Fingerprinting of hydroxyl radical-attacked polysaccharides by N-isopropyl-2-aminoacridone labelling

Hydroxyl radicals ((•)OH) cause non-enzymic scission of polysaccharides in diverse biological systems. Such reactions can be detrimental (e.g. causing rheumatic and arthritic diseases in mammals) or beneficial (e.g. promoting the softening of ripening fruit, and biomass saccharification). Here we present a method for documenting (•)OH action, based on fluorescent labelling of the oxo groups that are introduced as glycosulose residues when (•)OH attacks polysaccharides. The method was tested on several polysaccharides, especially pectin, after treatment with Fenton reagents. 2-Aminoacridone plus cyanoborohydride reductively aminated the oxo groups in treated polysaccharides; the product was then reacted with acetone plus cyanoborohydride, forming a stable tertiary amine with the carbohydrate linked to N-isopropyl-2-aminoacridone (pAMAC). Digestion of labelled pectin with ‘Driselase’ yielded several fluorescent products which on electrophoresis and HPLC provided a useful ‘fingerprint’ indicating (•)OH attack. The most diagnostic product was a disaccharide conjugate of the type pAMAC·UA-GalA (UA=unspecified uronic acid), whose UA-GalA bond was Driselase-resistant (product 2A). 2A was clearly distinguishable from GalA-GalA–pAMAC (disaccharide labelled at its reducing end), which was digestible to GalA–pAMAC. The methodology is applicable, with appropriate enzymes in place of Driselase, for detecting natural and artificial (•)OH attack in diverse plant, animal and microbial polysaccharides

5-HT1A receptor agonist-mediated protection from MPTP toxicity in mouse and macaque models of Parkinson's disease

Excitotoxicity-mediated cell death is involved in Parkinson's disease (PD). 5-HT1A receptor agonists can protect from such mechanisms. The current study demonstrates that the 5-HT1A agonists BAY 639044 and repinotan have neuroprotective effects in a subacute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. In addition, we also show that both compounds delay the appearance of parkinsonian motor abnormalities in a MPTP monkey model that recapitulates the progressive nature of PD. Thus, BAY 639044 or repinotan treatment was initiated when there was 30% neuronal death in the substantia nigra pars compacta, and nerve terminal loss in the striatum was 40%, i.e., compatible with the clinical situation where early symptomatic patients would receive such a treatment. The delay in appearance of parkinsonian motor abnormalities is a consequence of partial neuroprotection of nigrostriatal dopamine neurons, both at neuronal and terminal levels as shown for BAY 639044. These results suggest that 5-HT1A agonists, such as BAY 639044, may protect from neurodegeneration and delay the worsening of motor symptoms in Parkinson patients. © 2006.Peer Reviewe