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Journal articles on the topic 'Stereoisomeric forms'

Author: Grafiati

Published: 5 June 2025

Last updated: 1 August 2025

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1

Sheikh, Ishfaq Ahmad, and Mohd Amin Beg. "Structural Aspects of Potential Endocrine-Disrupting Activity of Stereoisomers for a Common Pesticide Permethrin against Androgen Receptor." Biology 10, no. 2 (2021): 143. http://dx.doi.org/10.3390/biology10020143.

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Endocrine-disrupting chemicals (EDCs) are a serious global public health and environmental concern. Pyrethroids are insecticide chemicals that are extensively used for crop protection and household purposes but have been identified as EDCs. On account of their ubiquitous environmental presence, human exposure occurs via food, dermal, or inhalation routes and is associated with health problems, including reproductive dysfunction. Permethrin is the most commonly used pyrethroid, and with two chiral centers in its structure, it has four stereoisomeric forms (two enantiomer pairs), i.e., permethri

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2

Leitgeb, Balázs. "Spatial relationships between the pharmacophores of endomorphin-2: a comparative study of stereoisomers." Open Chemistry 10, no. 6 (2012): 1791–98. http://dx.doi.org/10.2478/s11532-012-0105-3.

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AbstractThe spatial relationships between the pharmacophore elements were investigated in the case of four different stereoisomeric forms of opioid tetrapeptide, endomorphin-2, taking into account the L-D and cis-trans isomerisms. On the basis of distances and angles measured between the pharmacophoric points, a comparative analysis of conformational distributions was performed, applying a variety of distance-angle maps. The results obtained by this theoretical study indicated that the stereoisomers of endomorphin-2 could be distinguished from one another, based on the comparative analysis of

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3

Bello, Jan E., J. Steven McElfresh, and Jocelyn G. Millar. "Isolation and determination of absolute configurations of insect-produced methyl-branched hydrocarbons." Proceedings of the National Academy of Sciences 112, no. 4 (2015): 1077–82. http://dx.doi.org/10.1073/pnas.1417605112.

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Although the effects of stereochemistry have been studied extensively for volatile insect pheromones, little is known about the effects of chirality in the nonvolatile methyl-branched hydrocarbons (MBCHs) used by many insects as contact pheromones. MBCHs generally contain one or more chiral centers and so two or more stereoisomeric forms are possible for each structure. However, it is not known whether insects biosynthesize these molecules in high stereoisomeric purity, nor is it known whether insects can distinguish the different stereoisomeric forms of MBCHs. This knowledge gap is due in par

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4

Leitgeb, Balázs. "Conformational Similarities and Dissimilarities Between the Stereoisomeric Forms of Endomorphin-2." Chemical Biology & Drug Design 79, no. 3 (2011): 313–25. http://dx.doi.org/10.1111/j.1747-0285.2011.01275.x.

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5

Yakovleva, M. P., V. A. Vydrina, N. M. Ishmuratova, and G. Yu Ishmuratov. "CONTRIBUTION OF UFA SCIENTISTS TO THE CHEMISTRY OF OPTICALLY ACTIVE SEX PHEROMONE OF PINE SAWFLIES." ÈKOBIOTEH 3, no. 4 (2020): 634–42. http://dx.doi.org/10.31163/2618-964x-2020-3-4-634-642.

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Pine sawflies of the genera Neodiprion, Diprion and Gilpinia (Diprionidae) are malignant and economically important pests of coniferous trees. The most effective and environmentally safe method of controlling and regulating the number of pine sawflies is the use in traps of synthetically obtained sex feromone, identified for its different species as acetates and propionates of 3,7-dimethyl-2-pentadecan-2-ol (diprionol) in the form of various stereoisomeric forms due to the presence of three asymmetric carbon atoms. At the same time, it was noted that the 2S configuration of the optical centre

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6

Gill, Brendon D., Jackie E. Wood та Harvey E. Indyk. "Analysis of α-Tocopherol Stereoisomers in Fortified Infant Formula by Chiral Chromatography". Journal of AOAC INTERNATIONAL 104, № 3 (2021): 725–31. http://dx.doi.org/10.1093/jaoacint/qsab012.

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Abstract Background Direct measurement of the bioavailable α-tocopherol content presents a significant analytical challenge and requires chiral separation of the α-tocopherol stereoisomers. Objective The objective of the study was to validate an analytical method for the analysis of α-tocopherol stereoisomers in infant formulas and dairy products. Method Samples were saponified at elevated temperature and lipophilic components were extracted into an organic solvent, with subsequent chromatographic separation of the α-tocopherol stereoisomers achieved by HPLC with a chiral column and fluorescen

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7

Diukendjieva, Antonia, Merilin Al Sharif, Petko Alov, Tania Pencheva, Ivanka Tsakovska, and Ilza Pajeva. "ADME/Tox Properties and Biochemical Interactions of Silybin Congeners: In silico Study." Natural Product Communications 12, no. 2 (2017): 1934578X1701200. http://dx.doi.org/10.1177/1934578x1701200208.

