Prevalence of joint pain and osteoarthritis in obese brazilian population

sem informaçãoHigh body mass index, as well as maintaining this condition for a long period of time, are important risk factors for the development of osteoarthritis. Aim: To determine joint pain and osteoarthritis prevalence in patients referred to bariatric surgery311E1344E1344sem informaçãosem informaçãosem informaçã

Relationship between nitrogen sources, germination and vigor of soybean seeds

This research was conducted in two experimental areas; the first had been under cultivation with Bradyrhizobium japonicum anually inoculated for several years and the second was cultivated with sugarcane for many years receiving only mineral fertilization. Mineral nitrogen (urea and ammonium) effect was compared with the effects of inoculant treatments (liquid and peat carriers) on plant development, yield and seed quality. After harvesting, seeds were stored under normal environmental conditions and tested periodically. Germination, accelerated aging, electrical conductivity and seedling emergence tests showed that seeds coming from the area where inoculation was practiced have better quality. Best plant performance regarding plant height at different growth stages and yield was also found in this area. Among the nitrogen sources studied, best results were obtained when peat was the inoculant carrier.A pesquisa foi conduzida em duas áreas experimentais do Departamento de Agricultura, ESALQ/USP. A primeira, cultivada com soja anualmente inoculada com Bradyrhizobium japonicum, durante vários anos e, a segunda, anteriormente cultivada com cana-de-açúcar, recebendo apenas adubação mineral. Os efeitos da aplicação de uréia e de sulfato de amonio foram comparados com os da inoculação de sementes, utilizando-se, produtos veiculados em turfa ou em meio líquido; avaliaram-se o desenvolvimento das plantas, a produção final e a qualidade das sementes (testes de germinação e de vigor) logo após a colheita e durante o armazenamento. Os resultados permitiram constatar o melhor desempenho fisiológico das sementes produzidas em área anteriormente cultivada com soja, o mesmo ocorrendo com o desenvolvimento inicial das plantas. Dentre as fontes de nitrogênio avaliadas, a utilização de inoculante veiculado em turfa se mostrou mais favorável

Early menarche and teenager pregnancy as risk factors for morbid obesity among reproductive-age women: a case-control study

sem informaçãoThe aim of this study was to evaluate potential risk factors, including non-communicable diseases, for morbid obesity in women between 20 and 49 years of age. We performed a case-control study with 110 morbidly obese women and 110 women with adequate wei729547553sem informaçãosem informaçãosem informaçã

Photoacoustic Monitoring Of Magnetite-crystal Formation From Iron(iii) Hydroxide Acetate: Comparison With Esr Results

The formation of crystalline magnetite by 1-h heat treatment of iron(III) hydroxide acetate is described. This amorphous-crystalline solid transformation is monitored by electron-spin resonance and photoacoustic spectroscopies. No significant changes were detected for samples heated below 190 °C. Above this temperature both techniques presented results following a definite pattern, namely, the enhancement of ion mobility leading to particle growth and crystallization for a temperature up to 240 °C and the onset of magnetic ordering of magnetite near this temperature.65125150515

Role of association in chiral catalysis: from asymmetric synthesis to spin selectivity

