ABSTRACT
The objective of this present investigation was to develop and formulate floating sustained release matrix tablets of s (-) atenolol, by using different polymer combinations and filler, to optimize by using surface response methodology for different drug release variables and to evaluate the drug release pattern of the optimized product. Floating sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: Hydroxypropyl methylcellulose, sodium bicarbonate as a gas generating agent, polyvinyl pyrrolidone as a binder and lactose monohydrate as filler. The 3(2) full factorial design was employed to investigate the effect of formulation variables on different properties of tablets applicable to floating lag time, buoyancy time, % drug release in 1 and 6 h (D1 h,D6 h) and time required to 90% drug release (t90%). Significance of result was analyzed using analysis of non variance and P < 0.05 was considered statistically significant. S (-) atenolol floating sustained release matrix tablets followed the Higuchi drug release kinetics that indicates the release of drug follows anomalous (non-Fickian) diffusion mechanism. The developed floating sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet.
ABSTRACT
Tri-n-butyltin hydride mediated ring opening of 1,2-cyclo- propanated-D-glycals led to the formation of 1-C-methyl 2,3-unsaturated sugars. However, corresponding catalytic version provided an unusual S-methylglycosyl-S-methyldithiocarbonate derivative whose mechanism of formation has been proposed.
ABSTRACT
Syntheses of the ethyl glycosides of 5-O-(beta-D-galactofuranosyl)-beta-D-galactofuranose and 5-O-(alpha-D-arabinofuranosyl)-6-O-(beta-D-galactofuranosyl)-beta-D-galactofuranose present in motifs D and E of Mycobacterium tuberculosis arabinogalactan, respectively, have been presented. The pentenyl-mediated O-glycosylation reaction was utilized to obtain the disaccharide of motif D. The first coupling reaction to prepare the inner disaccharide portion of motif E was accomplished by trichloroacetamidate method while the installation of the terminal sugar by pentenyl glycosylation approach was successful.
Subject(s)
Galactans/chemical synthesis , Mycobacterium tuberculosis/chemistry , Oligosaccharides/chemical synthesis , Carbohydrate Sequence , Galactans/chemistry , Molecular Conformation , Oligosaccharides/chemistryABSTRACT
[figure: see text] The stereocontrolled synthesis of the trisaccharide ethyl 5-O-(alpha-D-arabinofuranosyl)-6-O-(beta-D-galactofuranosyl)- beta-D-galactofuranoside present in motif E of the Mycobacterium tuberculosis cell wall is described.
Subject(s)
Polysaccharides, Bacterial/chemistry , Trisaccharides/chemistry , Trisaccharides/chemical synthesis , Carbohydrate Conformation , Carbohydrate Sequence , Cell Wall/metabolism , Molecular Sequence Data , Mycobacterium tuberculosis/metabolism , Polysaccharides, Bacterial/metabolismSubject(s)
Lipopolysaccharides/chemistry , Mycobacterium/chemistry , Trisaccharides/chemistry , Trisaccharides/chemical synthesis , Carbohydrate Conformation , Carbohydrate Sequence , Humans , Indicators and Reagents , Lipopolysaccharides/chemical synthesis , Magnetic Resonance Spectroscopy , Molecular Sequence Data , Mycobacterium/isolation & purification , Optical RotationSubject(s)
Antigens, Bacterial/chemistry , Disaccharides/chemical synthesis , Lipopolysaccharides/chemistry , Mycobacterium/chemistry , Trisaccharides/chemical synthesis , Carbohydrate Sequence , Fucose/analogs & derivatives , Glucosides/chemical synthesis , Molecular Sequence Data , Rhamnose/analogs & derivativesABSTRACT
Syntheses of the title glycosides are described. The critical O-glycosylations were carried out in the presence of boron trifluoride etherate with a high degree of alpha-selectivity.
Subject(s)
Antigens, Bacterial , Disaccharides/chemical synthesis , Glycolipids/chemistry , Mycobacterium/chemistry , Trisaccharides/chemical synthesis , Carbohydrate Sequence , Fucose/analogs & derivatives , Molecular Sequence Data , Rhamnose/analogs & derivativesABSTRACT
1H and 13C NMR study of 3'-azido-2',3'-dideoxyribosylthymine (AZT), an inhibitor of HIV (human immunodeficiency virus) replication, has been undertaken. Modified Karplus relations have been used to obtain the molecular structure from the indirect coupling constants. NMR results are consistent with an anti glycosyl angle, a sugar pucker with equilibrium between C2'-endo and C3'-endo geometries and a predominantly g+ conformation about C4'-C5' bond. These results are in variance with those obtained in the solid state by X-ray diffraction studies.
