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S. Špirtović-Halilović

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Sustainable development demands research into safe, renewable energy sources. Wood briquettes offer numerous advantages, but they can contain heavy metal(oid)s, posing environmental challenges, particularly in the ash produced during combustion. This study examines the concentrations of heavy metal(oid)s (Cd, Cr, Cu, Fe, Mn, Ni, Pb, Co, Zn, and As) in wood briquettes and their residual ash. Samples were prepared via wet digestion using 65% nitric acid (HNO3) in polytetrafluoroethylene vessels, followed by analysis using flame and graphite furnace atomic absorption spectrometry. The results showed that arsenic (As) had the lowest concentration in wood briquettes, while iron (Fe) was the highest. In the ash, chromium (Cr) was detected at the lowest concentration (0.80 mg/kg), while iron (Fe) reached 5830 mg/kg. Heavy metal concentrations in wood briquettes often exceeded permissible limits, and the concentrations in ash were significantly higher, making some ash samples unsuitable for agricultural use. The ash content ranged from 0.70% to 2.34%. This study provides valuable quantitative data on heavy metal(oid)s before and after combustion, highlighting their potential environmental impact and emphasizing the need for careful management of wood briquette ash.

Marine natural products represent a diverse collection of structurally distinct metabolites, many of which have untapped therapeutic potential. This study screened 161 marine-derived coumarin and xanthene compounds for their binding affinity to the histamine H2 receptor and the gastric H+/K+-ATPase, the primary regulators of gastric acid secretion. Docking simulations were performed using curated structures of both targets, followed by an evaluation of the compounds for drug-likeness and predicted absorption, distribution, metabolism, and excretion (ADME) properties. Thirty-four compounds demonstrated a stronger predicted affinity for the H2 receptor than famotidine; however, only three compounds (1, 5, and 150) met all drug-likeness criteria, achieving quantitative estimates of drug-likeness (QED) values exceeding 0.67. Screening against the proton pump yielded 98 hits with higher affinity than soraprazan, with compound 150 being the only candidate to fulfill all medicinal chemistry filters. Interaction analysis indicated that compound 150 binds to the proton pump in a manner that largely overlaps with soraprazan. Density functional theory (DFT) calculations were utilized to characterize the electronic properties of the most promising compounds. ADME predictions suggested favorable permeability and a low risk for human ether-à-go-go-related gene (hERG) inhibition, although high plasma protein binding and the potential for cytochrome P450 (CYP) inhibition may require further optimization. These findings underscore the potential of pyranocoumarin compound 150, along with xanthene derivatives 1 and 5, as promising candidates for the development of new acid-suppressive agents.

Benzoxazoles possess a wide range of therapeutic activities, including antimicrobial, antitumor, anti‐inflammatory, and other. Using in silico and in vitro approaches, we determined the potential antitumor activity of benzoxazoles synthesized from thymoquinone in diffuse large B‐cell lymphoma (DLBCL) cells. Molecular docking analysis showed strong binding affinities of benzoxazoles toward Akt and nuclear factor kappa B (NF‐κB) protein targets that promote cancer cell proliferation and survival and whose expression is linked to tumorigenesis of activated B‐cell (ABC) and germinal center B‐cell (GCB) DLBCL subtypes. WST‐8 assay showed the highest inhibitory activity of benzoxazole derivative bearing thiophene substituent in both DLBCL models. Western blot analysis indicated the inhibitory activity of selected compounds in HBL‐1 cells, with decreased p‐NF‐κB and p‐Akt protein expression, whereas treatment of DHL‐4 cells stimulated the expression of p‐Akt and p‐NF‐κB protein levels. These data suggest distinct, cell line‐dependent activities of the substances that potentially act through diverse oncogenic signaling pathways in DLBCL cells and activation of compensatory cell mechanisms that could be an important step for combinatorial treatment approaches.

Although COVID-19 is not a pandemic anymore, the virus frequently mutates, resulting in new strains and presenting global public health challenges. The lack of oral antiviral drugs makes it difficult to treat him, which makes the creation of broadly acting antivirals necessary to fight current and next epidemics of viruses. Using the molecular docking approach, 118 compounds derived from marine organisms and 92 previously synthesized compounds were screened to assess their binding affinity for the main protease and papain-like protease enzymes of SARS-CoV-2. The best candidates from the xanthene, benzoxazole, and coumarin classes were identified. Marine-derived compounds showed slightly better potential as enzyme inhibitors, though the binding affinities of synthesized compounds were similar, with the best candidates displaying affinity values between 0.2 and 0.4 mM. Xanthenes, among both marine origin and synthesized compounds, emerged as the most promising scaffolds for further research as inhibitors. The papain-like protease was found to be more druggable than the main protease. Additionally, all top candidates met the criteria for various drug-likeness properties, indicating good oral bioavailability and low risk of adverse effects. This research provides valuable insights into the comparative affinities of marine origin and synthesized compounds from the xanthene, coumarin, and benzoxazole classes, highlighting promising candidates for further in vitro and in vivo studies.

