ANALYTICAL APPROACHES IN THE DISCOVERY OF INHIBITORS OF DEGENERATIVE DISORDERS INDUCED BY CARBONYL STRESS
Tesi di Dottorato
Data di Pubblicazione:
2009
Citazione:
ANALYTICAL APPROACHES IN THE DISCOVERY OF INHIBITORS OF DEGENERATIVE DISORDERS INDUCED BY CARBONYL STRESS / M.c. Benfatto ; tutor: Marina Carini ; coordinatore Carlo de Micheli. DIPARTIMENTO DI SCIENZE FARMACEUTICHE "PIETRO PRATESI", 2009. 22. ciclo, Anno Accademico 2006/2007.
Abstract:
Among the molecular mechanisms responsible of oxidative damage involved in the pathogenesis and/or progression of several degenerative disorders including aging, inflammation, diabetes, cardiovascular and neurodegenerative diseases, structure modification of protein, lipids and nucleic acids induced by reactive oxygen species (ROS) and reactive carbonyl species (RCS) derived from lipid oxidation plays a key role. RCS, characterized by a keto/aldehydic function, are important cytotoxic mediators, since by inducing irreversible structural modifications to biomolecules, lead to alteration of the cellular function [1-4].
Most of the biological effects of RCS generated by oxidation of omega-6 polyunsaturated fatty acids, such as dialdehydes (malondiladehyde, glyoxal) and alpha,beta-unsaturated aldehydes, 4-hydroxy-trans-2-nonenal (HNE) and acrolein, are attributed to their strong electrophilic nature: these compounds can react, through a Michael addition, with the nucleophilic sites of proteins/peptides (lysine, cysteine and histidine residues), and with nucleic acids (deoxyguanosine) to form covalently modified biomolecules which can alter/disrupt important cellular functions and induce mutations [2].
The causal involvement of unsaturated aldehydes in the lipid peroxidation-mediated pathologies has been only recently demonstrated by the use of mono- and poli-clonal antibodies raised against HNE or acrolein [5]. HNE or acrolein adducts with proteins have been immunohistochemically detected in bioptic and autoptic specimens of subjects affected by diabetes, atherosclerosis, muscolar distrophy, rheumatoid arthtritis, actinic elastosis, cerebral ischemia, and neurodegenerative disorders such as Alzheimer's and Parkinson's diseases [5-9].
Hence, RCS can be considered an important target for the development of a new class of biologically active compounds with carbonyl-quencher properties, nucleophilic compounds able to deactivate the reactive carbonyl function through the formation of Michael adducts or Schiff bases, as demonstrated for aminoguanidine, hydralazine and pyridoxamine [8, 10].
However, the low selectivity towards lipoxidation-derived aldehydes represents the main limiting factor to the pharmacological use of these compounds: hydralazine and aminoguanidine, being characterized by a strong nucleophilic center, react not only with RCS, but also with physiologically relevant aldehydes (pyridoxal phosphate, Schiff base formation), inducing their depletion. In addition, the promiscuous activity of some RCS quenchers, as aminoguanidine (inhibitory action on inducible NO-synthase) or hydralazine (vasodilating and antihypertensive effect) greatly limits their clinical use as carbonyl trapping agents [11].
On the basis of these considerations, we have undertaken in the last years a research program with the aim to identify endogenous peptides able to quench RCS, and in particular the most toxic alfa,beta-unsaturated aldehydes. The strategy was firstly based on a peptidomic approach focused to identify endogenous compounds involved in the detoxification of RCS in those tissues (skeletal muscle) highly susceptible of oxidative attack [12]. This approach allowed identifying, besides GSH, a series of histidine-containing peptides such as carnosine (β-alanyl-L-histidine), anserine and homocarnosine (gamma-aminobutiryl-L-histidine), dipeptides present in high concentrations in human skeletal muscle and brain, whose carbonyl quenching ability was previously proposed [13,14].
Further in vitro studies performed in our laboratory [15-17] confirmed the potent quenching activity of carnosine and analogues towards HNE and acrolein. By ESI-MS/MS and NMR analyses it was possible to characterize in homogeneous solution the conjugated products o
Tipologia IRIS:
13 - Tesi di dottorato discussa entro ottobre 2010
Elenco autori:
M.C. Benfatto
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