The enzymatic method for the quantitative determination of benzalkonium chloride in the antiseptic solution “CUTASEPT® F”

Aim. To develop an alternative method for the quantitative determination of the benzalkonium chloride content as an active pharmaceutical ingredient in the disinfectant solution “CUTASEPT® F”.Materials and methods. The method is based on the ability of benzalkonium chloride to inhibit the enzymatic hydrolysis of acetylcholine by acetylcholinesterase. The reaction rate is assessed by the non-hydrolyzed acetylcholine residue, which is determined by the amount of peracetic acid produced during the interaction with the excess of the hydrogen peroxide solution. The indicator reaction is the interaction of p-phenetidine with peracetic acid that leads to the formation of 4,4’-azoxyphenetole with λmax = 358 nm (log10 ε = 4.2).Results and discussion. As a result of the research conducted the linear dependence of the degree of inhibition of the enzymatic hydrolysis of acetylcholine (U, %) on the concentration of benzalkonium chloride was determined in the concentration range of (0.5 – 7.0) × 10–6 mol L-1 with the correlation coefficient of 0.999. The limit of quantitation was 1.9 × 10–6 mol L-1.Conclusions. As a result of the research conducted the kinetic enzymatic method for the quantitative determination of benzalkonium chloride has been developed by its inhibitory effect in the biochemical reaction of acetylcholine hydrolysis. This method is fast, cheap and easy to perform, does not require expensive equipment, and available for use in the field.

Changes to the Collagen Structure using Vibrational Spectroscopy and Chemometrics: A Comparison between Chemical and Sulfide-Free Leather Process

Chemical and physical changes take place when hides and skins are processed to leather that affect the quality and strength of the material. Understanding the structure at each leather-making stage is the basis of this study but also intend to improve the process through a biochemical approach, employing a proteolytic enzyme for processing leather more cleanly with reduced environmental impact. Raman and ATR-FTIR spectroscopy in conjunction with chemometrics was used to investigate each leather-making stage from fresh green cattle hide to dry crust leather. The changes in proteins, lipids, nucleic acids and other biomolecules with leather processing was measured and reported using three novel Raman ratiometric markers, 920/1476, 1345/1259 and 1605/1476 cm-1, to discriminate the structural changes in collagen of hide using standard chemical and enzymatic method. Amide I band was deconvoluted to investigate thecollagen secondary structures using curve fitting by Gaussians function. The results of Principal Component Analysis are well-corroborated with the ratiometric markers of structural changes.

Influence of Cardboard Pretreatment on the Determination of Starch Content by the Enzymatic Method

We determined the amount of starch by the enzymatic method in different samples of corrugated cardboard, including the sample produced of primary semi-finished products and corrugated cardboard made of 100 % waste paper. For starch enzymatic degradation, it is necessary to extract it from the corrugated board structure, since the processes of compression and keratinization of pulp fibers reduce the availability of starch for extraction. Enzymatic treatment requires the use of a complex amylolytic preparation for complete hydrolysis of starch to glucose. We were able to determine, respectively, 70 and 84 % of starch obtained from primary semi-finished products by mechanical methods, such as defibrillation in water and degradation in a liquid nitrogen medium, and added at the production stage of corrugated cardboard. It was shown that extraction with alkaline agents was necessary for more complete extraction of starch from corrugated cardboard. The influence of alkaline treatment on the characteristics of fibers of waste paper fractions obtained at the Sukhonsky Cardboard and Paper Mill has been analyzed. The fibers swell in alkali, resulting in an increase in fiber width and its shortening, as well as a decrease in crystallinity, which can be a positive opportunity for more complete starch extraction. Fiber swelling and crystallinity reduction are more intensive for the short fiber fraction compared to the long fiber fraction. When determining starch in corrugated cardboard using the standard method SCAN-P 91:09 SСAN-W 13:09 it was not possible to detect all the starch added at the production stage of corrugated cardboard from primary semi-finished products. Also the processing conditions of this methodology lead to degradation of the partially hydrolyzed starch. The most complete extraction of starch from corrugated cardboard was achieved by two stages of alkaline extraction under the following conditions: 5 % NaOH, temperature of 20 °C, the duration of each extraction – 2 h. Under these processing conditions it was possible to determine all the starch (22.8 kg/t) in the corrugated cardboard produced of primary semi-finished products with known consumption of starch; the starch content in the corrugated cardboard produced of 100 % waste paper was 48.2 kg/t. For citation: Khadyko I.A., Novozhilov E.V., Chukhchin D.G. Influence of Cardboard Pretreatment on the Determination of Starch Content by the Enzymatic Method. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 150–162. DOI: 10.37482/0536-1036-2021-5-150-162

