Experimental and computational evaluation of dipeptidyl peptidase III inhibitors based on quinazolinone-Schiff's bases

Dipeptidyl peptidase III (DPP III) is a zinc-dependent enzyme that sequentially hydrolyzes biologically active peptides by cleaving dipeptides from their N-termini. Although its fundamental role is not been fully elucidated, human DPP III (hDPP III) has been recognized in several pathophysiological processes of interest for drug development. In this article 27 quinazolinone-Schiff's bases were studied for their inhibitory activity against hDPP III combining an in vitro experiment with a computational approach. The biochemical assay showed that most compounds exhibited inhibitory activity at the 100 μM concentration. The best QSAR model included descriptors from the following 2D descriptor groups: information content indices, 2D autocorrelations, and edge adjacency indices. Five compounds were found to be the most potent inhibitors with IC50 values below 10 µM, while molecular docking predicted that these compounds bind to the central enzyme cleft and interact with residues of the substrate binding subsites. Molecular dynamics simulations of the most potent inhibitor (IC50=0.96 µM) provided valuable information explaining the role of PHE109, ARG319, GLU327, GLU329, and ILE386 in the mechanism of the inhibitor binding and stabilization. This is the first study that gives insight into quinazolinone-Schiff's bases binding to this metalloenzyme.Communicated by Ramaswamy H. Sarma.

Antifungal Activities of Fluorinated Pyrazole Aldehydes on Phytopathogenic Fungi, and Their Effect on Entomopathogenic Nematodes, and Soil-Beneficial Bacteria

Fluoro-substituted pyrazoles have a wide range of biological activities, such as antibacterial, antiviral, and antifungal activities. The aim of this study was to evaluate the antifungal activities of fluorinated 4,5-dihydro-1H-pyrazole derivatives on four phytopathogenic fungi: Sclerotinia sclerotiorum, Macrophomina phaseolina, Fusarium oxysporum f. sp. lycopersici, and F. culmorum. Moreover, they were tested on two soil beneficial bacteria-Bacillus mycoides and Bradyrhizobium japonicum-as well as two entomopathogenic nematodes (EPNs)-Heterorhabditis bacteriophora and Steinernema feltiae. The molecular docking was performed on the three enzymes responsible for fungal growth, the three plant cell wall-degrading enzymes, and acetylcholinesterase (AChE). The most active compounds against fungi S. sclerotiorum were 2-chlorophenyl derivative (H9) (43.07% of inhibition) and 2,5-dimethoxyphenyl derivative (H7) (42.23% of inhibition), as well as H9 against F. culmorum (46.75% of inhibition). Compounds were shown to be safe for beneficial soil bacteria and nematodes, except for compound H9 on EPN H. bacteriophora (18.75% mortality), which also showed the strongest inhibition against AChE (79.50% of inhibition). The molecular docking study revealed that antifungal activity is possible through the inhibition of proteinase K, and nematicidal activity is possible through the inhibition of AChE. The fluorinated pyrazole aldehydes are promising components of future plant protection products that could be environmentally and toxicologically acceptable.

Antioxidant Activity, Metabolism, and Bioavailability of Polyphenols in the Diet of Animals

As the world’s population grows, so does the need for more and more animal feed. In 2006, the EU banned the use of antibiotics and other chemicals in order to reduce chemical residues in food consumed by humans. It is well known that oxidative stress and inflammatory processes must be combated to achieve higher productivity. The adverse effects of the use of pharmaceuticals and other synthetic compounds on animal health and product quality and safety have increased interest in phytocompounds. With the use of plant polyphenols in animal nutrition, they are gaining more attention as a supplement to animal feed. Livestock feeding based on a sustainable, environmentally friendly approach (clean, safe, and green agriculture) would also be a win–win for farmers and society. There is an increasing interest in producing healthier products of animal origin with a higher ratio of polyunsaturated fatty acids (PUFAs) to saturated fatty acids by modulating animal nutrition. Secondary plant metabolites (polyphenols) are essential chemical compounds for plant physiology as they are involved in various functions such as growth, pigmentation, and resistance to pathogenic organisms. Polyphenols are exogenous antioxidants that act as one of the first lines of cell defense. Therefore, the discoveries on the intracellular antioxidant activity of polyphenols as a plant supplement have contributed significantly to the improvement of antioxidant activity, as polyphenols prevent oxidative stress damage and eliminate excessively produced free radicals. To achieve animal welfare, reduce stress and the need for medicines, and increase the quality of food of animal origin, the addition of polyphenols to research and breeding can be practised in part with a free-choice approach to animal nutrition.