"This is the peer reviewed version of the following article: Ageeva, Aleksandra A., Ekaterina A. Khramtsova, Ilya M. Magin, Peter A. Purtov, Miguel A. Miranda, and Tatyana V. Leshina. 2018. Role of Association in Chiral Catalysis: From Asymmetric Synthesis to Spin Selectivity. Chemistry A European Journal 24 (70). Wiley: 18587 600. doi:10.1002/chem.201801625, which has been published in final form at https://doi.org/10.1002/chem.201801625. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] The origin of biomolecules in the pre-biological period is still a matter of debate, as is the unclarified nature of the differences in enantiomer properties, especially for the medically important activity of chiral drugs. With regards to the first issue, significant progress was made in the last decade of the 20th century through experimental confirmation of Frank's popular theory on chiral catalysis in spontaneous asymmetric synthesis. Soai examined the chiral catalysis of the alkylation of achiral aldehydes by achiral reagents. Attempts to model this process demonstrated the key role of chiral compounds associates as templates for chiral synthesis. However, the elementary mechanism of alkylation and the role of free radicals in this process are still incompletely understood. Meanwhile, the influence of external magnetic fields on chiral enrichment in the radical path of alkylation has been predicted. In addition, the role of chiral dyad association in another radical process, electron transfer (ET), has been recently demonstrated by the following methods: chemically induced dynamic nuclear polarisation (CIDNP), NMR spectroscopy, XRD and photochemistry. The CIDNP analysis of ET in two dyads has revealed a phenomenon first observed for chiral systems, spin selectivity, which results in the difference between the CIDNP enhancement coefficients of dyad diastereomers. These dyads are linked systems consisting of the widespread drug (S)-naproxen (NPX) or its R analogue and electron donors, namely, (S)-tryptophan and (S)-N-methylpyrrolidine. Because NPX is one of the most striking examples of the difference in the therapeutic properties of enantiomers, the appearance of spin selectivity in dyads with (S)- and (R)-NPX and S donors can shed light on the chemical nature of these differences. This review is devoted to discussing the chemical nature of spin selectivity and the role of chiral associates in the chiral catalysis of an elementary radical reaction: ET in chiral dyads.The work was supported by the Russian Science Foundation (18-13-00047).Ageeva, A.; Khramtsova, E.; Magin, I.; Purtov, P.; Miranda Alonso, MÁ.; Leshina, T. (2018). Role of association in chiral catalysis: from asymmetric synthesis to spin selectivity. Chemistry - A European Journal. 24(70):18587-18600. https://doi.org/10.1002/chem.201801625S18587186002470Avalos, M., Babiano, R., Cintas, P., Jiménez, J. L., Palacios, J. C., & Barron, L. D. (1998). Absolute Asymmetric Synthesis under Physical Fields:  Facts and Fictions. Chemical Reviews, 98(7), 2391-2404. doi:10.1021/cr970096oLin, G.-Q., Zhang, J.-G., & Cheng, J.-F. (2011). Overview of Chirality and Chiral Drugs. Chiral Drugs, 3-28. doi:10.1002/9781118075647.ch1Liu, Y., & Gu, X.-H. (2011). Pharmacology of Chiral Drugs. Chiral Drugs, 323-345. doi:10.1002/9781118075647.ch8Frank, F. C. (1953). On spontaneous asymmetric synthesis. Biochimica et Biophysica Acta, 11, 459-463. doi:10.1016/0006-3002(53)90082-1Soai, K., Kawasaki, T., & Matsumoto, A. (2014). Asymmetric Autocatalysis of Pyrimidyl Alkanol and Its Application to the Study on the Origin of Homochirality. Accounts of Chemical Research, 47(12), 3643-3654. doi:10.1021/ar5003208Soai, K., Kawasaki, T., & Matsumoto, A. (2014). The Origins of Homochirality Examined by Using Asymmetric Autocatalysis. The Chemical Record, 14(1), 70-83. doi:10.1002/tcr.201300028Soai, K., Matsumoto, A., & Kawasaki, T. (2017). Asymmetric Autocatalysis and the Origins of Homochirality of Organic Compounds. An Overview. Advances in Asymmetric Autocatalysis and Related Topics, 1-30. doi:10.1016/b978-0-12-812824-4.00001-0Matsumoto, A., Kawasaki, T., & Soai, K. (2017). Structural Study of Asymmetric Autocatalysis by X-Ray Crystallography. Advances in Asymmetric Autocatalysis and Related Topics, 183-202. doi:10.1016/b978-0-12-812824-4.00010-1Schiaffino, L., & Ercolani, G. (2010). Mechanism of the Asymmetric Autocatalytic Soai Reaction Studied by Density Functional Theory. Chemistry - A European Journal, 16(10), 