China
Africa
Explore chapters and articles related to this topic
Macrocyclic Receptors for Biomolecules and Biochemical Sensing
Published in Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney, Macrocyclic Receptors for Environmental and Biosensing Applications, 2022
Satish Kumar, Priya Ranjan Sahoo, Violet Rajeshwari Macwan, Jaspreet Kaur, Mukesh, Rachana Sahney
Polar lipids such as glycerophospholipids and sterols consisting of polar heads and nonpolar hydrocarbon chain are major components of the cell membrane. Biophysical properties of plasma membrane such as surface curvature and internal fluidity can be modulated by their lipid compositions. The presence of sterols, such as cholesterol or ergosterol, greatly affects the membrane packing and structural integrity (Dufourc 2008). Interaction of lipid molecules with membrane proteins regulates G-protein and GPCRs activity. Sterols are crucial membrane components in the formation of local liquid-ordered membrane phases called ‘lipid rafts’, which also contain transmembrane proteins and are involved in biological signaling and trafficking processes (Simons and Sampaio 2011). Essential Fatty Acids (EFA) are indispensable for one’s health as they serve as dietary precursors for the formation of prostanoids and other eicosanoids important for health and modulation of disease conditions. Poly-Unsaturated Fatty Acids (PUFA) like Omega-3 (w-3) fatty acids is an essential requirement for one’s health which cannot be synthesized by the human physiological system and must therefore be obtained through a nutritional diet (Uauy 1999). The endoplasmic reticulum is the bulk supplier of lipids to other organelles in the eukaryotic cell. The transport and metabolism of lipid is governed by various protein receptors that selectively associate with lipids and transfer them to specific locations with the help of supra-molecular transporting assemblies (Holthuis and Menon 2014).
Mechanisms for Carbon Assimilation and Utilization in Microalgae and Their Metabolites for Value-Added Products
Published in Ashok Kumar, Swati Sharma, 2 Utilization, 2020
Varsha S.S. Vuppaladadiyam, Zenab T. Baig, Abdul F. Soomro, Arun K. Vuppaladadiyam
Sterols are bioactive compounds and are presented in eukaryotes, which can significantly affect the physicochemical properties of plasma membrane (Volkman 2016). The sterol content in the plasma membrane can reach up to 20%–30% in the eukaryotes and is highly diverse when compared to sterols in animals (Abdul et al. 2016, Martin-Creuzburg and Merkel 2016). Sterols derived from microalgae include sterols, fucosterols, and phytosterols and found their application in health and food industry (Volkman 2016). Structures of common sterols found in marine microalgae are shown in Figure 12.3. Sterols are reported to lower the levels of cholesterol in blood and are also considered as anticarcinogenic (Leblond et al. 2011, Tang and Suter 2011), anti-inflammatory (Caroprese et al. 2012, Jung et al. 2013), immunomodulatory (Caroprese et al. 2012), antioxidative (Abdul et al. 2016, Lee et al. 2003), hepatoprotective (Jung et al. 2013, Demirbas and Fatih Demirbas 2011), and antihypercholesterolaemic (Chen et al. 2014). Additionally, they act as precursors to other bioactive compounds. Recently, in a study done on sterol extracts from Schizochytrium, Adarme-Vega et al. (2012) reported that the intestinal gene expression ACAT2283 was found to be responsible for the absorption of cholesterol in intestine.
Extraction of Valuable Compounds from Leaf Vegetables By-Products
Published in Francisco J. Barba, Elena Roselló-Soto, Mladen Brnčić, Jose M. Lorenzo, Green Extraction and Valorization of By-Products from Food Processing, 2019
João Carlos Martins Barreira, Isabel Cristina Fernandes Rodrigues Ferreira
Structurally, phytosterols resemble cholesterol, containing 28 or 29 carbons and one or two double C–C bonds, characteristically one in the sterol nucleus and often a second in the alkyl side chain. Sterols derive from hydroxylated polycyclic isopentenoids having a 1,2-cyclopentanophenanthrene structure and comprise the largest proportion of the unsaponifiable fraction of lipids (Valitova et al., 2016). More than 200 sterols have been reported, among which the 4-desmethylsterols, such as β-sitosterol, campesterol, stigmasterol, and ∆5-avenasterol (Figure 12.3). In plants, β-sitosterol is clearly the predominant sterol (Barreira and Ferreira, 2015).
Bio-oil production from oleaginous microorganisms using hydrothermal liquefaction: A biorefinery approach
Published in Critical Reviews in Environmental Science and Technology, 2022
Tanushree Paul, Arindam Sinharoy, Divya Baskaran, Kannan Pakshirajan, G. Pugazhenthi, Piet N. L. Lens
In particular, polar lipids present in microbial biomass consisting of acyl chains are considered as direct precursors for potential biofuel production with a remarkably high yield. However, phytol chains in chlorophyll as well as hydrocarbon backbones in sterols can also be converted into biofuels by catalytic upgrading processes (Dong et al., 2016).
Lipid biomarkers as organic matter source indicators of estuarine mangrove ecosystems
Published in Chemistry and Ecology, 2022
C. S. Ratheesh Kumar, O. S. Gayathry, V. B. Rakesh, A. Sudha, Roshni Mohan, P. M. Salas, P. Resmi, Manju Mary Joseph, K. Shameem, N. Chandramohanakumar
Sterols: Sterols are common constituents of higher plants in which they are typically represented by cholesterol (C27), campesterol (C28), β-sitosterol (C29) and stigmasterol (C29). β-sitosterol along with other pentacyclic triterpenoids have been utilized as chemotaxonomical markers for mangrove species [46]. It has been well established as a major sterol in mangroves [40] and the presence of this C27 sterol could be recognized as the evidence for contribution from vascular plants including mangroves. The occurrence of this compound has also been recorded in diatoms, green algae and cyanobacteria [47,48] and is thus not a unique indicator for terrestrial lipid input. The content of stigmasterol varied from 0.38 ± 0.08 to 2.84 ± 0.37 µg/g and was observed at all the stations (Figure 3(c)). C24 alkylated sterols are found in marine microorganisms as well as terrestrial plants [47]. In the present investigation, all stations except E1 recorded campesterol (Figure 3(c)) similar to the previous research reports [49]. The occurrence of this compound in Acanthus ilicifolius and Avicennia marina species has already been published [50] and the distribution of Acanthus ilicifolius species was noticed at M2 and M3 during the present investigation. Cholest-5-en-3β-ol was the major sterol detected in all the sites (range: 1.98 ± 0.44 to 5.78 ± 0.23 µg/g). Content of this sterol in Bruguiera gymnorrhiza and Acanthus ilicifolius has already been reported [50] and the occurrence of patches of Acanthus species has been observed at all the mangrove sites. Cholest-5-en-3β-ol is the most abundant and ubiquitous sterol in the environment due to a variety of sources [51], limiting its use as a biomarker. Moreover, cholesterol has been recorded as the major sterol in faecal matter [52], and hence its abundance in estuarine sediments reflected high level of zooplankton grazing and subsequent sinking of faecal pellets. Compared to estuarine sediments, the higher relative abundance of cholesterol in mangrove sediments at M3 (Figure 3(c)) can be due to leaf litter input [49]. 5β-Coprostanol (5β-cholestan-3β-ol) is a C27 stanol formed from the biohydrogenation of cholesterol (cholest-5en-3β-ol) in the gut of higher animals and birds [53]. It was detected only in sediment extracts of M2 and its source was assigned to sewage input ascribed to increasing population density and poor sanitation facilities in this coastal area.