Synthesis, Antiproliferative Evaluation and QSAR Analysis of Novel Halogen- and Amidino-Substituted Benzothiazoles and Benzimidazoles

Syntheses of 6-halogen-substituted benzothiazoles were performed by condensation of 4-hydroxybenzaldehydes and 2-aminotiophenoles and subsequent O-alkylation with appropriate halides, whereas 6-amidino-substituted benzothiazoles were synthesized by condensation of 5-amidino-2-aminothiophenoles and corresponding benzaldehydes. While most of the compounds from non-substituted and halogen-substituted benzothiazole series showed marginal antiproliferative activity on tested tumor cell lines, amidino benzazoles exhibited stronger inhibitory activity. Generally, imidazolyl benzothiazoles showed pronounced and nonselective activity, with the exception of 36c which had a strong inhibitory effect on HuT78 cells (IC50 = 1.6 µM) without adverse cytotoxicity on normal BJ cells (IC50 >100 µM). Compared to benzothiazoles, benzimidazole structural analogs 45a−45c and 46c containing the 1,2,3-triazole ring exhibited pronounced and selective antiproliferative activity against HuT78 cells with IC50 < 10 µM. Moreover, compounds 45c and 46c containing the methoxy group at the phenoxy unit were not toxic to normal BJ cells. Of all the tested compounds, benzimidazole 45a with the unsubstituted phenoxy central core showed the most pronounced cell growth inhibition on THP1 cells in the nanomolar range (IC50 = 0.8 µM; SI = 70). QSAR models of antiproliferative activity for benzazoles on T-cell lymphoma (HuT78) and non-tumor MDCK-1 cells elucidated the effects of the substituents at position 6 of benzazoles, demonstrating their dependence on the topological and spatial distribution of atomic mass, polarizability, and van der Waals volumes. A notable cell cycle perturbation with higher accumulation of cells in the G2/M phase, and a significant cell increase in subG0/G1 phase were found in HuT78 cells treated with 36c, 42c, 45a−45c and 46c. Apoptotic morphological changes, an externalization of phosphatidylserine, and changes in the mitochondrial membrane potential of treated cells were observed as well.

Effects of Defoliation Treatments of Babica Grape Variety(Vitis vinifera L.) on Volatile Compounds Content in Wine

The aim of this study was to determine the effects of defoliation performed in the Babica red grape variety on the volatile compounds in produced wine. Three treatments were performed during 2017 and 2018: the removal of six leaves before flowering (FL) and at the end of veraison (VER), as well as control (C). Volatile compounds were analyzed using a gas chromatograph coupled to a mass spectrophotometric detector. Results were statistically evaluated by analysis of variance (ANOVA at the p = 0.05 level) and principal component analysis (PCA). Defoliation treatments were affected by the concentration of several compounds, but only in one year. The VER2017 treatment significantly increased the concentration of three aliphatic esters up to 8 C atoms and octanoic acid ethyl ester. The FL2017 treatment increased the concentration of three aliphatic alcohols. The FL2018 treatment has significantly enhanced the concentration ethyl cinnamate but decreased the concentrations of eugenol and dihydro-2-methyl-3(2H)-thiophenone. Both defoliation treatments reduced the concentration of γ-decanolactone in 2017. Aldehydes, monoterpenoles, and monoterpenes remained unaffected by the defoliation treatments. Vintage was found to be the largest source of variability for most volatile compounds under investigation, which was confirmed by PCA. The effect of defoliation in the mild-Mediterranean climate was found to mostly depend on seasonal weather conditions.

Coumarin Derivatives Act as Novel Inhibitors of Human Dipeptidyl Peptidase III: Combined In Vitro and In Silico Study

Dipeptidyl peptidase III (DPP III), a zinc-dependent exopeptidase, is a member of the metalloproteinase family M49 with distribution detected in almost all forms of life. Although the physiological role of human DPP III (hDPP III) is not yet fully elucidated, its involvement in pathophysiological processes such as mammalian pain modulation, blood pressure regulation, and cancer processes, underscores the need to find new hDPP III inhibitors. In this research, five series of structurally different coumarin derivatives were studied to provide a relationship between their inhibitory profile toward hDPP III combining an in vitro assay with an in silico molecular modeling study. The experimental results showed that 26 of the 40 tested compounds exhibited hDPP III inhibitory activity at a concentration of 10 µM. Compound 12 (3-benzoyl-7-hydroxy-2H-chromen-2-one) proved to be the most potent inhibitor with IC₅₀ value of 1.10 μM. QSAR modeling indicates that the presence of larger substituents with double and triple bonds and aromatic hydroxyl groups on coumarin derivatives increases their inhibitory activity. Docking predicts that 12 binds to the region of inter-domain cleft of hDPP III while binding mode analysis obtained by MD simulations revealed the importance of 7-OH group on the coumarin core as well as enzyme residues Ile315, Ser317, Glu329, Phe381, Pro387, and Ile390 for the mechanism of the binding pattern and compound 12 stabilization. The present investigation, for the first time, provides an insight into the inhibitory effect of coumarin derivatives on this human metalloproteinase.

