OH Position Research Articles

Preparation of esculin acetates through transesterification reaction catalyzed by Novozyme 435® and their Purification followed by NMR characterization

In this study, biocatalytic transesterification reaction using Novozyme 435® (N435) lipase was employed to enhance the hydrophobicity of esculin, aiming to improve its solubility for commercial applications and enhance its bioactivity and oral viability. The acylation reaction of esculin with vinyl acetate was conducted at 60 °C and 200 rpm for 24 h. After chromatographic and spectroscopic analysis, two products were identified: the first one was monoacylated at the 6′-OH position of the glucosyl moiety of esculin (TR: 10.3 min and m/z 382.93 [M + H]+), and the second one was diacylated at the 6′-OH and 3′-OH positions (TR: 13.0 min and m/z 424.93 [M + H]+). The latter was the major product, with a conversion rate of 53.550 ± 0.368%, while the monoacetylated one showed 8.715 ± 0.064%. Both products were isolated by high-speed counter-current chromatography (HSCCC) using a two-phase system HEMWat 1:9:1:9 and characterized by NMR. In this way, these results improve the practical application of esculin, through the obtention of esculin mono and diacetates by fast and efficient biocatalysis reaction.

Nicotinamide Riboside and CD38: Covalent Inhibition and Live-Cell Labeling.

Nicotinamide adenine dinucleotide (NAD+) is required for a myriad of metabolic, signaling, and post-translational events in cells. Its levels in tissues and organs are closely associated with health conditions. The homeostasis of NAD+ is regulated by biosynthetic pathways and consuming enzymes. As a membrane-bound protein with robust NAD+ hydrolase activity, cluster of differentiation 38 (CD38) is a major degrader of NAD+. Deficiency or inhibition of CD38 enhances NAD+ levels in vivo, resulting in various therapeutic benefits. As a metabolic precursor of NAD+, nicotinamide mononucleotide can be rapidly hydrolyzed by CD38, whereas nicotinamide riboside (NR) lacks CD38 substrate activity. Given their structural similarities, we explored the inhibition potential of NR. To our surprise, NR exhibits marked inhibitory activity against CD38 by forming a stable ribosyl-ester bond with the glutamate residue 226 at the active site. Inspired by this discovery, we designed and synthesized a clickable NR featuring an azido substitution at the 5'-OH position. This cell-permeable NR analogue enables covalent labeling and imaging of both extracellular and intracellular CD38 in live cells. Our work discovers an unrecognized molecular function of NR and generates a covalent probe for health-related CD38. These findings offer new insights into the role of NR in modulating NAD+ metabolism and CD38-mediated signaling as well as an innovative tool for in-depth studies of CD38 in physiology and pathophysiology.

A regio-specific 4’-O-methyltransferase from Epimedium pseudowushanense regiospecifically catalyzing 8-prenylkeampferol to icaritin

Epimedium is widely used in traditional Chinese medicine and contains rich bioactive compounds. These compounds often have a methyl group at their 4’-OH position catalyzed by methyltransferases. Therefore, studying methyltransferases in Epimedium plants is of great significance. In this study, a flavonol methyltransferase, EpOMT4, was isolated from Epimedium pseudowushanense B.L. Guo. The recombinant enzyme regiospecifically transferred a methyl group to the 4’-OH position of 8-prenylkaempferol forming icaritin. The study demonstrates that enzymatic methylation of flavonoids in Epimedium plants holds significant potential and could provide a promising alternative method for the biosynthetic production of bioactive methylated prenylflavonoids.

Systematic Identification and Characterization of O-Methyltransferase Gene Family Members Involved in Flavonoid Biosynthesis in Chrysanthemum indicum L.