3147-3156. doi:10.1002/chem.200902543Buono, F. G., & Blackmond, D. G. (2003). Kinetic Evidence for a Tetrameric Transition State in the Asymmetric Autocatalytic Alkylation of Pyrimidyl Aldehydes†. Journal of the American Chemical Society, 125(30), 8978-8979. doi:10.1021/ja034705nGridnev, I. D., & Vorobiev, A. K. (2012). Quantification of Sophisticated Equilibria in the Reaction Pool and Amplifying Catalytic Cycle of the Soai Reaction. ACS Catalysis, 2(10), 2137-2149. doi:10.1021/cs300497hGridnev, I. D., Serafimov, J. M., & Brown, J. M. (2004). Solution Structure and Reagent Binding of the Zinc Alkoxide Catalyst in the Soai Asymmetric Autocatalytic Reaction. Angewandte Chemie International Edition, 43(37), 4884-4887. doi:10.1002/anie.200353572Gridnev, I. D., Serafimov, J. M., & Brown, J. M. (2004). Solution Structure and Reagent Binding of the Zinc Alkoxide Catalyst in the Soai Asymmetric Autocatalytic Reaction. Angewandte Chemie, 116(37), 4992-4995. doi:10.1002/ange.200353572Noble-Terán, M. E., Cruz, J.-M., Micheau, J.-C., & Buhse, T. (2018). A Quantification of the Soai Reaction. ChemCatChem, 10(3), 642-648. doi:10.1002/cctc.201701554Girard, C., & Kagan, H. B. (1998). Nonlinear Effects in Asymmetric Synthesis and Stereoselective Reactions: Ten Years of Investigation. Angewandte Chemie International Edition, 37(21), 2922-2959. doi:10.1002/(sici)1521-3773(19981116)37:213.0.co;2-1Girard, C., & Kagan, H. B. (1998). Nichtlineare Effekte bei asymmetrischen Synthesen und stereoselektiven Reaktionen. Angewandte Chemie, 110(21), 3088-3127. doi:10.1002/(sici)1521-3757(19981102)110:213.0.co;2-aNoble-Terán, M. E., Buhse, T., Cruz, J.-M., Coudret, C., & Micheau, J.-C. (2016). Nonlinear Effects in Asymmetric Synthesis: A Practical Tool for the Discrimination between Monomer and Dimer Catalysis. ChemCatChem, 8(10), 1836-1845. doi:10.1002/cctc.201600216Blackmond, D. G. (2000). Kinetic Aspects of Nonlinear Effects in Asymmetric Catalysis. Accounts of Chemical Research, 33(6), 402-411. doi:10.1021/ar990083sMatsumoto, A., Abe, T., Hara, A., Tobita, T., Sasagawa, T., Kawasaki, T., & Soai, K. (2015). Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess. Angewandte Chemie International Edition, 54(50), 15218-15221. doi:10.1002/anie.201508036Matsumoto, A., Abe, T., Hara, A., Tobita, T., Sasagawa, T., Kawasaki, T., & Soai, K. (2015). Crystal Structure of the Isopropylzinc Alkoxide of Pyrimidyl Alkanol: Mechanistic Insights for Asymmetric Autocatalysis with Amplification of Enantiomeric Excess. Angewandte Chemie, 127(50), 15433-15436. doi:10.1002/ange.201508036Ashby, E. C., Lopp, I. G., & Buhler, J. D. (1975). Mechanisms of Grignard reactions with ketones. Polar vs. single electron transfer pathways. Journal of the American Chemical Society, 97(7), 1964-1966. doi:10.1021/ja00840a066Ashby, E. C. (1988). Single-electron transfer, a major reaction pathway in organic chemistry. An answer to recent criticisms. Accounts of Chemical Research, 21(11), 414-421. doi:10.1021/ar00155a005Hegstrom, R. A., & Kondepudi, D. K. (1996). Influence of static magnetic fields on chirally autocatalytic radical-pair reactions. Chemical Physics Letters, 253(3-4), 322-326. doi:10.1016/0009-2614(96)00248-5K. M. Salikhov Yu. N. Molin R. Z. Sagdeev A. L. Buchachenko Spin Polarization and Magnetic Effects in Radical Reactions 1984 Akademiai Kiado Budapest Hungary 65 72Welch, C. J., Zawatzky, K., Makarov, A. A., Fujiwara, S., Matsumoto, A., & Soai, K. (2017). Can the analyte-triggered asymmetric autocatalytic Soai reaction serve as a universal analytical tool for measuring enantiopurity and assigning absolute configuration? Organic & Biomolecular Chemistry, 15(1), 96-101. doi:10.1039/c6ob01939kAgeeva, A. A., Khramtsova, E. A., Magin, I. M., Rychkov, D. A., Purtov, P. A., Miranda, M. A., & Leshina, T. V. (2018). Spin Selectivity in Chiral Linked Systems. Chemistry - A European Journal, 24(15), 3882-3892. doi:10.1002/chem.201705863Khramtsova, E. A., Sosnovsky, D. V., Ageeva, A. A., Nuin, E., Marin, M. L., Purtov, P. A., … Leshina, T. V. (2016). Impact of chirality on the photoinduced charge transfer in linked systems containing naproxen enantiomers. Physical Chemistry Chemical Physics, 18(18), 12733-12741. doi:10.1039/c5cp07305gKhramtsova, E. A., Ageeva, A. A., Stepanov, A. A., Plyusnin, V. F., & Leshina, T. V. (2017). Photoinduced Electron Transfer in Dyads with (R)-/(S)-Naproxen and (S)-Tryptophan. Zeitschrift für Physikalische Chemie, 231(3). doi:10.1515/zpch-2016-0842Magin, I. M., Polyakov, N. E., Kruppa, A. I., Purtov, P. A., Leshina, T. V., Kiryutin, A. S., … Marin, M. L. (2016). Low