Bruce K. Cassels - Academia.edu (original) (raw)
Papers by Bruce K. Cassels
ChemInform, Jan 6, 2004
For Abstract see ChemInform Abstract in Full Text.
Pacific Science, Apr 1, 2000
The Alkaloids, 1989
Publisher Summary This chapter reviews the azafluorenone alkaloids as completely as possible, dis... more Publisher Summary This chapter reviews the azafluorenone alkaloids as completely as possible, discusses a small number of structurally unusual though not unprecedented compounds, and also updates the older contributions on the mainline isoquinoline alkaloids insofar as the genus Guatteria is concerned. Guutteriu alkaloids can be classified into eight main types depending on the structural characteristics of their skeleton, and these eight skeletal types are biosynthetically related, or at least conceivable proposals for their formation in vivo are reported. Aporphinoids are by far the most abundant alkaloids in this genus and also, generally speaking, in the family Annonaceae. Guatteria has proved to be a rich source of unusual structures of this general type. Dehydronornuciferine and O-methyldehydroisopiline are isolated from G. ouregou, where they cooccur with the corresponding noraporphines, and the N-formyl derivatives dehydroformouregine and formouregine.
Revista chilena de neuro-psiquiatría, Nov 1, 2003
La enfermedad de Alzheimer constituye un desafio terapeutico de primera magnitud que ha respondid... more La enfermedad de Alzheimer constituye un desafio terapeutico de primera magnitud que ha respondido de manera muy poco satisfactoria a los tratamientos actuales. Avances en el conocimiento de los procesos que estan asociados con la patogenesis y el curso de esta enfermedad permiten proponer nuevos enfoques terapeuticos, algunos de los cuales se encuentran en etapas de experimentacion clinica mientras otros todavia son objeto de investigaciones basicas
Chemischer Informationsdienst, Oct 29, 1974
Contribuciones científicas y tecnológicas, 1970
RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de... more RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de Chile conocido por los nombre de pelú y pilo. pilo, que se asemeja mucho desde el punto de vista morfológico a las especies neozelandesas S. tetraptera J. Mill. Y S. microphylla Ait. Un estudio preliminar de los alcaloides de las semillas de esta planta chilena permitió aislar citisina, metilcitisina y matrina en proporciones que apoyan la separación taxonómica del pelú de las especies nativas de Nueva Zelandia. SUMMARY-Sophora tetraptera, sensu R,eiche, is the scientific name assigned to a southem Chilean tree known by the names pelú and pilopilo, which closely resembles the N ew Zealand species S. tetraptera J. Mill. and S. microphylla Ait. from a morphological viewpoint. A preliminalj' study of the seed alkaloids of this Chilean plant yielded cytisine, methylcytisine, and matrine in a ratio which supports the taxonomic segregation of the pelú from the species native to New Zealand.
New Journal of Chemistry, 2021
DFT calculations were performed on nine flavones and flavonols to explain their high antioxidant ... more DFT calculations were performed on nine flavones and flavonols to explain their high antioxidant activity and variations in their activity. Conformational analysis showed that only flavonols with 3-OH directed toward the Bring are nonplanar; however, flavones and resulted radicals are planar. Hydroxyl group eligible for dissociation is the one with ortho OH directed toward it; otherwise, one of Bring (in 2′ or 4′-position) hydroxyl group. There are two main factors responsible for stabilizing the resulted radicals and lowering the bond dissociation energy and hence there were found well correlated with the experimental activity. First, driving force resulted from the conversion of nonplanar flavonols to planar radicals accompanied by resonance toward the carbonyl group and H-bond formation with 3-OH and second, radical stabilization by H-bond with ortho hydroxyl group with resonance toward carbonyl or pyrone oxygen. All resonance and H-bonds were confirmed by spin density, bond length, and molecular orbital calculations.
