Study of coumarin-resveratrol hybrids as potent antioxidant compounds

In the present work we synthesized a selected series of hydroxylated 3-phenylcoumarins 5–8, with the aim of evaluating in detail their antioxidant properties. From an in depth study of the antioxidant capacity data (ORAC-FL, ESR, CV and ROS inhibition) it was concluded that these derivatives are very good antioxidants, with very interesting profiles in all the performed assays. The study of the effect of the number and position of the hydroxyl groups on the antioxidant activity was the principal aim of this study. In particular, 7-hydroxy-3-(3'-hydroxy)phenylcoumarin (8) proved to be the most active and effective antioxidant of the selected series in four of the performed assays (ORAC-FL = 11.8, capacity of scavenging hydroxyl radicals = 54%, Trolox index = 2.33 and AI30 index = 0.18). However, the presence of two hydroxyl groups on this molecule did not increase greatly the activity profile. Theoretical evaluation of ADME properties of all the derivatives was also carried out. All the compounds can act as potential candidates for preventing or minimizing the free radical overproduction in oxidative-stress related diseases. OPEN ACCESS Molecules 2015, 20 3291 These preliminary findings encourage us to perform a future structural optimization of this family of compoundsThis project was partially supported by the FONDECYT (projects 1110029 and 1090078), PhD fellowship CONICYT, fellowship for operational expenses (N°21120376), Spanish researchers personal founds, University of Santiago de Compostela and Fundação para a Ciência e Tecnologia (FCT) for the Pest/C-QUI/UI0081/2013. MJ Matos was supported by the fellowship from Fundação para a Ciência e Tecnologia (FCT), POPH (Programa Operacional Potencial Humano) and QREN (Quadro de Referência Estratégica Nacional) (SFRH/BPD/95345/2013). S Vazquez-Rodriguez was supported by the Universidade de Porto postdoctoral grant NORTE-07-0124-FEDER-000065S

Remarkable antioxidant properties of a series of hydroxy-3-arylcoumarins

In the present work we synthesized a series of hydroxy-3-arylcoumarins (compounds 1–9), some of them previously described as MAO-B selective inhibitors, with the aim of evaluating their antioxidant properties. Theoretical evaluation of ADME properties of all the derivatives was also carried out. From the ORAC-FL, ESR and CV data it was concluded that these derivatives are very good antioxidants, with a very interesting hydroxyl, DPPH and superoxide radicals scavenging profiles. In particular compound 9 is the most active and effective antioxidant of the series (ORAC-FL = 13.5, capacity of scavenging hydroxyl radicals = 100%, capacity of scavenging DPPH radicals = 65.9% and capacity of scavenging superoxide radicals = 71.5%). Kinetics profile for protection fluorescein probe against peroxyl radicals by addition of antioxidant molecule 9 was also performed. Therefore, it can operate as a potential candidate for preventing or minimizing the free radicals overproduction in oxidative-stress related diseasesThe current work was supported by Mecesup (Project UCH-0601), CONICYT-Chile (Project N 24110059), Fundação para a Ciência e Tecnologia (Project PTDC/QUI-QUI/113687/2009) and personal funds from the researchers. M.J. Matos thanks Fundação para a Ciência e Tecnologia (SFRH/BD/61262/2009) Ph.D. Grant, F. Pérez-Cruz thanks CONICYT-Chile PhD. grant, Becas-Chile and Fulbright doctoral stay fellowships and S. Vazquez-Rodriguez thanks Ministerio de Educación y Ciencia (AP2008-04263) PhD. GrantS

Polyphenolic Composition and Antioxidant Activity (ORAC, EPR and Cellular) of Different Extracts of Argylia radiata Vitroplants and Natural Roots

Plant biochemistry studies have increased in recent years due to their potential to improve human health. Argylia radiata is an extremophile plant with an interesting polyphenolic profile. However, its biomass is scarce and occasionally available. Argylia in vitro biomass was obtained from tissue culture and compared with in vivo roots regarding its polyphenolic and flavonoid content. Different solvents were used to prepare extracts from the in vitro tissue of callus and aerial plant organs and in vivo roots. UPLC-MS/MS was used to assess the chemical composition of each extract. ORAC-FL and scavenging of free radicals (DPPH and OH) methods were used to determine the antioxidant capacity of extracts. Furthermore, the biological activity of the extracts was established using the cellular antioxidant activity method. The vitroplants were a good source of polyphenols (25–68 mg GAE/100 g tissue FW), and methanol was the most efficient solvent. Eight polyphenolic compounds were identified, and their antioxidant properties were investigated by different chemical methods with EPR demonstrating its specific scavenging activity against free radicals. All extracts showed cellular dose-dependent antioxidant activity. The methanolic extract of vitroplants showed the highest cellular antioxidant activity (44.6% and 51%) at 1 and 10 µg/mL of extract, respectively. Vitroplants of A. radiata are proposed as a biotechnological product as a source of antioxidant compounds with multiple applications

Novel Phenazine 5,10-Dioxides Release •OH in Simulated Hypoxia and Induce Reduction of Tumour Volume In Vivo