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Silymarin, the active constituent of Silybum marianum (milk thistle), and its main component, silybin, are products with well-known hepatoprotective, cytoprotective, antioxidant, and chemopreventative properties. Despite substantial in vitro and in vivo investigations of these flavonolignans, their mechanisms of action and potential toxic effects are not fully defined. In this study we explored important ADME/Tox properties and biochemical interactions of selected flavonolignans using in silico methods. A quantitative structure–activity relationship (QSAR) model based on data from a parallel a

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8

Yakovleva, Marina Petrovna, Valentina Afanasievna Vydrina, Nailya Mavletzyanovna Ishmuratova, and Gumer Yusupovich Ishmuratov. "OPTICALLY ACTIVE PINE SEX PHEROMONE SAWS: SYNTHESIS AND BIOLOGICAL ACTIVITY." chemistry of plant raw material, no. 2 (June 12, 2024): 26–54. https://doi.org/10.14258/jcprm.20240312696.

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The most dangerous pest for coniferous trees, by right, can be called pine sawflies of the genera Diprion, Neodiprion and Gilpinia (Diprionidae) – insects that can cause tremendous harm to plants or even destroy them. Scots pines suffer the most from the pest, especially at the age of 20–40, however, ornamental plant species are often subject to mass attack by insects. The review article presents mechanical, biological and chemical methods of combating pine sawflies, the main part of the review is devoted to the use of the sex pheromone of males of these pests, namely, identification methods (

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9

Serra, Stefano, Davide De Simeis, and Sara Papili. "A Practical Laboratory-Scale Synthesis of All Eight Stereoisomeric Forms of Terpene Linalool Oxide." Chemistry 3, no. 4 (2021): 1247–57. http://dx.doi.org/10.3390/chemistry3040090.

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In this work, we describe a user-friendly procedure for the preparation of all the isomeric forms of the terpene linalool oxide. The presented method is based on the transformation of the linalool enantiomers into the corresponding diastereoisomeric mixtures of the two furanoid oxides and two pyranoid oxides. Taking advantage of the different steric hindrance of the hydroxyl functional groups, the pyranoid forms were separated as a diastereoisomeric mixtures of their benzoate esters. Conversely, the cis- and trans-furanoid isomers were transformed in the corresponding acetates, which were dire

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10

Gasanov, Arif G., Ilgar G. Ayyubov, Gulsum E. Hajiyeva, and Fidan S. Qurbanova. "Study of the relationship between geometric isomerism and biologically active properties of compounds." Izvestiya of Saratov University. Chemistry. Biology. Ecology 21, no. 4 (2021): 405–14. http://dx.doi.org/10.18500/1816-9775-2021-21-4-405-414.

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The results of the research in the field of studying the relationship of the geometric structure of organic compounds with their biological activity are presented. It has been shown that the stereospecific structure of organic and inorganic molecules can have a direct effect on the biologically active properties of substances. Among the known types of stereoisomerism (geometric and optical), this work summarizes the effect of various types of geometric isomerism on the bioactivity of compounds. In addition, the results of the authors’ own research are presented. In particular, the results of s

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11

Kranjc, Krištof, Amadej Juranovič, Marijan Kočevar, and Franc Perdih. "Supramolecular Diversity of Oxabicyclo[2.2.2]octenes Formed between Substituted 2H-Pyran-2-ones and Vinyl-Moiety-Containing Dienophiles." Symmetry 12, no. 10 (2020): 1714. http://dx.doi.org/10.3390/sym12101714.

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In Diels–Alder reactions, 2H-pyran-2-ones as dienes can yield a large variety of cycloadducts with up to four contiguous carbon stereogenic centers. Some of the potentially most useful, however difficult to prepare due to their low thermal stability, are the primary CO2-containing oxabicyclo[2.2.2]octenes, which could be formed as eight distinctive isomers (two sets of regioisomers, each of these composed of four different stereoisomers). A high-pressure synthesis of such products was recently described in a few cases where vinyl-moiety-containing dienophiles were used as synthetic equivalents

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12

Hale, Paul W., and Alphonse Poklis. "Cardiotoxicity of thioridazine and two stereoisomeric forms of thioridazine 5-sulfoxide in the isolated perfused rat heart." Toxicology and Applied Pharmacology 86, no. 1 (1986): 44–55. http://dx.doi.org/10.1016/0041-008x(86)90398-4.

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13

Shimotori, Yasutaka, Masayuki Hoshi, Hayato Okabe, Tetsuo Miyakoshi, Taisei Kanamoto, and Hideki Nakashima. "Synthesis, odour characteristics and antibacterial activities of the stereoisomeric forms of whisky lactone and its thiono analogues." Flavour and Fragrance Journal 32, no. 1 (2016): 29–35. http://dx.doi.org/10.1002/ffj.3341.

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14

Padnya, Pavel, Ksenia Shibaeva, Maxim Arsenyev, et al. "Catechol-Containing Schiff Bases on Thiacalixarene: Synthesis, Copper (II) Recognition, and Formation of Organic-Inorganic Copper-Based Materials." Molecules 26, no. 8 (2021): 2334. http://dx.doi.org/10.3390/molecules26082334.