Addiction Biology, May 29, 2015
Ethanol is oxidized in the brain to acetaldehyde, which can condense with dopamine to generate (R... more Ethanol is oxidized in the brain to acetaldehyde, which can condense with dopamine to generate (R/S)-salsolinol [(RS)-SAL]. Racemic salsolinol [(RS)-SAL] is self-infused by rats into the posterior ventral tegmental area (VTA) at significantly lower concentrations than those of acetaldehyde, suggesting that (RS)-SAL is a most active product of ethanol metabolism. Early studies showed that repeated intraperitoneal or intra-VTA administration of (RS)-SAL (10 mg/kg) induced conditioned place preference, led to locomotor sensitization and increased voluntary ethanol consumption. In the present study, we separated the (R)-and (S)-enantiomers from a commercial (RS)-SAL using a high-performance liquid chromatography with electrochemical detection system fitted with a β-cyclodextrin-modified column. We injected (R)-SAL or (S)-SAL (30 pmol/1.0 μl) into the VTA of naïve UChB rats bred as alcohol drinkers to study whether one or both SAL enantiomers are responsible for the motivated behavioral effects, sensitization and increase in voluntary ethanol intake. The present results show that repeated administration of (R)-SAL leads to (1) conditioned place preference; (2) locomotor sensitization; and (3) marked increases in binge-like ethanol intake. Conversely, (S)-SAL did not influence any of these parameters. Overall, data indicate that (R)-SAL stereospecifically induces motivational effects, behavioral sensitization and increases ethanol intake.
Tetrahedron Letters, 1987
Precursor feeding experiments to Annona reticulata leaves demonstrated that coclaurine and reticu... more Precursor feeding experiments to Annona reticulata leaves demonstrated that coclaurine and reticuline are both derived from the common intermediate norcoclaurine; furthermore (S)-coclaurine was found to be the specific precursor to the major classes of isoquinoline alkaloids: protoberberines, benzophenanthridines and morphinandienones.
Assmcr.-The 13C-nmr chemical shifts of onychine (l-methyl4-aza8uoren-9-one) [l] were assigned wit... more Assmcr.-The 13C-nmr chemical shifts of onychine (l-methyl4-aza8uoren-9-one) [l] were assigned with the aid ofheternnuclear 2D-nmr spectraand these results were used to interpret the 13C n m r spectra of several other synthetic duorenones.
Current traditional medicine, Jun 3, 2019
Boldo leaves (Boldo folium, from Peumus boldus Mol.) are very frequently used as a medicinal herb... more Boldo leaves (Boldo folium, from Peumus boldus Mol.) are very frequently used as a medicinal herb in Chile and are exported to many countries to be used in teas or as extracts included in herbal remedies, primarily as an aid to digestion and as a mild sedative. Scientific support for these uses is scanty, and boldine, an alkaloid viewed as characteristic of the tree and present in high concentration in the bark, is extracted by specialized companies and sold as the supposed main active constituent. Consequently, boldine has been the subject of a considerable number of research papers, while some of the other alkaloids present to a greater extent in the leaves have been relatively neglected except when found in large amounts in other species. These studies range from assays of antioxidant activity to anti-inflammatory, antineoplastic and other medical applications. The essential oil, usually containing a large percentage of the toxic ascaridole, was once used as a vermifuge and is now regarded with caution, but is still of interest as a possible natural insecticide, fungicide, antiparasitic and herbicide. The last decade has seen an explosive increase in papers pointing to possible uses of boldo and its constituents. This review attempts to bring these publications together in a comprehensive way with the purpose of stimulating and orienting further research into the useful properties of this Chilean endemic tree.
