Diacetylene-containing polymers,II. Polyesters and polyurethanes containing m,m′-butadiynylenedibenzyl groups

Diacetylene-containing polyesters and polyurethanes were prepared by the reaction of m,m-butadiynylenedibenzyl alcohol with isophthaloyl chloride, sebacoyl chloride, hexamethylene diisocyanate and 2,4-tolylene diisocyanate. Their thermal behavior was studied by optical microscope and differential scanning calorimetry (DSC). The polyesters were crystalline. The polyurethane prepared from hexamethylene diisocyanate and polyphthalates crystallized on cooling from their melts. All turned a reddish brown color on heating at temperatures above 200°C, and prolonged heating led to a black resin, but thermal decomposition could not be avoided. Irradiation by γ-ray and UV light at room temperature deepened the color of the films, but the polymerization of the diacetylene groups was not appreciable. Simultaneous heating and irradiation was necessary to obtain transparent, amorphous, wine red colored films.     

Carbon-13 nuclear magnetic resonance spectra of some heterocyclic D-homoandrostanes

The ¹³C chemical shift data of several D-homoandrostanes with heteroatoms (N,O) in the 17a-position are reported. Heteroatom effects on the shieldings of the carbons of rings C and D are discussed.     

Kinetische Untersuchungen über den Zerfall der Äthylnitrolsäure in saurer Lösung

Zusammenfassung Die Kinetik der Zersetzung der Äthylnitrolsäure in saurer Lösung zu Essigsäure und Stickoxydul wird an der Abnahme der Nitrolsäure und an der Bildung des Stickoxyduls gemessen. Zur Ermittlung der jeweiligen Konzentrationen der Nitrolsäure werden Proben des Reaktionsgemisches mit überschüssiger Natronlauge versetzt; der Gehalt dieser Lösungen an (rotgefärbtem) Natriumsalz der Nitrolsäure wird mit dem Stufenphotometer ermittelt. Es wird gefunden, daß unter den gegebenen Versuchsbedingungen die Äthylnitrolsäure nach dem Gesetz erster Ordnung zerfällt und daß diese Reaktion von Wasserstoffionen katalysiert wird.Mit 5 Abbildungen.Auszug aus der Dissertation vonA. Mirna, Techn. Hochschule Wien (1949).     

Chemical Analysis and In Vitro Bioactivity of Essential Oil of Laurelia sempervirens and Safrole Derivatives against Oomycete Fish Pathogens

In this study, the essential oil (EO) from Laurelia sempervirens was analyzed by GC/MS and safrole (1) was identified as the major metabolite 1, was subjected to direct reactions on the oxygenated groups in the aromatic ring and in the side chain, and eight compounds (4 to 12) were obtained by the process. EO and compounds 4–12 were subjected to biological assays on 24 strains of the genus Saprolegnia, specifically of the species 12 S. parasitica and 12 S. australis. EO showed a significant effect against Saprolegnia strains. Compound 6 presents the highest activity against two resistant strains, with minimum inhibitory concentration (MIC) and minimum oomyceticidal concentration (MOC) values of 25 to 100 and 75 to 125 µg/mL, respectively. The results show that compound 6 exhibited superior activities compared to the commercial controls bronopol and azoxystrobin used to combat these pathogens.     

Traceless chemical ligations from O-acyl serine sites

Chemical ligation via O- to N-acyl transfer of O-acylated serine containing peptides affords serine containing native peptides via 8- and 11-membered cyclic transition states opening the door to a wide variety of potential applications to peptide elaboration. The feasibility of these traceless chemical ligations is feasible as supported by computation.     

Coffee Chlorogenic Acids Incorporation for Bioactivity Enhancement of Foods: A Review

The demand of foods with high antioxidant capacity have increased and research on these foods continues to grow. This review is focused on chlorogenic acids (CGAs) from green coffee, which is the most abundant source. The main CGA in coffee is 5-O-caffeoylquinic acid (5-CQA). Coffee extracts are currently the most widely used source to enhance the antioxidant activity of foods. Due to the solubility of CGAs, their extraction is mainly performed with organic solvents. CGAs have been associated with health benefits, such as antioxidant, antiviral, antibacterial, anticancer, and anti-inflammatory activity, and others that reduce the risk of cardiovascular diseases, type 2 diabetes, and Alzheimer’s disease. However, the biological activities depend on the stability of CGAs, which are sensitive to pH, temperature, and light. The anti-inflammatory activity of 5-CQA is attributed to reducing the proinflammatory activity of cytokines. 5-CQA can negatively affect colon microbiota. An increase in anthocyanins and antioxidant activity was observed when CGAs extracts were added to different food matrices such as dairy products, coffee drinks, chocolate, and bakery products. The fortification of foods with coffee CGAs has the potential to improve the functionality of foods.     

A novel bis-phenanthridine triamine with pH controlled binding to nucleotides and nucleic acids

The new bis-phenanthridine triamine is characterised by three pK(a) values: 3.65; 6.0 and >7.5. A significant difference in the protonation state of at pH = 5 (four positive charges) and at pH = 7 (less than two positive charges) accounts for the strong dependence of -nucleotide binding constants on nucleotide charge under acidic conditions, whereas at neutral pH all -nucleotide complexes are of comparable stability. All experimental data point at intercalation as the dominant binding mode of to polynucleotides. However, there is no indication of bis-intercalation of the two phenanthridine subunits in binding to double stranded polynucleotides, the respective complexes being most likely mono-intercalative. Thermal stabilisation of calf thymus DNA (ct-DNA) and poly A-poly U duplexes upon addition of is significantly higher at pH = 5 than at neutral conditions. This is not the case with poly dA-poly dT, indicating that the specific secondary structure of the latter, most likely the shape of the minor groove, plays a key role in complex stability. At pH = 5 acts as a fluorimetric probe for poly G (emission quenching) as opposed to other ss-polynucleotides (emission increase), while at neutral conditions this specificity is lost. One order of magnitude higher cytotoxicity of compared to its "monomer" can be accounted for by cooperative action of two phenanthridinium units and the charged triamine linker. The results presented here are of interest to the development of e.g. sequence-selective cytostatic drugs, and in particular for the possibility to control the drug activity properties over binding to DNA and/or RNA by variation of the pH of its surrounding.     

Sulfide analysis by the silver sulfide-silver electrode

Summary The study was performed to evaluate the usefulness of the silver sulfide-silver electrode for measuringsulfldes in foods by means of the electromotive force of the cell saturated calomel electrode/S^2–/Ag₂S, Ag. The electrode response to sulfide ion activity over the pH interval 3 to 12 was determined, and procedures for the standardization of the silver sulfide-silver electrode are discussed.

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Sulfidanalyse mit Hilfe der Silbersulfid/Silberelektrode

Zusammenfassung Ziel der Untersuchungen ist es, die Silbersulfid/Silberelektrode auf ihre Verwendbarkeit zurMessung von Sulfiden in Lebensmitteln zu prüfen. Die vorliegende Mitteilung befaßt sich mit dem Einfluß des pH-Wertes im Bereich von 3–12 auf das Potential sowie mit den Möglichkeiten der Standardisierung des Elektrodensystems gesättigte Kalomelelektrode/S^2–/Ag₂S, Ag.