Maria Teresa Molina - Academia.edu (original) (raw)
Papers by Maria Teresa Molina
The Journal of Organic Chemistry, 1987
Page 1. J. Org. Chem. 1987,52,1273-1276 Synthesis of Deoxyfrenolicin and Nanaomycin A 1273 George... more Page 1. J. Org. Chem. 1987,52,1273-1276 Synthesis of Deoxyfrenolicin and Nanaomycin A 1273 George A. Kraus,* Maria Teresa Molina, and John A. Walling Department of Chemistry, Zowa State University, Ames, Zowa 50011 Received September 30, 1986 ...
Journal of photochemistry and photobiology. B, Biology
The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluore... more The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluorescence of thylakoid membranes was examined. Both the fluorescence and the photochemical activity depend on the 1,4-anthraquinone substituent. Stronger quinone-induced quenching of the chlorophyll fluorescence than quinone-induced changes in the activity of photosystem II is observed. The type (Cl or Br) and the position (Cl) of the chalogen atom strongly influence the degree of inhibition of PSII electron transport and the quenching of chlorophyll fluorescence. The data suggest that the quenching of chlorophyll fluorescence is due rather to the interaction of the 1,4-anthraquinones and chlorophyll molecules than to an indirect effect caused by stimulation of the photochemistry.
Cheminform, 2005
For Abstract see ChemInform Abstract in Full Text.
Cheminform, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Cheminform, 1993
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Cheminform, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Journal of Medicinal Chemistry, 2003
Journal of Physical Chemistry A, 1998
We have determined the gas-phase basicities of S 6 and S 8 by means of Fourier transform ion cycl... more We have determined the gas-phase basicities of S 6 and S 8 by means of Fourier transform ion cyclotron resonance spectroscopy (FT-ICR): 167.8 and 187.1 kcal/mol, respectively. An ab initio investigation of the local minima of the S 6 H + potential energy surface shows that the most stable protonated species corresponds to a distorted five-membered ring structure rather than to a six-membered ring species. When the final energy of the aforementioned protonated species is evaluated at the G2(SVP,MP2) level, the agreement with the experimental value is very good. A G2(MP2) survey of the S 4 and S 4 H + potential energy surfaces shows that the most stable neutral and protonated species present cis open-chain structures. The relative stabilities of the different species investigated are extremely sensitive to electron correlation effects. At the G2(MP2) level S 4 is predicted to be slightly more basic than S 6 in the gas phase. Some preliminary ab initio calculations on the most probable structures of S 8 H + are also reported.
Journal of Organic Chemistry, 1996
The gas phase acidity and basicity of 2,2,2-trifluoroethanethiol (TFET), i.e., the standard Gibbs... more The gas phase acidity and basicity of 2,2,2-trifluoroethanethiol (TFET), i.e., the standard Gibbs energy changes for the following two reactions have been determined by means of Fourier transform ion cyclotron resonance spectroscopy: CF 3 CH 2 SH(g) f CF 3 CH 2 S -(g) + H + (g) and CF 3 CH 2 SH 2 + (g) f CF 3 CH 2 SH(g) + H + (g). Also determined were the equilibrium constants for the 1:1 associations in dilute solution between TFET and pyridine N-oxide, 3,4-dinitrophenol (both in cyclohexane), and molecular iodine (in tetrachloromethane). Quantum-mechanical treatments at the G2(MP2) level were carried out on TFET, 2,2,2-trifluoroethanol, ethanethiol, and ethanol as neutral, protonated, and deprotonated species. Topological analyses of the charge densities and the Laplacians thereof were performed on all of them. This combination of experimental and theoretical information leads to a vastly enlarged view of structural effects on the reactivity of alcohols and thiols as well as to a satisfactory rationalization of the reactivity of TFET.
