Mechanistic studies of the enolization of 2-methylcyclohexanone mediated by lithium hexamethyldisilazide (LiHMDS; TMS2NLi) in toluene and toluene/amine mixtures are described. NMR spectroscopic studies of LiHMDS/ketone mixtures in toluene reveal the ketone-complexed cyclic dimer (TMS2NLi)2(ketone). Rate studies using in situ IR spectroscopy show the enolization proceeds via a dimer-based transi...

Elite athletes and coaches are in a constant search for training methods and nutritional strategies to support training and recovery efforts that may ultimately maximize athletes' performance. Recently, there has been a re-emerging interest in the role of ketone bodies in exercise metabolism, with considerable media speculation about ketone body supplements being routinely used by professional ...

BACKGROUND Raspberry ketone is the primary aroma compound found in raspberries and naturally derived raspberry ketone is a valuable flavoring agent. The economic incentives for the production of raspberry ketone, combined with the very poor yields from plant tissue, therefore make this compound an excellent target for heterologous production in synthetically engineered microbial strains. METH...

Bioassay-guided fractionation of a CH(2)Cl(2)-MeOH extract of the aerial parts of Albizia inundata resulted in the isolation of two new natural oleanane-type triterpene saponins {3-O-[α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl oleanolic acid (1) and 3-O-[α-L-arabinopyranosyl(1→2)-α-L-arabinopyranosyl(1→6)]-2-acetamido-2-deoxy-β-D-glucopyranosyl acacic acid lactone (2)} al...

BACKGROUND Paullinia pinnata L. (Sapindaceae) is an African woody vine, which is widely used in traditional medicine for the treatment of human malaria, erectile dysfunction and bacterial infections. A phytochemical investigation of its methanol leaf and stem extracts led to the isolation of seven compounds which were evaluated for their antimicrobial properties. METHODS The extracts were fra...

Bacillus pumilus strain Sh18 cell wall polysaccharide (CWP), cross-reactive with the capsular polysaccharide of Haemophilus influenzae type b, was purified and its chemical structure was elucidated using fast atom bombardment mass spectrometry, nuclear magnetic resonance techniques, and sugar-specific degradation procedures. Two major structures, 1,5-poly(ribitol phosphate) and 1,3-poly(glycero...

Muramic acid is found in many peptide natural products containing oligo(poly)saccharide moieties. Taking into consideration that the Fmoc methodology is routinely used for solid-phase peptide synthesis, preparation of orthogonally protected muramic acid building blocks for total solid-phase synthesis of these natural products is of particular practical importance. Herein a simple and efficient ...

The endo-type chitin deacetylase (EC 3.5.1.41) from a deuteromycete, Colletotrichum lindemuthianum (ATCC 56676), catalyses the hydrolysis of the acetamido group of GlcNAc (2-acetamido-2-deoxy-D-glucose) residues in chitin or chito-oligosaccharides with a degree of polymerization (n) equal to or greater than 2. The steady-state kinetic parameters for the initial deacetylation reactions of (GlcNA...