field photo-CIDNP in the intramolecular electron transfer of naproxen–pyrrolidine dyads. Physical Chemistry Chemical Physics, 18(2), 901-907. doi:10.1039/c5cp04233jDuggan, K. C., Hermanson, D. J., Musee, J., Prusakiewicz, J. J., Scheib, J. L., Carter, B. D., … Marnett, L. J. (2011). (R)-Profens are substrate-selective inhibitors of endocannabinoid oxygenation by COX-2. Nature Chemical Biology, 7(11), 803-809. doi:10.1038/nchembio.663Duggan, K. C., Walters, M. J., Musee, J., Harp, J. M., Kiefer, J. R., Oates, J. A., & Marnett, L. J. (2010). Molecular Basis for Cyclooxygenase Inhibition by the Non-steroidal Anti-inflammatory Drug Naproxen. Journal of Biological Chemistry, 285(45), 34950-34959. doi:10.1074/jbc.m110.162982Miners, J. O., Coulter, S., Tukey, R. H., Veronese, M. E., & Birkett, D. J. (1996). Cytochromes P450, 1A2, and 2C9 are responsible for the human hepatic O-demethylation of R- and S-naproxen. Biochemical Pharmacology, 51(8), 1003-1008. doi:10.1016/0006-2952(96)85085-4Levkin, P. A., Kokorin, A. I., Schurig, V., & Kostyanovsky, R. G. (2006). Solid-state ESR differentiation between racemate versus enantiomer. Chirality, 18(4), 232-238. doi:10.1002/chir.20242Khlestkin, V. K., Glasachev, Y. I., Kokorin, A. I., & Kostyanovsky, R. G. (2004). ESR study of stereochemistry in chiral nitroxide radical crystals. Mendeleev Communications, 14(6), 318-320. doi:10.1070/mc2004v014n06abeh002055Mäurer, M., & Stegmann, H. B. (1990). Chiral recognition of diastereomeric esters and acetals by EPR and NMR investigations. Chemische Berichte, 123(8), 1679-1685. doi:10.1002/cber.19901230817Kreilick, R. W., Becher, J., & Ullman, E. F. (1969). Stable free radicals. V. Electron spin resonance studies of nitronylnitroxide radicals with asymmetric centers. Journal of the American Chemical Society, 91(18), 5121-5124. doi:10.1021/ja01046a032Schuler, P., Schaber, F.-M., Stegmann, H. B., & Janzen, E. (1999). Recognition of chirality in nitroxides using EPR and ENDOR spectroscopy. Magnetic Resonance in Chemistry, 37(11), 805-813. doi:10.1002/(sici)1097-458x(199911)37:113.0.co;2-kNaaman, R., & Waldeck, D. H. (2012). Chiral-Induced Spin Selectivity Effect. The Journal of Physical Chemistry Letters, 3(16), 2178-2187. doi:10.1021/jz300793yYin, P., Zhang, Z.-M., Lv, H., Li, T., Haso, F., Hu, L., … Liu, T. (2015). Chiral recognition and selection during the self-assembly process of protein-mimic macroanions. Nature Communications, 6(1). doi:10.1038/ncomms7475Ishida, Y., & Aida, T. (2002). Homochiral Supramolecular Polymerization of an «S»-Shaped Chiral Monomer:  Translation of Optical Purity into Molecular Weight Distribution. Journal of the American Chemical Society, 124(47), 14017-14019. doi:10.1021/ja028403hSato, K., Itoh, Y., & Aida, T. (2014). Homochiral supramolecular polymerization of bowl-shaped chiral macrocycles in solution. Chem. Sci., 5(1), 136-140. doi:10.1039/c3sc52449cDubinets, N. O., Safonov, A. A., & Bagaturyants, A. A. (2016). Structures and Binding Energies of the Naphthalene Dimer in Its Ground and Excited States. The Journal of Physical Chemistry A, 120(17), 2779-2782. doi:10.1021/acs.jpca.6b03761‘Excimer’ fluorescence VII. Spectral studies of naphthalene and its derivatives. (1965). Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 284(1399), 551-565. doi:10.1098/rspa.1965.0080Jiménez, M. C., Pischel, U., & Miranda, M. A. (2007). Photoinduced processes in naproxen-based chiral dyads. Journal of Photochemistry and Photobiology C: Photochemistry Reviews, 8(3), 128-142. doi:10.1016/j.jphotochemrev.2007.10.001Kerr, H. E., Softley, L. K., Suresh, K., Hodgkinson, P., & Evans, I. R. (2017). Structure and physicochemical characterization of a naproxen–picolinamide cocrystal. Acta Crystallographica Section C Structural Chemistry, 73(3), 168-175. doi:10.1107/s2053229616011980Hatton, J. V., & Richards, R. E. (1962). Solvent effects in N.M.R. spectra of amide solutions. Molecular Physics, 5(2), 139-152. doi:10.1080/00268976200100141Muñoz, M. ., Ferrero, R., Carmona, C., & Balón, M. (2004). Hydrogen bonding interactions between indole and benzenoid-π-bases. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 60(1-2), 193-200. doi:10.1016/s1386-1425(03)00206-3Mäurer, M., Stegmann, H. B., Hiller, W., & Müller, B. (1992). Stereoelectronic and Steric Effects in the Synthesis and Recognition of Diastereomeric Ethers by NMR and EPR Spectroscopy. Chemische Berichte, 125(4), 857-865. doi:10.1002/cber.1992125041