![Research paper thumbnail of Structural effects on the thermochemical properties of cycloalkanones. III. Enthalpy of combustion, vapour pressures, and enthalpy of sublimation, and standard enthalpy of formation in the gaseous phase of pentacyclo[5.4.0.0 2,6.0 3,10.0 5,9]undecane-8,11-dione](https://attachments.academia-assets.com/50397590/thumbnails/1.jpg)
](Journal of Chemical Thermodynamics, 1996
The standard molar energy of combustion of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione h... more The standard molar energy of combustion of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione has been determined by using a static bomb calorimeter. The vapour pressure of the compound was measured in the intervalT = 325.64 K toT = 340.97 K by the Knudsen-effusion technique. Enthalpy of fusion and enthalpy of transition measurements were carried out by differential scanning calorimetry (d.s.c.). From the experimental results of this work, the standard enthalpies of combustion, sublimation, and formation in the crystalline and gaseous state at the temperature 298.15 K have been derived for pentacyclo[5.4.0.02,6.03,10.05,9] undecane-8,11-dione: ΔfHmo(cr) = −(206.2 ± 3.2) kJ · mol−1, ΔsubHmo = (92.6 ± 1) kJ· mol−1, ΔfHmo(g) = −(113.6 ± 3.4) kJ− mol−1. Strain energy due to the presence of the two carbonyl groups in the molecule is estimated by three different methods with consistent results.
Journal of The American Chemical Society, 2000
Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT ICR) has revealed the existence o... more Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT ICR) has revealed the existence of the P 4 Li + ion as a stable species in the gas phase. High-level ab initio calculations show that P 4 Li + appears as a "planetary system" wherein the lithium cation can easily move around the P 4 moiety along paths (or "orbits") connecting the points above the middle points of the P-P edges with points above the center of the PPP faces, the movement toward the corners of the tetrahedron being the less favored. Due to symmetry, this orbiting is 4-fold degenerate.
Journal of Organic Chemistry, 2009
The NHC-catalyzed conjugate hydroacylation of 1,4-naphthoquinones allows for the synthesis of mon... more The NHC-catalyzed conjugate hydroacylation of 1,4-naphthoquinones allows for the synthesis of monoacylated 1,4-dihydroxynaphthalene derivatives. These targets, difficult to prepare selectively by standard protocols, represent important intermediates in the elaboration of highly substituted 1,4-naphthoquinone derivatives, which constitute relevant pharmaceutical scaffolds. High regioselectivity has been observed in the hydroacylation reaction when starting from nonsymmetrical quinones.
Organic Letters, 2009
The first examples of the direct arylation of benzo-fused 1,4-quinones by the dicationic Pd(II)-c... more The first examples of the direct arylation of benzo-fused 1,4-quinones by the dicationic Pd(II)-catalyzed addition of arylboronic acids are reported. The addition reaction is carried out under very mild conditions (dioxane-H(2)O, rt, open air atmosphere) and is tolerant of free OH groups. In addition, the reaction shows high regioselectivity when using nonsymmetrical quinones as starting materials.
Journal of Photochemistry and Photobiology B-biology, 2005
The chlorophyll fluorescence, photochemical activity and surface electric properties of thylakoid... more The chlorophyll fluorescence, photochemical activity and surface electric properties of thylakoid membranes with different stoichiometry of pigment–protein complexes and organization of the light-harvesting chlorophyll a/b protein complex of photosystem II (LHCII) were studied in the presence of substituted 1,4-anthraquinones. Data show strong dependence of the quenching of the chlorophyll fluorescence on the structural organization of LHCII. The increase of the LHCII oligomerization, which is associated with significant reduction of the transmembrane electric charge asymmetry and electric polarizability of the membrane, correlates with enhanced quenching effect of substituted 1,4-athraquinones. Crucial for the large quinone-induced changes in the membrane electric dipole moments is the structure of the quinone molecule. The strongest reduction in the values of the dipole moments is observed after interaction of thylakoids with 3-chloro-9-hydroxy-1,4-anthraquinone (TF33) which has the highest quenching efficiency. The quinone induced changes in the photochemical activity of photosystem II (PSII) correlate with the total amount of the supramolecular LHCII–PSII complex and depend on the number of substituents in the 1,4-anthraquinone molecule.