Properties of Potato Starch Roasted with Apple Distillery Wastewater

This study aimed to produce starch esters by roasting potato starch with apple distillery wastewater at various temperatures and aimed to determine the effects of esterification conditions on selected properties of the modified preparations. Apple distillery wastewater was concentrated, mixed with starch (30 g of dry matter per 100 g of starch), dried, and roasted at temperatures of 110, 130 or 150 °C for 3 h. The resulting preparations were rinsed 30 times with a 60% ethanol solution, dried, and disintegrated. After that, the following analyses were performed: content of substituted acids (after alkaline de-esterification) with high performance liquid chromatography (HPLC); thermal characteristics with differential scanning calorimetry (DSC); swelling power and solubility in water at 80 °C; color changes with a colorimeter; rheology of the pastes based on the plotted flow curves; and the pastes’ resistance to amyloglucosidase. Starch treatments with apple distillery wastewater at 130 and 150 °C caused significant changes to its properties when compared to the control samples of native starch and starch roasted without wastewater, including: a lower temperature and heat of pasting, lower swelling power and solubility in water, darker color, higher resistance to amyloglucosidase, and the formation of pastes with a lower viscosity.

Lipoxygenase Inhibition Activity of Coumarin Derivatives-QSAR and Molecular Docking Study

Lipoxygenases (LOXs) are a family of enzymes found in plants, mammals, and microorganisms. In animals and plants, the enzyme has the capability for the peroxidation of unsaturated fatty acids. Although LOXs participate in the plant defense system, the enzyme’s metabolites can have numerous negative effects on human health. Therefore, many types of research are searching for compounds that can inhibit LOXs. The best quantitative structure–activity relationship (QSAR) model was obtained using a Genetic Algorithm (GA). Molecular docking was performed with iGEMDOCK. The inhibition of lipoxygenase was in the range of 7.1 to 96.6%, and the inhibition of lipid peroxidation was 7.0–91.0%. Among the synthesized compounds, the strongest inhibitor of soybean LOX-3 (96.6%) was found to be 3-benzoyl-7-(benzyloxy)-2H-chromen-2-one. A lipid peroxidation inhibition of 91.0% was achieved with ethyl 7-methoxy-2-oxo-2H-chromene-3-carboxylate. The docking scores for the soybean LOX-3 and human 5-LOX also indicated that this compound has the best affinity for these LOX enzymes. The best multiple linear QSAR model contains the atom-centered fragment descriptors C-06, RDF035p, and HATS8p. QSAR and molecular docking studies elucidated the structural features important for the enhanced inhibitory activity of the most active compounds, such as the presence of the benzoyl ring at the 3-position of coumarin’s core. Compounds with benzoyl substituents are promising candidates as potent lipoxygenase inhibitors.

Simultaneous Determination of Acrylamide and Hydroxymethylfurfural in Extruded Products by LC-MS/MS Method

The aim of this study was to develop a liquid chromatography/tandem mass spectrometry LC-MS/MS method for the simultaneous determination of acrylamide and hydroxymethylfurfural (HMF) in corn snack products enriched with food industry by-products: brewer's spent grain (BSG), sugar beet pulp (SBP) and apple pomace (AP). Development of the method included the study of different sources for ionization, different mobile phases, different extraction conditions as well as different methods of sample preparation. Finally, the single LC-MS/MS method was developed for the analysis of both analytes in one step with a duration of 20 min using a simple single-step extraction. The method with apparent recoveries of 91.4 and 90.4 for acrylamide and HMF, respectively, was applied for the analysis of non-extruded and extruded samples. The obtained results shown that the acrylamide content was Collapse

Key Words

• LC-MS/MS method
• acrylamide
• extruded snack products
• hydroxymethylfurfural

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MESH Headings

• Acrylamide/analysis
• Beta vulgaris/chemistry
• Chromatography, High Pressure Liquid
• Food Contamination/analysis
• Food Industry
• Furaldehyde/analogs & derivatives
• Furaldehyde/analysis
• Malus/chemistry
• Tandem Mass Spectrometry/methods
• Zea mays/chemistry

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Grants

• 1321 Hrvatska Zaklada za Znanost

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Affiliation(s)

Antun Jozinović Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.
Bojan Šarkanj Department of Food Technology, University Centre Koprivnica, University North, Trg dr. Žarka Dolinara 1, 48000 Koprivnica, Croatia.
Đurđica Ačkar Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.
Jelena Panak Balentić Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.
Domagoj Šubarić Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, 10000 Zagreb, Croatia.
Tanja Cvetković Research and Development, Podravka d.d., Ante Starčevića 32, 48000 Koprivnica, Croatia.
Jasmina Ranilović Research and Development, Podravka d.d., Ante Starčevića 32, 48000 Koprivnica, Croatia.
Sunčica Guberac Faculty of Agrobiotechnical Sciences Osijek, Josip Juraj Strossmayer University of Osijek, Vladimira Preloga 1, Osijek 31000, Croatia.
Jurislav Babić Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, 31000 Osijek, Croatia.

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