Thermodynamic Properties of Binary Mixtures of Cyclohexanone with n-Alkanols (C1–C5) at 293.15 K

The excess molar volumes (V^E), excess surface tensions (σ^E), and deviations in molar refraction (R^E) and isentropic compressibility (k_s^E) of binary mixtures of cyclohexanone with methanol, ethanol, 1-propanol, 1-butanol, and 1-pentanol have been determined over the entire composition range at 293.15 K. The results were fitted by the Redlich–Kister polynomial equation and the corresponding binary coefficients A_k have been derived. The standard deviations between the calculated and the experimental excess properties have been determined. The results provide information on the interactions of the molecules in the pure liquids as well as in the binary mixtures.     

Solvation of copper(II) sulfate in binary water/N,N-dimethylformamide mixtures: from the solution to the gas phase

The solvation of copper(II) sulfate in binary mixtures of water and N,N-dimethylformamide (DMF) is studied by a combined approach using electrochemical studies in solution and a mass spectrometric assay of the solvated ions formed from these solutions upon electrospray ionization (ESI). In the condensed phase, the limiting transference numbers (t(+/-)(o)) and the apparent ion association constants (K(A)'s) of CuSO(4) have been determined in water/DMF solutions at 20 degrees C. The t(+)(o) values decrease with increasing DMF content, demonstrating a gradual solvation of Cu(2+) by DMF molecules. The association constants indicate that aggregation becomes more pronounced as the DMF content increases. In order to achieve complementary insight, the intrinsic interactions among the ions and solvent molecules are investigated in gas-phase experiments of the CuSO(4)/water/DMF system using ESI mass spectrometry. Under the conditions used, the dications [Cu(DMF)(n)](2+) (n = 3-6), [Cu(2)(DMF)(n)SO(4)](2+) (n = 2-7), and [Cu(3)(DMF)(n)(SO(4))(2)](2+) (n = 2-7), and the monocations [Cu(OH)(DMF)(n)](+), [Cu(DMF)(n)(HSO(4))](+) (both, n = 1-3), and [Cu(DMF)(n)](+) (n = 1, 2), are formed as the leading copper-containing cations. Likewise, polynuclear copper clusters observed in the anion ESI spectra support partial aggregation occurring in solution. The gas-phase studies clearly support the conclusions that (i) DMF is a highly preferred ligand for CuII in comparison to water and that (ii) DMF supports ion association for which the mass spectrometric data suggest the formation of polynuclear copper clusters.     

New metabolites with antibacterial activity from the marine angiosperm Cymodocea nodosa

Four new metabolites (1-4) have been isolated from the organic extract of the seagrass Cymodocea nodosa, collected at the coastal area of Porto Germeno, in Attica Greece. Compounds 1 and 2 belong to the structural class of diarylheptanoids, which have been found only once before in marine organisms [Kontiza, I.; Vagias, C.; Jakupovic, J.; Moreau, D.; Roussakis, C.; Roussis, V. Tetrahedron Lett.2005, 46, 2845-2847]. Compound 3 is a new meroterpenoid, while compound 4, to the best of our knowledge, is the first briarane diterpene isolated from seaweeds, and only the second analog of this class with a tricyclic skeleton. Furthermore metabolite 4 is the first brominated briarane diterpene. The structures and the relative stereochemistry of the new natural products were established by spectral data analyses. The new metabolites were submitted for evaluation of their antibacterial activity against multidrug-resistant (MDR) pathogens including methicillin-resistant (MRSA) strains of Staphylococcus aureus, as well as the rapidly growing mycobacteria, Mycobacterium phlei, Mycobacterium smegmatis, and Mycobacterium fortuitum.     

Occurrence of Disinfection By-Products in Swimming Pools in the Area of Thessaloniki,Northern Greece. Assessment of Multi-Pathway Exposure and Risk

This study investigated the occurrence of disinfection by-products (DBPs) (trihalomethanes (THMs), haloacetic acids (HAAs), halonitriles (HANs), halonitromethane (TCNM) and haloketones (HKs)) in different type of swimming pools in the area of Thessaloniki, northern Greece by employing the EPA methods 551.1 and 552.3. Moreover, general water quality parameters (pH, residual chlorine, dissolved organic carbon, UV₂₅₄ absorption, total nitrogen, alkalinity and conductivity) were also measured. The concentrations of DBPs showed great variability among swimming pools as well as within the same pool between sampling campaigns. HAAs exhibited the highest concentrations followed by THMs, HANs, TCNM and HKs. Exposure doses for four age groups (3–<6 y, 6–<11 y, 11–<16 y and adults) were calculated. Route-specific exposures varied among DBPs groups. Inhalation was the dominant exposure route to THMs and TCNM (up to 92–95%). Ingestion and dermal absorption were the main exposure routes to HAAs (40–82% and 18–59%, respectively), depending on the age of swimmers. HANs contributed up to 75% to the calculated cytotoxicity of pool water. Hazard indices for different exposure routes were <1, suggesting non-carcinogenic risk. Inhalation posed the higher carcinogenic risk for THMs, whereas risk via oral and dermal routes was low. Ingestion and dermal contact posed the higher risk for HAAs. Risk management strategies that minimise DBPs exposure without compromising disinfection efficiency in swimming pools are necessary.     