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For the first time, a series of catechol-containing Schiff bases, tetrasubstituted at the lower rim thiacalix[4]arene derivatives in three stereoisomeric forms, cone, partial cone, and 1,3-alternate, were synthesized. The structure of the obtained compounds was proved by modern physical methods, such as NMR, IR spectroscopy, and HRMS. Selective recognition (Kb difference by three orders of magnitude) of copper (II) cation in the series of d-metal cations (Cu2+, Ni2+, Co2+, Zn2+) was shown by UV-vis spectroscopy. Copper (II) ions are coordinated at the nitrogen atom of the imine group and the n

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15

Serra, Stefano. "A General Strategy for the Stereoselective Synthesis of the Furanosesquiterpenes Structurally Related to Pallescensins 1–2." Marine Drugs 17, no. 4 (2019): 245. http://dx.doi.org/10.3390/md17040245.

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Here, we describe a general stereoselective synthesis of the marine furanosesquiterpenes structurally related to pallescensins 1–2. The stereoisomeric forms of the pallescensin 1, pallescensin 2, and dihydropallescensin 2 were obtained in high chemical and isomeric purity, whereas isomicrocionin-3 was synthesized for the first time. The sesquiterpene framework was built up by means of the coupling of the C10 cyclogeranyl moiety with the C5 3-(methylene)furan moiety. The key steps of our synthetic procedure are the stereoselective synthesis of four cyclogeraniol isomers, their conversion into t

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16

Sharma, Yogita. "One pot facile synthesis of flavanoidal oxadiazinanones: In vitro antibacterial activity, docking and MD simulation using DNA gyrase." Universal Research Reports 10, no. 1 (2024): 218–26. http://dx.doi.org/10.36676/urr.v10.i1.1297.

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Flavanones are commonly spread in nature because they are essential intermediates in the biosynthetic flavonoid pathway1 and are of therapeutic significance because of their broad variety of biological activities such as hypertensive, antifungal, antibacterial, and antitumor activities2. Therefore, the field of flavanones is of numerous attentions to medicinal chemists for drug discovery. Flavanones have a 2,3- dihydro skeleton in the C6-C3-C6 structure of the flavonoid and do not have a double bond between C2 and C3, (Fig. 1) which renders them chiral in the C2 position3 hence two stereoisome

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17

Yeomans, Brett D., Laurence S. Kelso, Peter A. Tregloan, and F. Richard Keene. "Redox Characteristics and Anion Association Behaviour of Stereoisomeric Forms of Mono- and Oligonuclear Metal Complexes Using High Pressure Electrochemistry." European Journal of Inorganic Chemistry 2001, no. 1 (2001): 239–46. http://dx.doi.org/10.1002/1099-0682(20011)2001:1<239::aid-ejic239>3.0.co;2-2.

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18

Serra, Stefano. "Enantioselective Synthesis of Natural Trinorsesquiterpene Tetralones by Chemo-enzymatic Approaches." Natural Product Communications 8, no. 7 (2013): 1934578X1300800. http://dx.doi.org/10.1177/1934578x1300800704.

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The enantioselective syntheses of both the enantiomeric forms of the four natural tetralones 1a-d are here described. The aforementioned trinorsesquiterpenes were prepared starting either from substituted ( S)-3-arylbutanols 5a-c or from substituted ( S)-2-arylpropanols 7a-c. The latter chiral building blocks were in turn obtained through two different kinds of enzymatic transformations consisting of the baker's yeast mediated reduction of substituted ( E)-3-aryl-but-2-enals 4a-c and the lipase-mediated resolution of racemic 2-arylpropanols 7a-c, respectively. Further key steps of the presente

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19

Shiabiev, Igor, Dmitry Pysin, Alan Akhmedov, et al. "Towards Antibacterial Agents: Synthesis and Biological Activity of Multivalent Amide Derivatives of Thiacalix[4]arene with Hydroxyl and Amine Groups." Pharmaceutics 15, no. 12 (2023): 2731. http://dx.doi.org/10.3390/pharmaceutics15122731.

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Antimicrobial resistance to modern antibiotics stimulates the search for new ways to synthesize and modify antimicrobial drugs. The development of synthetic approaches that can easily change different fragments of the molecule is a promising solution to this problem. In this work, a synthetic approach was developed to obtain multivalent thiacalix[4]arene derivatives containing different number of amine and hydroxyl groups. A series of macrocyclic compounds in cone, partial cone, and 1,3-alternate stereoisomeric forms containing -NHCH2CH2R (R = NH2, N(CH3)2, and OH) and -N(CH2CH2OH)2 terminal f

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20

Zhang, Na, Shuang Ding, Alexander Kolbanovskiy, et al. "NMR and Computational Studies of Stereoisomeric Equine Estrogen-Derived DNA Cytidine Adducts in Oligonucleotide Duplexes: Opposite Orientations of Diastereomeric Forms." Biochemistry 48, no. 30 (2009): 7098–109. http://dx.doi.org/10.1021/bi9006429.

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21

Cortinas, Lucia, Ana Barroeta, Jaume Galobart та Søren K. Jensen. "Distribution of α-tocopherol stereoisomers in liver and thigh of chickens". British Journal of Nutrition 92, № 2 (2004): 295–301. http://dx.doi.org/10.1079/bjn20041188.

