Production of Bioactive Peptides from Baltic Herring (Clupea harengus membras): Dipeptidyl Peptidase-4 Inhibitory,Antioxidant and Antiproliferative Properties

This study aimed to produce bioactive protein hydrolysates from undervalued fish, namely Baltic herring, and its filleting by-products. Protein hydrolysates were produced with Alcalase and Flavourzyme to achieve effective hydrolysis. The hydrolysates were evaluated for chemical composition, molecular weight distribution, antioxidant capacity, dipeptidyl-peptidase 4 (DPP4) inhibitory activity, effects on cell proliferation and surface hydrophobicity. The protein content of the hydrolysates was high, from 86% to 91% (dm), while the fat content was low, from 0.3% to 0.4% (dm). The hydrolysates showed high DPP4 inhibition activities with IC₅₀ values from 5.38 mg/mL to 7.92 mg/mL. The scavenging activity of the hydrolysates towards DPPH was low, but an intermediate Folin–Ciocalteu reducing capacity and Cu²⁺ chelating ability was observed. The solid phase extraction with Sep-Pak C18 cartridges increased the DPP4 inhibition activity and antioxidant capacity, indicating peptides’ crucial role in the bioactivities. The cytotoxicity of the hydrolysates was evaluated on the HCT8, IMR90, and A549 cell lines. The hydrolysates inhibited cell growth in the cancer and normal cells, although they did not reduce cell viability and were not lethal. Overall, our results indicate that protein hydrolysates from Baltic herring have potential as health-promoting foods and nutraceuticals, especially for enhancing healthy blood glucose regulation.     

Differentiation of diastereomeric cyclic beta-amino acids by varying the neutral reagent in ion/molecule reactions studied by electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry

Stereochemical differentiation of diasteromeric pairs of cis- and trans-2-aminocyclohexane-, -2-amino-4-cyclohexene-, and -2-aminocyclopentanecarboxylic acids was investigated with host-guest complexes where tetraethyl resorcarene was the host molecule. Diastereoselectivity was evaluated by ion/molecule reactions and collision-induced dissociation with electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS). The effect of varying the neutral reagent (n-propylamine, i-propylamine, diethylamine, and triethylamine) in ion/molecule reactions was evaluated. Both steric interactions and proton affinity of the neutral reagents influenced the reaction rates. High proton affinity of the neutral reagent apparently had a twofold effect. If the proton affinity of the neutral reagent was too high, the reaction tended to become too exothermic and part of the host-guest complex decomposed instead of transforming to a new host-guest complex, effecting a decrease in the reaction rate. The remaining portion of the host-guest complexes meanwhile reacted very fast with the neutral reagent due to high proton affinity causing an increase in the reaction rate. n-Propylamine and i-propylamine proved to be the best neutral reagents, providing clear diastereoselectivity for beta-amino acids in ion/molecule reactions. Interestingly, diastereoselectivity was better for flexible cyclohexane beta-amino acids (2 and 3) than for more rigid cyclopentane beta-amino acids (6 and 7). The results of ab initio and hybrid density functional theory calculations on the structures of the host-guest complexes of saturated beta-amino acids were in good agreement with the experimental results.     

The complexation of two different ammonium ions with resorcarenes in protic solvent medium investigated by electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry

The complexations of two ammonium ions (guests) with two resorcarenes (hosts) were investigated using electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry. Although the two guests and the two hosts were noticeably similar, the quantity of the corresponding supramolecular complexes formed varied significantly due to the differences in host conformations and guest ability to form non-covalent interactions.     

Hydrogen bonding in phosphonate cavitands: Investigation of host-guest complexes with ammonium salts

The H-bonding in alkylammonium complexes of phosphonate cavitands were studied by mass spectrometric methods and theoretical calculations. The alkylammonium ions included primary, secondary, and tertiary methyl- and ethylammonium ions. Their complexation with mono-, tetra-, and two di-phosphonate cavitands, which differ according to the number and position of H-bond acceptor P = O groups, was evaluated by using different competition experiments, energy-resolved CID, gas-phase H/D-exchange, and ligand-exchange reactions, together with ab initio theoretical optimization of the complexes. The phosphonate cavitands with two or more adjacent P = O groups were found to be selective towards secondary alkylammonium ions, due to simultaneous formation of two stable hydrogen bonds. In the ion-molecule reactions (both H/D- and ligand-exchange), the formation of two stable hydrogen bonds was observed either to slow down the reaction or to completely prevent it. This was, however, limited to situations where two hydrogen bonds are formed between the H-bond donor sites of the alkyl ammonium ion and the vicinal H-bond acceptor sites of the cavitand.     

Points of {varepsilon} Differentiability of Lipschitz Functions from Rn to Rn-1

This paper proves that for every Lipschitz function f : RⁿR^m,m < n, there exists at least one point of -differentiabilityof f which is in the union of all m-dimensional affine subspacesof the form q0 +span{q1,q2,...,q_m}, where q_j (j = 0,1,...,m)are points in Rⁿ with rational coordinates. 2000 MathematicsSubject Classification 26B05, 26B35.     

