The Scientific Basis of Medicine
John S. Axford, Chris A. O'Callaghan in Medicine for Finals and Beyond, 2023
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.
Nanomaterials in Chemotherapy
D. Sakthi Kumar, Aswathy Ravindran Girija in Bionanotechnology in Cancer, 2023
Lipids are highly hydrophobic in nature, hence insoluble in water, and typically consist of saturated or unsaturated hydrocarbon motifs often connected to glycerol. For instance, a triglyceride is composed of three fatty acids linked via ester bonds to glycerol. Many of the lipids are isolated from their biological origin, which then purified via chromatographic separations. Progresses in the field of lipid synthesis with high purity diversified the scope of using lipid as a ‘solubilizer’ in cosmetics and foods, and as a ‘building block’ for making nanoscale materials. Phospholipids are a class of lipids with amphiphilic characteristics due to the presence of both hydrophobic fatty acid chain and a hydrophilic phosphate group. In an aqueous environment, phospholipid tends to form a bilayer architecture as in the case of the biological cell membrane. Since the phosphate part of the phospholipids can be easily functionalized with organic molecules, such as choline, a wide variety of modified phospholipids have been developed that form interesting nanostructures. Liposome is a representative example formed by the self-assembly of phospholipid derivatives, such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylglycerol, which have been found applications in various fields including DDSs.
Envisioning Utilization of Super Grains for Healthcare
Megh R. Goyal, Preeti Birwal, Santosh K. Mishra in 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].
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].
Long-circulating doxorubicin and schizandrin A liposome with drug-resistant liver cancer activity: preparation, characterization, and pharmacokinetic
Published in Journal of Liposome Research, 2022
Shi-Yi Xu, Hui Su, Xing-Yu Zhu, Xue-Ying Li, Jie Li, Xi Chen, Qi Wang, Ruo-Yi Hao, Xue-Ying Yan
Phospholipid is an important part of lipid preparation. Different kinds of phospholipids will affect the encapsulation efficiency of the preparation after hydration. Natural lecithin was chosen because of its good biocompatibility, high safety and low price. The commonly used natural lecithin is egg yolk lecithin, hydrogenated phospholipids and soybean lecithin. Single factor study was used to determine whether high purity soybean lecithin (PC 80% and 95%, injection grade), hydrogenated phospholipids (PC200sh, injection grade), natural yolk phospholipids (Lipoid EPCs, Ludwigshafen, Germany, injection grade) and hydrogenated phospholipids (Lipoid SPC-3, injection grade) were suitable for the preparation of liposomes. The results showed that the liposomes prepared from Lipoid EPCS were very unstable and easy to be stratified. PC200sh and lipoid SPC-3 are hydrogenated phospholipids with high phase transition temperature, poor solubility in organic solvents, and white particles appear during hydration. Soybean lecithin has good solubility, and the prepared liposomes were uniform and stable. The encapsulation efficiency of compound liposomes prepared by soybean lecithin with 95% purity of PC was higher. PC could form complex with drugs to increase the solubility of drugs and the stability of preparations. Hence, we chose soya lecithin with purity of 95% in injection grade.
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].
Related Knowledge Centers
- Alcohol
- Choline
- Docosahexaenoic Acid
- Eicosapentaenoic Acid
- Ethanolamine
- Fatty Acid
- Glycerol
- Phosphate
- Lipid
- Omega-3 Fatty Acid