The emergence of COVID-19 has caused worldwide concern due to its high infectivity and mortality. Research groups around the world have prioritised drug development against COVID-19. Repurposing of ...already approved drugs, including the antimalarial drug chloroquine, has attracted considerable attention. The aim of this article is to (i) provide an overview of the recent chemical methods used to synthesise chloroquine and hydroxychloroquine, and (ii) provide insight into the data collected in 2020 on their efficacy against COVID-19. Unfortunately, the promising early results have not been confirmed and a clear and unambiguous conclusion on their clinical efficacy has not yet been drawn.
A combined strategy utilizing experimental (infrared, nuclear magnetic resonance, circular dichroism, X-ray) and computational (time-dependent density functional theory) techniques is illustrated on ...tripeptides to investigate their chiroptical properties. Eight stereoisomers of monosubstituted ferrocene, Boc-Pro-Pro-Ala-NHFc, have been prepared and conformationally characterized in depth to reach some guidelines for a future design of ferrocene-based chromophores. The origin of the sign change in circular dichroism spectra near the absorption maximum of a ferrocene chromophore (about 470 nm) is strongly correlated with the sign of the dihedral angle describing deviation of the directly attached amide plane from planarity of the cyclopentadienyl ring. These findings may provide some guidelines for the design of new chiroptical ferrocene-based probes for the assignment of the screw-sense preference of short peptides.
Ispitivan je način priprave fotokatalitički aktivnog ZnO sloja taloženjem iz otopine. Slojevi bazičnog cinkova acetata (LBZA) uspješno su naneseni na podloge različitih morfologija, a prethodna ...hidroliza podloge pogoduje dobivanju debljih i čvršće vezanih slojeva. No postupak priprave znatno je osjetljiv na varijacije u uvjetima što čini prevlačenje većih površina zahtjevnijim. Reproducibilnost fotokatalitičke aktivnosti ZnO slojeva dobivenih žarenjem LBZA slaba je i varira do 50 %, bez jasne pravilnosti.
Preparation of photocatalytically active ZnO layer by chemical bath deposition was investigated. Layers of layered basic zinc acetate (LBZA) were successfully deposited on substrates of varying morphologies, and the substrate hydrolysis led to formation of thicker and better adhering layers. However, the process was quite sensitive to variations in conditions, which makes coating of larger surfaces more challenging. Photocatalytic activity of ZnO layers obtained from LBZA by calcining had poor reproducibility, varying up to 50 % without obvious regularity.
The development of turn-based inhibitors of protein-protein interactions has attracted considerable attention in medicinal chemistry. Our group has synthesized a series of peptides derived from an ...amino-functionalized ferrocene to investigate their potential to mimic protein turn structures. Detailed DFT and spectroscopic studies (IR, NMR, CD) have shown that, for peptides, the backbone chirality and bulkiness of the amino acid side chains determine the hydrogen-bond pattern, allowing tuning of the size of the preferred hydrogen-bonded ring in turn-folded structures. However, their biological potential is more dependent on their lipophilicity. In addition, our pioneering work on the chiroptical properties of aminoferrocene-containing peptides enables the correlation of their geometry with the sign of the CD signal in the absorption region of the ferrocene chromophore. These studies have opened up the possibility of using aminoferrocene and its derivatives as chirooptical probes for the determination of various chirality elements, such as the central chirality of amino acids and the helicity of peptide sequences.
With the increase in awareness of the importance of engagement in physical activities, high requirements have been placed on polymers intended for use in sports. A number of authors investigated the ...influence of aging factors on the performance of the polymer. Still, there is a lack of aging protocols that would be product-centered, especially when high performance is imperative. This paper presents a new approach to polymer aging and examines the change of the identified set of properties due to aging under different conditions, and the duration of each (topography, thickness, moisture management, elongation, and bursting force). The results of the testing revealed the increase in thickness due to exposure, especially to the sun-exposed materials. The ability of materials to elongate until the moment of rupture decreases due to exposure to the sun (strong relationship to the time of exposure; R
reaches 0.99) and the bursting force (up to 6.8%). Furthermore, results indicate the significantly impaired capacity of the polymer material to absorb moisture. The results of measurements indicated (derived) by spectroscopic studies, based on the ATR-FTIR (attenuated total reflectance) method, showed that there was no detectable influence of aging in the sun or shade on the chemical structure of polyester samples.
