Design, synthesis, and antioxidant potency of novel alpha-tocopherol analogues in isolated membranes and intact cells.

In this study, we have designed novel chromanyl derivatives that share with alpha-tocopherol a chromanyl head but differ in the lateral chain in: (i) length and saturation (FEBL-45, 50, 70), (ii) position of double bonds in Z or E (FEBL-50 and 53 and their respective 6-chromanyl methyl derivatives FEBL-161 and 162), or (iii) presence of additional antioxidant molecules, such as the catechol compound hydroxytyrosol (FEBL-80) or dopamine (FEBL-82, 95). The efficiency of these compounds in preventing free-radical-induced oxidative stress was investigated in isolated membranes as well as intact cells. The results of this study clearly show that all compounds synthesized were active in: (i) inhibiting AAPH- or tert-BOOH-induced lipid peroxidation in microsomes and (ii) preventing H2O2-induced ROS production, cell damage, and heat-shock protein expression in immortalized RAT-1 fibroblasts. Such effects were dose- and time-dependent. Independent of the kind of pro-oxidant used, differences in the antioxidant potency of these compounds were found in relation to the chemical structure with respect to the natural alpha-tocopherol: (1) The concomitant presence of a chromanyl head and an additional aromatic ring markedly increased the antioxidant potency of the molecule. In particular, FEBL-82 and FEBL-95, resulting from the molecular combination of trolox and dopamine, were much more potent than alpha-tocopherol, alpha-tocotrienol, and the other synthetic compounds. Moreover, they were also more potent than trolox and dopamine, used alone or in combination, suggesting synergistic cooperative interactions in the molecule between chromanyl and catechol moieties. (2) The length of the side chain affected the antioxidant properties of the molecule: FEBL-70, which displays a bulky squalene side chain, was less effective than the natural alpha-tocotrienol and the synthetic FEBL-45 and FEBL-50. (3) The presence of polyunsaturated double bonds in the side chain in the Z configuration (FEBL-53, FEBL-162) increased the antioxidant potency of the molecule with respect to the E configuration (FEBL-50, FEBL-161).

Protective effects of Fe-Aox29, a novel antioxidant derived from a molecular combination of Idebenone and vitamin E, in immortalized fibroblasts and fibroblasts from patients with Friedreich Ataxia.

Friedreich Ataxia (FRDA), the most frequent inherited ataxia, is not only characterized by progressive gait and limb ataxia, but in most cases is also accompanied by a severe hypertrophic cardiomyopathy. This life threatening symptom can be ameliorated by the administration of idebenone, a short chain quinone antioxidant, supporting additional evidence that oxidative stress plays a major role in the pathogenesis of this disease. In this study we analyze the combinatorial effect of different antioxidants on cell viability of FRDA fibroblasts and of RAT-1 immortalized fibroblasts exposed to oxidative stress. We find that an equimolar mixture of idebenone and vitamin E is more potent than each of the compound alone. Increased potency was also obtained with a novel synthetic antioxidant (Fe-Aox29) combining the active groups from both idebenone and vitamin E. These results indicate, that idebenone and vitamin E might act synergistically to counteract oxidative stress in fibroblasts from FRDA patients.

Novel selective human mitochondrial kinase inhibitors: design, synthesis and enzymatic activity.

Selective and effective TK2 inhibitors can be obtained by introduction of bulky lipophilic chains (acyl or alkyl entities) at the 2' position of araT and BVaraU, nucleoside analogues naturally endowed with a low TK2 affinity. These derivatives showed a competitive inhibitory activity against TK2 in micromolar range. BVaraU nucleoside analogues, modified on the 2'-O-acyl chain with a terminal N-Boc amino-group, conserved or increased the inhibitory activity against TK2 (7l and 7m IC(50): 6.4 and 3.8 microM, respectively). The substitution of an ester for a carboxamide moiety at the 2' position of araT afforded a consistent reduction of the inhibitory activity (25, IC(50): 480 microM). On the contrary, modifications at 2'-OH position of araC and araG, have provided inactive derivatives against TK2 and dGK, respectively. The biological activity of a representative compound, 2'-O-decanoyl-BVaraU, was also investigated in normal human fibroblasts and was found to impair mitochondrial function due to TK2 inhibition.