Browsing by Author "Cassels, Bruce K."

Now showing 1 - 12 of 12
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    2-Arylthiomorpholine derivatives as potent and selective monoamine oxidase B inhibitors
    (2010) Luhr, Susan; Vilches-Herrera, Marcelo; Fierro Huerta, Angélica; Ramsay, Rona R.; Edmondson, Dale E.; Reyes-Parada, Miguel; Cassels, Bruce K.; Iturriaga-Vasquez, Patricio
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    5-HT2 Receptor Subfamily and the Halogen Bond Promise
    (2021) Fierro, Angelica; Matthies, Douglas J.; Cassels, Bruce K.; Jaque, Pablo; Zapata-Torres, Gerald
    The binding of C-4-halogenated 1-(4-X-2,5-dimethoxyphenyl)-2-aminopropane (DOX) serotonin agonist psychedelics at all three 5-HT2 receptor subtypes is up to two orders of magnitude stronger for X = Cl, Br, or I (but not F) than when C-4 bears a hydrogen atom and more than expected from their hydrophobicities. Our docking and molecular dynamics simulations agree with the fact that increasing the polarizability of halogens results in halogen-oxygen distances to specific backbone C=O groups, and C-X center dot center dot center dot O angles, in ranges expected for halogen bonds (XBs), which could contribute to the high affinities observed. Good linear correlations are found for each receptor type, indicating that the binding pocketl-igand affinity is enhanced as the XB interaction becomes stronger (i.e., I approximate to Br > Cl > F). It is also striking to note how the linear equations unveil that the receptor's response on the strength of the XB interaction is quite similar among 5-HT2A and 5-HT2C, whereas the 5-HT2B's sensitivity is less. The calculated dipole polarizabilities in the binding pocket of the receptors reflect the experimental affinity values, indicating that less-polarizable and harder binding sites are more prone to XB formation.
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    A selective fluorescent probe for the detection of mercury (II) in aqueous media and its applications in living cells
    (2012) Garcia-Beltran, Olimpo; Mena, Natalia; Berrios, Tania A.; Castro R., Enrique; Cassels, Bruce K.; Nuñez, Marco T.; Aliaga Miranda, Margarita Elly
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    Aporphine metho salts as neuronal nicotinic acetylcholine receptor blockers
    (2007) Iturriaga-Vasquez, Patricio; Pérez Hernández, Edwin Gregorio; Slater, E. Yvonne; Bermudez, Isabel; Cassels, Bruce K.
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    Coumarin-Based Fluorescent Probes for Dual Recognition of Copper(II) and Iron(III) Ions and Their Application in Bio-Imaging
    (2014) Martínez Ahumada, Natalia del Pilar; Pavez Guerrero, Paulina Isabel; Aliaga Miranda, Margarita Elly; García Beltrán, Olimpo; Cassels, Bruce K.; Pérez, Claudio; Mena, Natalia; Núñez, Marcos T.
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    Cytisine: a natural product lead for the development of drugs acting at nicotinic acetylcholine receptors
    (2012) Pérez Hernández, Edwin Gregorio; Mendez-Galvez, Carolina; Cassels, Bruce K.