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The effect of supplementation with different levels of all-rac-α-tocopheryl acetate and the inclusion of different dietary contents of PUFA on the deposition of α-tocopherol stereoisomers in liver and thigh of chickens was evaluated. Ninety-six 1-d-old Ross female broiler chickens were randomly distributed into eight experimental treatments (three replicates each) resulting from four levels of α-tocopheryl acetate without supplementation and supplemented with 100, 200 and 400 mg α-tocopheryl acetate/kg and two levels of dietary PUFA (15 and 61 g/kg). The feeds supplemented with α-tocopheryl ac

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22

McKeage, Mark J., Peter Papathanasiou, Geoffrey Salem, et al. "Antitumor Activity of Gold(I), Silver(I) and Copper(I) Complexes Containing Chiral Tertiary Phosphines." Metal-Based Drugs 5, no. 4 (1998): 217–23. http://dx.doi.org/10.1155/mbd.1998.217.

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The in vitro cytotoxicities of a number of gold(I), silver(I) and copper(I) complexes containing chiral tertiary phosphine ligands have been examined against the mouse tumour cell lines P815 mastocytoma, B16 melanoma [gold(I) and silver(I) compounds] and P388 leukaemia [gold(I) complexes only] with many of the complexes having IC50 values comparable to that of the reference compounds cis-diamminedichloroplatinum(ll), cisplatin, and bis[1,2-bis(diphenylphosphino) ethane]gold(I) iodide. The chiral tertiary phosphine ligands used in this study include (R)-(2-aminophenyl)methylphenylphosphine; (R,

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23

Mahmoud, Abdelhalim Babiker, Ombeline Danton, Marcel Kaiser, et al. "Lignans, Amides, and Saponins from Haplophyllum tuberculatum and Their Antiprotozoal Activity." Molecules 25, no. 12 (2020): 2825. http://dx.doi.org/10.3390/molecules25122825.

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A screening of Sudanese medicinal plants for antiprotozoal activities revealed that the chloroform and water fractions of the ethanolic root extract of Haplophyllum tuberculatum exhibited appreciable bioactivity against Leishmania donovani. The antileishmanial activity was tracked by HPLC-based activity profiling, and eight compounds were isolated from the chloroform fraction. These included lignans tetrahydrofuroguaiacin B (1), nectandrin B (2), furoguaiaoxidin (7), and 3,3′-dimethoxy-4,4′-dihydroxylignan-9-ol (10), and four cinnamoylphenethyl amides, namely dihydro-feruloyltyramine (5), (E)-

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24

Rose, R. C., and J. L. Choi. "Intestinal absorption and metabolism of ascorbic acid in rainbow trout." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 258, no. 5 (1990): R1238—R1241. http://dx.doi.org/10.1152/ajpregu.1990.258.5.r1238.

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Transport and metabolism of the reduced and oxidized forms of vitamin C were evaluated in trout intestine in vitro. Transepithelial fluxes of [14C]ascorbic acid were determined with the substrate present at 10 microM. The mucosa-to-serosa flux was fourfold greater than the serosa-to-mucosa flux with ascorbic acid present in both bathing solutions. Cellular accumulation of the reduced molecule occurred with a final tissue-to-medium ratio of 1.64. Ascorbic acid influx across the brush-border membrane was determined under conditions that inhibit transport of other nutrients. Influx was not reduce

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25

Valente, Tiago Neves Pereira, Cláudia Batista Sampaio, Erico da Silva Lima, Bruno Borges Deminicis, Andréia Santos Cezário, and Wallacy Barbacena Rosa dos Santos. "Aspects of Acidosis in Ruminants with a Focus on Nutrition: A Review." Journal of Agricultural Science 9, no. 3 (2017): 90. http://dx.doi.org/10.5539/jas.v9n3p90.

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An increased risk of acidosis in animals is associated with a high dry matter intake (DMI), which in turn results in the consumption of more fermentable organic matter (OM) in the rumen leading to a high production of volatile fatty acids (VFA). This is observed in lactating dairy cows and animals in a feedlot. Acute acidosis occurs when there is a severe drop in the pH of the rumen. A prolonged period when pH of in rumen remains low, it leads to sub-acute ruminal acidosis (SARA), which is a temporary imbalance between acid production and absorption. An associated change of an acute increase i

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Kuner, Maximilian, Jan Lisec, Tatjana Mauch, Jörg Konetzki, Hajo Haase, and Matthias Koch. "Quantification of Ergot Alkaloids via Lysergic Acid Hydrazide—Development and Comparison of a Sum Parameter Screening Method." Molecules 28, no. 9 (2023): 3701. http://dx.doi.org/10.3390/molecules28093701.

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Ergot alkaloids are a group of mycotoxins occurring in products derived from various grasses (e.g., rye) and have been regulated in the EU recently. The new maximum levels refer to the sum of the six most common ergot alkaloids in their two stereoisomeric forms in different food matrices. Typically, these twelve compounds are individually quantified via HPLC-MS/MS or -FLD and subsequently summed up to evaluate food safety in a time-consuming process. Since all these structures share the same ergoline backbone, we developed a novel sum parameter method (SPM) targeting all ergot alkaloids simult

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27

Toshtay, K., and A. B. Auyezov. "NEW STEREOSELECTIVE CATALYSTS FOR THE HYDROGENATION OF SUNFLOWER OIL." Chemical Journal of Kazakhstan, no. 4 (December 15, 2023): 131–41. http://dx.doi.org/10.51580/2023-4.2710-1185.46.