Preparation of 1‐substituted‐5‐[(2‐oxo‐2‐phenyl)ethyl]imidazoles

New high yield preparation methods were developed for the pharmaceutically interesting compounds, 1‐benzyl‐, 1‐methyl‐, and 1H‐5‐[(2‐oxo‐2‐phenyl)ethyl]imidazoles 1a‐c , respectively. The title compounds were synthesized by four different methods using various starting materials. Two of the methods involved transformation reactions of the key intermediates, 1‐substituted‐5‐[(2‐nitro‐2‐phenyl)ethenyl]imidazoles 2a‐c and 1‐substituted‐5‐[(2‐nitro‐2‐phenyl)ethyl]imidazoles 3a‐c , while the other two utilized the oxidation of 1‐substituted‐5‐[(2‐hydroxy‐2‐phenyl)ethyl]imidazoles 4a‐c , with chromic oxide, and the umpolung reaction of benzaldehyde followed by a condensation reaction of the umpolung intermediate with imidazolecarboxaldehydes 6a‐c.     

A qualitative model for polymerisation of propylene with a MgCl2-supported TiCl4 Ziegler-Natta catalyst

A qualitative model for polymerisation of propylene with a MgCl₂-supported TiCl₄ Ziegler-Natta catalyst is developed. A series of polymerisation with increasing external electron donor/Ti ratio is performed and the polymers are analysed with GPC, ¹³C NMR and DSC. The model explains the trends in isotacticity and isotactic sequence length based on an equilibrium reaction of the electron donor, which is either coordinated next to an active site or extracted to the solution by the cocatalyst AlR₃. Different rates for propagation and termination reactions when the donor is present or absent are used to explain the trends in activity and molar mass. The possibilities for a quantitative model and parameter estimation are discussed.     

Functional Gene Abundances (nahAc, alkB, xylE) in the Assessment of the Efficacy of Bioremediation

In this study, we compared the mineralization rates of three selected (14)C-labeled hydrocarbon compounds, octacosane, toluene, and naphthalene, with the presence of the corresponding functional genes (alkB, xylE, nahAc) in a large number of soil samples representing different types of soil and petroleum hydrocarbon contamination. Functional genes were enumerated by the replicate limited dilution (RLD) polymerase chain reaction (PCR) technique. RLD-PCR was further compared to real-time PCR measurements for nahAc and xylE for some samples. At a heating oil-contaminated site, octacosane mineralization rates were higher (on average 0.0015 day(-1)) when compared to aerobic naphthalene and toluene mineralization (on average 0.00003 and 0.0007 day(-1)). The corresponding gene abundances measured by RLD-PCR were on average 0.95, 0.3, and 0.13 x 10(3) gene copies g(-1) soil for alkB, nahAc, and xylE, respectively. At a site contaminated with gasoline, the situation was the opposite: Toluene mineralization was the highest (on average 0.0031 day(-1)), and only xylE genes could be detected (on average 0.13 x 10(3) gene copies g(-1) soil by RLD-PCR). XylE and nahAc gene abundances were correlated with the (14)C-toluene and naphthalene mineralization activities, respectively, in samples from aerobic layers. AlkB gene abundances were not correlated with the octacosane mineralization. Real-time PCR was a more sensitive method than RLD-PCR by a factor of 1,200 for nahAc and 300 for xylE. In conclusion, functional gene abundances seemed to reflect the type of the contamination. With optimized assays, the gene abundances can be used to assess bioremediation efficacy.     

Regiochemistry of N‐substitution of some 4(5)‐substituted imidazoles under solvent‐free conditions

Imidazole‐4(5)‐carboxaldehyde and 4(5)‐cyanoimidazole were N‐benzylated and N‐methylated using benzyl chloride and methyl iodide on zinc oxide (ZnO), alumina, and KF/alumina under basic conditions without solvent. Triethylamine (Et₃N) or potassium carbonate was added as base in the reactions on ZnO and alumina. Imidazole‐4(5)‐carboxaldehyde was also benzylated on silica and carbon nanotubes. The effect of bases and solids on the product distribution of 1,4‐ and 1,5‐substituted compounds was investigated. In some cases, the product ratios were different for imidazole‐4(5)‐carboxaldehyde and 4(5)‐cyanoimidazole. In the reactions on KF/alumina the 1,4‐product was favored for both compounds. The combination of Et₃N and ZnO favored the 1,5‐product, however for the nitrile effect was not so pronounced. When N‐benzylation and methylation of the aldehyde were performed in the presence of catalytic amount of zinc chloride with Et₃N as base, the product distributions were the same as in the reactions on ZnO. Nitrile gave different product ratios on ZnO and in the presence of ZnCl₂. In addition, a mixture of N‐benzylimidazole and 1,3‐dibenzylimidazolium was produced when imidazole was benzylated on KF/alumina. Only the latter product was afforded when two equivalents of benzyl chloride were used.     

Measuring H-bonding in supramolecular complexes by gas phase ion-molecule reactions

H/D and guest-exchange ion-molecule reactions have been used as a new tool to elucidate the operation of multiple hydrogen bonding in gas-phase complexes formed between phosphonate cavitands and ethyl-substituted ammonium ions.