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1.
Biomater Sci ; 8(22): 6246-6260, 2020 Nov 21.
Article in English | MEDLINE | ID: mdl-33016285

ABSTRACT

Intravitreal administration is widely used in ophthalmological practice to maintain therapeutic drug levels near the neuroretina and because drug delivery systems are necessary to avoid reinjections and sight-threatening side effects. However, currently there is no intravitreal treatment for glaucoma. The brimonidine-LAPONITE® formulation was created with the aim of treating glaucoma for extended periods with a single intravitreal injection. Glaucoma was induced by producing ocular hypertension in two rat cohorts: [BRI-LAP] and [non-bri], with and without treatment, respectively. Eyes treated with brimonidine-LAPONITE® showed lower ocular pressure levels up to week 8 (p < 0.001), functional neuroprotection explored by scotopic and photopic negative response electroretinography (p = 0.042), and structural protection of the retina, retinal nerve fibre layer and ganglion cell layer (p = 0.038), especially on the superior-inferior axis explored by optical coherence tomography, which was corroborated by a higher retinal ganglion cell count (p = 0.040) using immunohistochemistry (Brn3a antibody) up to the end of the study (week 24). Furthermore, delayed neuroprotection was detected in the contralateral eye. Brimonidine was detected in treated rat eyes for up to 6 months. Brimonidine-LAPONITE® seems to be a potential sustained-delivery intravitreal drug for glaucoma treatment.


Subject(s)
Glaucoma , Neuroprotective Agents , Animals , Brimonidine Tartrate , Follow-Up Studies , Glaucoma/drug therapy , Rats , Silicates
2.
Bioresour Technol ; 102(3): 2590-4, 2011 Feb.
Article in English | MEDLINE | ID: mdl-21035329

ABSTRACT

One of the main drawbacks of the use of biodiesel is its bad behavior at low temperatures. In this work, we show that it is possible to take profit of the presence of free fatty acids in the starting materials used for biodiesel production (i.e. reused oils) by synthesizing additives able to improve cold flow properties. The synthesis of fatty acid derivatives have been successfully carried out by esterification of stearic, oleic and linoleic acids with bulky linear and cyclic alcohols and by epoxidation of methyl oleate and subsequent ring-opening reaction with the same alcohols. The study of crystallization patterns of pure derivatives by DSC and optical microscopy revealed the improvement of cold properties of biodiesel. Blends of biodiesel with up to 5% of some of these compounds allowed a decrease of CFPP (Cold Filter Pour Point). Both observations reveal the utility of these compounds as cheap and renewable additives.


Subject(s)
Biofuels , Conservation of Natural Resources/methods , Fatty Acids/chemistry , Temperature , Viscosity
3.
J Org Chem ; 72(12): 4344-50, 2007 Jun 08.
Article in English | MEDLINE | ID: mdl-17500566

ABSTRACT

Supported catalysts having pybox chiral moieties were prepared as macroporous monolithic miniflow systems. These catalysts are based on styrene-divinylbenzene polymeric backbones having different compositions and pybox chiral moieties. Their corresponding ruthenium complexes were tested for the continuous flow cyclopropanation reaction between styrene and ethyldiazoacetate (EDA) under conventional conditions and in supercritical carbon dioxide (scCO2). Ru-Pybox monolithic miniflow reactors not only provided a highly efficient and robust heterogeneous chiral catalyst but also allowed us to develop more environmental reaction conditions without sacrificing the global efficiency of the process.

4.
Bioorg Med Chem Lett ; 12(14): 1821-4, 2002 Jul 22.
Article in English | MEDLINE | ID: mdl-12086825

ABSTRACT

A functionalized chiral bis(oxazoline) is used as a chiral monomer in polymerization reactions leading to homo- and copolymers of different morphology. Polymers with a high content of chiral monomer lead to enantioselectivities that are higher than those obtained with the soluble ligand, but the chiral ligand is not used in an optimal way. A hyperbranched polymer, obtained by using a hexavinyldendrimer as the cross-linker, leads to the same enantioselectivities with a more efficient use of the chiral ligand.


Subject(s)
Oxazoles/chemistry , Polymers/chemistry , Catalysis , Copper/chemistry , Cross-Linking Reagents/chemical synthesis , Cyclopropanes/chemistry , Diazonium Compounds/chemistry , Ligands , Polystyrenes/chemistry , Spectroscopy, Fourier Transform Infrared , Spectrum Analysis, Raman , Stereoisomerism
5.
J Org Chem ; 66(26): 8893-901, 2001 Dec 28.
Article in English | MEDLINE | ID: mdl-11749620

