The process of identifying the protein targets and off-targets of a biologically active compound is of great importance in modern drug discovery. Various chemical proteomics approaches have been ...established for this purpose. To compare the different approaches, and to understand which method would provide the best results, we have chosen the EGFR inhibitor lapatinib as an example molecule. Lapatinib derivatives were designed using linkers with motifs, including amino (amidation), alkyne (click chemistry) and the diazirine group (photo-affinity). These modified lapatinib analogues were validated for their ability to inhibit EGFR activity in vitro and were shown to pull down purified recombinant EGFR protein. In all of the approaches evaluated here, we identified EGFR as the main protein target from the lysate of immortalised cell line expressing EGFR, thus validating its potential use to identify unknown protein targets. Taken together, the results reported here give insight into the cellular activities of lapatinib.
Autotaxin (ATX) is an extracellular enzyme that hydrolyses lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA), which has a role in the mediation of inflammation, fibrosis and cancer. ATX is ...a drug target that has been the focus of many research groups during the last ten years. To date, only one molecule, Ziritaxestat (GLPG1690) has entered the clinic; it is currently in Phase 3 clinical trials for idiopathic pulmonary fibrosis. Other small molecules, with different binding modes, have been investigated as ATX inhibitors for cancer including compounds possessing a boronic acid motif such as HA155. In this work, we targeted new, improved inhibitors of ATX that mimic the important interactions of boronic acid using a benzoxaborole motif as the acidic warhead. Furthermore, we aimed to improve the plasma stability of the new compounds by using a more stable core spacer than that embedded in HA155. Compounds were synthesized, evaluated for their ATX inhibitory activity and ADME properties in vitro, culminating in a new benzoxaborole compound, 37, which retains the ATX inhibition activity of HA155 but has improved ADME properties (plasma protein binding, good kinetic solubility and rat/human plasma stability).
•NPK fertilisation suppressed the uptake of several radionuclides by maize.•No suppression for radionuclides which are or can mimic biogenic elements.•No suppression for radionuclides which ...accumulated on stem from air.•Low radionuclide concentrations in grain.•Fertilisation did not change the radiological properties of the soil.
The goal of this study is to shed more light on the influence of fertilisation on radionuclide transfer from soil to crops, which is a significant ecological issue in present-day agriculture due to the intensive use of soil amendments. Research on this subject has not been extensive, hence there are still numerous open questions that require an interdisciplinary approach involving agroecology and radioecology. Maize was chosen for our investigation because it has been used, in considerable quantities and worldwide, as both food and feed, which makes it part of numerous food chains with humans as final consumers. The agricultural part of the experiment was carried out on an acidic soil in northwestern Croatia, and it was based on seven treatments with different levels of NPK fertilisation. Radionuclide activity concentrations in sampled soil, stem, and grain were measured by means of high-resolution γ-ray spectrometry. We found that the radiological properties of the soil were not affected by the addition of the fertiliser. Soil-to-stem uptake for radionuclides of the whole 232Th decay chain was first suppressed by mild fertilisation, and then, at higher fertiliser concentrations, it stayed low and became independent of fertilisation level. The same effect was observed for the 238U decay chain before gaseous 222Rn. We present arguments in favour of the cause of the observed suppression being radionuclide complexation with constituents of the fertiliser. However, the concentration of 210Pb in stem did not depend on fertilisation, which was most probably a consequence of the decay of airborne 222Rn and the deposition of its progenies onto stem. Radionuclide translocation from stem to grain did not depend on fertilisation either, and it was appreciable only for 40K and 137Cs. In grain, radionuclide concentrations were lower than in stem. Overall, in our case, fertilisation had positive effects, reducing the presence of radionuclides in the maize while having no detectable impact on the radiological properties of the soil. This finding may have implications for future work, especially regarding concerns about the impact of soil amendments on food production.
