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Influence of Air on Essential Oil Constituents
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Darija Gajić, Gerhard Buchbauer
It represents the reaction between the excited singlet state of oxygen molecule 1O2 and an allylic hydrogen atom (Figure 29.3). This results in shifting the double bond to a position adjacent to the original double bond; that is, an allylic hydroperoxide is formed. Notably, the direct excitation (transition of the ground state oxygen 3O2 by light to a singlet form) is highly unlikely. Hence, singlet oxygen (unlike almost all molecules) is uncommon in a standard environment and its excitation usually requires a certain sensitizing molecule.
From Designer Food Formulation to Oxidative Stress Mitigation: Health-Boosting Constituents of Cabbage
Published in Megh R. Goyal, Hafiz Ansar Rasul Suleria, Ramasamy Harikrishnan, The Role of Phytoconstitutents in Health Care, 2020
Faiza Ashfaq, Masood Sadiq Butt, Ahmad Bilal, Kanza Aziz Awan, Hafiz Ansar Rasul Suleria
Furthermore, the pro-inflammatory end products of lipid peroxidation (MDA (malondialdehyde) and 4-hydroxynonenal (aldehyde by-products)) enhances LDL deposition around the vasculature and are responsible for hepato-pathological features. Furthermore, prolonged consumption of hypercaloric diet depletes antioxidant reserves or compromises innate antioxidant defense system of oxygen-dependent organisms that fight against pro-oxidants (active oxygen molecules) by converting them to lipid peroxides and finally to non-toxic alcohol. The first line of defense against oxidative damage is SOD: catalyzes superoxide anions, O2– (generated by one-electron reduction in oxygen molecule by transition metal ion) to hydrogen peroxide (H2O2) that get converted to (OH·) radicals, promptly reacting with cellular components (lipids, proteins, and nucleic acids) leading to lipid peroxidation and cell death. However, presence of CAT (hemeprotein) and GSH are considered as second line of defense and its related enzymes (GPx and GST) detoxify (OH·) radicals to non-toxic metabolites like H2O [2, 30, 35, 41, 64, 66, 67, 73, 78, 98, 104, 129, 132, 151, 160, 164, 179, 180, 182].
General Radiobiology Refresher
Published in Loredana G. Marcu, Iuliana Toma-Dasu, Alexandru Dasu, Claes Mercke, Radiotherapy and Clinical Radiobiology of Head and Neck Cancer, 2018
Loredana G. Marcu, Iuliana Toma-Dasu, Alexandru Dasu, Claes Mercke
The oxygen effect is the name given to the modulation of the biological effects of radiation by the presence of oxygen. Although several factors are known to modulate the response of tissues to radiation, some of these being presented in the previous sections, the oxygen effect has a prominent role in radiation biology due to the physiological importance of oxygen for living tissues and the magnitude of the modulation which is one of the largest in radiation biology. In this context, it is important to note that the oxygen effect does not originate in any metabolic or physiological effect of the oxygen, but simply in the electron affinity of the oxygen molecule that makes it one of the most reactive chemical species. This chemical affinity enables oxygen to act on the free radicals formed by radiation and through them to potentiate the indirect effect of radiation (Hall & Giaccia 2011) or to fixate existing damage to the DNA molecule (Prise, Gillies & Michael 1999). Since the nature of the chemical reactions involved in these processes, the presence of oxygen is required during or at most a few milliseconds after irradiation, during the lifetime of the free radicals created through the indirect mode of action of radiation. This has been demonstrated in advanced experiments allowing oxygen to rapidly mix with anoxic cells in timing-controlled microexplosions at various times before or after very short pulses of radiation (Michael et al. 1973).