Colloids and Surfaces B-biointerfaces, 2003
The interaction of the substituted 1,4-anthraquinones with purple membranes (PM) is studied by th... more The interaction of the substituted 1,4-anthraquinones with purple membranes (PM) is studied by the fluorescence and electric light scattering techniques. Substituted 1,4-anthraquinones are shown to quench bacteriorhodopsin tryptophan fluorescence. The quenching efficiency of 1,4-anthraquinone derivatives is smaller than that of 1,4-anthraquinone. It is the smallest at di-substituted 1,4-anthraquinones (R9=OCOCH3 and R3=Cl or Br). The type of the halogen atom as substituent does not affect the quenching efficiency of di-substituted 1,4-anthraquinones (R9=OH or OCOCH3 and R3=Cl or Br). The quenching efficiency depends on the position of the Cl atom for di-substituted 1,4-anthraquinone derivatives (R9=OH and R3=Cl or R9=OH and R10=Cl). 9-Hydroxy-1,4-anthraquinones induce decrease in purple membrane charge asymmetry distribution whereas mono-substituted 1,4-anthraquinones containing R9=OCH3 or R9=OCOCH3 induce increase in the membrane charge asymmetry. The membrane electric polarizability, related to the structure and dynamics of the electric double layer, decreases in the presence of 1,4-anthraquinone derivatives, the greatest effect being observed for the 9-hydroxy-1,4-anthraquinones. The energy transfer and the quenching of bR tryptophan fluorescence from 9-hydroxy-1,4-anthraquinones correlate with the variation of the surface electric properties of PM in the presence of relatively low concentrations of substituted 1,4-anthraquinones.
Journal of Photochemistry and Photobiology B-biology, 2003
The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluore... more The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluorescence of thylakoid membranes was examined. Both the fluorescence and the photochemical activity depend on the 1,4-anthraquinone substituent. Stronger quinone-induced quenching of the chlorophyll fluorescence than quinone-induced changes in the activity of photosystem II is observed. The type (Cl or Br) and the position (Cl) of the chalogen atom strongly influence the degree of inhibition of PSII electron transport and the quenching of chlorophyll fluorescence. The data suggest that the quenching of chlorophyll fluorescence is due rather to the interaction of the 1,4-anthraquinones and chlorophyll molecules than to an indirect effect caused by stimulation of the photochemistry.
Journal of Organic Chemistry, 1988
Journal of Organic Chemistry, 1989
Synthesis of 4,11-Dideoxydaunomycinone C, 70.80; H, 7.92. Found: C, 70.37; H, 7.91. Acyclic Napht... more Synthesis of 4,11-Dideoxydaunomycinone C, 70.80; H, 7.92. Found: C, 70.37; H, 7.91. Acyclic Naphthol Diketone 16. To a suspension of hexane-washed NaH (0.04 g, 1.64 mmol) in 2 mL of THF was added a solution of ketone 15 (0.53 g, 1.49 mmol) in THF. The resulting solution was stirred at 0 "C for 15 min. A solution of acid chloride 13 (0.34 g, 1.64 mmol) in THF was added dropwise, and the solution was stirred at 0 "C for 30 min. The solution was then cooled to -78 "C, and LDA (3.28 mmol) in THF was added dropwise. The solution was then stirred for 15 min. It was diluted with water and acidified to pH 6 with 6 N HC1. The aqueous layer was extracted with ether. The combined organic layers were washed with brine, dried, and concentrated. The crude product was purified by flash chromatography with 7:l hexanes-ethyl acetate to afford 0.58 g of ketone 16 (74% yield). NMR (CDCI,): 6 0.17 (s, 6 H), 1.10 (s, 9 H), 1.96 (s, 3 H), 3.40-3.75 (m, 6 H), 4.9-5.1 (m, 2 H), 5.90-5.97 (m, 1 H), 6.02 (d, J = 16 Hz, 1 H), 7.00 (d, J = 16 Hz, 1 H), 7.5-7.6 (m, 2 H), 7.97 (d, J = 8.4 Hz, 1 H), 8.34
Bioorganic & Medicinal Chemistry Letters, 2011
BACE1 activity, inhibition of Aβ aggregation, and disaggregation of preformed Aβ fibrils constitu... more BACE1 activity, inhibition of Aβ aggregation, and disaggregation of preformed Aβ fibrils constitute the three major targets in the development of small-molecule lipophilic new drugs for the treatment of Alzheimer’s disease (AD). Quinones are widely distributed among natural products and possess relevant and varied biological activities including antitumor and antibiotic, inhibition of HIV-1 reverse transcriptase, antidiabetic, or COX-inhibition, among others. We report herein the interaction of several arylquinones and their derivatives with the amyloidogenic pathway of the amyloid precursor protein processing. Our studies put forward that these compounds are promising candidates in the development of new drugs which are effective simultaneously towards the three major targets of AD.