Considering the enormous importance of protein turns as participants in various biological events, such as protein–protein interactions, great efforts have been made to develop their conformationally ...and proteolytically stable mimetics. Ferrocene-1,1′-diamine was previously shown to nucleate the stable turn structures in peptides prepared by conjugation with Ala (III) and Ala–Pro (VI). Here, we prepared the homochiral conjugates of ferrocene-1,1′-diamine with l-/d-Phe (32/35), l-/d-Val (33/36), and l-/d-Leu (34/37) to investigate (1) whether the organometallic template induces the turn structure upon conjugation with amino acids, and (2) whether the bulky or branched side chains of Phe, Val, and Leu affect hydrogen bonding. Detailed spectroscopic (IR, NMR, CD), X-ray, and DFT studies revealed the presence of two simultaneous 10-membered interstrand hydrogen bonds, i.e., two simultaneous β-turns in goal compounds. A preliminary biological evaluation of d-Leu conjugate 37 showed its modest potential to induce cell cycle arrest in the G0/G1 phase in the HeLa cell line but these results need further investigation.
The concept of peptidomimetics is based on structural modifications of natural peptides that aim not only to mimic their 3D shape and biological function, but also to reduce their limitations. The ...peptidomimetic approach is used in medicinal chemistry to develop drug-like compounds that are more active and selective than natural peptides and have fewer side effects. One of the synthetic strategies for obtaining peptidomimetics involves mimicking peptide α-helices, β-sheets or turns. Turns are usually located on the protein surface where they interact with various receptors and are therefore involved in numerous biological events. Among the various synthetic tools for turn mimetic design reported so far, our group uses an approach based on the insertion of different ferrocene templates into the peptide backbone that both induce turn formation and reduce conformational flexibility. Here, we conjugated methyl 1'-aminoferrocene-carboxylate with homo- and heterochiral Pro-Ala dipeptides to investigate the turn formation potential and antiproliferative properties of the resulting peptidomimetics
-
. Detailed spectroscopic (IR, NMR, CD), X-ray and DFT studies showed that the heterochiral conjugates
and
were more suitable for the formation of β-turns. Cell viability study, clonogenic assay and cell death analysis showed the highest biological potential of homochiral peptide
.
The aim of the present study was to examine changes in phenolic compounds during refining of rapeseed oil. In crude rapeseed oil, 4-vinylsyringol (canolol) is the dominant phenolic compound, ...accounting for 85% of total phenolics. Refining decreased the total amount of phenolic compounds by 90%. NMR and MS analyses of edible rapeseed oil phenolic extracts identified 4-vinylsyringol dimer as the dominant phenolic compound. This phenolic compound appears to form through acid-catalyzed dimerization-aromatic substitution of 4-vinylsyringol monomers. Analysis of rapeseed oils from different stages of the refining process suggest that 4-vinylsyringol dimer forms during the neutralization phase, when H3PO4 acts as a catalyst, or during bleaching, when acid-activated bleaching earth acts as the catalyst. Whether 4-vinylsyringol forms during one or the other phase appears to depend on the phospholipid content of the crude oil. These insights may be useful for designing rapeseed oil refining processes that maximize levels of 4-vinylsyringol dimer.
The aim of the present study was to develop, for the first time, highly efficient spray-dried encapsulation systems of ground ivy (Glechoma hederacea L.) polyphenols using partially hydrolyzed guar ...gum (PHGG) and its binary systems with collagen hydrolyzates, carboxymethyl cellulose, nutriose, mucin and xylan. All carriers were subjected to differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) to estimate their thermal behavior and stability. In the formulated spray-dried particles, the influence of different carriers on their physical-chemical (wettability, bulk density, zeta potential, morphology, size and FT-IR spectroscopy) and bioactive (encapsulation yield and simulated gastrointestinal digestion) properties were determined. The addition of each of the polymers used to the PHGG system increased the process yield and affected most of the physical parameters, with the exception of the diameter of the particles. The highest encapsulation yield (94.64%) for the most dominant phenolic compound - rosmarinic acid, was observed for particles made of PHGG and mucin, while PHGG-carboxymethyl cellulose particles showed controlled and continuous release in simulated gastrointestinal digestion, that can be associated with the highest values for wettability (2553.5 s) and water contact angle (87°).
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•PHGG should be combined with other polymers to achieve suitable physical properties.•High encapsulation efficiency of extracted phenolics into delivery systems was achieved.•Integration of carboxymethyl cellulose into PHGG system provided desirable in vitro release.
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