesize a great variety of secondary metabolites, many of which are unique. Developments in analytical techniques and experimental methods have resulted in the identification of about 1050 lichen substances (including those found in cultures). In addition to their role in lichen chemotaxonomy and systematics, lichen secondary compounds have several possible biological roles, including photoprotection against intense radiation, as well as allelochemical, antiviral, antitumor, antibacterial, antiherbivore, and antioxidant action. These compounds are also important factors in metal homeostasis and pollution tolerance of lichen thalli. Although our knowledge of the contribution of these extracellular products to the success of the lichen symbiosis has increased significantly in the last decades, their biotic and abiotic roles have not been entirely explored.

Study on the release of chlorhexidine base and salts from different liquid crystalline structures.

The aim of this study was to investigate the influence of two types of chlorhexidine species, chlorhexidine base and its salts, on the physico-chemical features of liquid crystalline systems and on drug transport through lipophilic membranes. A non-ionic surfactant, Synperonic A7 (PEG7-C13-15) was selected for the preparation of the liquid crystalline systems. Mixtures of different ratios of Synperonic A7 and water were prepared. The liquid crystalline systems were characterized using polarizing microscopy and dynamic oscillatory test. Membrane transport was also examined. The addition of chlorhexidine species to the liquid crystalline system modified the structure of the liquid crystalline system. As a result of the changes of liquid crystalline structures, the drug release of various types of chlorhexidine could be also modified. The combination of the base and salt forms of the drug in one dosage form could eliminate the drug release changes from liquid crystalline systems of dynamically changeable structures.

Cryptothecia austrocoreana (Arthoniales, Arthoniaceae), a New Species from South Korea.

Cryptothecia austrocoreana is a new lichen species from South Korea. The species is characterized by the presence of a heteromerous thallus and faveolate ascigerous area (ascomata) immersed in a slightly raised thallus. The species has muriform ascospores, (4)6-8-spored 8-11 × 3-4 septate, (34)36-48(51) × (17)19-23(25) µm. Atranorin, chloroatranorin, and barbatic acid are present. In the phylogenetic tree, C. austrocoreana belongs to the arthonioid clade in Arthoniaceae.

Effect of long-term storage and use on the properties of reversed-phase liquid chromatographic columns.

In order to study column deterioration as a result of long-term storage and/or usage in liquid chromatography analyses, 55 pairs (same batch) of different commercial reversed-phase C(18) columns were examined using an already existing column characterisation system. After initial testing, one column was stored and the other was used to analyse different pharmaceuticals. All columns were characterized by four chromatographic parameters reflecting hydrophobicity, silanol activity, metal impurity and steric selectivity at the beginning and at the end of the test. An F-value was calculated to express the change of column properties with one single number. After performing analyses, higher F-values were obtained as compared to the non-used, stored columns. Although the time during which the columns were used to perform analyses was relatively short, an obvious influence was noticed, mainly resulting from small changes in silanol activity and hydrophobicity. Most of the affected columns have no endcapping and/or no base deactivation, making them more vulnerable for degradation, resulting in higher silanol activity and faster ageing. This effect is observed less with columns equipped with polar-embedded groups and/or polar endcapping, protecting the column by blocking the silanol groups and attracting a shielding water layer. Also columns with higher coverages and bulky or long chains show more resistance towards degradation.

Kinetics and mechanism of the reactions of CH3CO and CH3C(O)CH2 radicals with O2. Low-pressure discharge flow experiments and quantum chemical computations.

The reactions CH(3)CO + O(2)--> products (1), CH(3)CO + O(2)--> OH +other products (1b) and CH(3)C(O)CH(2) + O(2)--> products (2) have been studied in isothermal discharge flow reactors with laser induced fluorescence monitoring of OH and CH(3)C(O)CH(2) radicals. The experiments have been performed at overall pressures between 1.33 and 10.91 mbar of helium and 298 +/- 1 K reaction temperature. OH formation has been found to be the dominant reaction channel for CH(3)CO + O(2): the branching ratio, Gamma(1b) = k(1b)/k(1), is close to unity at around 1 mbar, but decreases rapidly with increasing pressure. The rate constant of the overall reaction, k(2), has been found to be pressure dependent: the fall-off behaviour has been analysed in comparison with reported data. Electronic structure calculations have confirmed that at room temperature the reaction of CH(3)C(O)CH(2) with O(2) is essentially a recombination-type process. At high temperatures, the further reactions of the acetonyl-peroxyl adduct may yield OH radicals, but the most probable channel seems to be the O(2)-catalysed keto-enol transformation of acetonyl. Implications of the results for atmospheric modelling studies have been discussed.