Chemometric Approach to Prediction of Antibacterial Agent Production by Streptomyces hygroscopicus

The nutritional requirements for antimicrobial agent production using Streptomyces hygroscopicus were analyzed in shake flask experiments. Antimicrobial activity was tested against Staphylococcus aureus and Bacillus cereus. The mathematical models have been generated with relative high complexity in order to give an adequate fit to the data. All the results suggest a high dependence of produced antimicrobial agent quantities on the amount of carbon, nitrogen, and phosphorus in cultivation medium. The statistical results of the generated models reflect the high predictive ability. The derived models were validated using leave-one-out cross-validation technique, and from statistical point of view, they have significantly high values of the cross-validation parameters.     

Natural radioactivity around former uranium mine,Gabrovnica in Eastern Serbia

Gabrovnica near Kalna village was the first uranium mine established in Yugoslavia. In 1963, the Nuclear Energy Commission began operating the mine and mill. Between 1964 and 1966, the staff at Kalna extracted and produced an estimated 900 kg of UO₂ and 400 kg of uranium metal. The Kalna ore was of poor quality, containing very low uranium content, which required higher-cost mining and refining methods. That was the main reason for closing this mine. This paper presents results obtained by measuring the activity concentration of soil samples measured by gamma spectrometry and also indoor ²²²Rn activity concentrations in houses in the nearby village Kalna. There is a presence of elevated radioactivity levels in the most of the measured samples. The mine was never officially decommissioned. The results obtained might be useful for the future decommissioning procedure.     

Thermodynamic and Kinetic Studies on Reactions of Pt(II) Complexes with Pyrazole, Pyridazine, and 1,2,4-Triazole

Substitution reactions of the complexes [Pt(dien)H₂O]²⁺ and [PtCl(dien)]⁺, where dien = diethylentriamine or 1,5-diamino-3-azapentane, with some nitrogen-donor ligands such as 1,2,4-triazole, pyrazole, and pyridazine, were studied in an aqueous 0.10 M NaClO₄ at pH = 2.5 using variable-temperature spectrophotometry and ¹H NMR spectroscopy. The second-order rate constants indicate that the aqua complex, [Pt(dien)H₂O]²⁺, is more reactive than the corresponding chloro complex, [PtCl(dien)]⁺. The reactivity of the used ligands follows the order: 1,2,4-triazole > pyridazine > pyrazole. Activation parameters were determined for all reactions and the negative entropies of activation (ΔS ^≠) support an associative ligand substitution mechanism.     

Enantiodivergent synthesis of cytotoxic styryl lactones from d-xylose. The first total synthesis of (+)- and (−)-crassalactone C

Enantiodivergent total syntheses of both (+)- and (−)-enantiomers of goniofufurone, 7-epi-goniofufurone and crassalactone C have been accomplished starting from d-xylose. The key steps of the synthesis of 7-epi-(+)-goniofufurone were a stereo-selective addition of phenyl magnesium bromide to a protected dialdose, and a stereospecific furano-lactone ring formation by reaction of a related hemiacetal derivative with Meldrum's acid. Synthesis of both (+)-goniofufurone and (+)-crassalactone C required a configurational inversion at C-5 in the common intermediate that was efficiently achieved under the standard Mitsunobu conditions, or alternatively through a sequential oxidation of the benzylic hydroxyl group followed by a stereo-selective reduction with borohydride. A similar approach was then applied to the synthesis of the unnatural (−)-enantiomers of goniofufurone, 7-epi-goniofufurone and crassalactone C, as well as two novel, conformationally constrained analogues of both (+)- and (−)-goniofufurone. Their in vitro antiproliferative activities against a number of human tumour cell lines were recorded and compared with those observed for the parent natural products.     

Light-actuated resorcin[4]arene cavitands

A light-actuated resorcin[4]arene cavitand equipped with two quinone (Q) and two opposite Ru(II)-based photosensitizing walls was synthesized and investigated. The cavitand is capable of switching from an open to a contracted conformation upon reduction of the two Q to the corresponding SQ radical anions by intramolecular photoinduced electron transfer in the presence of a sacrificial donor. The molecular switch was investigated by cyclic and rotating disc voltammetry, UV–Vis–NIR spectroelectrochemistry, transient absorption, NMR, and EPR spectroscopy. This study provides the basis for the development of future light-activated switches and molecular actuating nanodevices.     

Reverse order law for generalized inverses of multiple operator product

In this paper, we consider the reverse order law for generalized inverses of operators on Hilbert spaces. We derive necessary and sufficient conditions for various inclusions concerning the reverse order law for generalized inverses of multiple operator product. We extend the finite dimensional results from (Wei M. Reverse order laws for generalized inverses of multiple matrix products. Linear Algebra Appl. 1999;293:13.) to infinite dimensional settings.     

