Hydroxylated Derivative (hydroxylated + derivative)

Distribution by Scientific Domains

Selected Abstracts

High-performance liquid chromatography/electrospray ionization tandem mass spectrometry of hydroxylated uroporphyrin and urochlorin derivatives formed by photochemical oxidation of uroporphyrinogen I

Malcolm Danton
Abstract Hydroxylated uroporphyrin I and urochlorin I derivatives formed by photochemical oxidation of uroporphyrinogen I were separated by high-performance liquid chromatography and fully characterized by electrospray ionization tandem mass spectrometry. The porphyrins and chlorins were identified by analysis of their product ion spectra with each hydroxylated derivative giving a characteristic collision-induced dissociation fragmentation pattern. The porphyrins and chlorins characterized were meso -hydroxyuroporphyrin I, , -hydroxypropionic acid uroporphyrin I, , -hydroxypropionic acid uroporphyrin I, hydroxyacetic acid uroporphyrin I, trans- 7-hydroxy-8-spirolactoneurochlorin I, cis- 7-hydroxy-8-spirolactoneurochlorin I and trans- and cis- 7,8-dihydroxyurochlorins I. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Dissection of the Late Steps in Aureothin Biosynthesis

CHEMBIOCHEM, Issue 1 2006
Markus Müller
Part of the queue. Biosynthesis of the cytostatic polyketide aureothin (1) in Streptomyces thioluteus was found to involve two tailoring steps (see scheme). Mutational biosynthesis of nor -deoxyaureothin (,- 2) and a hydroxylated derivative (3), together with biotransformation experiments revealed a well-defined order for the polyketide-tailoring steps. Regioselective ,-pyrone methylation was found to be the penultimate biosynthetic step prior to furan-ring formation. [source]

Importance of hydrogen-bonding sites in the chiral recognition mechanism between racemic D3 terbium(III) complexes and amino acids

CHIRALITY, Issue 5 2009
Ahmed Moussa
Abstract The perturbation of the racemic equilibrium of luminescent D3 terbium(III) complexes with chelidamic acid (CDA), a hydroxylated derivative of 2,6-pyridine-dicarboxylic acid (DPA), by added chiral biomolecules such as L -amino acids has been studied using circularly polarized luminescence and 13C NMR spectroscopy. It is shown in this work that the chiral-induced equilibrium shift of [Tb(CDA)3]6, by L -amino acids (i.e. L -proline or L -arginine) was largely influenced by the hydrogen-bonding networks formed between the ligand interface of racemic [Tb(CDA)3]6, and these added chiral agents. The capping of potential hydrogen-bonding sites by acetylation in L -proline led to a ,100-fold drop in the induced optical activity of the [Tb(CDA)3]6,:N -acetyl- L -proline system. This result suggested that the hydrogen-bonding networks serve as the basis for further noncovalent discriminatory interactions between racemic [Tb(CDA)3]6, and added L -amino acids. Chirality, 2009. © 2008 Wiley-Liss, Inc. [source]

Structural determination of two new triterpenoids biotransformed from glycyrrhetinic acid by Mucor polymorphosporus

Xiu Lan Xin
Abstract Five hydroxylated derivatives of glycyrrhetinic acid by Mucor polymorphosporus were isolated. Among them, 6,, 7,-dihydroxyglycyrrhentic acid (2) and 27-hydroxyglycyrrhentic acid (3) are new compounds. Their chemical structures were identified by spectral methods including 2D-NMR. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A novel approach for identification and measurement of hemoglobin adducts with 1,2,3,4-diepoxybutane by liquid chromatography/electrospray ionisation mass spectrometry and matrix-assisted laser desorption/ionisation tandem mass spectrometry

Adriana Basile
The structural characterisation of the adducts formed by in vitro interaction of hemoglobin (Hb) with 1,2,3,4-diepoxybutane (DEB), the most reactive 1,3-butadiene (BD) metabolite, was obtained by liquid chromatography/electrospray ionisation mass spectrometry (LC/ES-MS) analysis of modified tryptic peptides of human hemoglobin chains. The reactive sites of human hemoglobin towards DEB and its hydroxylated derivatives (trihydroxybutyl (THB)-derivatives) were identified through the characterisation of alkylated tryptic peptides by matrix-assisted laser desorption/ionisation tandem mass spectrometry (MALDI-MS/MS). Based on this characterisation, a procedure was set up to measure the Hb-adducts of THB-derivatives by isotope dilution mass spectrometry with the use of a deuterated peptide standard. The results obtained here could permit optimisation of molecular dosimetry of BD-adducts, and extension of the analysis to the biological monitoring of occupational exposure to butadiene. Copyright © 2001 John Wiley & Sons, Ltd. [source]