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    Human and rat monoamine oxidase-A are differentially inhibited by (S)-4-alkylthioamphetamine derivatives: Insights from molecular modeling studies
    (2007) Fierro Huerta, Angélica; Osorio-Olivares, Mauricio; Cassels, Bruce K.; Edmondson, Dale E.; Sepulveda-Boza, Silvia; Reyes-Parada, Miguel
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    Phytochemical variation of wild and farmed populations of boldo (Peumus boldus Molina)
    (2023) Fuentes-Barros, Gonzalo; Echeverria, Javier; Mattar, Cesar; Liberona, Leonel; Giordano, Ady; Suarez-Rozas, Cristian; Salas-Norambuena, Julio; Gonzalez-Cooper, Antonia; Cassels, Bruce K.; Castro-Saavedra, Sebastian
    The phytochemical profile of six wild and one cultivated Peumus boldus (boldo) populations from different regions of north-central, central and south-central Chile was studied. In leaves, wood, and bark, alkaloids and phenolics were analyzed by UHPLC-MS-MS and leaf essential oils by GC-MS. In each population, compounds were found to exhibit high variability, but important differences were recorded at the population level. The north-central wild populations showed higher concentrations of alkaloids and polyphenols in leaves and alkaloids in the bark compared to more southern populations. Saplings farmed under different shade conditions contained higher species-characteristic leaf polyphenolic concentrations with increasing light while most alkaloids increased with the shade. When analyzed the following year, higenamine, boldine, isocorydine and Nmethyllaurotetanine increased. The principal components of the leaf essential oils from the wild populations were p-cymene, ascaridole and 1,8-cineole, while in the farmed trees ascaridole was replaced by its precursor & alpha;-terpinene as the second most abundant constituent. Although multiple factors may affect the concentration of secondary metabolites and geographic provenances with its attending differences in sunlight and rainfall has been suggested as one of these, the present work shows that latitude by itself cannot explain differences that have a clear impact on quality from the medicinal standpoint.
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    Synthesis of N-Arylcytisine Derivatives Using the Copper-Catalyzed Chan-Lam Coupling
    (2021) Sanchez-Velasco, Oriel A.; Saavedra-Olavarria, Jorge; Araya-Santelices, Daniel A. A.; Hermosilla-Ibanez, Patricio; Cassels, Bruce K.; Perez, Edwin G.
    N-Arylcytisine derivatives are quite rare. We report here a practical methodology to obtain these compounds. Using the copper-catalyzed Chan-Lam coupling, we synthesized new N-arylcytisine derivatives at room temperature, in air and using inexpensive phenylboronic acids. Cytisine and 3,5-dihalocytisines can act as substrates, and among the products, the p-Br-derivative 2r was used as a substrate to obtain biaryl derivatives under Pd-coupling conditions; ester 2j was converted into its acid and amide derivatives using classical carbodiimide conditions. This shows that the Chan-Lam cross-coupling reaction can be included as a versatile synthetic tool in the derivatization of natural products.
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    The development of a fluorescence turn-on sensor for cysteine, glutathione and other biothiols. A kinetic study
    (2011) García Beltrán, Olimpo; Mena, Natalia; Pérez Hernández, Edwin Gregorio; Cassels, Bruce K.; Núñez, Marco T; Werlinger, Francisca; Zavala, Daniel; Aliaga Miranda, Margarita Elly; Pavez Guerrero, Paulina Isabel
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    Topical anti-inflammatory activity of 2α-hydroxy pentacyclic triterpene acids from the leaves of Ugni molinae
    (2006) Aguirre, Maria C.; Delporte, Carla; Backhouse, Nadine; Erazo, Silvia; Letelier, Maria Eugenia; Cassels, Bruce K.; Silva, Ximena; Alegria, Sergio; Negrete, Rosa
    Leaf extracts of Ugni molinae Turcz. are used in the Chilean cosmetic industry on the assumption that they have decongestant, regenerative, and anti-aging properties. A bioassay-guided fractionation of this plant material showed that some extracts have potent anti-inflammatory activities. Further fractionation led to the isolation and identification of betulinic acid, a mixture of ursolic and oleanolic acids, and the 2 alpha-hydroxy derivatives alphitolic, asiatic, and corosolic acids. The latter three were evaluated in vivo in the mouse ear assay for their topical anti-inflammatory activity, inducing inflammation with either arachidonic acid (AA) or 12-O-tetradecanoylphorbol-13 acetate (TPA). Only corosolic acid was active in the AA assay, with similar potency to nimesulide, but all three triterpene acids inhibited TPA-induced inflammation with potencies comparable to that of indomethacin. (c) 2006 Elsevier Ltd. All rights reserved.
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    Variation of the alkaloid content of Peumus boldus (boldo)
    (2018) Fuentes-Barros, Gonzalo; Castro-Saavedra, Sebastian; Liberona, Leonel; Acevedo-Fuentes, Williams; Tirapegui, Cristian; Mattar, Cesar; Cassels, Bruce K.