Tetrahedron, 1974
The known alkaloids zizyphine-A (1) and-B (2), abyssinine-A (4) and-B (5), and the previously und... more The known alkaloids zizyphine-A (1) and-B (2), abyssinine-A (4) and-B (5), and the previously undescribed zizyphine-C (3),-D (6) and-E (7) have been isolated from the stem bark of Zizyphus oenoplia. The structures of the new compounds were elucidated by spectroscopic methods applied to the alkaloids and to some of their transformation products, and by chemical degradation reactions. While working up the crude bases obtained from the stem bark of Zizyphus oenoplia MilI.t for a revision of the structure of zizyphine-A (1)/ the mixture was found to contain, besides this substance and the previously described zizyphine-B (zizyphinine) (2),2,3 several other alkaloids, some of which are now reported. Extensive chromatography of the crude bases furnished eight apparentIy homogeneous fractions (Table 1), one of which was subsequentIy shown to be composed of two substances separable only by chemical means. Of these nine alkaloids, the structures of four are already known: zizyphine-A and-B, and abyssinine-A (4) and-B (5).' Two of the so far undescribed substances were present in insufficient amounts for structural work to be carried out. Of the remaining three, one, zizyphine-C (3) was found to contain a 13-membered ring like zizyphine-A and-B. The other two new compounds, zizyphine-D (6) and-E (7), have 15-membered rings like abyssinine-A and-B, with the peculiarity that one of the amino acids is 3-hydroxy-isoleucine.
![Research paper thumbnail of Crystal structure of 5-methoxy-2,3-dihydro-7Z/-dibenzo[de,h]quinolin- 7-one, C17H13NO2](https://attachments.academia-assets.com/115012620/thumbnails/1.jpg)
](Zeitschrift Fur Kristallographie-new Crystal Structures, Dec 1, 2003
Chemischer Informationsdienst, Mar 26, 1974
ChemInform Abstract Tryptamin (I) reagiert in Aceton (II) mitÄthylpolyphosphat als Katalysator di... more ChemInform Abstract Tryptamin (I) reagiert in Aceton (II) mitÄthylpolyphosphat als Katalysator direkt zum Carbolin (III). In Cyclopentanon (IVa) und Cyclohexanon (IVb) werden die Carboline (Va) und (Vb) erhalten.-(IR-, UV-, NMR-Spektren).
Chemischer Informationsdienst, Aug 29, 1972
ChemInform Abstract Aus den Amphetaminen (I) entstehen durch Bromierung die Derivate (II), wobei ... more ChemInform Abstract Aus den Amphetaminen (I) entstehen durch Bromierung die Derivate (II), wobei die Ausgangsamine z.Tl. aus den Aldehyden (III) und Nitroäthan (IV)über die Zwischenstufen (V) erhalten werden. Ferner werden aus den bromierten Aldehyden (VI) die romierten Nitropropene (VII) hergestellt. Die dargestellten Verbindungen werden harrnakologisch untersucht.
Chemischer Informationsdienst, Jul 1, 1980
![Research paper thumbnail of Crystal structure of 2-[(3,4-dimethoxy)-phenethyl-3-(3,4-dimethoxy)- phenethylamino]-2,3-dihydro-isoindol-1-one, C28H32N2O5](https://attachments.academia-assets.com/115012525/thumbnails/1.jpg)
](Zeitschrift Fur Kristallographie-new Crystal Structures, Mar 1, 2003
Source of material A solution of phthalaldehydic acid (1 g, 6.67 mmol) in 30 mL of toluene was tr... more Source of material A solution of phthalaldehydic acid (1 g, 6.67 mmol) in 30 mL of toluene was treated with homoveratrylamine (2.25 mL, 13.3 mmol) and refluxed under a Dean-Stark trap with constant stirring for 2 hours. After concentrating to dryness, the title product was purified by crystallization in cyclohexane affording white needles (yield 95%). Experimental details The hydrogen atom H10B (linked to N10) was located on a difference electron-density map and refined. The other hydrogen atoms were included in idealised positions with isotropic displacement parameters. Discussion The isoindolone moiety is planar and lies parallel to the phenethylamine linked to N2, having a torsion angle C25-C24-C23-N2 of 175.4(2)°. All methoxyl group carbon atoms are coplanar with the respective aromatic rings. However, the phenethylamine linked to C3 is twisted with respect to the isoindolone moiety forming a dihedral angle C3-N10-C11-C12 of-161.5(2)°.