Chrysanthemum indicum L. capitulum is an enriched source of flavonoids with broad-ranging biological activities, mainly due to their anti-inflammatory, anti-cancer, immune regulation, anti-microbial activity, hepatoprotective, and neuroprotective effects. The O-methylation of various secondary metabolites has previously been demonstrated to be mainly catalyzed by S-adenosyl-L-methionine-dependent O-methyltransferase (OMT) proteins encoded by the OMT gene family. However, limited comprehensive study was published on the OMT gene family, especially the CCoAOMT subfamily, involved in the O-methylation of flavonoids in Chrysanthemum. Here, we analyzed the spatiotemporal expression patterns of C. indicum OMT genes in leaf and flower at different developmental stages. Transcriptome sequencing and qRT-PCR analysis showed that COMTs were mainly highly expressed in capitulum, especially in full bloom, while CCoAOMTs were mainly highly expressed in leaves. Correlation analysis of OMT gene expression and flavonoids accumulation revealed that four OMTs (CHR00029120, CHR00029783, CHR00077404, and CHR00078333) were putatively involved in most methylated flavonoids biosynthesis in the capitulum. Furthermore, we identified a true CCoAOMT enzyme, CiCCoAOMT1, and found that it catalyzed O-methylation of quercetin and luteolin at the 3'-OH position. In summary, this work provides an important theoretical basis for further research on the biological functions of OMTs in C. indicum.

Bio-spectroscopic investigation linking changes of retinal structure with short-term administration of Amiodarone and revealing the ameliorative effect of vitamin E supplementation

Long term use of Amiodarone (AMIO) is associated with the development of ocular adverse effects. This study investigates the short term effects, and the ameliorative consequence of vitamin E on retinal changes that were associated with administration of AMIO. This is accomplished by investigating both retinal structural and conformational characteristics using Fourier transform infrared spectroscopy (FTIR) and Fundus examination. Three groups of healthy rabbits of both sexes were used; the first group served as control. The second group was orally treated with AMIO (160 mg /kg body weight) in a daily basis for two weeks. The last group orally received AMIO as the second group for two weeks then, oral administration of vitamin E (100 mg/kg body weight) for another two weeks as well. FTIR results revealed significant structural and conformational changes in retinal tissue constituents that include lipids and proteins due to AMIO administration. AMIO treatment was associated with fluctuated changes (increased/decreased) in the band position and bandwidth of NH, OH, and CH bonds. This was concomitant with changes in the percentage of retinal protein constituents in particularly α-helix and Turns. AMIO facilitates the formation of intra-molecular hydrogen bonding and turned retinal lipids to be more disordered structure. In conclusion, the obtained FTIR data together with principal component analysis provide evidence that administration of vitamin E following the treatment with AMIO can ameliorate these retinal changes and, these biophysical changes are too early to be detected by Fundus examination.

Biochemical characterization of a flavonoid O-methyltransferase from Artemisia annua and its application in tamarixetin production

The O-position methylation of flavonoids is widely recognized as a key modification that substantially boosts their bioactivity and bioavailability, leading to enhanced absorption. The use of specific O-methyltransferases is frequently necessary for various substrate modifications. Here, a novel Artemisia annua O-methyltransferase (AaOMT) gene was cloned, heterologously expressed in Escherichia coli, and its biochemical properties against various flavonoids were characterized. Amino acid and phylogenic analyses indicated that AaOMT is a new flavonoid O-methyltransferase that belongs to the Class II O-methyltransferases family. It could specifically methylate most flavonoids at the 4′-OH position unless flavanones. The optimal temperature and pH for in vitro reactions were 35 °C and 8.0, respectively. Kinetic analysis revealed that AaOMT exhibits the highest affinity and relatively high catalytic efficiency towards quercetin. Consequently, recombinant strains harboring AaOMT were used to convert quercetin into tamarixetin in vivo. Additionally, different vectors with promoters and E. coli hosts were screened to enhance tamarixetin production. By optimizing cultivation conditions and scaling up fermentation capacity, we achieved a maximum tamarixetin titer of 706.9 mg/L (∼2.24 mM) finally. This study provides a novel, efficient, and regioselective 4′-O-methyltransferase (4′-OMT) and a strategy for the mass production of those rare and high-value 4′-methoxyflavonoids through metabolic engineering in vivo.

