Dalibor Broznić

Effects of temperature on sorption-desorption processes of imidacloprid in soils of Croatian coastal regions

Sorption-desorption behavior of imidacloprid in six soils collected from five coastal regions in Croatia at 20, 30 and 40°C was investigated using batch equilibrium technique. Isothermal data were applied to Freundlich, Langmuir and Temkin equations, and the thermodynamic parameters ΔH°, ΔG°, ΔS° were calculated. The sorption isotherm curves were non-linear and may be classified as L-type, suggesting a relatively high sorption capacity for imidacloprid. Our results showed that the K sor F values decreased for all the tested soils as the temperature increased, indicating that the temperature strongly influences the sorption. Values of ΔG° were negative (−4.65 to −2.00 kJ/mol) indicating that at all experimental temperatures the interactions of imidacloprid with soils were spontaneous processes. The negative and small ΔH° values (−19.79 to −8.89 kJ/mol) were in the range of weak forces, such as H-bonds, consistent with interactions and partitioning of the imidacloprid molecules into soil organic matter. The ΔS° values followed the range of −57.12 to −14.51 J/molK, suggesting that imidacloprid molecules lose entropy during transition from the solution phase to soil surface. It was found that imidacloprid desorption from soil was concentration and temperature-dependent, i.e. at lower imidacloprid concentrations and temperature, lower desorption percentage occurred. Desorption studies revealed that hysteretic behavior under different temperature treatments existed, and it was more pronounced at 20°C in the soils with higher OC content. The study results emphasize the importance of thermodynamic parameters in controlling soil pesticide mobility in different geographical locations, seasons and greenhouse conditions.

Hysteretic Behavior of Imidacloprid Sorption-Desorption in Soils of Croatian Coastal Regions

Sorption and desorption are important processes that influence the transport, transformation, and bioavailability of imidacloprid in the soils. Equilibrium batch experiments were carried out using six coastal Croatian soils. The equilibrium sorption and desorption experimental data showed the best fit to the Freundlich equation. Sorption parameters predicted with the Freundlich model, KF sor and 1/n ranged from 2.92 to 5.74 (mg/kg)/(mg/L)1/n, and 0.888 to 0.919, respectively. The sorption of imidacloprid was found to be sensitive to organic carbon (OC) content. The highest sorption was observed in Krk soil (OC 4.74%) and the lowest in Zadar soil (OC 1.06%). Fitted desorption parameter values, KF des , were consistently higher than those associated with sorption. The opposite trend was observed for the exponential parameter 1/n. Results also suggested that imidacloprid sorption-desorption by soil is concentration-dependent, i.e. at lower imidacloprid concentrations a greater sorption percentage and lower desorption percentage occurred. Desorption studies revealed that there was a hysteresis effect in all the tested soils. Hysteresis coefficient values (H) varied from 0.656 to 0.859. The study results emphasize that the controlled application of imidacloprid is obligatory, especially in soils with a low organic carbon content, in order to minimize a risk of environmental and groundwater pollution.

Metallothionein expression and tissue metal kinetics after partial hepatectomy in mice

To better elucidate previous results showing that partial hepatectomy noticeably changes the tissue content of zinc, calcium, magnesium, and iron(II) ions in regenerating the liver, thymus, and spleen, we report on the correlation of these metal tissue kinetics in these organs with the expression of metallothionein-I+II (MT-I+II) proteins and MT-I mRNA in early postoperative period (1, 2, 6, 12, and 24 h) after one-third hepatectomy (pHx). The results showed that 2 h after pHx the regenerating liver accumulated Zn2+, Ca2+, Mg2+, and Fe2+ ions while decreasing the concentration of all these metals in the spleen and of Zn2+ in the thymus. On the 24th h, a new high accumulation of Zn2+ and Ca2+ was seen in the regenerating liver and of Zn2+, Ca2+, and Fe2+ in the spleen. Simultaneously, MT-I mRNA increased in the liver and spleen. In hepatocytes and on several spleen and thymus mononuclear lymphatic cells, the increased expression of MT proteins was found mainly in the cytoplasm and nuclei. The areas expressing MTs in regenerating liver inversely correlated with those containing apoptotic cells, suggesting that these proteins participate in tissue restoration through reduction or increase of metal ions after injury to the liver.

