Propolis Extract and Its Bioactive Compounds—From Traditional to Modern Extraction Technologies

Propolis is a honeybee product known for its antioxidant, anti-inflammatory, anticancer, and antimicrobial effects. It is rich in bioactive molecules whose content varies depending on the botanical and geographical origin of propolis. These bioactive molecules have been studied individually and as a part of propolis extracts, as they can be used as representative markers for propolis standardization. Here, we compare the pharmacological effects of representative polyphenols and whole propolis extracts. Based on the literature data, polyphenols and extracts act by suppressing similar targets, from pro-inflammatory TNF/NF-κB to the pro-proliferative MAPK/ERK pathway. In addition, they activate similar antioxidant mechanisms of action, like Nrf2-ARE intracellular antioxidant pathway, and they all have antimicrobial activity. These similarities do not imply that we should attribute the action of propolis solely to the most representative compounds. Moreover, its pharmacological effects will depend on the efficacy of these compounds’ extraction. Thus, we also give an overview of different propolis extraction technologies, from traditional to modern ones, which are environmentally friendlier. These technologies belong to an open research area that needs further effective solutions in terms of well-standardized liquid and solid extracts, which would be reliable in their pharmacological effects, environmentally friendly, and sustainable for production.     

Study of the structure,prooxidative, and cytotoxic activity of some chelate copper(II) complexes

The six chelate N,O-copper(II) complexes were synthesised starting from salicylaldehyde anil Schiff bases, as ligands. Their structure is elucidated using experimental and theoretical tools. In vitro biological activities, i.e. cytotoxic and prooxidative effects against human epithelial mammary gland/breast metastatic carcinoma MDA-MB-231, epithelial colorectal carcinoma HCT-116, and foetal lung fibroblast healthy MRC-5 cell lines of investigated compounds are also determined. Complexes Cu-1, Cu-6, and especially Cu-7 showed significant cytotoxic effects, with IC₅₀ values comparable with effects of positive control CisPt. In addition, investigated complexes induced extreme oxidative and nitrosative stress in all treated cell lines. The most prominent effect is observed on HCT-116 cells, and on MRC-5 cells, while MDA-MB-231 cells showed higher resistance to the investigated cell lines, giving us direction towards the substances with more specific selectivity.     

Parallel Water/Aromatic Interactions of Non‐Coordinated and Coordinated Water

The parallel interactions of non‐coordinated and coordinated water molecules with an aromatic ring were studied by analyzing data in the Cambridge structural database (CSD) and by using quantum chemical calculations. The CSD data show that water/aromatic contacts prefer parallel to OH/π interactions, which indicates the importance of parallel interactions. The results reveal the influence of water coordination to a metal ion; the interactions of aqua complexes are stronger. Coordinated water molecules prefer a parallel‐down orientation in which one O?H bond is parallel to the aromatic ring, whereas the other O?H bond points to the plane of the ring. The interactions of aqua complexes with parallel‐down water/benzene orientation are as strong as the much better known OH/π orientations. The strongest calculated interaction energy is ?14.89 kcal mol^?1. The large number of parallel contacts in crystal structures and the quite strong interactions indicate the importance of parallel orientation in water/benzene interactions.     

Using xanthated Lagenaria vulgaris shell biosorbent for removal of Pb(II) ions from wastewater

Chemically modified Lagenaria vulgaris shell was applied as a new sorbent for the removal of lead (II) ions from aqueous solution in a batch process mode. The influence of contact time, initial concentration of lead (II) ions, initial pH value, biosorbent dosage, particle size and stirring speed on the removal efficiency was evaluated. Biosorbent characterization was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four kinetic models (pseudo-first order, pseudo-second order, Elovich model and Intraparticle diffusion model) were used to determine the kinetic parameters. The experimental results were fitted to the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models of isotherm. Pseudo-second order kinetic model and Langmuir isotherm model best fitted the experimental data. Sorption process is obtained to be fast and equilibrium was attained within 40 min of contact time. The maximum sorption capacity was 33.21 mg g^?1. Biosorption was highly pH-dependent where optimum pH was found to be 5. The results of FTIR and SEM analysis showed the presence of new sulfur functional groups. This study indicated that xanthated Lagenaria vulgaris shell could be used as an effective and low-cost biosorbent for the removal of lead (II) ions from aqueous solution.     

Application of the Solvatic Model for Prediction of Retention in RP-LC for Multi-Step Gradient Profiles

Application of the solvatic retention model of reversed-phase liquid chromatography was studied to predict retention of phenylisothiocyanate derivatives of amino acids from structural formulae and stationary and mobile phase properties. The gradient elution mode with methanol and acetonitrile aqueous mobile phases was used. It was shown that practically acceptable prediction or retention time values can be achieved after the first approximation step when experimental data of one run are used. The zero approximation level predictions—from structural formulae, column and mobile phase properties can be used as a “first guess” method from which further optimization can begin.