How do practically trained (student) caregivers in nursing homes learn?:A scoping review

Background and objective: Practically trained (student) caregivers (further: caregivers) make up the majority of care staff in nursing homes (NHs). To keep up with the fast-changing healthcare environment and ensure a high quality of care, it is important to know how to stimulate continuous work-based learning (WBL) among this group. The purpose of the study was to systematically study the scientific literature published to date on (1) how caregivers learn in NHs and (2) what facilitates or impedes their learning. Methods: A scoping review was carried out, systematically searching six scientific databases. A total of 35 studies published from January 2009 to February 2021 were included. Study characteristics, learning mechanisms, facilitators, and barriers to learning were extracted and synthesized. Results: None of the studies specifically focused on how caregivers learn. Yet, we identified various learning mechanisms, and found that learning by theory or supervision was most frequently engaged in. Most learning mechanisms used among the groups in the included studies were planned and formal and developed and initiated by others out of the context. Three main themes were identified among the facilitators and barriers of WBL: individual learning, collective learning, and resources for learning. An interdependency between (sub)themes was found. Conclusions: The way caregivers in NHs learn is understudied. Moreover, both their informal learning and the support they receive to be(come) active learners has been overlooked. As WBL provides caregivers with opportunities to learn within a real-life setting, we suggest more research on informal learning mechanisms