The Journal of Organic Chemistry, 1987
Page 1. J. Org. Chem. 1987,52,1273-1276 Synthesis of Deoxyfrenolicin and Nanaomycin A 1273 George... more Page 1. J. Org. Chem. 1987,52,1273-1276 Synthesis of Deoxyfrenolicin and Nanaomycin A 1273 George A. Kraus,* Maria Teresa Molina, and John A. Walling Department of Chemistry, Zowa State University, Ames, Zowa 50011 Received September 30, 1986 ...
Journal of photochemistry and photobiology. B, Biology
The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluore... more The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluorescence of thylakoid membranes was examined. Both the fluorescence and the photochemical activity depend on the 1,4-anthraquinone substituent. Stronger quinone-induced quenching of the chlorophyll fluorescence than quinone-induced changes in the activity of photosystem II is observed. The type (Cl or Br) and the position (Cl) of the chalogen atom strongly influence the degree of inhibition of PSII electron transport and the quenching of chlorophyll fluorescence. The data suggest that the quenching of chlorophyll fluorescence is due rather to the interaction of the 1,4-anthraquinones and chlorophyll molecules than to an indirect effect caused by stimulation of the photochemistry.
Cheminform, 2005
For Abstract see ChemInform Abstract in Full Text.
Cheminform, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Cheminform, 1993
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Cheminform, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Journal of Medicinal Chemistry, 2003
Journal of Physical Chemistry A, 1998
We have determined the gas-phase basicities of S 6 and S 8 by means of Fourier transform ion cycl... more We have determined the gas-phase basicities of S 6 and S 8 by means of Fourier transform ion cyclotron resonance spectroscopy (FT-ICR): 167.8 and 187.1 kcal/mol, respectively. An ab initio investigation of the local minima of the S 6 H + potential energy surface shows that the most stable protonated species corresponds to a distorted five-membered ring structure rather than to a six-membered ring species. When the final energy of the aforementioned protonated species is evaluated at the G2(SVP,MP2) level, the agreement with the experimental value is very good. A G2(MP2) survey of the S 4 and S 4 H + potential energy surfaces shows that the most stable neutral and protonated species present cis open-chain structures. The relative stabilities of the different species investigated are extremely sensitive to electron correlation effects. At the G2(MP2) level S 4 is predicted to be slightly more basic than S 6 in the gas phase. Some preliminary ab initio calculations on the most probable structures of S 8 H + are also reported.
Journal of Organic Chemistry, 1996
The gas phase acidity and basicity of 2,2,2-trifluoroethanethiol (TFET), i.e., the standard Gibbs... more The gas phase acidity and basicity of 2,2,2-trifluoroethanethiol (TFET), i.e., the standard Gibbs energy changes for the following two reactions have been determined by means of Fourier transform ion cyclotron resonance spectroscopy: CF 3 CH 2 SH(g) f CF 3 CH 2 S -(g) + H + (g) and CF 3 CH 2 SH 2 + (g) f CF 3 CH 2 SH(g) + H + (g). Also determined were the equilibrium constants for the 1:1 associations in dilute solution between TFET and pyridine N-oxide, 3,4-dinitrophenol (both in cyclohexane), and molecular iodine (in tetrachloromethane). Quantum-mechanical treatments at the G2(MP2) level were carried out on TFET, 2,2,2-trifluoroethanol, ethanethiol, and ethanol as neutral, protonated, and deprotonated species. Topological analyses of the charge densities and the Laplacians thereof were performed on all of them. This combination of experimental and theoretical information leads to a vastly enlarged view of structural effects on the reactivity of alcohols and thiols as well as to a satisfactory rationalization of the reactivity of TFET.