ChemInform, Jan 6, 2004
For Abstract see ChemInform Abstract in Full Text.
Pacific Science, Apr 1, 2000
The Alkaloids, 1989
Publisher Summary This chapter reviews the azafluorenone alkaloids as completely as possible, dis... more Publisher Summary This chapter reviews the azafluorenone alkaloids as completely as possible, discusses a small number of structurally unusual though not unprecedented compounds, and also updates the older contributions on the mainline isoquinoline alkaloids insofar as the genus Guatteria is concerned. Guutteriu alkaloids can be classified into eight main types depending on the structural characteristics of their skeleton, and these eight skeletal types are biosynthetically related, or at least conceivable proposals for their formation in vivo are reported. Aporphinoids are by far the most abundant alkaloids in this genus and also, generally speaking, in the family Annonaceae. Guatteria has proved to be a rich source of unusual structures of this general type. Dehydronornuciferine and O-methyldehydroisopiline are isolated from G. ouregou, where they cooccur with the corresponding noraporphines, and the N-formyl derivatives dehydroformouregine and formouregine.
Revista chilena de neuro-psiquiatría, Nov 1, 2003
La enfermedad de Alzheimer constituye un desafio terapeutico de primera magnitud que ha respondid... more La enfermedad de Alzheimer constituye un desafio terapeutico de primera magnitud que ha respondido de manera muy poco satisfactoria a los tratamientos actuales. Avances en el conocimiento de los procesos que estan asociados con la patogenesis y el curso de esta enfermedad permiten proponer nuevos enfoques terapeuticos, algunos de los cuales se encuentran en etapas de experimentacion clinica mientras otros todavia son objeto de investigaciones basicas
Chemischer Informationsdienst, Oct 29, 1974
Contribuciones científicas y tecnológicas, 1970
RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de... more RESUMEN• Sophora tetraptera, sensu Reiche, es el nombre científico asignado a un árbol del sur de Chile conocido por los nombre de pelú y pilo. pilo, que se asemeja mucho desde el punto de vista morfológico a las especies neozelandesas S. tetraptera J. Mill. Y S. microphylla Ait. Un estudio preliminar de los alcaloides de las semillas de esta planta chilena permitió aislar citisina, metilcitisina y matrina en proporciones que apoyan la separación taxonómica del pelú de las especies nativas de Nueva Zelandia. SUMMARY-Sophora tetraptera, sensu R,eiche, is the scientific name assigned to a southem Chilean tree known by the names pelú and pilopilo, which closely resembles the N ew Zealand species S. tetraptera J. Mill. and S. microphylla Ait. from a morphological viewpoint. A preliminalj' study of the seed alkaloids of this Chilean plant yielded cytisine, methylcytisine, and matrine in a ratio which supports the taxonomic segregation of the pelú from the species native to New Zealand.
New Journal of Chemistry, 2021
DFT calculations were performed on nine flavones and flavonols to explain their high antioxidant ... more DFT calculations were performed on nine flavones and flavonols to explain their high antioxidant activity and variations in their activity. Conformational analysis showed that only flavonols with 3-OH directed toward the Bring are nonplanar; however, flavones and resulted radicals are planar. Hydroxyl group eligible for dissociation is the one with ortho OH directed toward it; otherwise, one of Bring (in 2′ or 4′-position) hydroxyl group. There are two main factors responsible for stabilizing the resulted radicals and lowering the bond dissociation energy and hence there were found well correlated with the experimental activity. First, driving force resulted from the conversion of nonplanar flavonols to planar radicals accompanied by resonance toward the carbonyl group and H-bond formation with 3-OH and second, radical stabilization by H-bond with ortho hydroxyl group with resonance toward carbonyl or pyrone oxygen. All resonance and H-bonds were confirmed by spin density, bond length, and molecular orbital calculations.