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The work is devoted to the creation of new stereoselective catalysts for the hydrogenation of sunflower oil, which can significantly reduce the trans-isomers of fatty acids. Thus, on nickel catalysts used in industry, the content of trans-isomers of fatty acids reaches up to 30%. Platinum deposited on diatomite (processed natural clay) 0.2 to 1% is offered as a catalyst. Methodology. The hydrogenation was carried out in an autoclave, excluding external diffusion inhibition, at hydrogen pressures ranging from 0.25 to 1.0 MPa and temperatures ranging from 90 to 110°C. Results and discussion. Chr

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28

Il`in, E. G., A. S. Parshakov, V. G. Yarzhemsky, E. A. Ugolkova, L. V. Goyeva, and V. I. Privalov. "Physical chemistry CeF4 complexes in organic solvents." Доклады Академии наук 488, no. 1 (2019): 47–51. http://dx.doi.org/10.31857/s0869-5652488147-51.

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The first complexes of cerium tetrafluoride in solutions were investigated by 19F NMR and IR spectroscopy. The temperature dependence of the 19F NMR spectra was, studied and it was concluded that mobile equilibrium exists between the molecular adduct and singly charged ionic forms, including geometric isomers. The static probability of stereoisomer formation [CeF4(dmso)4] was calculated using the square antiprism configuration and, based on the relative intensity of the 19F NMR resonance signals, they were assigned to possible stereoisomers. Quantum-chemical calculations of the structure of th

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Kálmán, Alajos, Gyula Argay, László Fábián, Gábor Bernáth, and Ferenc Fülöp. "Basic forms of supramolecular self-assembly organized by parallel and antiparallel hydrogen bonds in the racemic crystal structures of six disubstituted and trisubstituted cyclopentane derivatives." Acta Crystallographica Section B Structural Science 57, no. 4 (2001): 539–50. http://dx.doi.org/10.1107/s0108768101006723.

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A selection of stereoisomeric 2-hydroxy-1-cyclopentanecarboxamides, a 4-tert-butyl derivative and three tert-butyl derivatives of the respective carboxylic acid were subjected to X-ray crystallography. The optically active molecules (I)–(VI) form racemic crystals. Each racemic structure is basically determined by two intermolecular hydrogen bonds of O—H...O=C—XH and O=C—X—H...OH types (X = O, NH). The partially similar patterns of close packing observed reflect five basic forms of supramolecular self-assembly. In the racemic crystals of chiral molecules, there are homo- and heterochiral chains

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Belhadj-Tahar, Hafid, Pierre Payoux, Mathieu Tafani, Yvon Coulais, Serge Calet, and Azzedine Bousseksou. "Toxicological Methods for Tracing Drug Abuse: Chromatographic, Spectroscopic and Biological Characterisation of Ecstasy Derivatives." Archives of Industrial Hygiene and Toxicology 61, no. 1 (2010): 53–59. http://dx.doi.org/10.2478/10004-1254-61-2010-1937.

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Toxicological Methods for Tracing Drug Abuse: Chromatographic, Spectroscopic and Biological Characterisation of Ecstasy DerivativesAnalysis often reveals variability in the composition of ecstasy pills from pure 3,4-methylenedioxymethamphetamine (MDMA) to mixtures of MDMA derivatives, amphetamine, and other unidentified substances. For a comprehensive toxicological analysis one needs to know all steps to MDMA synthesis which may originate impurities. The aim of this study was to synthesise and determine the chemical-physical andin vitrobiological properties of a series of MDMA derivatives.3,4-

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Shaw, Jiajiu, Kenneth Swartz, Frederick Valeriote, et al. "Identification of the Metabolites of a Novel Anti-MRSA Compound, Kaempferol-3-O-Alpha-L-(2″,3″-di-p-coumaroyl)rhamnoside (KCR), Extracted from American Sycamore." Natural Product Communications 13, no. 3 (2018): 1934578X1801300. http://dx.doi.org/10.1177/1934578x1801300321.

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Fractionation of an extract from American sycamore leaves produced the small molecule, kaempferol-3- O-alpha-L-(2″,3″-di- p-coumaroyl)rhamnoside (KCR), which exists in four stereoisomeric forms ( EE, EZ, ZE, and ZZ) at the olefin in the p-coumaroyl; all four isomers exhibit potent anti-MRSA activity in vitro. As part of the preclinical development of KCR, we set out to investigate the metabolites of KCR in mouse plasma as a prelude of ADME studies and therapeutic assessment. When KCR was added to mouse plasma at 37 °C, two new HPLC peaks appeared with increasing intensity as the incubation tim

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32

Dyrkheeva, Nadezhda S., Irina A. Chernyshova, Georgy A. Ivanov, et al. "In Vitro and In Silico Studies of Human Tyrosyl-DNA Phosphodiesterase 1 (Tdp1) Inhibition by Stereoisomeric Forms of Lipophilic Nucleosides: The Role of Carbohydrate Stereochemistry in Ligand-Enzyme Interactions." Molecules 27, no. 8 (2022): 2433. http://dx.doi.org/10.3390/molecules27082433.