An Exploratory Study of the Enzymatic Hydroxycinnamoylation of Sucrose and Its Derivatives.

Phenylpropanoid sucrose esters are a large and important group of natural substances with significant therapeutic potential. This work describes a pilot study of the enzymatic hydroxycinnamoylation of sucrose and its derivatives which was carried out with the aim of obtaining precursors of natural phenylpropanoid sucrose esters, e.g., vanicoside B. In addition to sucrose, some chemically prepared sucrose acetonides and substituted 3'-O-cinnamates were subjected to enzymatic transesterification with vinyl esters of coumaric, ferulic and 3,4,5-trimethoxycinnamic acid. Commercial enzyme preparations of Lipozyme TL IM lipase and Pentopan 500 BG exhibiting feruloyl esterase activity were tested as biocatalysts in these reactions. The substrate specificity of the used biocatalysts for the donor and acceptor as well as the regioselectivity of the reactions were evaluated and discussed. Surprisingly, Lipozyme TL IM catalyzed the cinnamoylation of sucrose derivatives more to the 1'-OH and 4'-OH positions than to the 6'-OH when the 3'-OH was free and the 6-OH was blocked by isopropylidene. In this case, Pentopan reacted comparably to 1'-OH and 6'-OH positions. If sucrose 3'-O-coumarate was used as an acceptor, in the case of feruloylation with Lipozyme in CH3CN, 6-O-ferulate was the main product (63%). Pentopan feruloylated sucrose 3'-O-coumarate comparably well at the 6-OH and 6'-OH positions (77%). When a proton-donor solvent was used, migration of the 3'-O-cinnamoyl group from fructose to the 2-OH position of glucose was observed. The enzyme hydroxycinnamoylations studied can shorten the targeted syntheses of various phenylpropanoid sucrose esters.

Adsorption simulation of gas released during oxidation of bituminous coal

ABSTRACT The adsorption of gases released during coal oxidation have a significant impact on the accuracy of CSC prediction. However, there are few research on the adsorption of C2H4 and C2H6 by coal. Therefore, the adsorption characteristics of N2/CO2/C2H4/C2H6 released during the spontaneous combustion of bituminous coal were investigated by programmed heating experiment and molecular simulation. The results showed that the low-volatile coal exhibited a higher adsorption capacity for CO2, N2, and C2H4 compared to high-volatile coal. The sequence of adsorption capacity for both low-volatile coal and High-volatile coal was CO2 > C2H6. The electrostatic potential of oxygen functional groups was ranked as follows: Ph-OH > Ph-COOH > R-COOH > R-OH. The interaction energy of gases at the -COOH position was greater than that at the -OH position, indicating that -COOH is more likely to provide adsorption sites for gases.

Unravelling the Influence of Chlorogenic Acid on the Antioxidant Phytochemistry of Avocado (Persea americana Mill.) Fruit Peel.

Oxidative stress is pivotal in the pathology of many diseases. This study investigated the antioxidant phytochemistry of avocado (Persea americana Mill.) peel. Different solvent extracts (dichloromethane, ethyl acetate, methanol, and water) of avocado peel were subjected to total phenol and flavonoid quantification, as well as in vitro radical scavenging and ferric reducing evaluation. The methanol extract was subjected to gradient column chromatographic fractionation. Fraction 8 (eluted with hexane:chloroform:methanol volume ratio of 3:6.5:0.5, respectively) was subjected to LC-MS analysis. It was assessed for cellular inhibition of lipid peroxidation and lipopolysaccharide (LPS)-induced ROS and NO production. The DPPH radical scavenging mechanism of chlorogenic acid was investigated using Density Functional Theory (DFT). The methanol extract and fraction 8 had the highest phenol content and radical scavenging activity. Chlorogenic acid (103.5 mg/mL) and 1-O-caffeoylquinic acid (102.3 mg/mL) were the most abundant phenolics in the fraction. Fraction 8 and chlorogenic acid dose-dependently inhibited in vitro (IC50 = 5.73 and 6.17 µg/mL) and cellular (IC50 = 15.9 and 9.34 µg/mL) FeSO4-induced lipid peroxidation, as well as LPS-induced ROS (IC50 = 39.6 and 28.2 µg/mL) and NO (IC50 = 63.5 and 107 µg/mL) production, while modulating antioxidant enzyme activity. The fraction and chlorogenic acid were not cytotoxic. DFT analysis suggest that an electron transfer, followed by proton transfer at carbons 3'OH and 4'OH positions may be the radical scavenging mechanism of chlorogenic acid. Considering this study is bioassay-guided, it is logical to conclude that chlorogenic acid strongly influences the antioxidant capacity of avocado fruit peel.

