Search results for "radical"

Tetrabromobisphenol A (TBBPA)-stimulated reactive oxygen species (ROS) production in cell-free model using the 2′,7′-dichlorodihydrofluorescein diace…

2016

t Tetrabromobisphenol A (TBBPA) is a widely used brominated flame retardant, applied in a variety of commercial and household products, mainly electronic ones. Since the production of reactive oxygen species (ROS) is considered one of the principal cytotoxicity mechanisms, numerous studies undertake that aspect of TBBPA’s mechanism of action. The present study verifies if the fluorogenic substrate 2′,7′- dichlorodihydrofluorescein diacetate (H2DCFDA) should be used to detect ROS production induced by TBBPA. To determine the ability of TBBPA alone to stimulate the conversion of H2DCFDA to its fluorescent product 2’, 7’- dichlorofluorescein (DCF), we used a cell-free model. In the experiments…

From Ecology to Biotechnology, Study of the Defense Strategies of Algae and Halophytes (from Trapani Saltworks, NW Sicily) with a Focus on Antioxidan…

2019

This study aimed at the characterization of the antioxidant power of polyphenol extracts (PE) obtained from the algae Cystoseira foeniculacea (CYS) (Phaeophyta) and from the halophyte Halocnemum strobilaceum (HAL), growing in the solar saltworks of western Sicily (Italy), and at the evaluation of their anti-microfouling properties, in order to correlate these activities to defense strategies in extreme environmental conditions. The antioxidant properties were assessed in the PE based on the total antioxidant activity test and the reducing power test

Exercise training as a drug to treat age associated frailty

2016

Exercise causes an increase in the production of free radicals [1]. As a result of a hormetic mechanism antioxidant enzymes are synthesised and the cells are protected against further oxidative stress. Thus, exercise can be considered as an antioxidant [2]. Age-associated frailty is a major medical and social concern as it can easily lead to dependency. In this review we describe that oxidative stress is associated with frailty and the mechanism by which exercise prevents age-associated frailty. We propose that individually tailored multicomponent exercise programmes are one of the best ways to prevent and to treat age-associated frailty.

Prooxidative chain transfer activity by thiol groups in biological systems

2020

Cysteine is arguably the best-studied biological amino acid, whose thiol group frequently participates in catalysis or ligand binding by proteins. Still, cysteine's unusual biological distribution has remained mysterious, being strikingly underrepresented in transmembrane domains and on accessible protein surfaces, particularly in aerobic life forms (“cysteine anomaly”). Noting that lipophilic thiols have been used for decades as radical chain transfer agents in polymer chemistry, we speculated that the rapid formation of thiyl radicals in hydrophobic phases might provide a rationale for the cysteine anomaly. Hence, we have investigated the effects of dodecylthiol and related compounds in i…

Protecting group-free radical decarboxylation of bile acids: Synthesis of novel steroidal substituted maleic anhydrides and maleimides and evaluation…

2017

Abstract We report the first Barton radical decarboxylation of unprotected bile acids via in situ irradiation of their thiohydroxamic esters in the presence of citraconic anhydride and citracoimide, leading to the synthesis a series of steroidal maleic anhydrides and maleimides as novel hybrid bile acids. The cytotoxic activities were evaluated on C6 rat glioma cells.

Special Issue "Human performance and redox signaling in health and disease".

2016

The free radical theory of frailty: Mechanisms and opportunities for interventions to promote successful aging

2019

The free radical theory of ageing has provided a framework of research into ageing based on Harman's idea that ageing was caused by damage produced by free radicals. However, several experiments have cast doubts on the general validity of the theory. The postulation of the free radical theory of frailty came from two basic facts: first that radicals not only act as damaging molecules, but also as signals to control cell function and second that on many occasions oxidative damage does not correlate with chronological but rather with unsuccessful ageing. Frailty is a geriatric concept by which an older person shows a lack of the feeling of wellbeing, unintentional weight loss, a relatively lo…

Free energy profiles for two ubiquitous damaging agents: methylation and hydroxylation of guanine in B-DNA

2017

International audience; DNA methylation and hydroxylation are two ubiquitous reactions in DNA damage induction, yet insights are scarce concerning the free energy of activation within B-DNA. We resort to multiscale simulations to investigate the attack of a hydroxyl radical and of the primary diazonium onto a guanine embedded in a solvated dodecamer. Reaction free energy profiles characterize two strongly exergonic processes, yet allow unprecedented quantification of the barrier towards this damage reaction, not higher than 6 kcal mol−1 and sometimes inexistent, and of the exergonicities. In the case of the [G(C8)-OH]˙ intermediate, we challenge the functional dependence of such simulations…

Release of free amino acids upon oxidation of peptides and proteins by hydroxyl radicals

2017

Hydroxyl radical-induced oxidation of proteins and peptides can lead to the cleavage of the peptide, leading to a release of fragments. Here, we used high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and pre-column online ortho-phthalaldehyde (OPA) derivatization-based amino acid analysis by HPLC with diode array detection and fluorescence detection to identify and quantify free amino acids released upon oxidation of proteins and peptides by hydroxyl radicals. Bovine serum albumin (BSA), ovalbumin (OVA) as model proteins, and synthetic tripeptides (comprised of varying compositions of the amino acids Gly, Ala, Ser, and Met) were used for reactions with hydroxyl ra…

Endoscopic near infrared and indocyanine green to verify the viability of the subcutaneous flap for vulvar cancer.

2019

Abstract Introduction Vulvar cancer often requires radical vulvectomy with subsequent vulvar flap. Approximately in 20–60% of cases, there are post-operative complications ranging from infection to flap necrosis that often require reoperation. Several methods have been described to verify the vitality of the flap, but these are often expensive and require specific machinery that is not generally present in a gynecological clinic. In this case report, we present a viability verification of V Y fasciocutaneous advancement flap for vulvar reconstruction by Endoscopic Near-Infrared and Indocyanine Green. Methodology The patient was a 67-year-old woman with FIGO IB ≤ 4 cm squamous cell vulvar ca…