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Inhibition of human DNA repair enzyme tyrosyl-DNA phosphodiesterase 1 (Tdp1) by different chiral lipophilic nucleoside derivatives was studied. New Tdp1 inhibitors were found in the series of the studied compounds with IC50 = 2.7–6.7 μM. It was shown that D-lipophilic nucleoside derivatives manifested higher inhibition activity than their L-analogs, and configuration of the carbohydrate moiety can influence the mechanism of Tdp1 inhibition.

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Tatavarti, Bhagya Kumar, Rani N. Usha, Venkata Swamy Tangeti, and Bhavani K. Tulasi. "Chiral LC method development for stereo-selective separation and quantification of Ivosidenib and its S,R and R,R isomeric impurities in drug substance and finished product." Research Journal of Chemistry and Environment 29, no. 4 (2025): 79–85. https://doi.org/10.25303/294rjce079085.

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A robust and reliable chiral HPLC method was developed and validated for the separation and quantification of ivosidenib and its stereoisomeric impurities (S,R and R,R forms) in pharmaceutical formulations and bulk drug samples. The study optimized various analytical parameters including the mobile phase composition, pH modifiers, flow rate, detector wavelength and column temperature. A mobile phase comprising of methanol and 0.1% formic acid in 65:35 (v/v) ratio, with a flow rate of 0.8 mL/min and a detection wavelength of 248 nm, was identified as optimal. These conditions provided high-reso

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Nau, Carla, Werner Vogel, Gunter Hempelmann, and Michael E. Bräu. "Stereoselectivity of Bupivacaine in Local Anesthetic–sensitive Ion Channels of Peripheral Nerve." Anesthesiology 91, no. 3 (1999): 786. http://dx.doi.org/10.1097/00000542-199909000-00031.

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Background The local anesthetic bupivacaine exists in two stereoisomeric forms, R(+)- and S(-)-bupivacaine. Because of its lower cardiac and central nervous system toxicity, attempts were made recently to introduce S(-)-bupivacaine into clinical anesthesia. We investigated stereoselective actions of R(+)-and S(-)-bupivacaine toward two local anesthetic-sensitive ion channels in peripheral nerve, the Na+ and the flicker K+ channel. Methods In patch-clamp experiments on enzymatically demyelinated peripheral amphibian nerve fibers, Na+ and flicker K+ channels were investigated in outside-out patc

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Mizoguchi, Tadashi, Kazukimi Hara, Hiroyoshi Nagae, and Yasushi Koyama. "Structural Transformation Among the Aggregate Forms of Bacteriochlorophyll c as Determined by Electronic-Absorption and NMR Spectroscopies: Dependence on the Stereoisomeric Configuration and on the Bulkiness of the 8-C Side Chain ‡." Photochemistry and Photobiology 71, no. 5 (2000): 596–609. http://dx.doi.org/10.1562/0031-8655(2000)0710596stataf2.0.co2.

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Mizoguchi, Tadashi, Kazukimi Hara, Hiroyoshi Nagae, and Yasushi Koyama. "Structural Transformation Among the Aggregate Forms of Bacteriochlorophyll c as Determined by Electronic-Absorption and NMR Spectroscopies: Dependence on the Stereoisomeric Configuration and on the Bulkiness of the 8-C Side Chain‡." Photochemistry and Photobiology 71, no. 5 (2000): 596. http://dx.doi.org/10.1562/0031-8655(2000)071<0596:stataf>2.0.co;2.

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Meglia, Guillermo E., Søren K. Jensen, Charlotte Lauridsen та Karin Persson Waller. "α-Tocopherol concentration and stereoisomer composition in plasma and milk from dairy cows fed natural or synthetic vitamin E around calving". Journal of Dairy Research 73, № 2 (2006): 227–34. http://dx.doi.org/10.1017/s0022029906001701.

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The aim of this study was to compare the effects of supplementing dairy cows with 1000 IU/day of all-rac-α-tocopheryl acetate (SynAc), RRR-α-tocopheryl acetate (NatAc), or RRR-α-tocopherol (NatAlc), from approximately 3 weeks before estimated calving until 2 weeks after calving, on the concentration of α-tocopherol and its stereoisomers (RRR-, RSS-, RRS-, RSR- and the four 2S-forms of α-tocopherol) in blood and milk. An unsupplemented group was included as control. Blood samples were collected at 3, 2 and 1 weeks before estimated calving, at calving, and 3, 7 and 14 days after calving, while m

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38

Chotsaeng, Nawasit, Chamroon Laosinwattana, and Patchanee Charoenying. "Enantioselective and Synergistic Herbicidal Activities of Common Amino Acids Against Amaranthus tricolor and Echinochloa crus-galli." Molecules 26, no. 7 (2021): 2071. http://dx.doi.org/10.3390/molecules26072071.

