Structures and Properties of Self-Assembled Phospholipids in Excess Water
E. Nigel Harris, Thomas Exner, Graham R. V. Hughes, Ronald A. Asherson in Phospholipid-Binding Antibodies, 2020
Each class of the above mentioned diacyl phosphoglycerides refers to a family of lipid molecules with the same headgroup, but with different fatty acid composition in the hydrophobic tail. The complexity within each class can be demonstrated by the 13 major molecular species of phosphatidylcholine found in the human erythrocyte membrane,14 most of them having different fatty acyl chains at the sn-l and sn-2 carbons of the glycerol backbone (Table 1). It is important to note that for most of the major species shown in Table 1 a saturated fatty acyl chain is esterfied at the sn-1 position, and an unsaturated acyl chain at the sn-2 position. It should also be mentioned that the commonly observed unsaturated bond in most phospholipids is the double bond with a cis configuration. The position of the cis-double bond along the acyl chain most frequently occurs between carbons 9 and 10 from the carboxyl end. If two or more cis-double bonds are present, then these double bonds are always separated from each other by one methylene group. Some of the saturated and unsaturated fatty acids found in membrane phospholipids and their nomenclatures are given in Table 2.
Inhibitors of Human CYP2D6
Shufeng Zhou in Cytochrome P450 2D6, 2018
MDMA is a mechanism-based inhibitor of CYP2D6 (Figure 4.1) (Heydari et al. 2004; Van et al. 2007). The values of kinact (0.12–0.26 min−1) and Ki (8.8–45.3 μM) for MDMA are comparable to those reported for paroxetine (kinact = 0.17 min−1; Ki = 4.85 μM), another mechanism-based inhibitor of CYP2D6 that also contains a methylenedioxyphenyl ring (Bertelsen et al. 2003). The presence of the methylenedioxyphenyl ring in MDMA and methylenedioxyamphetamine is most probably involved in the formation of a metabolic intermediate complex with CYP2D6, although such complexes are also generated by amine groups. CYP-mediated oxidation of the methylene carbon in both compounds would lead to formation of unstable intermediates, which are then demethylenated to catechols (3,4-dihydroxymethamphetamine and a-methyldopamine) or dehydrated to carbenes. The former compounds may be oxidized further to orthoquinones, which can react with nucleophilic groups on macromolecules or conjugate with glutathione to form neurotoxins (Easton et al. 2003). The carbene intermediates are likely to form covalent complexes with the heme iron of CYP2D6.
Miscellaneous Methods of Analysis
Joseph Chamberlain in The Analysis of Drugs in Biological Fluids, 2018
Nuclear magnetic resonance spectroscopy is a powerful technique for examining the behavior of suitable atomic nuclei in a magnetic field. In its most familiar form, the technique separates signals due to single hydrogen nuclei depending on their chemical situation in the molecule, and the signal is further split depending on the immediate molecular environment of the hydrogen atom. Thus, Figure 9.5 shows the NMR spectrum of ethanol; three main signals are shown corresponding to the three types of hydrogen atom in the molecule: a hydrogen atom which is part of the methyl group, a hydrogen atom which is part of a methylene group, and a hydrogen atom which is part of a hydroxyl group. In this molecule, the methyl and methylene hydrogens are affected by the proximity of the other group and the signal is further subdivided. The methyl hydrogens are affected by two methylene hydrogens and are therefore split into a characteristic triplet pattern, the signals being in the ratio 1:2:1. The methylene hydrogens are similarly affected by the proximity of three methyl hydrogens and are split into a characteristic quartet, the signals being in the ratio 1:3:3:1. Integrating the groups of signals shown gives the the relative number of each type of hydrogen atom.