Journal of Chemical Thermodynamics, 1996
The standard molar energy of combustion of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione h... more The standard molar energy of combustion of pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8,11-dione has been determined by using a static bomb calorimeter. The vapour pressure of the compound was measured in the intervalT = 325.64 K toT = 340.97 K by the Knudsen-effusion technique. Enthalpy of fusion and enthalpy of transition measurements were carried out by differential scanning calorimetry (d.s.c.). From the experimental results of this work, the standard enthalpies of combustion, sublimation, and formation in the crystalline and gaseous state at the temperature 298.15 K have been derived for pentacyclo[5.4.0.02,6.03,10.05,9] undecane-8,11-dione: ΔfHmo(cr) = −(206.2 ± 3.2) kJ · mol−1, ΔsubHmo = (92.6 ± 1) kJ· mol−1, ΔfHmo(g) = −(113.6 ± 3.4) kJ− mol−1. Strain energy due to the presence of the two carbonyl groups in the molecule is estimated by three different methods with consistent results.
Journal of The American Chemical Society, 2000
Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT ICR) has revealed the existence o... more Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT ICR) has revealed the existence of the P 4 Li + ion as a stable species in the gas phase. High-level ab initio calculations show that P 4 Li + appears as a "planetary system" wherein the lithium cation can easily move around the P 4 moiety along paths (or "orbits") connecting the points above the middle points of the P-P edges with points above the center of the PPP faces, the movement toward the corners of the tetrahedron being the less favored. Due to symmetry, this orbiting is 4-fold degenerate.
Journal of Organic Chemistry, 2009
The NHC-catalyzed conjugate hydroacylation of 1,4-naphthoquinones allows for the synthesis of mon... more The NHC-catalyzed conjugate hydroacylation of 1,4-naphthoquinones allows for the synthesis of monoacylated 1,4-dihydroxynaphthalene derivatives. These targets, difficult to prepare selectively by standard protocols, represent important intermediates in the elaboration of highly substituted 1,4-naphthoquinone derivatives, which constitute relevant pharmaceutical scaffolds. High regioselectivity has been observed in the hydroacylation reaction when starting from nonsymmetrical quinones.
Organic Letters, 2009
The first examples of the direct arylation of benzo-fused 1,4-quinones by the dicationic Pd(II)-c... more The first examples of the direct arylation of benzo-fused 1,4-quinones by the dicationic Pd(II)-catalyzed addition of arylboronic acids are reported. The addition reaction is carried out under very mild conditions (dioxane-H(2)O, rt, open air atmosphere) and is tolerant of free OH groups. In addition, the reaction shows high regioselectivity when using nonsymmetrical quinones as starting materials.
Journal of Photochemistry and Photobiology B-biology, 2005
The chlorophyll fluorescence, photochemical activity and surface electric properties of thylakoid... more The chlorophyll fluorescence, photochemical activity and surface electric properties of thylakoid membranes with different stoichiometry of pigment–protein complexes and organization of the light-harvesting chlorophyll a/b protein complex of photosystem II (LHCII) were studied in the presence of substituted 1,4-anthraquinones. Data show strong dependence of the quenching of the chlorophyll fluorescence on the structural organization of LHCII. The increase of the LHCII oligomerization, which is associated with significant reduction of the transmembrane electric charge asymmetry and electric polarizability of the membrane, correlates with enhanced quenching effect of substituted 1,4-athraquinones. Crucial for the large quinone-induced changes in the membrane electric dipole moments is the structure of the quinone molecule. The strongest reduction in the values of the dipole moments is observed after interaction of thylakoids with 3-chloro-9-hydroxy-1,4-anthraquinone (TF33) which has the highest quenching efficiency. The quinone induced changes in the photochemical activity of photosystem II (PSII) correlate with the total amount of the supramolecular LHCII–PSII complex and depend on the number of substituents in the 1,4-anthraquinone molecule.
