Advances in Research on Food Bioactive Molecules and Health

Fresh and processed food products are rich in bioactive molecules, including polysaccharides, vitamins, carotenoids, peptides, antioxidants, phenolics, phytosterols, and novel lipids. Bioactive molecules in food could prevent several diseases (i.e., metabolic syndrome, cardiovascular diseases, cancer, etc.). Thus, consumer awareness is growing about the health-promoting impact of food bioactive molecules. Health claims are essential added-value features, wherein health-enhancing potential of bioactives depend on their chemical structure. On the other hand, the investigation of the structure-function relationship of food bioactive molecules is of importance. In this regard, Molecules is delighted to highlight the importance of food bioactive molecules and their effect on health. In this Special Issue of Molecules, researchers are invited to contribute original research and up-to-date reviews.     

The Biodiversity of the Genus Dictyota: Phytochemical and Pharmacological Natural Products Prospectives

Although a broad variety of classes of bioactive compounds have already been isolated from seaweeds of the genus Dictyota, most different species are still chemically and biologically unexplored. Dictyota species are well-known brown seaweeds belonging to the Dictyotaceae (Phaeophyta). The phytochemical composition within the genus Dictyota has recently received considerable interest, and a vast array of components, including diterpenes, sesquiterepenes, sterols, amino acids, as well as saturated and polyunsaturated fatty acids, have been characterized. The contribution of these valued metabolites to the biological potential, which includes anti-proliferative, anti-microbial, antiviral, antioxidant, anti-inflammatory, and anti-hyperpigmentation activities, of the genus Dictyota has also been explored. Therefore, this is the most comprehensive review, focusing on the published literature relevant to the chemically and pharmacologically diverse biopharmaceuticals isolated from different species of the genus Dictyota during the period from 1976 to now.     

A Glossary for Chemical Approaches towards Unlocking the Trove of Metabolic Treasures in Actinomycetes

Actinobacterial natural products showed a critical basis for the discovery of new antibiotics as well as other lead secondary metabolites. Varied environmental and physiological signals touch the antibiotic machinery that faced a serious decline in the last decades. The reason was exposed by genomic sequencing data, which revealed that Actinomycetes harbor a large portion of silent biosynthetic gene clusters in their genomes that encrypt for secondary metabolites. These gene clusters are linked with a great reservoir of yet unknown molecules, and arranging them is considered a major challenge for biotechnology approaches. In the present paper, we discuss the recent strategies that have been taken to augment the yield of secondary metabolites via awakening these cryptic genes in Actinomycetes with emphasis on chemical signaling molecules used to induce the antibiotics biosynthesis. The rationale, types, applications and mechanisms are discussed in detail, to reveal the productive path for the unearthing of new metabolites, covering the literature until the end of 2020.     

Stepwise charge transfer complexation of some pyrimidines with sigma-acceptor iodine involving a new unconventional acceptor

Interactions of some pyrimidine derivatives, 4-amino-2,6-dimethylpyrimidine, kyanmethin, (4AP), 2-amino-4,6-dimethylpyrimidine (2AP), 2-aminopyrimidine (AP), 2-amino-4-methylpyrimidine (AMP), 2-amino-4-methoxy-6-methylpyrimidine (AMMP), and 4-amino-5-chloro-2,6-dimethylpyrimidine (ACDP) as electron donors, with iodine (I(2)), as a typical sigma-electron acceptor, have been studied. Electronic absorption spectra of these interactions in several organic solvents of different polarities have performed instant appearance of clear charge transfer (CT) bands. Formation constants (KCT), molar absorption coefficients (epsilonCT) and thermodynamic properties, DeltaH, DeltaS, and DeltaG, of these interactions have been determined and discussed. Electronic absorption spectra of the solutions of the synthesized pyrimidines-iodine, P-I2, CT complexes have shown the characteristic bands of the triiodide ion, I3*. UV/vis spectral tracking of these interactions have shown that by lapse of time the first formed CT complex, P-I2, is transformed to the corresponding triiodide complex, P(+)I.I3*, then, the later interacts as a new unconventional acceptor and it forms a CT complex of the form (P).(P+I.I3*). Elemental analyses of these solid complexes have indicated the stoichiometric ratio 2:2, or formally 1:1, P:I2.     

Back Cover: Manipulating Intermetallic Charge Transfer for Switchable External Stimulus-Enhanced Water Oxidation Electrocatalysis (Angew. Chem. Int. Ed. 44/2023)

Electrocatalytic processes involving the oxygen evolution reaction (OER) present a kinetic bottleneck due to the existence of linear-scaling relationships, which bind the energies of the different intermediates in the mechanism limiting optimization. Here, we offer a way to break these scaling relationships and enhance the electrocatalytic activity of a Co−Fe Prussian blue modified electrode in OER by applying external stimuli. Improvements of ≈11 % and ≈57 % were achieved under magnetic field (0.2 T) and light irradiation (100 mW cm⁻²), respectively, when working at fixed overpotential, η=0.6 V at pH 7. The observed enhancements strongly tie in with the intermetallic charge transfer (IMCT) intensity between Fe and Co sites. Density Functional Theory simulations suggest that tuning the IMCT can lead to a change of the OER mechanism to an external stimuli-sensitive spin crossover-based pathway, which opens the way for switchable electrocatalytic devices.     

2-Cyano-N′-[(1,3-diphenyl-1H-pyrazol-4-yl)methylidene]acetohydrazide in the Synthesis of Nitrogen Heterocycles

Russian Journal of Organic Chemistry - Some interesting nitrogen heterocycles, as well as other products, were synthesized by reactions of...     

Aroyl and acyl cyanides as orthogonal protecting groups or as building blocks for the synthesis of heterocycles

Molecular Diversity - α-Cyanoketones represent a synthetically attractive scaffold possessing bifunctional reactivity which enabled synthesis of a diversity of products. This involves reaction...     

Regioselective formation of 1,2,4-triazoles by the reaction of amidrazones in the presence of diethyl azodicarboxylate and catalyzed by triethylamine

Molecular Diversity - A general method for the synthesis of 1,3,5-trisubstituted 1,2,4-triazoles has been developed from reaction of amidrazones with ethyl azodicarboxylate and triethylamine...     

Recent developments in the utility of Zn(L-proline)2 as benign and recyclable metallo-organocatalyst in organic synthesis

The coordination of Zn (II) with L - proline as a choral ligand makes the initiated complex Zn(L-proline)₂ a moderately soft Lewis acid. Recently Zn(L-proline)₂ has emerged as a promising reusable chiral catalyst which could be utilized in a diversity of transformations. The present short review article focuses mainly on recent developments in utility of Zn(L-proline)₂ in organic synthesis. This includes Aldol condensation, synthesis of heterocyclic compounds with five, six and fused rings.     

A thermoelastic diffusion interaction in an infinitely long annular cylinder

The present paper is aimed at studying a two-dimensional problem for an infinitely long solid conducting circular cylinder with a permeating substance in contact with its bounding surface. The problem is considered in the context of generalized thermoelastic diffusion theory with one relaxation time. The lateral surface of the solid is traction free and subjected to known temperature and chemical potential as functions of time. The solution is obtained by a transform method and a direct approach without the customary use of potential functions. Numerical inversion of the transformed solution is carried out to obtain the temperature, displacement, stress, and concentration of the diffusive material distributions. Numerical results are represented graphically and discussed. The second sound effect and the asymptotic behavior for the solution are discussed.