Addiction Biology, May 29, 2015
Ethanol is oxidized in the brain to acetaldehyde, which can condense with dopamine to generate (R... more Ethanol is oxidized in the brain to acetaldehyde, which can condense with dopamine to generate (R/S)-salsolinol [(RS)-SAL]. Racemic salsolinol [(RS)-SAL] is self-infused by rats into the posterior ventral tegmental area (VTA) at significantly lower concentrations than those of acetaldehyde, suggesting that (RS)-SAL is a most active product of ethanol metabolism. Early studies showed that repeated intraperitoneal or intra-VTA administration of (RS)-SAL (10 mg/kg) induced conditioned place preference, led to locomotor sensitization and increased voluntary ethanol consumption. In the present study, we separated the (R)-and (S)-enantiomers from a commercial (RS)-SAL using a high-performance liquid chromatography with electrochemical detection system fitted with a β-cyclodextrin-modified column. We injected (R)-SAL or (S)-SAL (30 pmol/1.0 μl) into the VTA of naïve UChB rats bred as alcohol drinkers to study whether one or both SAL enantiomers are responsible for the motivated behavioral effects, sensitization and increase in voluntary ethanol intake. The present results show that repeated administration of (R)-SAL leads to (1) conditioned place preference; (2) locomotor sensitization; and (3) marked increases in binge-like ethanol intake. Conversely, (S)-SAL did not influence any of these parameters. Overall, data indicate that (R)-SAL stereospecifically induces motivational effects, behavioral sensitization and increases ethanol intake.
Tetrahedron Letters, 1987
Precursor feeding experiments to Annona reticulata leaves demonstrated that coclaurine and reticu... more Precursor feeding experiments to Annona reticulata leaves demonstrated that coclaurine and reticuline are both derived from the common intermediate norcoclaurine; furthermore (S)-coclaurine was found to be the specific precursor to the major classes of isoquinoline alkaloids: protoberberines, benzophenanthridines and morphinandienones.
Assmcr.-The 13C-nmr chemical shifts of onychine (l-methyl4-aza8uoren-9-one) [l] were assigned wit... more Assmcr.-The 13C-nmr chemical shifts of onychine (l-methyl4-aza8uoren-9-one) [l] were assigned with the aid ofheternnuclear 2D-nmr spectraand these results were used to interpret the 13C n m r spectra of several other synthetic duorenones.
Current traditional medicine, Jun 3, 2019
Boldo leaves (Boldo folium, from Peumus boldus Mol.) are very frequently used as a medicinal herb... more Boldo leaves (Boldo folium, from Peumus boldus Mol.) are very frequently used as a medicinal herb in Chile and are exported to many countries to be used in teas or as extracts included in herbal remedies, primarily as an aid to digestion and as a mild sedative. Scientific support for these uses is scanty, and boldine, an alkaloid viewed as characteristic of the tree and present in high concentration in the bark, is extracted by specialized companies and sold as the supposed main active constituent. Consequently, boldine has been the subject of a considerable number of research papers, while some of the other alkaloids present to a greater extent in the leaves have been relatively neglected except when found in large amounts in other species. These studies range from assays of antioxidant activity to anti-inflammatory, antineoplastic and other medical applications. The essential oil, usually containing a large percentage of the toxic ascaridole, was once used as a vermifuge and is now regarded with caution, but is still of interest as a possible natural insecticide, fungicide, antiparasitic and herbicide. The last decade has seen an explosive increase in papers pointing to possible uses of boldo and its constituents. This review attempts to bring these publications together in a comprehensive way with the purpose of stimulating and orienting further research into the useful properties of this Chilean endemic tree.