The Presence of Uncoated Gold Nanoparticle Aggregates May Alter the Phase of Phosphatidylcholine Lipid as Evidenced by Vibrational Spectroscopies
Published in Journal of Liposome Research, 2023
Lea Pašalić, Qiqian Liu, Petra Vukosav, Tea Mišić Radić, Aicha Azziz, Marjan Majdinasab, Mathieu Edely, Marc Lamy de la Chapelle, Danijela Bakarić
When analyzing, both SERS and FTIR-ATR spectra were examined in four spectral regions (I (1800-1500 cm−1), II (1500-1300 cm−1), III (1300-950 cm−1), IV (950-650 cm−1) that contain the following vibrational signatures: I: carbonyl stretching of glycerol moiety (νC = O) and bending of water molecules (δHOH), II: scissoring of methylene moiety (γCH2), III: wagging of methylene group (ωCH2), (anti)symmetric stretching of C − O bond of glycerol moiety (ν(a)sC − O), (anti)symmetric stretching of phosphate groups (ν(a)sPO2−), IV: (anti)symmetric stretching of C − N bond of choline group (ν(a)sC − N), rocking of methylene moitey (ρCH2), stretching of hydrocarbon chain that encompasses at least three methylene groups (νC − C−C). Additionally, spectral region 2960-2820 cm−1 (V) that contains the signatures of (anti)symmetric stretching of methylene groups of a hydrocarbon chains are (ν(a)sCH2) is examined as well (using FTIR-ATR only). The signal intensities are labelled as very strong (vs), strong (s), medium (m), weak (w), very weak (vw), broad (b) or shoulder (sh) (the label ii is for inverted intensity that arise after subtracting the spectrum of PB from DPPC MLVs or HSs spectrum).
Construction and evaluation of an antioxidant synergistic system containing vitamin C and vitamin E
Published in Journal of Microencapsulation, 2023
Ran Tao, Qianyu Zhang, Jialing Duan, Ran Chen, Liyun Yao, Ruiteng Zhang, Gang Dong, Huali Chen
The antioxidant activity of the liposomes was evaluated using a β-carotene-linoleic acid model system (Emmons et al.1999). In the β-carotene-linoleic acid system, the yellow-orange colour of β-carotene was readily discoloured by the oxidation of linoleic acid. During oxidation, a hydrogen atom extracted from the active diallyl methylene could form a pentenyl radical. It attacked the highly unsaturated β-carotene molecule and regains a hydrogen atom. The carotene would therefore lose its characteristic orange colour. This oxidation process could be monitored spectrophotometrically. The presence of antioxidants could inhibit the extent of β-carotene damage through the linoleic acid radical and other free radicals formed within the system using its redox potential and other free radicals formed within the system (Vieira et al.1998, Argoti et al.2011). This, therefore, formed the basis for assessing the antioxidant potential of liposomes.
Dyhidro-β-agarofurans natural and synthetic as acetylcholinesterase and COX inhibitors: interaction with the peripheral anionic site (AChE-PAS), and anti-inflammatory potentials
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2022
Julio Alarcón-Enos, Evelyn Muñoz-Núñez, Margarita Gutiérrez, Soledad Quiroz-Carreño, Edgar Pastene-Navarrete, Carlos Céspedes Acuña
Compound 6 was obtained by esterification of 4 with furoyl chloride. The 1H NMR spectrum of compound 6 show the presence of three singlet signals in high field that were assigned to the methyl groups in C-12, C-13, and C-15. In addition, it is observed in this compound an AB system between at 4.01–3.98 (J= 6.5 Hz) and 3.65–3.63 (J= 8.6 Hz), that is not present in the precursor. Further comparison of the 1H and 13 C NMR spectroscopic data of compound 4 to those of compound 6 reveals that compound 6 contains one less methyl group and one more methylene bearing a hydroxyl group. This is further confirmed by the HMBC correlations of H-14 (δ H 3.99) with C-4 (δ C 47.57 ppm), C-3 (δ C 76.71 ppm) and C-5 (δ C 89.91 ppm). Similarly compound 7 was prepared by esterification of 4 with benzoyl chloride. The 1H NMR spectrum of compound 7 show the presence of three singlet signals in high field that were assigned to the methyl groups in C-12, C-13, and C-15. In addition, it is observed in this compound an AB system between at δ 3.91–3.88 (J= 8.0 Hz) and 3.55 − 3.52 (J= 10.6 Hz).
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