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Monographs of fragrance chemicals and extracts that have caused contact allergy / allergic contact dermatitis
Published in Anton C. de Groot, Monographs in Contact Allergy, 2021
The hypothesis that patients sensitized to p-phenylenediamine are at increased risk of concomitant reactivity to linalool hydroperoxides, owing to a ‘common pathway’ of skin protein oxidation, has been rejected (43).
Influence of Air on Essential Oil Constituents
Published in K. Hüsnü Can Başer, Gerhard Buchbauer, Handbook of Essential Oils, 2020
Darija Gajić, Gerhard Buchbauer
To conduct the analysis of the autoxidized linalool, GC with split/splitless injection would be an analytical method of choice because monoterpenes are volatile compounds with low UV absorption. However, this way, only the more stable secondary oxidation products are detected, and due to high temperatures, no hydroperoxides could be identified. Hence, the HPLC was used as a preferred method so that oxidative degradation of linalool could be completely investigated. It was also used to quantify the content of hydroperoxides. Finally, isolation of oxidation products was performed by flash chromatography and preparative HPLC as a preferred method for detection of less stabile primary oxidation products. Hence, together with NMR used for the isolation of impure fractions in low amounts, eight different constituents were confirmed (Figures 29.10 and 29.11).
Oxyfunctionalization of Pharmaceuticals by Fungal Peroxygenases
Published in Peter Grunwald, Pharmaceutical Biocatalysis, 2019
Jan Kiebist, Martin Hofrichter, Ralf Zuhse, Katrin Scheibner
Peroxygenases are a subclass of peroxide-dependent enzymes that catalyze the transfer of a peroxide-borne oxygen to diverse substrates. In the enzyme nomenclature system, they are classified under EC 1.11.2 (Fig. 18.1). Currently, this second subclass of enzymes that use peroxides as electron acceptor (EC 1.11)—besides that of classic peroxidases (EC 1.11.1)—includes unspecific peroxygenase (UPO, EC 1.11.2.1), mammalian myeloperoxidase (EC 1.11.2.2), plant seed peroxygenase (EC 1.11.2.3), bacterial fatty acid peroxygenase (EC 1.11.2.4) and 3-methyl-l-tyrosine peroxygenase (EC 1.11.2.5). Due to their frequent presence in the genomes of fungi and the diversity of catalyzed reactions, UPOs have become the key and model enzymes of subclass EC 1.11.2. The general reaction sequence of peroxygenases is shown in Eq. 18.1, where AH defines the substrate, R-OOH the co-substrate, a hydroperoxide (R implies an organic residue or a hydrogen atom in H2O2), A-OH the hydroxylated product and R-OH the reduced hydroperoxide or H2O (Hofrichter et al., 2015).
Effects of imidacloprid on viability and increase of reactive oxygen and nitrogen species in HepG2 cell line
Published in Toxicology Mechanisms and Methods, 2022
Anilda Rufino de Jesus Santos Guimarães, Paulo Francisco Veiga Bizerra, Camila Araújo Miranda, Fábio Erminio Mingatto
The accumulation of ROS/RNS was evaluated using CM-H2DCFDA, a reactive oxygen and nitrogen species indicator that becomes fluorescent in the presence of intracellular oxidation (Chernyak et al. 2006). HepG2 cells were cultured to a density of 1 × 105 cells/mL and then incubated with IMD (0.25–2.0 mM). Following this treatment, the cells were further incubated with a 2 mM CM-H2DCFDA solution for 1 h at 37 °C. Subsequently, the fluorescence of the CM-H2DCFDA was measured at excitation and emission wavelengths of 503 and 528 nm, respectively, using an RF-5301PC fluorescence spectrophotometer (Shimadzu, Tokyo, Japan). The results were shown as the difference in fluorescence from the control group. A tert-butyl hydroperoxide (100 μM) solution was used to induce oxidative stress.
The Quality Determination of Selected Commercial Online Purchased Edible Pomegranate Seed Oils With New Argentometric Liquid Chromatography Method
Published in Journal of Dietary Supplements, 2021
Agnieszka Białek, PhD, DSc, Małgorzata Białek, PhD, Tomasz Lepionka, PhD, Elżbieta Tober, Marian Czauderna, PhD
As there are no legal regulations dedicated to PSO dietary supplements, standard analytical methods used for quality determination of edible oils have been applied. Refractive index (nD) was determined according to ISO 6320:2017 (ISO 2017). The content of double bonds was determined as iodine value (IV) according to ISO 3961:2018 and expressed as mg I2/100 g oil (ISO 2018). The content of hydroperoxides was determined as peroxide value (PV) according to ISO 3960:2017 (ISO 2017). Results are expressed as mEq O/kg oil. The content of free fatty acids was determined as acidic value (AV) according to ISO 660:2009 (ISO 2009). Results are expressed as mg KOH/g oil. The color of oil was performed in CIE L*a*b* system using a Minolta CR-400 chromatometer with glass cell (10 mm optical path) attachment CA-A98 (Konica Minolta, Inc., Tokyo, Japan), according to Moczkowska et al. (2017). The diameter of the measuring head was 8 mm. The device was calibrated on a white standard plate (L* = 98.45, a* = −0.10, b* = −0.13). Illuminant D65 (color temperature: 6500 K) and a standard observer (2°) were used. Color coordinates: L* (lightness or luminance), a* (greenness/redness), b* (blueness/yellowness) were measured at ten randomly selected places on each sample surface and expresses as mean of ten repetitions.
Sulfur mustard triggers oxidative stress through glutathione depletion and altered expression of glutathione-related enzymes in human airways
Published in Immunopharmacology and Immunotoxicology, 2018
Issa Layali, Alireza Shahriary, Nima Rahmani Talatappe, Eisa Tahmasbpour, Hossein Rostami, Asghar Beigi Harchegani
Higher expression of GPXs family (GPX1, GPX2, and GPX7) was also observed in our study. The enzyme GPXs is a selenocysteine-containing protein, which serves as an important factor for cellular defense against oxidant stress by utilizing GSH to H2O2 [32,33]. It scavenges hydrogen and lipid peroxides, thereby protects the body against OS. In the absence of this enzyme, reduction in antioxidant defense occurs, which leads to increased ROS accumulation, and can also elicit numerous pathophysiological consequences [34]. Moreover, it might provide a barrier against hydroperoxides. However, several lines of studies have demonstrated that SM declines the activity of GPXs and GSTs enzymes in the human lung tissue [22,35], which may be related to depletion of GSH. Sawale et al. found that exposure to 2-chloroethyl ethyl sulfide (CEES) depletes intracellular GSH level and activity of GSR, GPX, and GST enzymes, which play a major role in preventing ROS production and OS [36]. Therefore, there is a tight link between GSH contents and activity of these antioxidants in oxidatively damaged cells.