The psuedo‐michael reaction of 2‐aminoimidazolines 2. Part 1. Synthesis and structure assignment of isomeric 5(1H)‐Oxo and 7(1H)‐Oxo‐2,3‐dihydroimidazo[1,2‐a]pyrimidine‐6‐carboxylates

The pseudo‐Michael reaction of 1‐aryl‐2‐aminoimidazolines‐2 with diethyl ethoxymethylenemalonate (DEEM) was investigated. Extensive structural studies were performed to confirm the reaction course. For derivatives with N1 aromatic substituents, it was found that the reaction course was temperature dependent. When the reaction temperature was held at ?10 °C only the formation of 1‐aryl‐7(1H)‐oxo‐2,3‐dihydroimi‐dazo[1,2‐a]pyrimidine‐6‐carboxylates ( 4 ) was observed in contrast to earlier suggestions. Under the room temperature conditions, the same reaction yielded mixtures, with varying ratio, of isomeric 1‐aryl‐7(1H)‐oxo‐ ( 4a‐4f ) and 1‐aryl‐5(1H)‐oxo‐2,3‐dihydroimidazo[1,2‐a]pyrimidine‐6‐carboxylates ( 5a‐5f ). The molecular structure of selected isomers, 4b and 5c , was confirmed by X‐ray crystallography. Frontal chro‐matography with delivery from the edge was applied for the separation of the isomeric esters. The isomer ratio of the reaction products depended on the character of the substituents on the phenyl ring. The 1‐aryl‐7(1H)‐oxo‐carboxylates ( 4a‐4f ) were preferably when the phenyl ring contained H, 4‐CH₃, 4‐OCH₃ and 3,4‐Cl₂ substituents. Chloro substitution at either position 3 or 4 in the phenyl ring favored the formation of isomers 5a‐5f . The isomer ratios were confirmed both by ¹H NMR and chromatography. The reaction of the respective hydrobromides of 1‐aryl‐2‐aminoimidazoline‐2 with DEEM, in the presence of triethylamine, gave selectively 5(1H)‐oxo‐esters ( 5a‐5f ).     

A definitive RNAA method for determination of selenium in biological samples: uncertainty evaluation and assessment of degree of accuracy

This article describes work on the development of a highly accurate RNAA method for determination of selenium in biological samples. The analytical post-irradiation procedure is based on a combination of cation-exchange and extraction chromatography with final selective and quantitative fixation of selenium on a column packed with 3,3′-diaminobenzidine (DAB) supported on Amberlite XAD4, followed by gamma-ray spectrometric measurement. The suitability and accuracy of the method was demonstrated by analysing CRMs with certified selenium content. The uncertainty budget for Se determination in standard reference material Peach Leaves NBS 1547 was estimated; the combined standard uncertainty was calculated as 1.7%. The described method fulfils all the criteria for definitive methods. It was subsequently used for determination of selenium in biological materials intended as new CRMs and proficiency test samples.     

H-bonded complexes of aniline with HF/F- and anilide with HF in terms of symmetry-adapted perturbation, atoms in molecules, and natural bond orbitals theories

The hydrogen-bonded isoelectronic complexes of aniline with HF/F- and an ionic form of aniline with HF were investigated by use of computational methods: Symmetry-Adapted Perturbation Theory (SAPT), Atoms in Molecules (AIM), and Natural Bond Orbitals (NBO) approaches. All computations were based on structural models previously generated at the B3LYP/6-311+(d,p) level. The differences between neutral (Ph-NH2...HF)and anionic (Ph-NH2...F- and Ph-NH-...HF) complexes were clearly outlined. The discussed charged complexes serve as Lewis acids and base, HF and F-, respectively. It was found that electrostatic and induction energy terms, obtained as a result of the SAPT method, are most dependent on the type of H-bonding (i.e.,charged or neutral). The electrostatic term is the most distinctive between the neutral and charge-assisted hydrogen bonds in the investigated two-body systems, whereas the latter is more significant in the case of weaker interactions (larger H...B distances). Application of Principal Component Analysis (PCA) to energy components obtained from the SAPT procedure indicated that all of them are relatively well intercorrelated.The above-mentioned terms together with the exchange energy terms are the most important contributions ofthe main principal component, which describes 95% of the total variance. Comparison of AIM parameters in bond critical points for modeled H-bond systems shows a good agreement with those from equilibrium complexes, both experimental and calculated ones. It was found that charged H-bonded complexes exhibit larger fluctuation of electron density and its Laplacian in bond critical points, in line with SAPT analysis. NBO results confirmed the effect of the strength of interaction on property changes both in the region of H-bonding and outside of it. The latter, more distant consequences follow the Bent-Walsh rule for all studied complexes.     