     

Ring Currents in Benzo‐ and Benzocyclobutadieno‐Annelated Biphenylene Derivatives

The effect of benzo and benzocyclobutadieno annelation on the current density induced in a series of biphenylene derivatives is examined at the B3LYP/cc‐pVDZ level of theory, by using the CTOCD‐DZ method. Angular benzo annelation increases, whereas linear benzo annelation decreases the intensity of paratropic (antiaromatic) current density along the four‐membered ring of biphenylene. The opposite effect is found for benzocyclobutadieno annelation. It is shown that the extent of local aromaticity of the four‐membered ring in biphenylene congeners can vary from highly antiaromatic to nonaromatic, as a result of different modes of annelation.     

Mixed‐ligand MnII and CuII complexes with alternating 2,2′‐bipyrimidine and terephthalate bridges

The novel polymeric complexes catena‐poly[[diaquamanganese(II)]‐μ‐2,2′‐bipyrimidine‐κ⁴N¹,N^1′:N³,N^3′‐[diaquamanganese(II)]‐bis(μ‐terephthalato‐κ²O¹:O⁴)], [Mn₂(C₈H₄O₄)₂(C₈H₆N₄)(H₂O)₄]_n, (I), and catena‐poly[[[aquacopper(II)]‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ²O¹:O^1′‐copper(II)‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ²O¹:O^1′‐[aquacopper(II)]‐μ‐2,2′‐bipyrimidine‐κ⁴N¹,N^1′:N³,N^3′] tetrahydrate], {[Cu₃(C₈H₄O₄)₂(OH)₂(C₈H₆N₄)(H₂O)₄]·4H₂O}_n, (II), containing bridging 2,2′‐bipyrimidine (bpym) ligands coordinated as bis‐chelates, have been prepared via a ligand‐exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht²⁻) anions were found. In (I), two tpht²⁻ anions acting as bis‐monodentate ligands bridge the Mn^II centres in a parallel fashion. In (II), the tpht²⁻ anions act as endo‐bridges and connect two Cu^II centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn₂(tpht)₂(bpym)(H₂O)₄] entity in (I) and the trinuclear [Cu₃(tpht)₂(OH)₂(bpym)(H₂O)₄]·4H₂O coordination entity in (II) build up one‐dimensional polymeric chains along the b axis. In (I), the Mn^II cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central Cu^II cation is also on a special position (site symmetry ). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face‐to‐face π–π interactions [in (I)], forming three‐dimensional metal–organic frameworks. The Mn^II cation in (I) has a trigonally deformed octahedral geometry, whereas the Cu^II cations in (II) are in distorted octahedral environments. The Cu^II polyhedra are inclined relative to each other and share common edges.     

Chemical Characteristics of Croatian Traditional Istarski pršut (PDO) Produced from Two Different Pig Genotypes

Chemical characteristics of raw and processed Istarski pršut (PDO) produced from two different pig genotypes were studied with special emphasis on amino and fatty acid composition and factors of lipid stability. Raw hams of Large White (LW)xLandrace (L), and (LWxL)xDuroc (D) pig genotypes were used in the study (20 hams of each genotype). All left raw hams from each carcass were processed in accordance with the PDO specification of Istarski pršut, and other half (the right ones) of LWxL)xD genotype were used for analyses of raw hams (fresh muscles). Istarski pršut was evaluated on the basis of the chemical parameters of the raw and matured lean ham. The process of dry curing significantly influenced the chemical properties of Istarski pršut. Despite the higher content of intramuscular fat and polyunsaturated fatty acids, the fat of (LWxL)xD ham was much more resistant to hydrolysis and oxidation, suggesting that fatty acid profile and other factors, also play a significant role. Significant differences between pig genotypes in the amino acid and fatty acid profiles were found. The analyzed Istarski pršut may be distinguished by prints of multivariate chemometric statistical analysis, based on their amino acid and fatty acid compositions.     

Asymptotic analysis of positive solutions of generalized Emden-Fowler differential equations in the framework of regular variation

Positive solutions of the nonlinear second-order differential equation $(p(t)|x'|^{\alpha - 1} x')' + q(t)|x|^{\beta - 1} x = 0,\alpha > \beta > 0,$ are studied under the assumption that p, q are generalized regularly varying functions. An application of the theory of regular variation gives the possibility of obtaining necessary and sufficient conditions for existence of three possible types of intermediate solutions, together with the precise information about asymptotic behavior at infinity of all solutions belonging to each type of solution classes.