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Antioxidant Supplements and Exercise Adaptations
Published in James N. Cobley, Gareth W. Davison, Oxidative Eustress in Exercise Physiology, 2022
Shaun A. Mason, Lewan Parker, Adam J. Trewin, Glenn D. Wadley
Elevated cellular concentrations of ROS/RNS may impair selective redox-sensitive pathways of energy metabolism. For instance, hydrogen peroxide (H2O2) and peroxynitrite (ONOO–) can inhibit glyceraldehyde 3-phosphate dehydrogenase (GAPDH) activity by reacting directly with the active site thiol, thus potentially impairing glycolysis (Quijano et al., 2016). Further, ROS can impair activity of the enzyme aconitase by releasing an Fe atom from an Fe-S cluster that functions as a Lewis acid during catalysis in the tricarboxylic acid cycle, potentially diminishing the supply of reducing agents to the electron transport chain and thus diminishing the rate of ROS production (Quijano et al., 2016). Elevated ROS and RNS may also reduce beta-oxidation efficiency through the generation of nitro-fatty acids that can undergo beta-oxidation in the mitochondria (Quijano et al., 2016). Despite the known interplay between oxidants and energy metabolism, effects of elevated ROS/RNS on these pathways of energy metabolism during exercise are unclear. Moreover, effects of antioxidants on energy metabolism pathways have been scarcely explored in the context of acute exercise or exercise training adaptations. Effects of exogenous antioxidants on substrate metabolism are likely complex and will depend on the specific antioxidant compound, its bioavailability, and dosing regimen administered.
The Modification of Lysine
Published in Roger L. Lundblad, Chemical Reagents for Protein Modification, 2020
The reaction of glyceraldehyde with carbonmonoxyhemoglobin S has been explored by Acharya and Manning.113 This reaction was performed with 0.010 M glyceraldehyde in phosphate-buffered saline, pH 7.4, and the resultant Schiff bases were stabilized by reduction with sodium borohydride. Using radiolabeled glyceraldehyde, these investigators were able to obtain support for the concept that there is selectivity in the reaction of sugar aldehydes with hemoglobin. The reaction product between glyceraldehyde and hemoglobin S did have stability properties without reduction that were not consistent with only Schiff base products. These investigators suggested that the glyceraldehyde-hemoglobin Schiff base could undergo an Amadori rearrangement (Figure 43) to form a stable ketoamine adduct which could be reduced with sodium borohydride to form a product identical to that obtained by direct reduction of the Schiff base. In a subsequent study, these investigators did show that the glyceraldehyde-hemoglobin S Schiff base could rearrange to form a ketamine via an Amadori rearrangement.114 These investigators were able to use reaction with phenylhydrazine to detect the protein-bound ketamine adduct as shown in Figure 44.
Vitamin C and Cancer
Published in Qi Chen, Margreet C.M. Vissers, Cancer and Vitamin C, 2020
Channing Paller, Tami Tamashiro, Thomas Luechtefeld, Amy Gravell, Mark Levine
While pharmacologic ascorbate appears to have cytotoxic effects on many cancer cells through hydrogen-peroxide-mediated pro-oxidant damage, in a subset of cancer cells, additional related mechanisms have been described. Cytotoxicity may be due to oxidation of ascorbate into an unstable metabolite and reversible oxidized form of ascorbate, dehydroascorbic acid [70]. Tumor cells internally reduce dehydroascorbic acid to ascorbate-triggering glutathione scavenging, inducing oxidative stress, inactivating glyceraldehyde 3-phosphate dehydrogenase, inhibiting glycolytic flux, and ultimately leading to an energy crisis leading to cell death [71,72]. For example, cultured human colorectal cancer cells with KRAS or BRAF mutations were selectively killed by pharmacologic ascorbate by depletion of intracellular glutathione. This is followed by inactivation of glyceraldehyde 3-phosphate dehydrogenase, leading to inhibition of glycolysis and death in cancer cells highly dependent on glycolysis [71]. Pharmacologic ascorbate can also induce metabolic stress by depletion of NAD in several cancer cell lines [73,74].
