Chemical Bulletin of Kazakh National University

The investigation prospect application of alcohol-water extract of lingonberry as antimicrobial, anti-fungi and antioxidant pharmaceutical

Tue, 08 Oct 2024 00:00:00 +0000

Infection diseases is a worldwide important problem for medicine and pharmacy. Every year 13.7 million people die from bacterial infections in the world. Thus, the search of new compounds with antimicrobial and anti-fungi activity is topical for today. The object of the study was lingonberry leaf 60% extract. The content of phenylpropanoids derivatives was evaluated by spectrophotometric method of analysis, whereas organic acids by alkalimetric method; antioxidant power was found by potentiometric method; antibacterial and antifungal activity was assessed by the method of “wells”.

According to the results of the study, it was shown that the lingonberry leaf extract is inferior to the green tea leaf extract in terms of the content of phenolic compounds, catechins, hydroxycinnamic and organic acids, but flavonoids dominate in the lingonberry extract. The study found that lingonberry leaf extract has a high level of antioxidant activity. When comparing the levels of antioxidant action of lingonberry extract with green tea extract and the «gold standard» – аepigallocatechin-3-O-gallate in one concentration of 0.03 mol/L, it was found that lingonberry extract had the best result. Escherichia coli bacteria was the most sensitive to the extract whereas Pseudomonas aeruginosa was the most resistant.

This work shows that 60% ethanolic lingonberry leaf extract has potent antioxidant, antimicrobial and antifungal effects. According to the obtained results, it can be concluded that 60% V. vitis-idaea leaf extract is promising for the development of new antimicrobial, antifungal and antioxidant pharmaceutical.

Supramolecular cyclodextrin complexes of biologically active nitrogen heterocycles

Tue, 08 Oct 2024 00:00:00 +0000

The review is devoted to the rapidly developing field of modern supramolecular chemistry - cyclodextrin complexes of biologically active nitrogen heterocycles, such as piperidines, piperazines, morpholines and pyridines. Interest in cyclodextrin complexes is growing due to the search and construction of supramolecular assemblies for targeted drug delivery. The latter is achieved as a result of supramolecular self-assembly, based on the principles of molecular recognition, and is one of the areas of modern chemistry, leading to the creation of new materials with new properties.

This review fully demonstrates the ongoing scientific and practical interest in the problem of encapsulation with cyclodextrins, including nanoencapsulation. Encapsulation with cyclodextrins provides a wide range of advantages: obtaining solid dosage forms from liquid ones, stabilizing and protecting active substances from the adverse effects of external factors, increasing solubility, increasing bioavailability, reducing toxicity, prolonging action, etc.

The presented review includes recent advances in the field of supramolecular complexes of biologically active nitrogen heterocycles with cyclodextrins and concludes with a discussion and identification of future promising directions for research. The review presents the results of supramolecular self-assembly of biologically active azaheterocycles with cyclodextrins.

Study of the structural and phase state of ceramics synthesized from 6YSZ - Al2O3 – HfO2 by semi–dry pressing followed by sintering in vacuum

Tue, 08 Oct 2024 00:00:00 +0000

The study investigates the properties of 6YSZ – Al₂O₃ – HfO₂ powder mixture and the resulting ceramics obtained by semi-dry pressing followed by sintering in vacuum. X-ray fluorescence spectrometry revealed the primary constituents as zirconium (81%), aluminum (8.7%), yttrium (5.7%), and hafnium (3.5%). The average particle diameter was 0.5 μm, with specific surface area and bulk weight recorded at 18,535 cm²/g and 0.84 g/cm³, respectively. X-ray phase analysis indicated a predominance of monoclinic zirconium dioxide. Sintering at 1400-1600°C transformed the phase composition, enhancing density and microhardness, with values peaking at 5.8 g/cm³ and 12.1 GPa at 1600°C. This process also increased the tetragonal phase content to 63%. The ceramics exhibited the highest crack resistance at 1600°C, attributed to the stabilized tetragonal zirconium dioxide. Microstructural analysis confirmed the homogenous distribution of the elements and the presence of fine fractions influencing microstructural properties. 1600°C was found to be the optimal temperature for sintering the 6YSZ – Al₂O₃ – HfO₂ ceramics.