Large-scale Production And Purification Of Recombinant Protein From An Insect Cell/baculovirus System In Erlenmeyer Flasks: Application To The Chicken Poly(adp-ribose) Polymerase Catalytic Domain

A simple and inexpensive shaker/Erlenmeyer flask system for large-scale cultivation of insect cells is described and compared to a commercial spinner system. On the basis of maximum cell density, average population doubling time and overproduction of recombinant protein, a better result was obtained with a simpler and less expensive bioreactor consisting of Erlenmeyer flasks and an ordinary shaker waterbath. Routinely, about 90 mg of pure poly(ADP-ribose) polymerase catalytic domain was obtained for a total of 3 × 109 infected cells in three liters of culture.308923928Althaus, F.R., Richter, C., ADP-ribosylation of proteins. Enzymology and biological significance (1987) Molecular Biology, Biochemistry and Biophysics, 37, pp. 1-126Lautier, D., Lagueaux, J., Ménard, L., Poirier, G.C., Molecular and biochemical features of poly(ADP-ribose) metabolism (1993) Molecular and Cellular Biochemistry, 122, pp. 171-193Satoh, M.S., Lindahl, T., Role of poly(ADP-ribose) formation in DNA repair (1992) Nature, 356, pp. 356-358Molinete, M., Vermeulen, W., Bürkle, A., Ménissier-de Murcia, J., Küpper, J., Hoeijmakers, J., De Murcia, G., Overproduction of the poly(ADP-ribose) polymerase DNA-binding domain blocks alkylation-induced DNA repair synthesis in mammalian cells (1993) EMBO Journal, 5, pp. 2109-2117Masson, M., Rolli, V., Dantzer, F., Trucco, C., Schrieber, V., Fribourg, S., Molinete, M., De Murcia, G., Poly(ADP-ribose) polymerase: Structure-function relationship (1995) Biochimie, 77, pp. 456-461Suto, M.L., Suto, M.S., Inhibitors of poly(ADP-ribose) polymerase (ADPRP): Potential chemotherapeutic agents (1991) Drugs of the Future, 16, pp. 723-739Giner, H., Simonin, F., De Murcia, G., Ménissier-de Murcia, J., Overproduction and large-scale purification of the human poly(ADP-ribose) polymerase using a baculovirus expression system (1992) Gene, 114, pp. 279-283Simonin, F., Höfferer, L., Panzeter, P., Muller, S., De Murcia, G., Althaus, F.R., The carboxy-terminal domain of human poly(ADP-ribose) polymerase: Overproduction in Escherichia coli, large scale purification and characterization (1993) Journal of Molecular Biology, 268, pp. 13454-13461Murhammer, D.W., Review and patents literature. The use of insect cell cultures for recombinant protein synthesis: Engineering aspects (1991) Applied Biochemistry and Biotechnology, 31, pp. 283-310Goosen, M.F.A., Large-scale insect cell culture (1992) Current Opinion in Biotechnology, 3, pp. 99-104Kamen, A.A., Tom, R.L., Caron, A.W., Chavarie, C., Massie, B., Archambault, J., Culture of insect cells in a helical ribbon impeller bioreactor (1991) Biotechnology and Bioengineering, 38, pp. 619-628Van Lier, F.L.J., Van Den End, E.J., Gooijer, C.D., Vlak, J.M., Tramper, J., Continuous production of baculovirus in a cascade insect-cell reactor (1990) Applied Microbiology and Biotechnology, 33, pp. 43-47Power, J., Greenfield, P.F., Nielsen, L., Reid, S., Modelling the growth and protein production by insect cells following infection by a recombinant baculovirus in suspension culture (1992) Cytotechnology, 9, pp. 149-155Stavroulakis, D.A., Kalogerakis, N., Behie, L.A., Latrou, K., Kinetic data for the BM-5 insect line in repeated-batch suspension culture (1991) Biotechnology, 38, pp. 116-126Neutra, R., Levi, B.-Z., Shoham, Y., Optimization of protein-production by the baculovirus expression vector system in shake flasks (1992) Applied Microbiology and Biotechnology, 37, pp. 74-78Luckow, V.A., Summers, M.D., Signals important for high level expression of foreign genes in Autographa californica nuclear polyhedrosis virus expression vectors (1989) Virology, 170, pp. 31-39O'Reily, D.R., Miller, L.K., Luckow, V.A., (1992) Baculovirus Expression System: A Laboratory Manual, , Freeman, New YorkScott, R.L., Blanchard, J.H., Fergusson, C.H.R., Effects of oxygen on recombinant protein production by suspension cultures of Spodoptera frugiperda Sf9 insect cell (1992) Enzyme and Microbial Technology, 14, pp. 798-80

