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Biosurfactants
Published in Girma Biresaw, K.L. Mittal, Surfactants in Tribology, 2019
Dina A. Ismail, Mona A. Youssif, Nabel A. Negm
Different types of fatty acids and phospholipid surfactants are produced by several bacteria and yeast during growth on n-alkanes [56–58]. When R. erythropolis grows on n-alkanes, it produces a substance known as phosphatidyl ethanolamine (Figure 3.5). Phosphatidylethanolamine is a class of phospholipids found in biological membranes [59], and is synthesized by the addition of cytidine diphosphate-ethanolamine to diglycerides, releasing cytidine monophosphate. Phosphatidylethanolamine decreases the interfacial tension between water and hexadecane to less than 1 mN/m and has a cmc of 30 mg/liter [60].
Organic Nanocarriers for Brain Drug Delivery
Published in Carla Vitorino, Andreia Jorge, Alberto Pais, Nanoparticles for Brain Drug Delivery, 2021
Marlene Lúcio, Carla M. Lopes, Eduarda Fernandes, Hugo Gonẹalves, Maria Elisabete C. D. Real Oliveira
The prevalence, impairment and mortality of CIR is high, in comparison to other neurological disorders mentioned so far [83]. CIR is characterised by a sudden decrease in brain blood flow because of cerebral vasculature obstruction, which affects the neural tissue (ischaemical penumbra zone) [83]. Unfortunately, CIR treatment is constrained by the poor ability to deliver therapeutic agents throughout the BBB [83]. Therefore, efforts have been made to recognise and improve the mechanisms of drug delivery to the brain [83]. Liposomes are considered potentially helpful to improve therapeutic effects in the treatment of CIR [83]. One of the possible treatments of CIR is citicoline, also known as cytidine diphosphate-choline (CDP-choline), the main phospholipid of the neuronal membrane which is degraded to free radicals and fatty acids throughout brain ischaemia [83]. Unfortunately, the crossing of the BBB was much lower than desired because of the polar nature of citicoline [83]. Therefore, liposomes containing CDP-choline have been found to enhance its bioavailability and its therapeutic efficacy in treating CIR [83, 100]. For example, liposomes composed of DPPC, dipalmitoylphosphatidylserine (DPPS), Chol and monosialotetrahexosylganglioside (GM1) were loaded with CDP-choline. In a similar approach to PEGylation of liposomes, the incorporation of GM1 ganglioside and anionic lipids such as DPPS into liposomes causes prolonged circulation time in vivo [100]. Thus, it is possible to obtain a stealth strategy without preparing a hybrid NC, as GM1 is a glycosphingolipid, and the resultant NC is entirely made of lipid components. After intraventricular injection in ischaemic rats, treatment with CDP-choline liposomes significantly decreased cerebral infarction compared to the equivalent dose of free CDP-choline [100]. The beneficial effects of CDP-choline liposomes in CIR may derive from a synergistic effect between the phospholipid components of liposomes and the encapsulated CDP-choline [100].
The enigma of environmental organoarsenicals: Insights and implications
Published in Critical Reviews in Environmental Science and Technology, 2022
Xi-Mei Xue, Chan Xiong, Masafumi Yoshinaga, Barry Rosen, Yong-Guan Zhu
The biosynthesis of AsSugPLs is predicted to start from Oxo-Gly with or without the formation of the intermediate Oxo-PO4 (Fig. 1F) (Zhu et al., 2017b). Diacylglycerol and cytidine diphosphate-diacylglycerol derived from phosphatidic acid serve as intermediates in the membrane phospholipid biosynthesis. Diacylglycerol is converted into phosphatidylserine, phosphatidylcholine, phosphatidylethanolamine, and phosphatidylthreonine, whereas cytidine diphosphate-diacylglycerol is a precursor for phosphatidylglycerol, phosphatidylinositol, cardiolipin, and phosphatidylserine in the prokaryotes (Jennings & Epand, 2020). However, whether AsSugPLs are synthesized from either Oxo-Gly and cytidine diphosphate-diacylglycerol or Oxo-PO4 and diacylglycerol is not clear yet. In addition, the biosynthesis of AsSugPLs likely takes place at the outer surface of the cytoplasmic membrane, similar to lipid biosynthesis.