Influence of Hydroxyl Groups on the Oxidative Reaction Characteristics of Active Groups in Lignite at Room Temperature.

In this paper, through the Fourier infrared spectrum analysis of the Inner Mongolia Hulunbeier Yannan coal mine lignite sample, phenyl and active groups, methoxy (-OCH3) and methylene (-CH2-), were taken as the research objects, and a simple small molecule model of hydroxyl (-OH) at the ortho, meta, and para positions of active groups was constructed. The structural optimization and simulation calculation of simple small molecules were carried out by Gaussview 6.0.16 and Gaussian 16 software at room temperature and pressure. The DFT-B3LYP method and 6-311G(d,p) basis set were used to study the effect of the -OH position on the oxidation reaction characteristics from various aspects of electrostatic potential, frontier orbital, activation energy, enthalpy change, and Gibbs free energy change. The results show that the coexistence of the active groups -OCH3 and -CH2- with -OH makes the small molecule model add an active site, that is, the oxygen atom in -OH, which makes the active groups generate hydrogen radicals (H•). Comparing different positions of -OH, the analysis shows that -OH at the ortho position has a vital impact on the oxidation reaction, and the oxidation reaction releases the largest amount of heat and has the fastest occurrence rate, making it easier to overcome energy barriers and making the reaction easier to proceed. The purpose of this study is to reveal the interaction and complex reaction path of lignite through an in-depth study of its properties, structural composition, and reaction behavior and to accurately grasp its chemical composition, thermal properties, and microstructure, so as to lay a foundation for further efficient conversion and comprehensive utilization.

Strategy for the Enzymatic Acylation of the Apple Flavonoid Phloretin Based on Prior α-Glucosylation.

The acylation of flavonoids serves as a means to alter their physicochemical properties, enhance their stability, and improve their bioactivity. Compared with natural flavonoid glycosides, the acylation of nonglycosylated flavonoids presents greater challenges since they contain fewer reactive sites. In this work, we propose an efficient strategy to solve this problem based on a first α-glucosylation step catalyzed by a sucrose phosphorylase, followed by acylation using a lipase. The method was applied to phloretin, a bioactive dihydrochalcone mainly present in apples. Phloretin underwent initial glucosylation at the 4'-OH position, followed by subsequent (and quantitative) acylation with C8, C12, and C16 acyl chains employing an immobilized lipase from Thermomyces lanuginosus. Electrospray ionization-mass spectrometry (ESI-MS) and two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) confirmed that the acylation took place at 6-OH of glucose. The water solubility of C8 acyl glucoside closely resembled that of aglycone, but for C12 and C16 derivatives, it was approximately 3 times lower. Compared with phloretin, the radical scavenging capacity of the new derivatives slightly decreased with 2,2-diphenyl-1-picrylhydrazyl (DPPH) and was similar to 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS•+). Interestingly, C12 acyl-α-glucoside displayed an enhanced (3-fold) transdermal absorption (using pig skin biopsies) compared to phloretin and its α-glucoside.