Toxicological assessment of electronic cigarette vaping: an emerging threat to force health, readiness and resilience in the U.S. Army
Published in Drug and Chemical Toxicology, 2022
Marc A. Williams, Gunda Reddy, Michael J. Quinn, Amy Millikan Bell
Additionally, acrolein oxidation by lung or liver microsomes forms the metabolite glycidaldehyde, which could promote skin tumors in mice on dermal contact (DHHS ATSDR 2007). Glycidaldehyde can be further metabolized to glyceraldehyde, which then enters the glycolytic pathways. In a proposed model (Patel et al.1980), glycidaldehyde appears to be the only chemical that could represent a risk to human health, since it exhibited carcinogenic properties in mice and rats when applied dermally (Van Duuren et al.1967a, 1967b, Shamberger et al.1974). Although this metabolic system has been demonstrated in animal models, it has not been shown in human biological systems on inhalation exposure. However, one particular study (Lam et al.1985), found a dose-related depletion of glutathione in the nasal respiratory mucosa in a rat model following inhalational exposure to 0.1–2.5 ppm of acrolein for three hours. This observation was interpreted as being consistent with a chemical reaction that yielded glutathione-acrolein adducts (Lam et al.1985).
Neuroprotective effects of oleuropein on retina photoreceptors cells primary culture and olive leaf extract and oleuropein inhibitory effects on aldose reductase in a diabetic model: Meriones shawi
Published in Archives of Physiology and Biochemistry, 2022
Maha Benlarbi, Hedya Jemai, Khouloud Hajri, Sihem Mbarek, Emna Amri, Mariem Jebbari, Imane Hammoun, Basma Baccouche, Nourhène Boudhrioua Mihoubi, Ayachi Zemmal, Rafika Ben Chaouacha-Chekir, Wissal Dhifi
In fact, AR which is a NADPH-dependent enzyme converts 3% glucose into sorbitol under normal physiological conditions. Its activity becomes important when the blood glucose level increases. In vitro, it converts glyceraldehyde to glycerol with an equimolar oxidation of NADPH. Our results were consistent with those of Travis et al. (1971), who reported that an activation of the polyol pathway was noticed when intracellular glucose levels increase. Indeed, the incubation of erythrocytes with 50 mM glucose increased the contents of two main metabolites generated by this pathway: sorbitol and fructose. In addition, our results were also in agreement with those of Reddy et al. (2008) according to them, AR in erythrocyte fraction was significantly elevated in patients with DR not only compared to non-diabetic animals but also to diabetic ones without developing DR. Moreover, the same authors reported an AR activity at early disease stages and not only in its advanced ones.
Scleral Cross-Linking Using Glyceraldehyde for the Prevention of Axial Elongation in the Rabbit: Blocked Axial Elongation and Altered Scleral Microstructure
Published in Current Eye Research, 2019
Xiao Lin, Rajeev K. Naidu, Jinhui Dai, Xingtao Zhou, Xiaomei Qu, Hao Zhou
As a natural CXL agent, glyceraldehyde represents the aldehyde of the open chain form of a simple sugar, which has been demonstrated to be effective in causing stiffening of biological tissue.8,9,22 With a molecular weight of 90 Da, glyceraldehyde can infiltrate the sclera efficiently and easily, which is permeable to molecules of 150,000 Da.22 The glycation-induced chemical CXL reactions resulting from glyceraldehyde are called the Maillard reactions.20,23 Through the Maillard reactions, glyceraldehyde can be added to the ends of protein molecules and can be further transformed to advanced glycation end products, which are more stable. The resultant covalent collagen cross-links promote enhanced tissue stiffness and resistance to enzymatic degradation.22,23