The Standardized Precipitation Index (SPI) for different time scales of
n = 1
,
2
,
3
,
6
,
9
,
12
, and
24
months and the monthly Palmer Drought Severity Index (PDSI) were calculated for the ...Zagreb-Grič Observatory, located in North-Western Croatia, for the period 1862–2012. The PDSI exhibits a stronger long-term negative trend than the SPI due to the influence of the global warming, which corresponds with the global scale results published in the 4th IPCC (Intergovernmental Panel on Climate Change) report. The SPI for a 9-month scale was compared with the PDSI for a monthly scale because the correlation between them is the highest in comparison with other SPI time scales. The Chapman percentile classification regarding dryness/wetness severity was used instead of the “originally” proposed classes. Thirty-year moving averages indicate that long-term variation in dryness/wetness severity is more clearly emphasised for the PDSI than for the SPI, showing the last 30-year period to be the driest on record. Autoregressive function analysis indicates that the SPI for a 1-month scale has serialy independent values, while the SPI for the 9-month scale and the monthly PDSI are close to a Markov process. A significant correlation was established between the SPI and PDSI indices and crop damages in Croatia.
The objective was to evaluate the ability of visible and near-infrared (NIR) spectroscopy to predict winter wheat grain yield, according to the performance of different prediction models. In situ ...reflectance measurements (350–1050 nm) were acquired from winter wheat flag leaves grown under nine mineral nitrogen (N) fertilization treatments (0–300 kg N ha
−1
), during stem extension developmental stage. Linear statistical models (MLR—multiple linear regression, PLSR—partial least squares regression) and non-linear prediction (ANN—artificial neural networks) were generated to estimate grain yield, based on derived variables from hyperspectral data as input features (first derivative of reflectance in form of principal components—PCs and vegetation indices—VIs). The expected influence of variable N fertilization on agronomic and spectral variables was recorded. The red and NIR reflectance contributed most to development of PCs, while VIs were calculated from 704 nm (
λ
RED
) and 785 nm (
λ
NIR
). Very strong positive relationship was determined between grain yield and VIs. ANN models were the most efficient in capturing the complex link between grain yield and leaf reflectance compared to the corresponding VIs, MLR and PLSR models, indicating good learning performance. In terms of N stress and non-N-limited environment, it can be concluded that the prediction methods used in this study can provide in-season estimates of winter wheat yield at a field scale based on hyperspectral data. Key spectral features and algorithms defined in this study should help to support site-specific and real-time yield forecasting in winter wheat production.
The mobility of nitrogen (N) in the environment is conditioned by its cycling between atmospheric, terrestrial, and marine ecosystems. It is a key element for global biogeochemistry, and although ...isotope analysis has been an integral part of many studies over the past eighty years, the complexity of the nitrogen cycle hinders a correct and detailed understanding of the mechanisms behind its processes. It could be argued that the interpretation of the isotopic signatures of nitrogen in soils is still in its infancy. In Croatia, such research has recently begun and is driven by a need for the comprehensive study of nitrogen isotopes in terrestrial ecosystems. The aim of this study was to compare the abundance of the 15N isotope in soils from continental and coastal parts of Croatia with different types of land use (arable land/crop production, meadows, forests, orchards, ski slopes, urban soil/city roads) and to authenticate the nitrogen origin in soils in relation to different soil management practices. This research was based on 27 soil samples collected at 11 locations in Croatia. The samples differed according to soil type, land use, applied mineral and organic nitrogen fertilization, and climatic condition at each specific location. The determination of δ15NT (T—total nitrogen) values in bulk samples was performed in duplicate with the IRMS (Isotope Ratio Mass Spectrometry) method using an IsoPrime100-Vario PYRO Cube (OH/CHN Pyrolyser/Elemental Analyzer). The results reveal that the mean δ15N abundance in soils according to different land use declines in the following order: crop production (+5.66 ± 1.06‰) > apple orchard (+5.60 ± 0.10‰) > city road (+4.33 ± 0.38‰) > meadow (+3.71 ± 0.85‰) > ski slope (+2.20 ± 0.10‰) > forest (+2.15 ± 1.86‰). The individual values were in the range from 0.00 ± 0.10‰ in the forest soil in continental Croatia to +7.19 ± 0.07‰ in the vegetable garden (crop production) soil in coastal Croatia. Among the investigated soil properties and weather conditions, PCA analysis identified close correlations between P2O5 content and δ115N abundance in arable soils, as well as between soil reaction (pH) and mean annual temperatures, while high C/N ratio values explained the isotopic distribution in non-arable soils (city roads and forests). Despite the long-term application of mineral nitrogen fertilizers, the results represent nitrogen of organic origin in the arable soils (crop production), which partly confirms the sustainable management of those agroecosystems.