Colloids and Surfaces B-biointerfaces, 2003
The interaction of the substituted 1,4-anthraquinones with purple membranes (PM) is studied by th... more The interaction of the substituted 1,4-anthraquinones with purple membranes (PM) is studied by the fluorescence and electric light scattering techniques. Substituted 1,4-anthraquinones are shown to quench bacteriorhodopsin tryptophan fluorescence. The quenching efficiency of 1,4-anthraquinone derivatives is smaller than that of 1,4-anthraquinone. It is the smallest at di-substituted 1,4-anthraquinones (R9=OCOCH3 and R3=Cl or Br). The type of the halogen atom as substituent does not affect the quenching efficiency of di-substituted 1,4-anthraquinones (R9=OH or OCOCH3 and R3=Cl or Br). The quenching efficiency depends on the position of the Cl atom for di-substituted 1,4-anthraquinone derivatives (R9=OH and R3=Cl or R9=OH and R10=Cl). 9-Hydroxy-1,4-anthraquinones induce decrease in purple membrane charge asymmetry distribution whereas mono-substituted 1,4-anthraquinones containing R9=OCH3 or R9=OCOCH3 induce increase in the membrane charge asymmetry. The membrane electric polarizability, related to the structure and dynamics of the electric double layer, decreases in the presence of 1,4-anthraquinone derivatives, the greatest effect being observed for the 9-hydroxy-1,4-anthraquinones. The energy transfer and the quenching of bR tryptophan fluorescence from 9-hydroxy-1,4-anthraquinones correlate with the variation of the surface electric properties of PM in the presence of relatively low concentrations of substituted 1,4-anthraquinones.
Journal of Photochemistry and Photobiology B-biology, 2003
The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluore... more The effect of substituted 1,4-anthraquinones on the photochemical activity and chlorophyll fluorescence of thylakoid membranes was examined. Both the fluorescence and the photochemical activity depend on the 1,4-anthraquinone substituent. Stronger quinone-induced quenching of the chlorophyll fluorescence than quinone-induced changes in the activity of photosystem II is observed. The type (Cl or Br) and the position (Cl) of the chalogen atom strongly influence the degree of inhibition of PSII electron transport and the quenching of chlorophyll fluorescence. The data suggest that the quenching of chlorophyll fluorescence is due rather to the interaction of the 1,4-anthraquinones and chlorophyll molecules than to an indirect effect caused by stimulation of the photochemistry.
Journal of Organic Chemistry, 1988
Journal of Organic Chemistry, 1989
Synthesis of 4,11-Dideoxydaunomycinone C, 70.80; H, 7.92. Found: C, 70.37; H, 7.91. Acyclic Napht... more Synthesis of 4,11-Dideoxydaunomycinone C, 70.80; H, 7.92. Found: C, 70.37; H, 7.91. Acyclic Naphthol Diketone 16. To a suspension of hexane-washed NaH (0.04 g, 1.64 mmol) in 2 mL of THF was added a solution of ketone 15 (0.53 g, 1.49 mmol) in THF. The resulting solution was stirred at 0 "C for 15 min. A solution of acid chloride 13 (0.34 g, 1.64 mmol) in THF was added dropwise, and the solution was stirred at 0 "C for 30 min. The solution was then cooled to -78 "C, and LDA (3.28 mmol) in THF was added dropwise. The solution was then stirred for 15 min. It was diluted with water and acidified to pH 6 with 6 N HC1. The aqueous layer was extracted with ether. The combined organic layers were washed with brine, dried, and concentrated. The crude product was purified by flash chromatography with 7:l hexanes-ethyl acetate to afford 0.58 g of ketone 16 (74% yield). NMR (CDCI,): 6 0.17 (s, 6 H), 1.10 (s, 9 H), 1.96 (s, 3 H), 3.40-3.75 (m, 6 H), 4.9-5.1 (m, 2 H), 5.90-5.97 (m, 1 H), 6.02 (d, J = 16 Hz, 1 H), 7.00 (d, J = 16 Hz, 1 H), 7.5-7.6 (m, 2 H), 7.97 (d, J = 8.4 Hz, 1 H), 8.34
Bioorganic & Medicinal Chemistry Letters, 2011
BACE1 activity, inhibition of Aβ aggregation, and disaggregation of preformed Aβ fibrils constitu... more BACE1 activity, inhibition of Aβ aggregation, and disaggregation of preformed Aβ fibrils constitute the three major targets in the development of small-molecule lipophilic new drugs for the treatment of Alzheimer’s disease (AD). Quinones are widely distributed among natural products and possess relevant and varied biological activities including antitumor and antibiotic, inhibition of HIV-1 reverse transcriptase, antidiabetic, or COX-inhibition, among others. We report herein the interaction of several arylquinones and their derivatives with the amyloidogenic pathway of the amyloid precursor protein processing. Our studies put forward that these compounds are promising candidates in the development of new drugs which are effective simultaneously towards the three major targets of AD.