Phenazine 5,10-dioxides (PDOs) are a new class of bioreductive cytotoxins, which could act towards tumours containing hypoxic regions. The PDOs selective-hypoxic bioreduction was probed in vitro; however, the mechanism of action has not been completely explained. Besides, PDOs in vivo antitumour activities have not been demonstrated hitherto. We study the mechanism of hypoxic/normoxic cytotoxicity of PDO representative members. Electron spin resonance is used to confirm •OH production, alkaline comet assay to determine genotoxicity, and gel electrophoresis and flow cytometry to analyze DNA fragmentation and cell cycle distribution. Chemically induced rat breast tumours are employed to evaluate in vivo activities. For the most selective cytotoxin, 7(8)-bromo-2-hydroxyphenazine 5,10-dioxide (PDO1), exclusive hypoxic •OH production is evidenced, while for the unselective ones, •OH is produced in both conditions (normoxia and simulated hypoxia). In normoxia (Caco-2 cells), PDO1 induces cell-cycle arrest and DNA fragmentation but does not significantly induce apoptosis neither at IC50 nor IC80. No difference in the comet-assay scores are observed in normoxia and simulated hypoxia being the unselective 2-amino-7(8)-bromophenazine 5,10-dioxide (PDO2) the most genotoxic. The in vivo efficacy with the absence of systemic toxicity of PDO1 and PDO2 is checked out. Results from this study highlight the potential of PDOs as new therapeutics for cancer

New heterobimetallic ferrocenyl derivatives are promising antitrypanosomal agents

In the search for a more effective chemotherapy for the treatment of Chagas´ disease and human African trypanosomiasis, caused by Trypanosoma cruzi and Trypanosoma brucei parasites, respectively, the use of organometallic compounds may be a promising strategy. In this work, eight new heterobimetallic compounds are described including four 5-nitrofuryl containing thiosemicarbazones as bioactive ligands (HL1-HL4) and dppf = 1,1′-bis(diphenylphosphino) ferrocene as an organometallic co-ligand. Complexes of the formula [MII(L)(dppf)](PF6) with M = Pd or Pt were synthesized and fully characterized in the solid state and in solution, including the determination of the molecular structure of four of them by single crystal X-ray diffraction methods. Most compounds showed activity in the low micromolar or submicromolar range against both parasites, with the platinum compounds being more active than the palladium analogues. Activity was significantly increased by generation of the M-dppf compounds (3-24 fold increase with respect to free ligands HL for T. cruzi and up to 99 fold increase with respect to HL for T. brucei). The inclusion of the organometallic co-ligand also led to lower toxicity in mammalian cells and higher selectivity towards both parasites when compared to the free HL compounds. The complexes interact with DNA and affect the redox metabolism of the parasites. Furthermore, the most active and selective compound of the new series showed no in vivo toxicity in zebrafish embryos.Fil: Rodríguez Arce, Esteban. Universidad de la República; UruguayFil: Putzu, Eugenia. Universidad de la República; UruguayFil: Lapier, Michel. Universidad de Chile; ChileFil: Maya, Juan Diego. Universidad de Chile; ChileFil: Olea Azar, Claudio. Universidad de Chile; ChileFil: Echeverría, Gustavo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Piro, Oscar Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Medeiros, Andrea. Instituto Pasteur de Montevideo; Uruguay. Universidad de la República; UruguayFil: Sardi, Florencia. Instituto Pasteur de Montevideo; UruguayFil: Comini, Marcelo. Instituto Pasteur de Montevideo; UruguayFil: Risi, Gastón. Instituto Pasteur de Montevideo; UruguayFil: Salinas, Gustavo. Instituto Pasteur de Montevideo; UruguayFil: Abad Villamor, Ana Isabel. Instituto Superior Técnico; PortugalFil: Pessoa, João Costa. Instituto Superior Técnico; PortugalFil: Otero, Lucía. Universidad de la República; UruguayFil: Gambino, Dinorah. Universidad de la República; Urugua

New heterobimetallic ferrocenyl derivatives are promising antitrypanosomal agents

In the search for a more effective chemotherapy for the treatment of Chagas’ disease and human African trypanosomiasis, caused by Trypanosoma cruzi and Trypanosoma brucei parasites, respectively, the use of organometallic compounds may be a promising strategy. In this work, eight new heterobimetallic compounds are described including four 5-nitrofuryl containing thiosemicarbazones as bioactive ligands (HL1–HL4) and dppf = 1,1′-bis(diphenylphosphino) ferrocene as an organometallic co-ligand. Complexes of the formula [MII(L)(dppf)](PF6) with M = Pd or Pt were synthesized and fully characterized in the solid state and in solution, including the determination of the molecular structure of four of them by single crystal X-ray diffraction methods. Most compounds showed activity in the low micromolar or submicromolar range against both parasites, with the platinum compounds being more active than the palladium analogues. Activity was significantly increased by generation of the M-dppf compounds (3–24 fold increase with respect to free ligands HL for T. cruzi and up to 99 fold increase with respect to HL for T. brucei). The inclusion of the organometallic co-ligand also led to lower toxicity in mammalian cells and higher selectivity towards both parasites when compared to the free HL compounds. The complexes interact with DNA and affect the redox metabolism of the parasites. Furthermore, the most active and selective compound of the new series showed no in vivo toxicity in zebrafish embryos.Instituto de Física La Plat

Formation of radical anions by electrochemical reduction of nitroimidazoles in aprotic solvents and mixed solvent

The EPR spectra of radicals obtained by electrohytical reduction of 2-nitroimidazole and 4-nitroimidazole were measured in mixed solvents. The behavior of the nitrogen coupling constants with the solvent composition is discussed in terms of equilibria between radicals in different solvents. The equilibrium constants of the DMSO/water system were determinated. Molecular orbital calculations in the frame of LCAO-HMO method account correctly for the spin distribution of both compounds investigated