ABSTRACT

Chiral bis(oxazolines) are readily dialkylated in the methylene bridge, opening the way to immobilization at that position, keeping the C(2) symmetry of the chiral ligand. Bis(oxazolines) functionalized with two allyl or vinylbenzyl groups are easily grafted onto mercaptopropylsilica. Another approach to immobilization is the polymerization of the ligands bearing vinylbenzyl groups to yield insoluble polymers. The Cu(OTf)(2) complexes of the immobilized ligands promote the enantioselective cyclopropanation reaction between styrene and ethyl diazoacetate. The results depend on the nature of the support and the method of immobilization. With regard to the type of solid, the best results, which are similar to or even better than those obtained with the corresponding dibenzylated homogeneous catalysts, are obtained with homopolymers. With regard to the bis(oxazoline), that bearing indan groups leads to good results both onto silica and polymers, whereas with the ligand bearing tert-butyl groups good enantioselectivities are only obtained with homopolymeric catalysts. Some of the heterogeneous catalysts can be easily recovered and reused, as much as five times, with the same yield and stereoselectivities.

6.
J Am Chem Soc ; 123(31): 7616-25, 2001 Aug 08.
Article in English | MEDLINE | ID: mdl-11480983

ABSTRACT

The mechanism of the copper(I)-catalyzed cyclopropanation reaction has been extensively investigated for a medium-size reaction model by means of B3LYP/6-31G(d) calculations. The starting ethylene complex of the N,N'-dimethylmalonaldiimine--copper (I) catalyst undergoes a ligand exchange with methyl diazoacetate to yield a reaction intermediate, which subsequently undergoes nitrogen extrusion to generate a copper--carbene complex. The cyclopropanation step takes place through a direct carbene insertion of the metal--carbene species to yield a catalyst--product complex, which can finally regenerate the starting complex. The stereochemical predictions of a more realistic model (by considering a chiral bis(oxazoline)--copper (I) catalyst) have been rationalized in terms of steric repulsions, showing good agreement with experimental data.

7.
Acc Chem Res ; 33(10): 658-64, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11041829

ABSTRACT

A revision of the most typical examples used to illustrate the existence of secondary orbital interactions (SOI) has been achieved. However, our analysis indicates that no conclusive evidence can be obtained from these cases. All five examples proposed by Woodward and Hoffmann in The Conservation of Orbital Symmetry have been revisited. A combination of well-known mechanisms (such as solvent effects, steric interactions, hydrogen bonds, electrostatic forces, and others) can be invoked instead to justify the endo/exo selectivity of Diels-Alder reactions.


Subject(s)
Chemistry , Chemical Phenomena , Furans/chemistry , Maleic Anhydrides/chemistry , Static Electricity , Thermodynamics
8.
Am J Clin Nutr ; 68(6 Suppl): 1354S-1357S, 1998 12.
Article in English | MEDLINE | ID: mdl-9848498

ABSTRACT

Intake of soyfoods containing isoflavonoids is related to positive effects on heart and kidney diseases. Urinary equol, a potent inhibitor of Na+-K+-2Cl- cotransport, originates from the metabolism of daidzein by intestinal bacteria. Loop diuretics (eg, furosemide), acting through inhibition of Na+-K+-2Cl- cotransport, are used to maintain adequate blood volume. In the present work, we compare isoflavonoids' inhibition of cotransport and effects on the function and hemodynamics of isolated perfused rat kidneys with those of furosemide. Equol [IC50 (half-maximal inhibitory concentration): 23.6 +/- 3.6 micromol/L], genistein (IC50: 34.8 +/- 2.6 micromol/L), and daidzein (IC50: 140.0 +/- 24 micromol/L) inhibited bumetanide-sensitive rubidium uptake in LLC-PK1 cells. The IC50 of equol and genistein was close to that of furosemide (IC50: 10.3 +/- 2.7 micromol/L). Furosemide, equol, and genistein stimulated water, sodium, and potassium excretion by isolated rat kidneys in the same temporal pattern. None of the isoflavonoids significantly increased the glomerular filtration rate, but genistein induced significant vasorelaxation. We conclude that isoflavonoids exhibit biological activities of furosemide in vitro, at concentrations similar to those reported for other in vitro effects. More research is needed to evaluate the participation of cotransport inhibition by isoflavonoids in the healthful effects claimed for soy intake.


Subject(s)
Diuretics/pharmacology , Furosemide/pharmacology , Ion Transport/drug effects , Isoflavones/pharmacology , Kidney/drug effects , Soybean Proteins/pharmacology , Animals , Chromans/pharmacology , Diuresis/drug effects , Enzyme Inhibitors/pharmacology , Equol , Genistein/pharmacology , Glomerular Filtration Rate/drug effects , Hemodynamics/drug effects , Monoamine Oxidase Inhibitors/pharmacology , Natriuresis/drug effects , Rats
9.
Hypertension ; 31(2): 706-11, 1998 Feb.
Article in English | MEDLINE | ID: mdl-9461244

