MiR-200c-3p maintains stemness and proliferative potential in adipose-derived stem cells by counteracting senescence mechanisms

Adipose-derived mesenchymal stem cells (ASCs) are promising therapeutic tools in regenerative medicine because they possess self-renewal, differentiation and immunomodulatory capacities. After isolation, ASCs are passaged multiple times in vitro passages to obtain a sufficient amount of cells for clinical applications. During this time-consuming procedure, ASCs become senescent and less proliferative, compromising their clinical efficacy. Here, we sought to investigate how in vitro passages impact ASC proliferation/senescence and expression of immune regulatory proteins. MicroRNAs are pivotal regulators of ASC physiology. Particularly, miR-200c is known to maintain pluripotency and targets the immune checkpoint Programmed death-ligand 1 (PD-L1). We therefore investigated its involvement in these critical characteristics of ASCs during in vitro passages. We found that when transiently expressed, miR-200c-3p promotes proliferation, maintains stemness, and contrasts senescence in late passaged ASCs. Additionally, this miRNA modulates PD-L1 and Indoleamine 2,3-Dioxygenase (IDO1) expression, thus most likely interfering with the immunoregulatory capacity of ASCs. Based on our results, we suggest that expression of miR-200c-3p may prime ASC towards a self-renewing phenotype by improving their in vitro expansion. Contrarily, its inhibition is associated with senescence, reduced proliferation and induction of immune regulators. Our data underline the potential use of miR-200c-3p as a switch for ASCs reprogramming and their clinical application

Reactivity of phthalimide N-oxyl radical (PINO) toward the phenolic O-H bond. A kinetic study

The reactivity of the phthalimide N-oxyl radical (PINO) toward the OH bond of a series of substituted phenols was kinetically investigated in CH3CN. The reaction selectivity and the deuterium kinetic isotope effect were determined. Information on the kinetic solvent effect was also obtained with phenol as the substrate

18(O) Incorporation in the Oxidation of N-methylcarbazole by Lignin Peroxidase and a Model Compound: a Mechanistic Insight into the Oxdiative N-demethylation of Aromatic Tertiary Amines

Using O-18 labelled reactants and/or solvent, the origin of the oxygen in the products of the oxidation of N-methylcarbazole by H2O2 catalysed by lignin peroxidase and a model compound has been determined, so getting important information about the mechanism of the oxidative N-demethylation of aromatic tertiary amines

Synthesis of Sulfoxides by the Hydrogen Peroxide Induced Oxidation of Sulfides Catalyzed by Iron Tetrakis(pentafluorophenyl)porphyrin:Scope and Chemoselectivity

The oxidation of sulfides with H2O2 catalyzed by iron tetrakis(pentafluorophenyl)porphyrin in EtOH is an efficient and chemoselective process. With a catalyst concentration 0.03-0.09% of that of the substrate, sulfoxides are obtained with yields generally around 90-95% of isolated product. With vinyl and allyl sulfides, no epoxidation is observed. With a catalyst concentration between 0.09% and 0.25% of that of the substrate, sulfones are obtained in almost quantitative yield and with the same high chemoselectivity observed in the synthesis of sulfoxides

The mediation of veratryl alcohol in oxidations promoted by lignin peroxidase: the lifetime of veratryl alcohol radical cation

The kinetics of decay of veratryl alcohol radical cation, generated by cerium(IV) ammonium nitrate induced oxidation of veratryl alcohol, have been followed spectrophotometrically in a stopped-flow apparatus. In acidic aqueous acetonitrile the radical cation was found to decay by a first-order process, due to deprotonation from the a-carbon leading to an a-hydroxybenzyl radical with the rate constant of 17.1 +/- 0.5 s(-1). This value is in full agreement with those obtained by pulse radiolysis studies but much lower than the value (1.2 x 10(3)s(-1)) indirectly determined by EPR experiments. The implications of these results with respect to the possible role of veratryl alcohol as a mediator in the oxidative biodegradation of lignin catalysed by lignin peroxidase are discussed. (C) 2002 Elsevier Science (USA). All rights reserved

Thermal and photochemical racemization of chiral aromatic sulfoxides via the intermediacy of sulfoxide radical cations

Efficient racemization of enantiomerically pure methyl aryl sulfoxides was obtained by N-methylquinolinium tetrafluoborate (NMQ+) sensitized photolysis and by one-electron oxidation catalyzed by tris(2,2′-bipyridyl)ruthenium(III) hexafluorophosphate. © 2007 American Chemical Society

Lignin peroxidase catalysed oxidation of 4-methoxymandelic acid. The role of mediator structure

A large number of substances have been tested as redox mediators in the LiP-catalysed oxidation of 4-methoxymandelic acid (4-MMA) to anisaldehyde. In some cases (i.e. thioanisole), the mediation efficiency is almost equal to the maximum value displayed by the natural mediator veratryl alcohol. The mediation efficiency is a function of the redox potential of the mediator and also appears to depend on the kinetic effectiveness with which the mediator is oxidised by the enzyme. In contrast, the lifetime of the mediator radical cation seems not to play any significant role, which would support the idea that the redox mediation is actually accomplished by a complex between the mediator radical cation and the enzyme. © 2002 Elsevier Science Ltd. All rights reserved

Aerobic oxidation of benzyl alcohols catalyzed by aryl substituted N-hydroxyphthalimides. Possible involvement of a charge-transfer complex

A series of aryl-substituted N-hydroxyphthalimides (X-NHPIs) containing either electron-withdrawing groups (4-CH(3)OCO, 3-F) or electron-donating groups (4-CH(3), 4-CH(3)O, 3-CH(3)O, 3,6-(CH(3)O)(2)) have been used as catalysts in the aerobic oxidation of primary and secondary benzylic alcohols. The selective formation of aromatic aldehydes was observed in the oxidation of primary alcohols; aromatic ketones were the exclusive products in the oxidation of secondary alcohols. O-H bond dissociation enthalpies (BDEs) of X-NHPIs have been determined by using the EPR radical equilibration technique. BDEs increase with increasing the electron-withdrawing properties of the aryl substituent. Kinetic isotope effect studies and the increase of the substrate oxidation rate by increasing the electron-withdrawing power of the NHPI aryl substituent indicate a rate-determining benzylic hydrogen atom transfer (HAT) from the alcohol to the aryl-substituted phthalimide-N-oxyl radical (X-PINO). Besides enthalpic effects, polar effects also play a role in the HAT process, as shown by the negative rho values of the Hammett correlation with sigma(+) and by the decrease of the rho values (from -0.54 to -0.70) by increasing the electron-withdrawing properties of the NHPI aryl substituent. The relative reactivity of 3-CH(3)O-C(6)H(4)CH(2)OH and 3,4-(CH(3)O)(2)-C(6)H(3)CH(2)OH, which is higher than expected on the basis of the sigma(+) values, the small values of relative reactivity of primary vs secondary benzylic alcohols, and the decrease of the rho values by increasing the electron-withdrawing properties of the NHPI aryl substituent, suggest that the HAT process takes place inside a charge-transfer (CT) complex formed by the X-PINO and the benzylic alcohol

Rates of C-S bond cleavage in tert-alkyl phenyl sulfide radical cations

Radical cations of tert-alkyl phenyl sulfides have been generated photochemically in MeCN in the presence of the N-methoxyphenanthridinium cation (MeOP+), and the rates of C-S bond cleavage have been determined by laser flash photolysis