To better understand the impact of conventional agricultural practices on soil and water resources, two main objectives were established in this study: to measure nitrate (NO3-) and sulphate (SO42-) ...concentrations in lysimeters and drainpipes leachates in response to different nitrogen fertilization levels and soil amendments and to identify organic contaminants that could have originated from the long-term use of agrochemicals in historically intensive agricultural area in Croatia. During the two-year study period leachate samples were collected from lysimeters and drainpipes. Research results indicate NO3- content in both lysimeters and drainpipes increased with rising doses of N fertilizer. The highest concentration of SO42- was recorded in the treatment with added phosphogypsum, while in all other treatments the concentrations were low. Over 40% of the 287 target substances were detected at least once during the two-year study period but only two substances (IPC/propham and carbosulfan) were found to have concentrations above 0.5 μg/L. Additionally, three priority substances were continuously present in the leachate samples: atrazine, simazine and isoproturon.
Spectral data contain information on soil organic and mineral composition, which can be useful for soil quality monitoring. The objective of research was to evaluate hyperspectral visible and near ...infrared reflectance (VNIR) spectroscopy for field-scale prediction of soil properties and assessment of factors affecting soil spectra. Two hundred soil samples taken from the experiment field (soil depth: 30 cm; sampling grid: 15 × 15 m) were scanned using portable spectroradiometer (350–1050 nm) to identify spectral differences of soil treated with ten different rates of mineral nitrogen (N) fertilizer (0–300 kg N/ha). Principal component analysis revealed distinction between higher- and lower-N level treatments conditioned by differences in soil pH, texture and soil organic matter (SOM) composition. Partial least square regression resulted in very strong correlation and low root mean square error (RMSE) between predicted and measured values for the calibration (C) and validation (V) dataset, respectively (SOM, %: RC2 = 0.75 and RV2 = 0.74; RMSEC = 0.334 and RMSEV = 0.346; soil pH: RC2 = 0.78 and RV2 = 0.62; RMSEC = 0.448 and RMSEV = 0.591). Results indicated that hyperspectral VNIR spectroscopy is an efficient method for measurement of soil functional attributes within precision farming framework.
Soil properties can be estimated non-destructively by visible and near infrared (VNIR) reflectance spectroscopy. However, results of calibration models differ in dependence of measurement precision, ...spectral range, variability of soil properties and calibration methods used for prediction. The objective of research was to estimate the ability of hyperspectral VNIR sensing for field-scale prediction of soil pH, total carbon (TC %) and total nitrogen (TN %) content in arable Stagnosols. Total of 200 soil samples taken from field experiment (soil depth: 30 cm; sampling grid: 15x15 m; 2016) were scanned in laboratory using portable spectroradiometer (FieldSpec®3, 350-1,050 nm). Partial least squares regression (PLSR) and artificial neural networks (ANN) were used to build prediction models of selected soil properties based on VNIR spectra. Very strong to complete correlation and low root mean squared error were obtained between predicted and measured values for the calibration and validation dataset, and both prediction methods. ANN models were more efficient in capturing the complex link between selected soil properties and soil reflectance spectra than PLSR. Calibrations defined in this research should help to support site-specific soil survey as addition to standard laboratory analysis, and represent valuable input for spectral database that should be built for Croatian soils.
Novel classes of antimalarial drugs are needed due to emerging drug resistance. Azithromycin, the first macrolide investigated for malaria treatment and prophylaxis, failed as a single agent and thus ...novel analogues were envisaged as the next generation with improved activity. We synthesized 42 new 9a-N substituted 15-membered azalides with amide and amine functionalities via simple and inexpensive chemical procedures using easily available building blocks. These compounds exhibited marked advances over azithromycin in vitro in terms of potency against Plasmodium falciparum (over 100-fold) and high selectivity for the parasite and were characterized by moderate oral bioavailability in vivo. Two amines and one amide derivative showed improved in vivo potency in comparison to azithromycin when tested in a mouse efficacy model. Results obtained for compound 6u, including improved in vitro potency, good pharmacokinetic parameters, and in vivo efficacy higher than azithromycin and comparable to chloroquine, warrant its further development for malaria treatment and prophylaxis.
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