Preparation of a Cellulose Column for Enhancing the Sensing Efficiency of the Biocide 2-n-Octyl-4-Isothiazolin-3-One

In this study, a cellulose acetate (CA) membrane with pores generated by a water pressure treatment was investigated for its ability to serve as a pretreatment filter device for the detection of 2-n-octyl-4-isothiazolin-3-one (OIT). Pores were generated by applying a water pressure of 8 bar to a membrane manufactured using a CA-based polymer solution. The CA used for the manufacturing was an environment-friendly, low-cost and highly energy-efficient material. Furthermore, since the fabricated porous CA polymeric film possessed many hydrophilic functional groups, it could strongly bind hydrophilic substances while avoiding interaction with hydrophobic substances. OIT, which comprises a hydrophobic bond that forms weak bonds over time, can break down more easily than hydrophilic impurities. The different extents of interaction occurring between either the toxic fungicide OIT or the hydrophilic impurities and the CA film were determined by Fourier-transform infrared (FT-IR) spectroscopy. The physicochemical changes in the resulting membrane, which occurred when the pores were generated, were investigated through scanning electron microscopy (SEM) and thermogravimetric analysis (TGA).

Prediction of Geraniol Bond Mode in Aspergillus niger Linalool Dehydratase – Isomerase

Geraniol is a very valuable aroma chemical and has commonly been used in fragrances and aroma compound. Geraniol biotransformation by Aspergillus niger has been studied. The main bioconversion products obtained from geraniol and liquid culture of A. niger are linalool and alpha-terpineol. Linalool plays a major role in anti-inflammatory, antibacterial and antioxidant activities. This study aims to know the interaction of geraniol in Aspergillus niger enzyme with docking molecular. Comparative modeling of Aspergillus niger enzyme was conducted by means of one of the crystal structure of Linalool Dehydratase – Idomerase (LDI) as a template. The best model of this comparative modeling was then used in docking molecular to investigate geraniol binding mode inactive site enzyme of Aspergillus niger. Inactive site enzyme of Aspergillus niger, geraniol is located with hydrophobic and hydrogen bonds: Amino acid – the amino acids are Asn 105, Arg 96, Lys 112 inactive site - OH with hydrogen bond, Arg 97 inactive site – CH3 with hydrophobic bond and Leu54 inactive site – CH3 with the hydrophobic bond. The distances among pharmacophore respectively are 3,603 A, 6,768 A, and 7,345A. It has higher score (ΔGbind: -3.4 kcal/mol) compared to linalool (ΔGbind: -3.6 kcal/mol). Virtual tethering of linalool with LDI Aspergillus niger enzyme in amino acid Leu120 and Glu118 had been done. The pharmacophore is - OH and methyl C8 group. The distances among pharmacophore respectively are 5,835 Å, 2,52 Å, and 5,32 Å. Virtual tethering of LDI Aspergillus niger enzyme with geraniol has a higher score (ΔGbind: -3.4 kcal/mol) compared to linalool (ΔGbind: -3.6 kcal/mol). It shows that interaction between linalool and LDI Aspergillus niger enzyme is easier to occur than the interaction between geraniol and LDI Aspergillus niger enzyme, geraniol reaction to linalool that occurs is rearrangement reaction.

Metabolism and Metabolic Inhibition of Xanthotoxol in Human Liver Microsomes

Cytochrome p450 (CYP450) enzymes are predominantly involved in Phase I metabolism of xenobiotics. In this study, the CYP450 isoforms involved in xanthotoxol metabolism were identified using recombinant CYP450s. In addition, the inhibitory effects of xanthotoxol on eight CYP450 isoforms and its pharmacokinetic parameters were determined using human liver microsomes. CYP1A2, one of CYP450s, played a key role in the metabolism of xanthotoxol compared to other CYP450s. Xanthotoxol showed stronger inhibition on CYP3A4 and CYP1A2 compared to other isoenzymes with the IC50of 7.43 μM for CYP3A4 and 27.82 μM for CYP1A2. The values of inhibition kinetic parameters (Ki) were 21.15 μM and 2.22 μM for CYP1A2 and CYP3A4, respectively. The metabolism of xanthotoxol obeyed the typical monophasic Michaelis-Menten kinetics andVmax,Km, andCLintvalues were calculated as 0.55 nmol·min−1·mg−1, 8.46 μM, and 0.06 mL·min−1·mg−1. In addition, the results of molecular docking showed that xanthotoxol was bound to CYP1A2 with hydrophobic andπ-πbond and CYP3A4 with hydrogen and hydrophobic bond. We predicted the hepatic clearance (CLH) and theCLHvalue was 15.91 mL·min−1·kg−1body weight. These data were significant for the application of xanthotoxol and xanthotoxol-containing herbs.

A Randomized Clinical Evaluation of a One- and Two-step Self-etch Adhesive Over 24 Months

Clinical Relevance The application of an extra hydrophobic bond layer over the self-etch adhesive system improved clinical performance over a 24-month period, mainly in terms of retention rate.

Dark and photoinduced interactions between riboflavin and indole auxins

Interactions between riboflavin (RF) and indole auxins in the darkness and under conditions of irradiation with visible light were carried out. Dark complexation takes place in buffered (pH 7) aqueous solution. The association constants determined by static fluorescence quenching range from 70 to 150 mol-1 dm3. The complexation is significant at relatively high indole auxin concentrations (above 10-3 mol dm-3). It is governed by an additive effect of charge transfer, known for flavine-indole systems, and of the hydrophobic bond formation. The latter appears in the case of auxins as the driving force of the interaction. No quenching of singlet-excited RF was detected up to indole auxin concentrations of 5 . 10-3 mol dm-3. Under irradiation with visible light a complex mechanism of competitive reactions is operative: both RF and especially the auxins are decomposed by a combination of type I and II photooxidations at indole auxins concentration of 10-4 mol dm-3. The rate constants of the order of 109 mol-1 dm3 s-1 were estimated for the quenching of triplet excited RF by the indoles. For comparative purposes Rose Bengal sensitized photooxidation of a series of indolecarboxylic acids of indole-3-acetic, -propionic and –butyric acid was examined. The rate constants of the photooxidative process, mediated by singelt molecular oxygen, were of the order of 107 mol-1 dm3 s-1 for the auxins. As a result of the interaction, RF is protected against photobleaching and the auxins decompose via a different mechanism, depending on the relative flavin-auxin concentrations.