S. Zukić, A. Osmanović, Anja Harej Hrkać, Sandra Kraljević Pavelić, S. Špirtović-Halilović, E. Veljović, S. Roca, S. Trifunović, D. Završnik et al.

The pyrimidine heterocycle plays an important role in anticancer research. In particular, the pyrimidine derivative families of uracil show promise as structural scaffolds relevant to cervical cancer. This group of chemicals lacks data-driven machine learning quantitative structure-activity relationships (QSARs) that allow for generalization and predictive capabilities in the search for new active compounds. To achieve this, a dataset of pyrimidine and uracil compounds from ChEMBL were collected and curated. A workflow was developed for data-driven machine learning QSAR using an intuitive dataset design and forwards selection of molecular descriptors. The model was thoroughly externally validated against available data. Blind validation was also performed by synthesis and antiproliferative evaluation of new synthesized uracil-based and pyrimidine derivatives. The most active compound among new synthesized derivatives, 2,4,5-trisubstituted pyrimidine was predicted with the QSAR model with differences of 0.02 compared to experimentally tested activity.

Morus alba L. is a plant with a long history of dietary and medicinal uses. We hypothesized that M. alba possesses a significant biological potential. In that sense, we aimed to generate the chemical, antimicrobial, toxicological, and molecular profile of M. alba leaf and fruit extracts. Our results showed that extracts were rich in vitamin C, phenols, and flavonoids, with quercetin and pterostilbene concentrated in the leaf, while fisetin, hesperidin, resveratrol, and luteolin were detected in fruit. Extracts exhibited antimicrobial activity against all tested bacteria, including multidrug-resistant strains. The widest inhibition zones were in Staphylococcus aureus ATCC 33591. The values of the minimum inhibitory concentration ranged from 15.62 μg/ml in Enterococcus faecalis to 500 μg/ml in several bacteria. Minimum bactericidal concentration ranged from 31.25 μg/ml to 1000 μg/ml. Extracts impacted the biofilm formation in a concentration-dependent and species-specific manner. A significant difference in the frequency of nucleoplasmic bridges between the methanolic extract of fruit (0.5 μg/ml, 1 μg/ml, 2 μg/ml), as well as for the frequency of micronuclei between ethanolic extract of leaf (2 μg/ml) and the control group was observed. Molecular docking suggested that hesperidin possesses the highest binding affinity for multidrug efflux transporter AcrB and acyl-PBP2a from MRSA, as well as for the SARS-CoV-2 Mpro. This study, by complementing previous research in this field, gives new insights that could be of great value in obtaining a more comprehensive picture of the Morus alba L. bioactive potential, chemical composition, antimicrobial and toxicological features, as well as molecular profile.

BACKGROUND: Computational research plays an important role in predicting the chemical and physical properties of biologically active compounds important in future structural modifications to improve or modify biological activity. OBJECTIVE: This research focuses on quantum chemical and spectroscopic investigations properties of synthesized 4-hydroxycoumarin derivatives. METHODS: Quantum chemical calculations were obtained using B3LYP, HF, and M06-2x level methods with the 6-31++G (d,p) basis set. Afterward, IR, 1H, 13C, UV-Visible experimentally parameters were compared with the results obtained using the B3LYP/6-31+G*(d) basis set of the molecules to be able to characterize the structures. RESULTS: Based on the quantum chemical calculations compound with acetamido group on the phenyl ring is the most reactive, and compound with nitro substituent is the least reactive and the the strongest electrophile among tested compounds. With the exception of compounds with dimethylamino group, all other compounds have a pronounced tautomer between OH and C = O group. The calculated and experimental values are in agreement with each other. CONCLUSION: The molecular structure in the ground state of six 3-cinnamoyl 4-hydroxycoumarin derivatives was optimized using density functional theory. The observed and computed values were compared and it can be concluded that the theoretical results were in good linear agreement with the experimental data.

Solvent and substitution effects on the UV/Vis spectroscopic and fluorescence behaviour of seven synthesized 3-substituted 4-hydroxycoumarin derivatives were tested. The tested compounds were dissolved in ethyl acetate, acetonitrile, and dimethyl sulfoxide. Absorption and emission spectra were recorded in the range of 200–800 nm. All tested 4-hydroxycoumarin derivatives showed good absorption in a wide range of 200–550 nm, depending on the properties of the substituents on the benzene ring of the cinnamoyl moiety and the type of solvent. In comparison to the unsubstituted analogue, compounds with an electron-donating group exhibited bathochromically shifted UV/Vis absorption and emission spectra. The highest fluorescence quantum yield was observed for compounds with dimethylamino and acetamido groups as substituents at the benzene ring. Considering that both substitution and solvent affect the absorption and emission spectra of the tested compounds, it can be concluded that judiciously selecting these parameters can improve their absorption and fluorescence properties, making them suitable for various analytical uses.

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