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Amino acids have a wide range of biological activities, which usually rely on the stereoisomer presented. In this study, glycine and 21 common α-amino acids were investigated for their herbicidal property against Chinese amaranth (Amaranthus tricolor L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.). Both d- and l-isomers, as well as a racemic mixture, were tested and found that most compounds barely inhibited germination but moderately suppressed seedling growth. Various ratios of d:l-mixture were studied and synergy between enantiomers was found. For Chinese amaranth, the most toxi

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Morgan, Phil G., Marianne F. Usiak, and Margaret M. Sedensky. "Genetic Differences Affecting the Potency of Stereoisomers of Isoflurane." Anesthesiology 85, no. 2 (1996): 385–92. http://dx.doi.org/10.1097/00000542-199608000-00021.

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Background In previous studies, researchers demonstrated the ability of a variety of organisms and in vitro sites of anesthetic action to distinguish between stereoisomers of isoflurane or halothane. However, it was not shown whether organisms with differing sensitivities to stereoisomers of one volatile anesthetic are able to distinguish between stereoisomers of another. In this study, the responses of mutants of Caenorbabditis elegans to stereoisomers of isoflurane were determined for comparison to previous results in halothane. Methods Mutant strains of C. elegans were isolated and grown by

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Kuchař, Miroslav, Marie Poppová, Antonín Jandera, et al. "Chiral Forms of 4-(2',4'-Difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic Acid (Flobufen) and Its Metabolite.Synthesis and Basic Biological Properties." Collection of Czechoslovak Chemical Communications 62, no. 3 (1997): 498–509. http://dx.doi.org/10.1135/cccc19970498.

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4-(2',4'-Difluorobiphenyl-4-yl)-2-methyl-4-oxobutanoic acid (1, flobufen) is subjected to clinical testing in the treatment of rheumatoid arthritis. Owing to the occurrence of a centre of chirality, the compound exists in two enantiomers, and its major human metabolite, viz. 4-(2',4'-difluorobiphenyl-4-yl)-4-hydroxy-2-methylbutanoic acid isolated in the lactone form (2), possesses two chiral centres, making possible the existence of four stereoisomers. All of the optical isomers of the substances 1 and 2 were prepared. For flobufen (1), the racemate was separated into the stereoisomers by usin

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Eerdekens, G., N. Yassaa, V. Sinha, et al. "VOC measurements within a boreal forest during spring 2005: on the occurrence of elevated monoterpene concentrations during night time intense particle concentration events." Atmospheric Chemistry and Physics 9, no. 21 (2009): 8331–50. http://dx.doi.org/10.5194/acp-9-8331-2009.

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Abstract. In this study we present measurements of selected trace gases and aerosols made in a boreal forest during the BACCI-QUEST IV intensive field campaign in Hyytiälä, Finland in April 2005. Springtime diel and vertical variations of VOCs are discussed in connection with the variations in other trace gases and with the prevailing meteorological conditions. A daytime and a nighttime event have been analysed in detail. The nighttime particle event occurred synchronously with huge increases in monoterpenes, while the second event type involved nucleation and was anti-correlated with sulphuri

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Cheesman, A. W., B. L. Turner, and K. R. Reddy. "Forms of organic phosphorus in wetland soils." Biogeosciences 11, no. 23 (2014): 6697–710. http://dx.doi.org/10.5194/bg-11-6697-2014.

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Abstract. Phosphorus (P) cycling in freshwater wetlands is dominated by biological mechanisms, yet there has been no comprehensive examination of the forms of biogenic P (i.e., forms derived from biological activity) in wetland soils. We used solution 31P NMR spectroscopy to identify and quantify P forms in surface soils of 28 palustrine wetlands spanning a range of climatic, hydrogeomorphic, and vegetation types. Total P concentrations ranged between 51 and 3516 μg P g-1, of which an average of 58% was extracted in a single-step NaOH–EDTA procedure. The extracts contained a broad range of P f

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Yamauchi, Satoshi, Hiroki Nishimura, and Hisashi Nishiwaki. "Stereoselective syntheses of cryptocarya diacetate and all its stereoisomers in optically pure forms." Bioscience, Biotechnology, and Biochemistry 79, no. 1 (2014): 16–24. http://dx.doi.org/10.1080/09168451.2014.962476.

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Flockhart, David A., and Harold S. Nelson. "Single Isomer Versus Racemate: Is There a Difference? Clinical Comparisons in Allergy and Gastroenterology." CNS Spectrums 7, S1 (2002): 23–27. http://dx.doi.org/10.1017/s109285290002856x.

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ABSTRACTMany commonly prescribed drugs exist as a mixture of two distinct chiral isomer forms (enantiomers), each with its own unique chemistry, receptor affinity, and pharmacokinetic profile. Much is unknown concerning the clinical utility of these single enantiomers. This review of the stereoisomers of two commonly used drugs—albuterol for asthma and omeprazole for gastroesophageal reflux disease (GERD) and peptic ulcers—examines the improved efficacy, pharmacokinetics, decreased adverse effects, and fewer drug-drug interactions associated with single enantiomers.

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Eerdekens, G., N. Yassaa, V. Sinha, et al. "VOC measurements within a boreal forest during spring 2005: the role of monoterpenes and sulphuric acid in selected intense nucleation events." Atmospheric Chemistry and Physics Discussions 9, no. 3 (2009): 12781–827. http://dx.doi.org/10.5194/acpd-9-12781-2009.