Mathematical prediction of imidacloprid persistence in two Croatian soils with different texture, organic matter content and acidity under laboratory conditions

In the present laboratory study, persistence of imidacloprid (IMI) as a function of initial insecticide concentration and soil properties in two Croatian soils (Krk sandy clay and Istria clay soils) was studied and described mathematically. Upon fitting the obtained experimental data for the higher concentration level (5 mg/kg) to mathematical models, statistical parameters (R 2, scaled root mean squared error and χ 2 error) indicated that the single first-order kinetics model provided the best prediction of IMI degradation in the Krk sandy clay soil, while in the Istria clay soil biphasic degradation was observed. At the lower concentration level (0.5 mg/kg), the biphasic models Gustafson and Holden models as well as the first-order double exponential model fitted the best experimental data in both soils. The disappearance time (DT50) values estimated by the single first-order double exponential model (from 50 to 132 days) proved that IMI can be categorized as a moderately persistent pesticide. In the Krk sandy clay soil, resulting DT50 values tended to increase with an increase of initial IMI concentration, while in the Istria clay soil, IMI persistence did not depend on the concentration. Organic matter of both experimental soils provided an accelerating effect on the degradation rate. The logistic model demonstrated that the effect of microbial activity was not the most important parameter for the biodegradation of IMI in the Istria clay soil, where IMI degradation could be dominated by chemical processes, such as chemical hydrolysis. The results pointed that mathematical modeling could be considered as the most convenient tool for predicting IMI persistence and contributes to the establishment of adequate monitoring of IMI residues in contaminated soil. Furthermore, IMI usage should be strictly controlled, especially in soils with low organic matter content where the risk of soil and groundwater contamination is much higher due to its longer persistence and consequent leaching and/or moving from soil surface prior to its degradation.

Bioactivity of Satureja montana L. honey extracts and their profile screening

Exploitation of natural compounds, including those from the honeys, as therapeutic agents is still gaining importance, but problems may arise due to poor knowledge of molecular effects and correlation of these effects with doses. The aim of the study was to characterize the extracts from winter savory (Satureja montana L.) honey, evaluate their bioactivity depending on the variety of obtained extracts, concentrations of main compounds and their interrelationship depending on doses. For this purpose the honey samples were processed by ultrasonic solvent extraction (solvent pentane:diethyl ether 1:2 v/v) and the obtained extracts were characterized by gas chromatography and mass spectrometry. For the first time, antioxidative and antiproliferative effects accompanied by apoptosis induction and cell death of S. montana honey samples and their extracts on tumour cell lines were presented. Methyl syringate (MS) and syringaldehyde (SA) were identified as the major components of S. montana honey extracts with radical scavenging capacity (Trolox equivalent antioxidant capacity; TEAC) of 13.04 mmol TEAC per kg (MS) and 422.02 mmol TEAC per kg (SA), respectively. Tested extracts, MS and SA did not exhibit any genotoxic effects detectable by the alkaline comet assay but they, as well as S. montana honey samples, clearly pointed to a strong antiproliferative effect in vitro on the tumour cell lines growth in a concentration-dependent manner accompanied with apoptosis induction and cell death.

Preexposure to Olive Oil Polyphenols Extract Increases Oxidative Load and Improves Liver Mass Restoration after Hepatectomy in Mice via Stress-Sensitive Genes

Polyphenols can act as oxidants in some conditions, inducing redox-sensitive genes. We investigated the effect of preexposure to the olive oil polyphenols extract (PFE) on time-dependent changes in the hepatic oxidative state in a model of liver regeneration—a process in which oxidative stress associated with the metabolic overload accounts for the early events that contribute to the onset of liver self-repair. Liver regeneration was induced by one-third hepatectomy in mice. Prior to hepatectomy, mice were intraperitoneally given either PFE (50 mg/kg body weight) or saline for seven consecutive days, while respective controls received vehicle alone. Redox state-regulating enzymes and thiol proteins along with the mRNA levels of Nrf2 gene and its targets γ-glutamylcysteine synthetase and heme oxygenase-1 were determined at different time intervals after hepatectomy. The liver mass restoration was calculated to assess hepatic regeneration. The resulting data demonstrate the effectiveness of preexposure to PFE in stimulating liver regeneration in a model of a small tissue loss which may be ascribed to the transient increase in oxidant load during the first hours after hepatectomy and associated induction of stress response gene-profiles under the control of Nrf2.

Behavior and Fate of Imidacloprid in Croatian Olive Orchard Soils Under Laboratory Conditions