Phytochemical and Biological Activity Studies on Nasturtium officinale (Watercress) Microshoot Cultures Grown in RITA® Temporary Immersion Systems

The main compounds in both extracts were gluconasturtiin, 4-methoxyglucobrassicin and rutoside, the amounts of which were, respectively, determined as 182.93, 58.86 and 23.24 mg/100 g dry weight (DW) in biomass extracts and 640.94, 23.47 and 7.20 mg/100 g DW in plant herb extracts. The antioxidant potential of all the studied extracts evaluated using CUPRAC (CUPric Reducing Antioxidant Activity), FRAP (Ferric Reducing Ability of Plasma), and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays was comparable. The anti-inflammatory activity of the extracts was tested based on the inhibition of 15-lipoxygenase, cyclooxygenase-1, cyclooxygenase-2 (COX-2), and phospholipase A₂. The results demonstrate significantly higher inhibition of COX-2 for in vitro cultured biomass compared with the herb extracts (75.4 and 41.1%, respectively). Moreover, all the studied extracts showed almost similar antibacterial and antifungal potential. Based on these findings, and due to the fact that the growth of in vitro microshoots is independent of environmental conditions and unaffected by environmental pollution, we propose that biomass that can be rapidly grown in RITA^® bioreactors can serve as an alternative source of bioactive compounds with valuable biological properties.     

The effect of UV-irradiation on composting of polyethylene modified by cellulose

LDPE and its blend with cellulose, obtained by extrusion, were UV-irradiated with different doses or biodegraded in soil up to 1 year. Simultaneously, the same samples were 1 year biodegraded after 20 h UV pre-irradiation in the same conditions. The course of photo- and biodegradation was monitored by estimation of average molecular weights and polydispersity, gel amount, changes of PE crystallinity and mechanical properties. Moreover, the biodegradation degree was calculated on the basis of carbon dioxide evolved and surface morphological changes were observed by SEM. It was found that biodegradation of PE + cellulose is hampered by intermolecular crosslinking of both components. Although, the rate of decomposition of PE + cellulose blends is low it is enough for disintegration of such materials in the natural environment.     

Production of Verbascoside,Isoverbascoside and Phenolic Acids in Callus,Suspension, and Bioreactor Cultures of Verbena officinalis and Biological Properties of Biomass Extracts

Callus, suspension and bioreactor cultures of Verbena officinalis were established, and optimized for biomass growth and production of phenylpropanoid glycosides, phenolic acids, flavonoids and iridoids. All types of cultures were maintained on/in the Murashige and Skoog (MS) media with 1 mg/L BAP and 1 mg/L NAA. The inoculum sizes were optimized in callus and suspension cultures. Moreover, the growth of the culture in two different types of bioreactors—a balloon bioreactor (BB) and a stirred-tank bioreactor (STB) was tested. In methanolic extracts from biomass of all types of in vitro cultures the presence of the same metabolites—verbascoside, isoverbascoside, and six phenolic acids: protocatechuic, chlorogenic, vanillic, caffeic, ferulic and rosmarinic acids was confirmed and quantified by the HPLC-DAD method. In the extracts from lyophilized culture media, no metabolites were found. The main metabolites in biomass extracts were verbascoside and isoverbascoside. Their maximum amounts in g/100 g DW (dry weight) in the tested types of cultures were as follow: 7.25 and 0.61 (callus), 7.06 and 0.48 (suspension), 7.69 and 0.31 (BB), 9.18 and 0.34 (STB). The amounts of phenolic acids were many times lower, max. total content reached of 26.90, 50.72, 19.88, and 36.78 mg/100 g DW, respectively. The highest content of verbascoside and also a high content of isoverbascoside obtained in STB (stirred-tank bioreactor) were 5.3 and 7.8 times higher than in extracts from overground parts of the parent plant. In the extracts from parent plant two iridoids—verbenalin and hastatoside, were also abundant. All investigated biomass extracts and the extracts from parent plant showed the antiproliferative, antioxidant and antibacterial activities. The strongest activities were documented for the cultures maintained in STB. We propose extracts from in vitro cultured biomass of vervain, especially from STB, as a rich source of bioactive metabolites with antiproliferative, antioxidant and antibacterial properties.