Hb Santa Juana (β 108(G10) Asn > Ser): a low oxygen affinity hemoglobin variant in a family of Bosnian background
Published in Hematology, 2023
N. P. Wildenberg, C. Rossi, A. E. Kulozik, J. B. Kunz
Hemoglobin is a heterotetramer composed of two α- and two β-globin chains, with a total of four heme groups as oxygen binding sites. According to the allosteric two-state-model [2], the heterotetramer can exist in a relaxed R state with high oxygen affinity and a strained T state with low oxygen affinity. Binding of an oxygen molecule to one heme group increases the oxygen affinity of the other subunits. This effect explains the sigmoidal shape of the oxygen binding curve. Hemoglobin variants with decreased oxygen affinity stabilize the T-state and result in increased oxygen delivery to the tissues, while oxygen uptake in the lungs is decreased. The oxygen dissociation curve is right-shifted and characterized by a higher oxygen tension required to reach 50% saturation (p50). However, additional factors contribute to oxygen release into the tissue, such as the concentration of 2,3-bisphosphoglycerate, pH, and CO2 tension. Weak oxygen binding to hemoglobin favors oxygen release into the tissue, suppressing erythropoietin secretion and causing normocytic anemia. Although some patients expressing hemoglobin variants with decreased oxygen affinity present with cyanosis, most are asymptomatic. A low oxygen affinity hemoglobin variant may be suggested by otherwise unexplained reduced pulse oximetry measurements and normocytic anemia.
Gallic acid mitigates diclofenac-induced liver toxicity by modulating oxidative stress and suppressing IL-1β gene expression in male rats
Published in Pharmaceutical Biology, 2020
Mohsen Esmaeilzadeh, Esfandiar Heidarian, Mehrnoosh Shaghaghi, Hoshang Roshanmehr, Mohammad Najafi, Alireza Moradi, Ali Nouri
CAT and SOD are vital enzymes of the antioxidant defense system. The SOD fuse two superoxide radicals (O2•−) and creates H2O2. H2O2 is eventually transformed into H2O and oxygen molecule by CAT in the peroxisomes (Sharifinasab et al. 2016; Wei et al. 2014). Various investigations have indicated that DIC could decline the actions of antioxidant enzymes in the liver (Ahmad et al. 2013; Nouri et al. 2019). GA as an antioxidant agent could noticeably raise the activity of antioxidant enzymes (Table 3). It confirms the prior findings that disclosed the anti-oxidative potential of GA (Karimi-Khouzani et al. 2017; Latief et al. 2016). The decline of SOD and CAT activities caused by DIC injection was manifest by elevated oxidative stress. However, GA treatment eventually reduced the MDA and elevated the activities of antioxidant defense system enzymes in hepatic tissue, reflecting its antioxidant potential mediated by hepatoprotective activity.
Antimicrobial sonodynamic and photodynamic therapies against Candida albicans
Published in Biofouling, 2018
Fernanda Alves, Ana Cláudia Pavarina, Ewerton Garcia de Oliveira Mima, Anthony P. McHale, John Francis Callan
The present investigation also demonstrated that the treatments mediated by the sensitizer PDZ were more effective on both planktonic and biofilm phase growths in comparison with the RB treatments. These results obtained may be attributed to the different characteristics of each sensitizer. The sensitizer PDZ, classified as a second-generation PS, is obtained from the cyanobacterium Spirulina platensis as a noncovalent complex of N-methyl-D-glucosamine chlorine e6 salt on basis of chlorophyll a derivatives. PDZ has an absorption peak in the red region of the spectrum (660 nm) and it is known to produce a high amount of singlet oxygen (Ferreira et al. 2008). On the other hand, the xanthene dye RB is an anionic water-soluble synthetic fluorescein derivative, which has an absorption peak in the green region of the spectrum (450–600 nm) and a low rate of photodegradation (Spagnul et al. 2015). This PS is capable of photo-catalytic conversion of an oxygen molecule to singlet oxygen under 532 nm light irradiation, with a singlet oxygen quantum yield of ~76% (Encinas et al. 2009). Moreover, the higher efficacy of the aPDT treatment mediated by PDZ in comparison with RB may also be attributed to the wavelength of the LED device used. PDZ was excited by a LED device with the appropriated wavelength for this sensitizer (660 nm) and RB was not, and this may influence the efficacy of the treatment.