Effect of OH position on adsorption behavior of Schiff-base derivatives in corrosion inhibition of carbon steel in 1 M HCl

In this work, we have synthesized two new Schiff-bases from 2,2-dimethylpropane-1,3-diamine and n-hydroxy-n-methoxybenzaldehyde. The synthesized Schiff-bases were characterized by 1H NMR, 13C NMR. The anti-corrosive property of the compounds were investigated using weight loss, polarization and EIS techniques against 1 M HCl solution. For additional support for this work, DFT studies also carried out for Schiff-bases. The surface morphology was examined by AFM and SEM to determine this inhibition mechanism. Schiff-base derivatives were found to successfully suppress steel corrosion. EIS studies showed that charge transfer resistance occurs because of the presence of an inhibitor. Moreover, increasing Schiff-bases concentration decreased the double-layer capacitance (Cdl) value because less charged species were attracted to the metal surface. Polarization measurements clearly showed that the inhibitors suppressed both anodic and cathodic reactions. In conclusion, this study demonstrates that these compounds inhibit corrosion via chemisorption of organic compounds. By studying the effects of hydroxyl groups in ortho-, para- positions, the best one as inhibitor was found to be ortho position of OH in Schiff base (i.e., 6-SH).

Hydrogen bonding interactions between Hibiscetin and ethanol/water: DFT studies on structure and topologies

The therapeutic effects of the plant Hibiscus sabdariffa are attributed significantly to the flavonoid Hibiscetin. Water and ethanol are frequently used as solvents in the extraction of flavonoids. Hydrogen bonding interactions are highly significant in the extraction process. Density functional theory (DFT) methods were used in the present investigation to theoretically examine hydrogen bonding interactions between Hibiscetin and ethanol/water. Molecular geometries, interaction energies, topological and charge studies of the complexes were investigated using the 6–311+G(d,p) basis set at the B3LYP-GD3 and M06–2X levels of theory. Eleven Hibiscetin-CH3CH2OH and nine Hibiscetin-H2O stable complexes were obtained after thorough optimization. 8OH and 5′OH positions were found to be the ideal interaction sites. The hydrogen bonds formed by the hydroxyl hydrogen atoms were moderately strong and partially covalent by the QTAIM, NCI, and ELF analyses. The MEP and NBO analyses validated the electron and charge transport from the hydrogen bond donor to the acceptor.

Porous antimicrobial crosslinked film of hydroxypropyl methylcellulose/carboxymethyl starch incorporating gallic acid for wound dressing application

Because of weak mechanical qualities and low degree of swelling of hydroxypropyl methylcellulose/carboxymethyl starch (HP/CMS) blended films for wound dressing application, this work prepared a unique antimicrobial crosslinked film utilizing succinic acid (SA) as a non-toxic crosslinker and gallic acid (GAL) as an antibacterial agent. It was observed that the infrared-shifted peak position of OH stretching and bending in HP/CMS/SA/GAL films was caused by hydrogen bond formation among HP, CMS and GAL components. The antimicrobial crosslinked films considerably enhanced their mechanical properties and swelling degree. After adding SA and GAL, the films retained their porosity structure as observed by scanning electron images. Moreover, GAL-loaded HP/CMS/SA films could inhibit Staphylococcus aureus and Escherichia coli growth, showing their wound dressing potential. Crystallinity percentage, water vapor transmission rate, gel fraction, water solubility, water uptake and cytotoxicity were also investigated.