Quality Parameters of Wheat Bread with the Addition of Untreated Cheese Whey

Τhe present study was carried out to evaluate wheat bread of three different flour compositions prepared by replacing water with untreated cheese whey (WCB). Bread prepared with water was taken as the control (CB). All breads were stored at 24 ± 1 °C for up to 6 days. Microbiological, physicochemical, and sensory analyses were determined as a function of storage time. WCB had lower total viable counts (TVC) (3.81 log cfu/g for CB and 2.78 log cfu/g for WCB on day 2 of storage) and showed delayed mold growth by 1 day (day 4 for CB and day 5 for WCB). WCB also had lower pH (5.91 for CB and 5.71 for WCB on day 0), higher titratable acidity values (TTA) (2.5–5.2 mL NaOH/10 g for CB and 4.5–6.8 mL NaOH/ 10 g for WCB), and higher protein content (PC) (PC 7.68% for CB and 8.88% for WCB). WCB was characterized by a more intense flavor, reduced hardness but similar cohesiveness, springiness, and adhesiveness compared to CB. Based primarily on sensory (appearance/mold formation) data, the shelf life of WCB was 4–5 days compared to 3–4 days for CB stored at 24 ± 1 °C. The proposed use of whey in bread preparation contributes decisively to the environmentally friendly management of whey.     

Nine enzymes are required for assembly of the pacidamycin group of peptidyl nucleoside antibiotics

Pacidamycins are a family of uridyl peptide antibiotics that inhibit the translocase MraY, an essential enzyme in bacterial cell wall biosynthesis that to date has not been clinically targeted. The pacidamycin structural skeleton contains a doubly inverted peptidyl chain with a β-peptide and a ureido linkage as well as a 3'-deoxyuridine nucleoside attached to DABA(3) of the peptidyl chain via an enamide linkage. Although the biosynthetic gene cluster for pacidamycins was identified recently, the assembly line of this group of peptidyl nucleoside antibiotics remained poorly understood because of the highly dissociated nature of the encoded nonribosomal peptide synthetase (NRPS) domains and modules. This work has identified a minimum set of enzymes needed for generation of the pacidamycin scaffold from amino acid and nucleoside monomers, highlighting a freestanding thiolation (T) domain (PacH) as a key carrier component in the peptidyl chain assembly as well as a freestanding condensation (C) domain (PacI) catalyzing the release of the assembled peptide by a nucleoside moiety. On the basis of the substrate promiscuity of this enzymatic assembly line, several pacidamycin analogues were produced using in vitro total biosynthesis.     

Triterpenoids from Eucalyptus camaldulensis Dehnh. Tissue Cultures

A chemical study on tissue cultures from leaves and flowers of E. camaldulensis Dehnh . afforded the new natural product (2α,3β)‐2,3,23‐trihydroxy‐13,28‐epoxyurs‐11‐en‐28‐one (dryobalanolide) together with the known pentacyclic triterpenoids: betulinic acid, oleanolic acid, ursolic acid, (2α,3β)‐2,3,23‐trihydroxyolean‐12‐en‐28‐oic acid (arjunolic acid), (2α,3β)‐2,3,23‐trihydroxyurs‐12‐en‐28‐oic acid (asiatic acid), (2α)‐2‐hydroxyursolic acid, (2α)‐2‐hydroxyoleanolic acid (maslinic acid), as well as β‐sitosterol. The extracts and the isolated compounds were evaluated against eleven human pathogenic microorganisms, exhibiting a very interesting antibacterial spectrum of activities.     

Evaluation of the antimicrobial and antioxidant activities of Origanum dictamnus extracts before and after encapsulation in liposomes

The antioxidant and antimicrobial activity of methanol or dichloromethane extracts of O. dictamnus, produced from wild and organic cultivated specimens, were determined. The Rancimat and malondialdehyde (MDA) by HPLC methods were used to measure the antioxidant action, in comparison with that of the common commercial antioxidants butylated hydroxytoluene (BHT) and alpha-tocopherol. The extracts that presented high antioxidant activity were encapsulated in liposomes and their antioxidant action was again estimated using differential scanning calorimetry (DSC). Thermaloxidative decomposition of the samples (pure liposomes and encapsulated extracts) and the modification of the main transition temperature for the lipid mixture and the splitting of the calorimetric peak in the presence of the antioxidants were also studied by the DSC method. All extracts showed antioxidant and antimicrobial activities. Their action proved superior to alpha-tocopherol. The methanol extract of organic cultivated O. dictamnus (240 ppm) showed higher activity than butylated hydroxytoluene. After encapsulation in liposomes the antioxidant as well as antimicrobial activities proved to be higher than those of the same extracts in pure form.     

Qualitative Analysis Related to Palynological Characterization and Biological Evaluation of Propolis from Prespa National Park (Greece)

Propolis samples from a geographical part of northwest Greece (Prespa National Park, PNP), which is characterized as a plant endemism center and biodiversity hotspot, were characterized through pollen analysis, chemically analyzed, and biologically evaluated. The majority of the studied propolis showed typical chemical constituents (phenolic acids, flavonoids, and chalcones) of European type, while a sample of Mediterranean-type propolis (rich in diterpenes) was also identified. The palynological characterization was implemented to determine the botanical origin and to explain the chemical composition. The total phenolic content and the DPPH assay showed that the European-type propolis samples possessed strong antioxidant activity (86–91% inhibition at 200 μg/mL). Moreover, promising antibacterial activity of the extracts (MIC values 0.56–1.95 mg/mL) and moderate antifungal activity (MIC values 1.13–2.40 mg/mL) were noticed, while the sample with the highest activity had a significant content in terpenes (Mediterranean type). Propolis samples from the PNP area represent a rich source of antibacterial and antioxidant compounds and confirm the fact that propolis is a significant natural product with potential use for improving human health and stimulating the body’s defense. Finally, it is noteworthy that a significant chemical diversity was demonstrated, even in samples from a limited geographical area as this of PNP.