Tetrahedron, 1974
The known alkaloids zizyphine-A (1) and-B (2), abyssinine-A (4) and-B (5), and the previously und... more The known alkaloids zizyphine-A (1) and-B (2), abyssinine-A (4) and-B (5), and the previously undescribed zizyphine-C (3),-D (6) and-E (7) have been isolated from the stem bark of Zizyphus oenoplia. The structures of the new compounds were elucidated by spectroscopic methods applied to the alkaloids and to some of their transformation products, and by chemical degradation reactions. While working up the crude bases obtained from the stem bark of Zizyphus oenoplia MilI.t for a revision of the structure of zizyphine-A (1)/ the mixture was found to contain, besides this substance and the previously described zizyphine-B (zizyphinine) (2),2,3 several other alkaloids, some of which are now reported. Extensive chromatography of the crude bases furnished eight apparentIy homogeneous fractions (Table 1), one of which was subsequentIy shown to be composed of two substances separable only by chemical means. Of these nine alkaloids, the structures of four are already known: zizyphine-A and-B, and abyssinine-A (4) and-B (5).' Two of the so far undescribed substances were present in insufficient amounts for structural work to be carried out. Of the remaining three, one, zizyphine-C (3) was found to contain a 13-membered ring like zizyphine-A and-B. The other two new compounds, zizyphine-D (6) and-E (7), have 15-membered rings like abyssinine-A and-B, with the peculiarity that one of the amino acids is 3-hydroxy-isoleucine.
Zeitschrift Fur Kristallographie-new Crystal Structures, Dec 1, 2003
Chemischer Informationsdienst, Mar 26, 1974
ChemInform Abstract Tryptamin (I) reagiert in Aceton (II) mitÄthylpolyphosphat als Katalysator di... more ChemInform Abstract Tryptamin (I) reagiert in Aceton (II) mitÄthylpolyphosphat als Katalysator direkt zum Carbolin (III). In Cyclopentanon (IVa) und Cyclohexanon (IVb) werden die Carboline (Va) und (Vb) erhalten.-(IR-, UV-, NMR-Spektren).
Chemischer Informationsdienst, Aug 29, 1972
ChemInform Abstract Aus den Amphetaminen (I) entstehen durch Bromierung die Derivate (II), wobei ... more ChemInform Abstract Aus den Amphetaminen (I) entstehen durch Bromierung die Derivate (II), wobei die Ausgangsamine z.Tl. aus den Aldehyden (III) und Nitroäthan (IV)über die Zwischenstufen (V) erhalten werden. Ferner werden aus den bromierten Aldehyden (VI) die romierten Nitropropene (VII) hergestellt. Die dargestellten Verbindungen werden harrnakologisch untersucht.
Chemischer Informationsdienst, Jul 1, 1980
Zeitschrift Fur Kristallographie-new Crystal Structures, Mar 1, 2003
Source of material A solution of phthalaldehydic acid (1 g, 6.67 mmol) in 30 mL of toluene was tr... more Source of material A solution of phthalaldehydic acid (1 g, 6.67 mmol) in 30 mL of toluene was treated with homoveratrylamine (2.25 mL, 13.3 mmol) and refluxed under a Dean-Stark trap with constant stirring for 2 hours. After concentrating to dryness, the title product was purified by crystallization in cyclohexane affording white needles (yield 95%). Experimental details The hydrogen atom H10B (linked to N10) was located on a difference electron-density map and refined. The other hydrogen atoms were included in idealised positions with isotropic displacement parameters. Discussion The isoindolone moiety is planar and lies parallel to the phenethylamine linked to N2, having a torsion angle C25-C24-C23-N2 of 175.4(2)°. All methoxyl group carbon atoms are coplanar with the respective aromatic rings. However, the phenethylamine linked to C3 is twisted with respect to the isoindolone moiety forming a dihedral angle C3-N10-C11-C12 of-161.5(2)°.