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Abstract. In this study we present measurements of selected trace gases and aerosol made in a boreal forest during the BACCI-QUEST IV intensive field campaign in Hyytiälä, Finland in April 2005. Several clear aerosol "nucleation events" were observed and characterized. One type of "event" occurred synchronously with huge increases in monoterpenes, while a second event type correlated instead with sulphuric acid. Here we elucidate the origin of these two distinct forms of aerosol production at the Hyytiälä site using the measurement data, airmass back trajectories and the optical stereoisomery

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Golka, A., DC Craig, and MN Paddonrow. "Crystal Structure of a Bis(2,2'-bipyridine)ruthenium(II) Complex of a Dimethoxynaphthalene-Norbornyl-Pyridazine Ligand." Australian Journal of Chemistry 47, no. 1 (1994): 101. http://dx.doi.org/10.1071/ch9940101.

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The bis (2,2′-bipyridine)(6,11-dimethoxy-1,4-di(2′-pyridyl)-5,12-dihydro-5,12-methanonaphtho-[2,3-g] phthalazine )ruthenium(II) complex exists in two diastereomeric forms, (3a) and (3b). In order to make an unambiguous assignment of the configuration of each stereoisomer, a single-crystal X-ray structure of the hexafluorophosphate salt of the less soluble isomer (in methanol/acetone) was carried out. It was found that the structure of this material corresponded to (3a). Differences in he 1H n.m.r. spectra of (3a) and (3b) are discussed in light of their structures.

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Zhang, Chunyuan, Xu Wu, Yanfang Xian, Lin Zhu, Ge Lin, and Zhi-Xiu Lin. "Evidence on Integrating Pharmacokinetics to Find Truly Therapeutic Agent for Alzheimer’s Disease: Comparative Pharmacokinetics and Disposition Kinetics Profiles of Stereoisomers Isorhynchophylline and Rhynchophylline in Rats." Evidence-Based Complementary and Alternative Medicine 2019 (February 3, 2019): 1–9. http://dx.doi.org/10.1155/2019/4016323.

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Isorhynchophylline (IRN) and rhynchophylline (RN), a pair of stereoisomers, are tetracyclic oxindole alkaloids isolated from Uncaria rhynchophylla, a commonly used Chinese medicinal herb. These two compounds have drawn extensive attention due to their potent neuroprotective effects with promising therapeutic potential for the treatment of Alzheimer’s disease (AD). However, IRN and RN can interconvert into each other in vivo after oral administration. The present study aimed to elucidate the pharmacokinetic profiles and disposition kinetics of the administered and generated stereoisomers in the

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Negi, Devendra Singh, Nisha Negi, Ashok Kumar, Katsuyoshi Matsunami, Stefan Schulz, and Peter G. Jones. "(±)-Asarinin." Acta Crystallographica Section C Crystal Structure Communications 69, no. 1 (2012): 87–89. http://dx.doi.org/10.1107/s0108270112049657.

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Asarinin, C20H18O6, was isolated as a racemate from the shrubZanthoxylum alatum. Both forms of the enantiomerically pure substance, (+)- and (−)-asarinin, have been the subject of a total of five previous structure determinations that are essentially identical except for the absolute stereochemistry. However, there seems to be some confusion in the literature concerning these structure determinations of asarinin and also those of its stereoisomer sesamin. The molecular structure of racemic asarinin differs from that of the pure enantiomers in the orientation of one ring system. In the packing

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Langer, Vratislav, Knut Lundquist, and Jim Parkås. "The stereochemistry and conformation of lignin as judged by X-ray crystallographic investigations of lignin model compounds: Arylglycerol beta-guaiacyl ethers." BioResources 2, no. 4 (2007): 590–97. http://dx.doi.org/10.15376/biores.2.4.590-597.

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The conformations of a variety of crystalline lignin models representing different diastereomeric forms of structural elements in lignin of the arylglycerol b-guaiacyl ether type have been studied using X-ray crystallography. Based on X-ray crystallographic data, sequences of units attached to each other by b-guaiacyl ether linkages were constructed. The appearance of the resulting oligomers shows that stereoisomerism can be expected to influence the shape of the lignin molecules to a great extent. The constructed oligomers provide an idea about the contribution to the complexity of lignins by

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Šaman, David, Martina Wimmerová та Zdeněk Wimmer. "Synthesis and Structure Assignment of 2-(4-Methoxybenzyl)cyclohexyl β-D-Galactopyranoside Stereoisomers". Collection of Czechoslovak Chemical Communications 71, № 8 (2006): 1186–98. http://dx.doi.org/10.1135/cccc20061186.

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Several promoters were used in the Koenigs-Knorr synthesis of the title alkyl β-D-galactopyranosides, both in their diastereoisomeric forms (5a/5b and 6a/6b), resulting from the synthesis performed with the respective racemic cis and trans isomers of 2-(4-methoxybenzyl)cyclohexan-1-ol, and in their enantiomerically pure forms 5a and 6a, starting only from the (1S,2S)- and (1S,2R)-enantiomers of 2-(4-methoxybenzyl)cyclohexan-1-ol. The aim of the study was to find convenient modification(s) of the Koenigs-Knorr synthesis of alkyl β-D-galactopyranosides from more hindered and more complex 2-subst

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