First results from the interaction between hydroxyl radicals and condensed water droplets: A spin-polarized DFT-MD study

The formation of clouds results from condensation of water vapor into liquid water droplets. These water droplets form on the surface of tiny particles that are suspended in the air, like dust. Atmospheric chemistry relies heavily on the hydroxyl radical (OH*), which is highly reactive and prone to combining with hydrogen atoms in other compounds. Despite previous studies concerning liquid, solid, and gas phase interactions, how hydroxyl radicals interact with condensed water droplets is still unknown. OH*-condensed droplet interactions show unique behavior, according to our studies. Several hydrogen transfers were detected during the interaction process. It takes approximately 3.5 kcal/mol of energy to initiate hydrogen transfer. Moreover, we revealed the dominant structures of hydrated radicals during the mobility of OH* into condensed droplets using Born–Oppenheimer molecular dynamics simulations. In contrast to our previous studies, the hemibond doesn't significantly affect the stability of OH*(H2O)n structures in condensed droplets. Our results showed that condensed droplets hinder the mobility of OH*, causing its diffusion coefficient to decrease. Moreover, several analyses were carried out to investigate condensed droplet surfaces, bonding patterns, and the position of OH* in conjunction with water molecules, including mobility analyses, radial distribution functions, coordination analyses, and population analyses.

Effects of flow rate and equivalence ratio on syngas flames in a multi-nozzle micromix model combustor

In this paper, the flame structural parameters, OH* distribution characteristics, and dynamic behavior of the global heat release rate of a novel multi-nozzle micromix model combustor are experimentally investigated. The experiments were conducted at atmospheric pressure, high air temperature (691 K), equivalence ratio of 0.1–1.2, and air velocity of 30–80 m/s. The results demonstrate that the combustor has a wide operation window of stable combustion. The flame height is weakly related to air velocity and varies with equivalence ratio from 4D to 19D (D = 10 mm). The peak position of axial OH* intensity at the same flow rate keeps unchanged at various equivalence ratios, and the peak position of axial OH* increases in the range of 1.5D∼2.3D with increasing air velocity. The global heat release fluctuation of the flame becomes larger as the equivalence ratio decreases, which shows unsteady combustion behavior.

Doable high energy density supercapacitors using rice husk-derived carbon in dihydroxybenzenes as redox-additive electrolytes

Though activated carbon made from various bio wastes is quite affordable and plentiful, the energy density of these electrodes in aqueous electrolytes is still questionable. Therefore, increasing the energy density of activated carbon for use in supercapacitors is a challenging issue. The ideal way to boost the energy density of supercapacitors in aqueous electrolytes is by using redox-additive electrolytes. Redox-additive electrolytes are the impeccable solution for thriving the energy density of supercapacitors in aqueous electrolytes. Here, three additives namely 1, 2-benzene diol, 1, 3-benzene diol, and 1, 4-benzene diol were utilized as redox-additives with 1 M H2SO4 to study the influence of the position of OH on their redox activity and electrochemical performance. The activated carbon derived from rice-husk delivered a high specific capacitance of 1414 F/g at 4 A/g with 1, 4-benzene diol/H2SO4 among the three redox additives. A symmetric supercapacitor was fabricated, which exhibited a remarkable energy density of 38 Wh/kg at 2 A/g with 1, 4-benzene diol/H2SO4, which is almost 4 times superior to the energy density of the same electrode with H2SO4 (10.6 Wh/kg at 2 A/g).

Effects of highland barley protein and β‐glucan addition on the flour structure, bread quality and starch digestibility of whole wheat bread

SummaryWhole wheat bread is rich in nutrition, but its starch digestibility is unsatisfactory. Thus, how to reduce its digestibility has attracted much attention. This study investigated the effects of highland barley protein and β‐glucan on the pasting properties, and thermal properties of whole wheat flour to reveal the mechanism of highland barley protein and β‐glucan regulating the in vitro digestibility. The digestibility results showed that β‐glucan and protein could slow down starch digestion to some degree. The cross‐section structure determination results indicated that β‐glucan and protein decreased the porosity. The differential scanning calorimetry and thermogravimetric analysis results showed that β‐glucan and protein increased the onset of pasting, decreased the peak temperature and enthalpy of pasting and decreased the thermal stability. The Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy results revealed a blue‐shift in the ‐OH position of the bread added with protein and β‐glucan (from 995.59 to 996.07 cm−1), indicating that the hydrogen bonding might form intramolecularly. In this study, the addition of highland barley protein and β‐glucan was proved to be helpful in decreasing the in vitro digestibility and showed modification in the texture quality of bread, which might be suitable for diabetic patients.

