ABSTRACT
Synthesis of water soluble porphyrin and phthalocyanine derivatives with, respectively, eight and sixteen galactose units has been carried out. The combined preliminary photophysical and photochemical features of the new products suggest that they might be promising photodynamic therapeutic agents.
Subject(s)
Galactose/chemistry , Indoles/chemistry , Porphyrins/chemistry , Galactose/radiation effects , Humans , Indoles/radiation effects , Isoindoles , Photochemical Processes , Photochemotherapy , Porphyrins/radiation effects , Serum Albumin/chemistry , Singlet Oxygen/chemistry , Ultraviolet RaysABSTRACT
All eight D-aldohexoses and aldohexoses derived from the non-reducing end of disaccharides were investigated by variable-wavelength infrared multiple-photon dissociation (IRMPD) as anions in the negative-ion mode. Spectroscopic evidence supports the existence of a relatively abundant open-chain configuration of the anions in the gas phase, based on the observation of a significant carbonyl absorption band near 1710 cm(-1). The abundance of the open-chain configuration of the aldohexose anions was approximately 1000-fold or greater than that of the neutral sugars in aqueous solution. This provides an explanation as to why it has not been possible to discriminate the anomeric configuration of aldohexose anions in the gas phase when derived from the non-reducing sugar of a disaccharide. Evidence from photodissociation spectra also indicates that the different aldohexoses yield product ions with maximal abundances at different wavelengths, and that the carbonyl stretch region is useful for differentiation of sugar stereochemistries. Quantum-chemical calculations indicate relatively low energy barriers to intramolecular proton transfer between hydroxyl groups and adjacent alkoxy sites located on open-chain sugar anions, suggesting that an ensemble of alkoxy charge locations contributes to their observed photodissociation spectra. Ring opening of monosaccharide anions and interconversion among configurations is an inherent property of the ions themselves and occurs in vacuo independent of solvent participation.
Subject(s)
Disaccharides/chemistry , Hexoses/chemistry , Infrared Rays , Anions , Carbohydrate Conformation , Fourier Analysis , Galactose/chemistry , Galactose/radiation effects , Gases , Glucose/chemistry , Glucose/radiation effects , Hexoses/radiation effects , Hydrogen Bonding , Lactones/chemistry , Lactones/radiation effects , Lasers , Mannose/chemistry , Mannose/radiation effects , Mass Spectrometry , Models, Molecular , Spectrophotometry, InfraredABSTRACT
Glucose, galactose, and mannose in H(2)O and D(2)O were ionized by an atmospheric pressure chemical ionization (APCI) method. Isotope effects on fragmentation patterns of the monosaccharides were examined by deuterium replacement of the -OH groups to distinguish the isomers with a single mass spectrometer. The most abundant ions were the [M+H(2)O](+)() and [M(D5)+D+D(2)O](+) for using H(2)O and D(2)O as solvent and eluent, respectively. Major fragment ions were the [M-OH](+) and [M-OH-H(2)O](+) in H(2)O, while those in D(2)O were the [M(D5)+D-D(2)O](+) and [M(D5)+D-2D(2)O](+). The differences in the product ions generated in H(2)O and D(2)O were due to enhancement of the strength of hydrogen bonding by the deuterium replacement. Variations of the ion intensity ratios of the [M-OH](+)/[M-OH-H(2)O](+) and [M(D5)-OD](+)/[M(D5)-OD-D(2)O](+) with the fragmentor voltage showed different trends depending on the kind of monosaccharides. By comparing the ion intensity ratios of the [M+H(2)O](+)()/M(+)(), [M(D5)+D+D(2)O](+)/[M(D5)+D](+), [M-OH](+)/[M-OH-H(2)O](+), and [M(D5)+D-D(2)O](+)/[M(D5)+D-2D(2)O](+), it was possible to distinguish the isomers of monosaccharides.
Subject(s)
Deuterium , Galactose/chemistry , Glucose/chemistry , Ions/chemistry , Mannose/chemistry , Atmospheric Pressure , Chemical Phenomena , Deuterium Exchange Measurement , Galactose/radiation effects , Glucose/radiation effects , Mannose/radiation effectsABSTRACT
Carbohydrate-based divalent and tetravalent lactoside glycodendrons were constructed in a convergent manner. The dendrons were synthesized beginning with the photoaddition of hepta-O-acetyl-1-thio-beta-lactose, in an anti-Markovnikov manner, to a bis-allyl AB2 trisaccharide to form a divalent dendron. Following two nearly quantitative deprotection steps, the divalent lactoside was coupled to another AB2 trisaccharide by reductive amination to afford a tetravalent dendron. These paucivalent compounds were characterized by NMR spectroscopy and mass spectrometry.