The sorption-desorption and degradation of IMI was examined to understand the influence of concentration and soil properties on its behavior and fate in soils of Croatian coastal regions. The experimental data revealed that the sorption and desorption isotherms of IMI in the tested soils were nonlinear over the concentration range used, which can be best described by the Freundlich equation. Soil sorption capacity of IMI depended significantly on the soil properties. Especially, the sorption behavior of IMI was largely dependent on the soil OC content, where the soils with higher OC content (Istria soils) showed higher sorption capacity and less potential mobility of IMI. Given the spatial difference between tested soils, statistically significant differences in soil sorption capacity were found among and within soils of Istrian and Krk region. According to calculated KOC values, IMI can be categorized as a medium mobility pesticide indicating that rational use of IMI entails little danger of the ground-water contamination. In all soils, a higher sorption capacity was observed at lower IMI concentrations, indicating that the percentage of desorbed amount of pesticide increased with increasing initial solution concentration. Desorption experimental data deviated significantly from the sorption data, indicating that these processes were distinctly different in tested soils. It can be assumed, that the desorption process appeared to be the result of a complex, time dependent interplay of several chemical and physical processes and irreversible binding of IMI to soil surfaces, leading to hysteresis. The negative and low values of the Gibbs free energy of the IMI sorption indicated exotermic characteristics of sorption reaction and corresponded to the physical process, suggesting that partitioning into soil organic matter was the main mechanism of IMI sorption in the soils used. IMI kinetic behavior in all tested soils at the high concentration level can be described by the first-order kinetic degradation model, except for Istria II soil, where biphasic kinetics was observed. In contrast, at the low concentration level, the two-compartment kinetic model took place, characterized by the fast initial phase in the first 15 days of degradation followed by a slow degradation phase up to 180 days. According to the pesticide persistence classification, IMI can be categorized as moderately persistent pesticide (DT50 from 50 – 165 days), showing that the slow degradation of IMI in the tested soils further enlarges the danger of environmental damage. Concentration level significantly affected IMIs degradation, where higher persistence of IMI at higher initial concentration level was observed. In all tested soils, organic matter provided an accelerating effect on the degradation rate. The study results emphasize the need for controlled IMI usage, especially in soils with low humus content (Krk soils), thus avoiding a risk of IMI leeching. Considering the abundant current use of IMI in the Croatian olive growing areas, regular monitoring is needed to evolve a strategy to manage the environmental hazards due to the IMI and its degradation products. Further research, aided also with the actual field data, will be directed to investigate the IMIs metabolism and binding mechanisms in order to better understand degradation pathway and the causes for hysteresis phenomena.

Kinetics of Tissue Iron in Experimental Autoimmune Encephalomyelitis in Rats

To elucidate the role of iron in the pathomechanisms of autoimmune CNS disorders, we estimated the tissue concentrations of Fe2+ in the brain, spinal cord, and liver in the chronic relapsing form of experimental autoimmune encephalomyelitis (EAE). The disease was induced in Dark Agouti (DA) strain of rats, by subcutaneous injection of bovine brain homogenate in complete Freunds adjuvant (CFA). Control rats consisted of unsensitized rats and of rats treated with CFA or saline. The data obtained by clinical assessment and by inductively coupled plasma spectrometry have shown that the attacks of disease (on the 12th and 22nd post-immunization day) were followed by high accumulation of iron in the liver. Additionally, during the second attack of disease, the decreased concentration of Fe2+ was found in cervical spinal cord. The data point to regulatory effects of iron and hepatic trace elements regulating mechanisms in the pathogenesis of EAE.

Influence of essential oil Helichrysum italicum (Roth) G. Don on the formation of non-tuberculous mycobacterial biofilm

Cilj: Ispitati antimikrobni i antioksidacijski ucinak te sposobnost inhibicije biofilma etericnog ulja (EU) smilja [Helichrysum italicum (Roth) G. D

In vitro Antiproliferative and Antimicrobial Activity of the Essential Oil from the Flowers and Leaves of Helichrysum italicum (Roth) G. Don Growing in Central Dalmatia (Croatia)

Abstract In the present paper, chemical composition, in vitro antimicrobial and antiproliferative activity of the essential oil from the flowers and leaves of Helichrysum italicum (Roth) G. Don (Central Dalmatia, Croatia) as a potential replacement for standard antibiotics and chemotherapeutic agents was analyzed. Essential oil was isolated by steam distillation and analyzed by GC/MS. Antimicrobial activity was carried out by agar-well diffusion and microdilution assays with Gram (+), Gram (-) bacteria and one yeast. Antiproliferative effect, apoptosis induction and cell death on cancer cell lines: HeLa, MCF-7, SW620, CFPAC-1 and MIA PaCa-2 were analyzed by cell viability and Annexin-V assay as well as by flow cytometric analysis. In essential oil, α-pinene, γ-curcumene and neryl acetate was found as major compounds. The antimicrobial assays, showed that essential oil had weak to moderate antimicrobial potential with S. aureus and S. epidermidis as the most sensitive bacterial strains. Essential oil treatment possessed moderate antiproliferative impact on MCF-7 and HeLa cell lines, while analyzing cell cycle treatment had no significant effect on tested cells except on MIA PaCa-2 with the highest cells increase in sub G1 phase cell cycle. However, treatment caused significantly induction of apoptosis in MCF-7 and HeLa cells, but not in MIA PaCa-2 cells. In this cell line, multiple cell death mechanism existed with involving apoptosis, senescence or necrosis. Results of the study provide a promising basis for the evaluation of the potential use of essential oil from H. italicum (Roth) G. Don as a source of alternative nature antibiotics or anticancer agents for the prevention or treatment of different diseases.