In Vitro Evaluation and In Silico Calculations of the Antioxidant and Anti-Inflammatory Properties of Secondary Metabolites from Leonurus sibiricus L. Root Extracts.

Leonurus sibiricus L. has great ethnobotanical and ethnomedicinal significance. This study aimed to assess the antioxidant and anti-inflammatory properties of Leonurus sibiricus L. transgenic roots extracts transformed by Rhizobium rhizogenes, with and without the AtPAP1 transcriptional factor. The study determined the total phenolic and flavonoid contents, as well as in vitro antioxidant assays, including hydrogen peroxide and nitric oxide scavenging activity. In addition, in silico computational studies and molecular docking were conducted to evaluate the antioxidant and anti-inflammatory potential of the identified compounds. The ligands were docked to NADPH oxidase, cyclooxygenase 2,5-lipoxygenase, inducible nitric synthase and xanthine oxidase: enzymes involved in the inflammatory process. The total phenolic and flavonoid contents ranged from 85.3 ± 0.35 to 57.4 ± 0.15 mg/g GAE/g and 25.6 ± 0.42 to 18.2 ± 0.44 mg/g QUE/g in hairy root extracts with and without AtPAP1, respectively. H2O2 scavenging activity (IC50) was found to be 29.3 µg/mL (with AtPAP1) and 37.5 µg/mL (without AtPAP1 transcriptional factor), and NO scavenging activity (IC50) was 48.0 µg/mL (with AtPAP1) and 68.8 µg/mL (without AtPAP1 transcriptional factor). Leonurus sibiricus L. transformed root extracts, both with and without AtPAP1, are a source of phytochemicals belonging to different classes of molecules, such as flavonoids (catechin and rutin), phenolic compounds (caffeic acid, coumaric acid, chlorogenic acid, ferulic acid) and phenylpropanoid (verbascoside). Among the radicals formed after H removal from the different -OH positions, the lowest bond dissociation enthalpy was observed for rutin (4'-OH). Rutin was found to bind with cyclooxygenase 2, inducible nitric synthases and xanthine oxidase, whereas chlorogenic acid demonstrated optimal binding with 5-lipoxygenase. Therefore, it appears that the Leonurus sibiricus L. transformed root extract, both with and without the AtPAP1 transcriptional factor, may serve as a potential source of active components with antioxidant and anti-inflammatory potential; however, the extract containing AtPAP1 demonstrates superior activities. These properties could be beneficial for human health.

Spectral Contamination of the 6300 Å Emission in Single‐Etalon Fabry‐Perot Interferometers

AbstractThe spectral line profile of the atomic oxygen O1D2—3P2 transition near 6300 Å in the airglow has been used for more than 50 years to extract neutral wind and temperature information from the F‐region ionosphere. A new spectral model and recent samples of this airglow emission in the presence of the nearby lambda‐doubled OH Meinel (9‐3) P2(2.5) emission lines underscores earlier cautions that OH can significantly distort the OI line center position and line width observed using a single‐etalon Fabry‐Perot interferometer (FPI). The consequence of these profile distortions in terms of the emission profile line width and Doppler position is a strong function of the selected etalon plate spacing. Single‐etalon Fabry‐Perot interferometers placed in the field for thermospheric measurements have widely varying etalon spacings, so that systematic wind biases caused by the OH line positions differ between instruments, complicating comparisons between sites. Based on the best current determinations of the OH and O1D line positions, the ideal gap for a single‐etalon FPI wind measurements places the OH emissions in the wings of the O1D spectral line profile. Optical systems that can accommodate prefilters with square passbands less than ∼3 Å in the optical beam can effectively block the OH contamination. When that is not possible, a method to fit for OH contamination and remove it in the spectral background of an active Fabry‐Perot system is evaluated.