ABSTRACT

The urinary isoflavonoid genistein inhibits membrane Na-K-Cl cotransporters at similar concentrations as furosemide, but the significance of this action is unknown. Genistein was therefore investigated in rats for its potential salidiuretic actions. In the isolated, perfused rat kidney, genistein induced a maximal salidiuretic action similar to that of furosemide but was 3 to 5 times less potent than furosemide in terms of active doses (natriuresis EC50, 237+/-92 versus 56+/-20 micromol/L for genistein and furosemide, respectively). Genistein and furosemide had no additive salidiuretic actions. Genistein had no significant effect on glomerular filtration rate but was able to significantly reduce renal vascular resistance with respect to vehicle isolated perfused kidney. Indomethacin (10 micromol/L), a blocker of prostaglandin biosynthesis, reduced salidiuresis and renal vasorelaxation by genistein. Subcutaneous genistein (15 mg/kg) induced a statistically significant increase in diuresis and natriuresis with respect to vehicle during the first 6 hours of administration in rats. In conclusion, genistein compares well with furosemide in vitro for its salidiuretic profile and potency in the isolated perfused rat kidney and is also natriuretic by the subcutaneous route in the rat. Further studies are required to investigate potential natriuretic and perhaps hypotensive actions of dietary genistein.


Subject(s)
Carrier Proteins/antagonists & inhibitors , Diuretics/pharmacology , Genistein/pharmacology , Kidney/drug effects , Animals , In Vitro Techniques , Injections, Subcutaneous , Isoflavones/pharmacology , Kidney/metabolism , Male , Perfusion , Rats , Rats, Wistar , Sodium-Potassium-Chloride Symporters
10.
J Hypertens ; 15(11): 1303-8, 1997 Nov.
Article in English | MEDLINE | ID: mdl-9383180

ABSTRACT

BACKGROUND: The urinary isoflavonoid equol inhibits membrane Na-K-Cl cotransporters at similar concentrations to those at which furosemide inhibits them, but the significance of this action is not known. OBJECTIVE: To investigate the potential salidiuretic and vascular actions of equol in the rat. METHODS: Renal functioning was assessed in vitro in the isolated perfused kidney and in vivo in conscious rats. The vascular contractility of isolated aorta was assessed. RESULTS: In the isolated perfused kidney equol was concentrated 50- to 70-fold in the urinary fluid, it was 3-4 times less potent than furosemide at increasing diuresis, natriuresis and kaliuresis (the difference was due to its higher protein-binding affinity), and it induced a modest but significant increase in glomerular filtration rate. In vivo, orally administered equol was a modest natriuretic agent, about 8-fold less potent than orally administered furosemide (in molar terms). In isolated aortic rings precontracted by administration of phenylephrine, administration of equol relaxed the contracted aorta at 10-fold lower concentrations (concentration for half-maximal activity 58.9 +/- 16 micromol/l, n = 3) than did furosemide (concentration for half-maximal activity 633 +/- 145 micromol/l, n = 3). CONCLUSIONS: Equol is a modest natriuretic and vasorelaxant agent in the rat. Further studies are required in order to investigate the potential natriuretic and perhaps hypotensive actions of dietary equol precursors (daidzein).


Subject(s)
Chromans/pharmacology , Isoflavones , Kidney/drug effects , Muscle, Smooth, Vascular/drug effects , Animals , Aorta/drug effects , Equol , In Vitro Techniques , Male , Muscle, Smooth, Vascular/physiology , Natriuresis/drug effects , Perfusion , Rats , Rats, Wistar , Serum Albumin/metabolism , Vasodilation/drug effects
11.
Biochem Biophys Res Commun ; 221(2): 279-85, 1996 Apr 16.
Article in English | MEDLINE | ID: mdl-8619846

ABSTRACT

A potent inhibitor of the Na-K-Cl cotransport system was purified from urines of salt-loaded rats. Mass spectroscopy revealed a molecular mass of 242 Da. Nuclear magnetic resonance showed a spectrum identical to that of 3,4-dihydro-3-(4-hydroxyphenyl)-2H-1-benzopyran-7-ol (an "estrogen-like" isoflavonoid: equol). This compound inhibited cotransport fluxes at similar concentrations (IC50=16-24 microM) as furosemide (IC50 approximately 10 microM). Cotransport inhibitory activity of urines from rats drinking tap water was fully explained by urinary equol concentrations (approximately 27 microM, measured by high-performance liquid chromatography). Slat-loading increased urinary equol excretion, but not sufficiently high to fully explain the very important increase in cotransport inhibitory potency. We conclude that: (i) under basal conditions urinary equol can regulate Na-K-Cl cotransport activity in the kidney and (ii) salt-loading should evoke the appearance of other cotransport inhibitors.


Subject(s)
Carrier Proteins/antagonists & inhibitors , Chromans/isolation & purification , Isoflavones , Animals , Chlorides/metabolism , Chromans/chemistry , Chromans/urine , Equol , Magnetic Resonance Spectroscopy , Mass Spectrometry , Potassium/metabolism , Rats , Rats, Wistar , Sodium/metabolism , Sodium-Potassium-Chloride Symporters
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