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The Scientific Basis of Medicine
Published in John S. Axford, Chris A. O'Callaghan, Medicine for Finals and Beyond, 2023
Chris O'Callaghan, Rachel Allen
The structural units of lipids are fatty acids, containing long chains of 4–24 carbon atoms joined to a carboxylic acid group (Figure 2.4). Fatty acids may be saturated or non-saturated depending on the presence of double bonds within their hydrocarbon tail. Polyunsaturated fatty acids contain multiple double bonds. One of the most important in vivo functions performed by lipids is the formation of cellular membranes. Phospholipids contain a hydrophilic phosphate group, linked by glycerol to a hydrophobic fatty acid tail. The amphipathic nature of phospholipids allows them to form a sealed membrane bilayer in aqueous solution. Another physiologically important group of lipids are the cholesterol derivatives (steroids). These molecules contain four hydrocarbon rings, one of which carries a hydroxyl group which gives the molecule an amphipathic nature.
Macronutrients
Published in Chuong Pham-Huy, Bruno Pham Huy, Food and Lifestyle in Health and Disease, 2022
Chuong Pham-Huy, Bruno Pham Huy
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.
Envisioning Utilization of Super Grains for Healthcare
Published in Megh R. Goyal, Preeti Birwal, Santosh K. Mishra, Phytochemicals and Medicinal Plants in Food Design, 2022
The lipid content of millets varies from 1% to 5% with pearl, proso, and foxtail millets containing the highest (5%) and kodo and finger millet containing lowest amounts (1%). Since the germ contains higher content of lipids, pearl, and foxtail millets have higher levels due to larger germs. Approximately 88% of the total pearl millet fat is concentrated in the germ, which contains 32% of the lipid content [177]. The lipids contain neutral lipids (85%), phospholipids (12%), and glycolipids (3%). The unsaturated fatty acids constitute 78%–82% with high levels of LA followed by oleic acid. Linolenic acid and erucic acid are also present in trace amounts [7, 81]. Oleic acid is the chief fatty acid in finger millet, which itself contains lower amount of lipids content, thus accounting for the superior shelf stability [177]. Major phospholipids include lysophosphatidylcholine (42%), phos-phatidylcholine (24%), lysophosphatidylethanolamine (21%), and traceable amounts of phosphatidylserine, phosphatidic acid, phosphatidylinositol, and phosphatidylglycerol [81].
Rationale utilization of phospholipid excipients: a distinctive tool for progressing state of the art in research of emerging drug carriers
Published in Journal of Liposome Research, 2023
Koilpillai Jebastin, Damodharan Narayanasamy
Phospholipids are made up of two fatty acid chains and glycerol. The phospholipid classes are determined by the head group formed by bringing nitrogen and polar phosphate groups together, which offers a hydrophilic region. The insoluble non-polar group of hydrophobic fatty acid components forms the tail (Figure 1). A glycerol linkage connects a polar or charged head group to a pair of non-polar fatty acyl tails in these molecules (Figure 2). These fatty acyl molecules are esterified at the sn-1 and sn-2 regions of glycerol, as well as possessing a head group connected by a phosphate residue at the sn-3 position. Because the fatty acyl side chains are hydrophobic, phospholipids have an amphipathic characteristic that allows cells to be compartmentalized. The solubility of phospholipids in an aqueous environment is divided, with solubility on one end and insolubility on the other. As a result, they function as a barrier to the passage of molecules and ions into and out of the biological cell membranes (Jacobs et al. 2005, van Hoogevest and Wendel 2014, Hoogevest et al. 2021).
Genistein prevents the decrease in ganglioside levels induced by amyloid-beta in the frontal cortex of rats
Published in Neurological Research, 2022
Fernanda dos Santos Petry, Juliana Bender Hoppe, Caroline Peres Klein, Bernardo Gindri dos Santos, Régis Mateus Hözer, Christianne Gazzana Salbego, Vera Maria Treis Trindade
The AD pathogenesis is closely related to changes in the lipid homeostasis, which can severely affect the physicochemical properties of cell membranes [4,5]. Gangliosides are sialic acid-containing glycosphingolipids, present in high concentrations in neuronal cell membranes, which play important roles in memory formation, neuritogenesis and synaptic transmission. Moreover, they are involved in cell differentiation and growth, ion channel modulation, and intercellular signaling [6]. Phospholipids exert structural functions in the membrane, also participating in cell signaling. Cholesterol, in turn, is an essential component for the structure and function of cell membranes, modulating their physicochemical properties and contributing to the formation of lipid rafts, specialized membrane microdomains that compartmentalize cellular processes [7]. Increasing evidence indicates that the Aβ peptide can alter the composition and structure of cell membranes, impairing neuronal functions [8,9].
Surface-modified polymeric nanoparticles for drug delivery to cancer cells
Published in Expert Opinion on Drug Delivery, 2021
Arsalan Ahmed, Shumaila Sarwar, Yong Hu, Muhammad Usman Munir, Muhammad Farrukh Nisar, Fakhera Ikram, Anila Asif, Saeed Ur Rahman, Aqif Anwar Chaudhry, Ihtasham Ur Rehman
Cell membrane functions as the main barrier for inward and outward movement of bio-entities [33]. Similarly, drug-loaded polymeric nanoparticles are also needed to cross the cell membrane to exhibit their efficiency. The composition, morphology, and functions of cell membrane have attracted scientists to fabricate nanoparticles, whose surfaces mimic cell membrane (Figure 3a). The cell membrane is composed of a phospholipid bilayer with embedded proteins and carbohydrates. Phospholipids consist of hydrophobic phosphate group-containing head linked to the hydrophobic tail of fatty acids. These phospholipids self-assemble into bilayers with hydrophilic regions facing toward outside and inside of the cell, while hydrophobic tails of phospholipids face each other. The incorporation of cholesterol and proteins enhances the stability of the cell membrane. Membrane proteins are inserted throughout the cell membrane asymmetrically. They are arranged in a way that their exterior surfaces can act as receptors for signaling molecules, whereas interior sides change their conformation in response to the binding signal. In some cases, membrane carbohydrates, in the form of glycolipids, work as recognition sites for proteins [34]. Research on biologically inspired nanoparticles has revealed that surface modification of nanoparticles with lipid bilayer or protein/carbohydrate embedding enhances the efficacy of drug-loaded nanoparticles [35], for instance increase in circulation time, improved biocompatibility, low toxicity and immunogenicity [36] and enhanced stability [37].