Macronutrients
Chuong Pham-Huy, Bruno Pham Huy in Food and Lifestyle in Health and Disease, 2022
Phospholipids also known as phosphoglycerides are fat compounds and have a glycerol backbone linked to a hydrophilic phosphate group, and two hydrophobic fatty-acid molecules. The phosphate group can be coupled with a nitrogen-containing compound and is water-soluble (67, 69, 114–115). So, phospholipids are amphipathic molecules, consisting of two hydrophobic fatty acid chains and a phosphate-containing hydrophilic head group, forming the fundamental building blocks of all cell membranes (115–116). By this special structure, phospholipids are amphiphilic compounds; they are both water-soluble and liposoluble. Because their fatty acid tails are insoluble in water, phospholipids spontaneously form stable bilayers in aqueous solutions, with the hydrophobic tails (fatty acids) buried in the interior of the cell membrane and the polar head groups (phosphates exposed to water present in the cell) (115). In blood and body fluids, phospholipids form structures in which fatty acids like omega-3, omega-6 fatty acids, cholesterol, and so on, are enclosed and transported throughout the bloodstream due to their amphiphilic nature (67). In cells, phospholipases hydrolyze phospholipids by releasing the transported fatty acids.
Phosphoinositide Metabolism
Enrique Pimentel in Handbook of Growth Factors, 2017
Phosphatidylinositol and its phosphorylated derivatives, which include mono- and polyphosphates, represent less than 6 to 8% of the components of the membranes of eukaryotic cells. However, they are important components of cell membranes and are crucially involved in receptor-mediated activation of intracellular signaling mechanisms. Various enzymes are involved in the regulation of phospholipid biosynthesis in eukaryotic cells,21 as well as in the phosphorylation and hydrolysis of cellular phospholipids.22 The hydrolytic enzymes involved in such processes include several phospholipases. The phosphorylation of phosphatidylinositol depends on the activity of phosphatidylinositol kinases with different substrate specificities. While the generation of phosphatidylinositol 4-monophosphate depends on the activity of phosphatidylinositol kinase type II, the type I enzyme is involved in the generation of phosphatidylinositol 3-monophosphate.23 Further phosphorylation of the monophosphate gives origin to phosphatidylinositol 4,5-bisphosphate, a compound that has been found to be involved in the activation of a low affinity form of human DNA polymerase-α, suggesting that it may function as a second messenger during the initiation of mitosis.24
The Inflammatory Response: A Bridge Between The Constitutive and Inducible Systems
Julius P. Kreier in Infection, Resistance, and Immunity, 2022
In addition to the vasoactive amines, histamine and serotonin, there are other vasoactive hormones released at the site of an inflammatory response. They include the prostaglandins and leukotrienes. The prostaglandins and leukotrienes are lipid hormones. They are derived from arachidonic acid which is cleaved from the membrane phospholipids by phospholipase A2 (Figure 4.2). The phospholipase is activated by substances that damage cell membranes. After release, the arachidonic acid is oxygenated by one or the other of two enzyme systems. These are the cyclooxygenase system, the actions of which result in the production of the prostaglandins, and the lipooxygenase system, the actions of which result in the production of the leukotrienes. A large number of different prostaglandins have been described. The major prostaglandins produced are PGE1, PGE2, PGF2a, prostacyclin (PG12), and Thromboxane A2. The leukotrienes produced include LTB4, LTC4, LTD4, LTE4, and LTF4.
Biological exploration of a novel 1,2,4-triazole-indole hybrid molecule as antifungal agent
Published in Journal of Enzyme Inhibition and Medicinal Chemistry, 2020
Fabrice Pagniez, Nicolas Lebouvier, Young Min Na, Isabelle Ourliac-Garnier, Carine Picot, Marc Le Borgne, Patrice Le Pape
Candida spp. are known to produce several types of phospholipases such as phospholipase B and phospholipase A which were detected in culture supernatant16,17. The virulence of Candida strains in G. mellonella is related to the quantity of phospholipases production18 and strains isolated from symptomatic women with vulvovaginal candidiasis exhibit high level of phospholipase activity19. Phospholipase B has been described as a pathogenic factor that contributes to host membrane degradation and penetration of C. albicans pseudohyphae20. Intracellular phospholipases, identified as phospholipases A, have been localised at the site of bud formation21. Triglyceride lipases with phospholipase A2-like activity (patatin-like homologs) have been described in Saccharomyces and Candida22. Already known function of this phospholipase is hydrolysis of fatty acids for membrane formation and sporulation. Since indole derivatives have been reported as inhibitors of phospholipase A2 activity10,23 our 2-dichlorophenyl-3-triazolyl-1-indolyl-propan-2-ol derivative (8 g) could be of interest to inhibit this enzyme activity.
Liquid biopsy markers for stroke diagnosis
Published in Expert Review of Molecular Diagnostics, 2020
Harshani Wijerathne, Malgorzata A. Witek, Alison E. Baird, Steven A. Soper
There are other biomolecules that do not belong in the aforementioned categories and have been shown to be potential biomarkers of stroke. As an example, atrial natriuretic peptide (ANP), a cardiac hormone whose main function is to lower blood pressure and control electrolyte homeostasis was elevated following a stroke event [104]. Plasma concentrations of ANP were significantly higher in stroke patient samples compared to healthy controls. Another marker, brain natriuretic peptides (BNP), also was shown to be elevated after AIS and subarachnoid hemorrhage. BNP is also used as a marker for diagnosing congestive heart failure, therefore it is still unclear whether the increased levels of BNP are of cardiac or brain origin [104]. Lipoprotein-associated phospholipase A2 is an enzyme that hydrolyzes oxidized phospholipids. This enzyme has also been studied as a biomarker for ischemic stroke [105]. Free hemoglobin has also been suggested as a potential marker for stroke because it has shown increased levels in AIS patients compared to healthy controls [106]. Table 4 summarizes currently reported biomarkers of stroke and their function.
Evaluation of anti-inflammatory impact of dexamethasone-loaded PCL-PEG-PCL micelles on endotoxin-induced uveitis in rabbits
Published in Pharmaceutical Development and Technology, 2019
Mitra Alami-Milani, Parvin Zakeri-Milani, Hadi Valizadeh, Shahram Sattari, Sara Salatin, Mitra Jelvehgari
Corticosteroids are the most common medication used to reduce the inflammatory symptoms in uveitis (Behar-Cohen et al. 1997). Among the corticosteroids, dexamethasone (DEX) is one of the most potent; with an anti-inflammatory activity that is thirty-fold greater than that of cortisol and six-fold greater than triamcinolone (Herrero-Vanrell et al. 2011; Bandello et al. 2015). The anti-inflammatory function of corticosteroids has been ascribed to a group of phospholipase A2 inhibitory proteins, conjointly called lipocortin (Wallner et al. 1986). Phospholipase A2 is an enzyme which acts on the cell membrane and releases arachidonic acid from membrane-bound phospholipids (Tamby et al. 1993). Application of DEX up-regulates the synthesis of lipocortin, thereby reducing the production of arachidonic acid metabolites (Lima et al. 2017).
Related Knowledge Centers
- Acyl Group
- Arachidonic Acid
- Diglyceride
- Fatty Acid
- Phospholipase A2
- Phospholipase C
- Phospholipid
- Second Messenger System
- Signal Transduction
- Phospholipase A1