Impact of chirality on the photoinduced charge transfer in linked systems containing naproxen enantiomers

[EN] The model reaction of photoinduced donor-acceptor interaction in linked systems (dyads) has been used to study the comparative reactivity of a well-known anti-inflammatory drug, (S)-naproxen (NPX) and its (R)-isomer. (R)- or (S)-NPX in these dyads is linked to (S)-N-methylpyrrolidine (Pyr) using a linear or cyclic amino acid bridge (AA or CyAA), to give (R)-/(S)-NPX-AA-(S)-Pyr flexible and (R)-/(S)-NPX-CyAA-(S)-Pyr rigid dyads. The donor-acceptor interaction is reminiscent of the binding (partial charge transfer, CT) and electron transfer (ET) processes involved in the extensively studied inhibition of the cyclooxygenase enzymes (COXs) by the NPX enantiomers. Besides that, both optical isomers undergo oxidative metabolism by enzymes from the P450 family, which also includes ET. The scheme proposed for the excitation quenching of the (R)- and (S)-NPX excited state in these dyads is based on the joint analysis of the chemically induced dynamic nuclear polarization (CIDNP) and fluorescence data. The H-1 CIDNP effects in this system appear in the back electron transfer in the biradical-zwitterion (BZ), which is formed via dyad photoirradiation. The rate constants of individual steps in the proposed scheme and the fluorescence quantum yields of the local excited (LE) states and exciplexes show stereoselectivity. It depends on the bridge's length, structure and solvent polarity. The CIDNP effects (experimental and calculated) also demonstrate stereodifferentiation. The exciplex quantum yields and the rates of formation are larger for the dyads containing (R)-NPX, which let us suggest a higher contribution from the CT processes with the (R)-optical isomer.The work was supported by the Russian Foundation for Fundamental Research (14-03-00192, 14-03-00692). All QS calculations were carried out on a cluster computer in the regional center for shared computer equipment at the Ufa Institute of Chemistry of RAS.Khramtsova, E.; Sosnovsky, D.; Ageeva, A.; Nuin Plá, NE.; Marín García, ML.; Purtov, P.; Borisevich, S.... (2016). Impact of chirality on the photoinduced charge transfer in linked systems containing naproxen enantiomers. Physical Chemistry Chemical Physics. 18(18):12733-12741. https://doi.org/10.1039/C5CP07305GS1273312741181

Spin effects in intramolecular electron transfer in naproxen-N-methylpyrrolidine dyad

[EN] The intramolecular electron transfer in the naproxen-N-methylpyrrolidine dyad has been investigated by spin chemistry methods. The existence of CIDNP in a high magnetic field points to electron transfer as a possible mechanism of the quenching of the excited state of a dyad. However, the failure to detect magnetic field effects on triplet yield makes us conclude that this quenching mechanism is not the only one. The observation of CIDNP effects in the dyad in the media of low polarity and the short risetime of triplet state formation indicate a potential role of exciplex in the quenching of the excited state of the dyad.This work was supported by the Grants 08-03-00372 and 11-03-01104 of Russian Foundation of Basic Research, and the grant of Priority Programs of RAS, No. 5.1.5.Magin, I.; Polyakov, N.; Khramtsova, E.; Kruppa, A.; Tsentalovich, Y.; Leshina, T.; Miranda Alonso, MÁ.... (2011). Spin effects in intramolecular electron transfer in naproxen-N-methylpyrrolidine dyad. Chemical Physics Letters. 516(1-3):51-55. https://doi.org/10.1016/j.cplett.2011.09.057S51555161-