Tailoring Atomoxetine Release Rate from DLP 3D-Printed Tablets Using Artificial Neural Networks: Influence of Tablet Thickness and Drug Loading

Various three-dimensional printing (3DP) technologies have been investigated so far in relation to their potential to produce customizable medicines and medical devices. The aim of this study was to examine the possibility of tailoring drug release rates from immediate to prolonged release by varying the tablet thickness and the drug loading, as well as to develop artificial neural network (ANN) predictive models for atomoxetine (ATH) release rate from DLP 3D-printed tablets. Photoreactive mixtures were comprised of poly(ethylene glycol) diacrylate (PEGDA) and poly(ethylene glycol) 400 in a constant ratio of 3:1, water, photoinitiator and ATH as a model drug whose content was varied from 5% to 20% (w/w). Designed 3D models of cylindrical shape tablets were of constant diameter, but different thickness. A series of tablets with doses ranging from 2.06 mg to 37.48 mg, exhibiting immediate- and modified-release profiles were successfully fabricated, confirming the potential of this technology in manufacturing dosage forms on demand, with the possibility to adjust the dose and release behavior by varying drug loading and dimensions of tablets. DSC (differential scanning calorimetry), XRPD (X-ray powder diffraction) and microscopic analysis showed that ATH remained in a crystalline form in tablets, while FTIR spectroscopy confirmed that no interactions occurred between ATH and polymers.     

White Chocolate with Resistant Starch: Impact on Physical Properties,Dietary Fiber Content and Sensory Characteristics

Resistant starch (RS) is a part of insoluble dietary fiber, and it could be recognized as a functional food ingredient in some types of confectionery products that lack dietary fiber. Unlike dark and milk chocolate, white chocolate does not contain fat-free cocoa solids rich in dietary fiber. In the present study, 5%, 10%, and 15% of white chocolate were substituted with RS in order to improve the nutritional value of enriched white chocolate. The influence of RS on rheological, textural, and thermal properties of the chocolate fat phase was firstly investigated, and then further influence on physical properties, dietary fiber content, and sensory characteristics of enriched white chocolates were investigated. The obtained results showed that enriched chocolates had increased content of total dietary fiber and reduced total fats and protein content in accordance with the added amount of RS. At the same time, RS increased viscosity and reduced the hardness and volume mean diameter in enriched chocolates in accordance with the added amount. RS improved the nutritional composition of white chocolate by increasing the content of dietary fiber. At the same time, RS did not impair the color and sensory characteristics of enriched white chocolates.     

The Evaluation of Healing Properties of Galium verum-Based Oral Gel in Aphthous Stomatitis in Rats

Although oral ulcers represent one of the most frequent oral mucosal diseases, the available treatment is not sufficient to provide complete ulcer recovery without side-effects. Therefore, the aim of our study was to prepare a mucoadhesive oral gel based on Galium verum ethanol extract (GVL gel) and reveal its healing effects in the model of aphthous stomatitis in rats. Rats with oral ulcers were divided into the following groups: control (untreated), gel base (ulcer was treated with the gel base, three times per day for 10 days), and GVL gel group (the ulcer was treated with GVL gel in the same way as the gel base). Animals from each group were sacrificed on days 0, 3, 6, and 10 for collecting blood and ulcer tissue samples. Healing properties of oral gel were determined by clinical evaluation, as well as biochemical and histopathological examinations. Our findings suggest a significant decrease in the ulcer size in GVL gel group, with healing effects achieved through the alleviation of oxidative stress, reduction in COX-2 immunopositivity, and increase in collagen content in buccal tissue. Significant ulcer repairing potential of GVL gel highlights this oral mucoadhesive gel as a promising tool for prevention and treatment of RAS.     

The Quest for Molecular Grippers: Photo-Electric Control of Molecular Gripping Machinery

The quest for nanoscale molecular machines has inspired the search for their close relatives, molecular grippers. This path was paved by the development of resorcin[4]arene cavitands and their quinone-based redox-active congeners. In this Concept article, the efforts to design and establish the control of quinone-functionalized resorcin[4]arenes by electronic and electromagnetic stimuli is described. This was achieved by relying on paramagnetic semiquinone radical anions formed electrochemically or by photoredox catalysis. The gripper-like motion of such species could not be studied by conventional NMR spectroscopy. Instead, an entirely different approach had to be developed that included various electroanalytical and spectroelectrochemical methods, including UV/Vis/NIR spectroelectrochemistry, pulsed EPR and Davies ¹H ENDOR spectroscopy, transient absorption spectroscopy, and time-resolved luminescence measurements, besides density functional theory calculations and X-ray crystallography. The conceptual breakthroughs are reviewed as well as the current state and future perspectives of photoredox-switchable molecular grippers.