Short HPLC gradient method for 20-Hydroxyecdysone (20E) quantification in malaria vectors v1

Ecdysteroids are arthropod steroid hormones that are primarily involved in insect moulting. In arthropod vectors, especially in mosquitoes, ecdysteroids of interest include mainly ecdysone (E) and 20-hydroxyecdysone (20E). These two compounds are involved in several important biological processes. Targeting these compounds and their regulatory pathways could lead to the characterisation of novel genetic tools towards implementing new malaria control strategies. To date, there are two main methods for quantifying E and 20E. These methods include an enzymatic method (Enzyme-Linked Immunosorbent Assay (ELISA)) and a chromatographic method (High-Performance Liquid Chromatography (HPLC)). However, for ecdysteroids quantification, the HPLC methods available in literature go from 30 minutes to one hour. Here, we developed a short HPLC gradient method for 20-hydroxyecdysone quantification in the malaria vector Anopheles gambiae. This method was developed specifically when sample material is limited as well as to save time and cost.

Redistribution of nutritionally important starch fractions beneficial to diabetic population by using oats as a functional ingredient in a wheat-based food product – Jereesh

Oats being important sources of β-glucan were incorporated at 10, 20 and 30% level in a wheat-based traditional Arabian breakfast cereal called Jereesh and evaluated for sensory acceptability. Sensory analysis reflected that the products with 10 and 20% oats incorporation were acceptable in terms of color, appearance, taste, aroma, mouthfeel, after taste and overall quality as indicated by the sensory scores which revealed no substantial differences between control jereesh (CJ) and oats incorporated jereesh (OJ). However, jereesh with 30% oats incorporation was very sticky (viscous) and scored low in sensory evaluation. Thus, nutritionally important starch fractions were measured in jereesh with 20% oats incorporation using a controlled in vitro multi-enzymatic method. Results indicated that, addition of oats at 20% level resulted in a substantial decrease (p<0.05) in total starch (TS), rapidly available glucose (RAG), and resistant starch content (RS), as well as a significant increase (p<0.05) in slowly digestible starch (SDS) compared to the control jereesh. The starch digestibility index remained unchanged. The findings of the study suggest that incorporation of oats helps in value addition of jereesh in terms of slow digestibility with increased soluble dietary fiber content that might lower glycemic index.

The influence of birth weight and gestational age on kidney function in premature infants

Introduction. The impact of prematurity on the functional state of the kidneys in infants has not yet been sufficiently studied. Aim. To determine the influence of birth weight and gestational age on the creatinine level in the blood and glomerular filtration rate (GFR) in early childhood. Materials and methods. A retrospective analysis was conducted on medical records of 316 children aged from 1 month to 1.5 years, hospitalized at the Department of Early Childhood Pathology (National Medical Research Center for Children’s Health, Moscow) from 2012 to 2020 due to consequences of perinatal CNS damage. Children without congenital kidney diseases, with normal urine values in medical history, without structural abnormalities on ultrasound were included in this study. Serum creatinine was determined by the enzymatic method, GFR - by the Schwartz’s formula using a coefficient of 0.413, as well as, previously proposed coefficients of 0.33 for premature and 0.44 for full-term infants. Results. In premature infants, notably born with extremely low birth weight and very low birth weight, at the age of 1 year, serum creatinine is reduced compared to full-term infants, GFR in deep-premature infants exceeds the level of GFR in full-term infants by the year. The results allow concluding the method of calculating GFR by formulas based on serum creatinine to be invalid. Due to possible hyperfiltration in preterm infants, they need regular monitoring urine tests, blood pressure, due to the risk of developing chronic kidney disease. Conclusions. It is necessary to search for other methods for determining GFR in extremely premature infants. The established indices of the blood creatinine content can be used as reference values for different periods of gestation and body weight at birth in institutions using the enzymatic method for determining blood creatinine. The obtained GFR indices as a reference can be recommended for full-term and premature babies born after 32 weeks of gestation and with a birth weight of more than 1500 g.