China
Africa
Explore chapters and articles related to this topic
Biomolecules from Microalgae for Commercial Applications
Published in Kalyan Gayen, Tridib Kumar Bhowmick, Sunil K. Maity, Sustainable Downstream Processing of Microalgae for Industrial Application, 2019
Meghna Rajvanshi, Uma Shankar Sagaram, G. Venkata Subhash, G. Raja Krishna Kumar, Chitranshu Kumar, Sridharan Govindachary, Santanu Dasgupta
Sterols from plant sources, commonly called phytosterols, are well known to reduce cholesterol and prevent cardiovascular disorders in humans. Whereas PUFAs derived from microalgae and their roles in promoting human health have been extensively studied, research on sterols from microalgae is poorly represented. However, there is accumulating evidence that phytosterols from microalgae possess anti-inflammatory, anti-cancer, anti-atherogenic and anti-oxidative activities and offer protection against nervous system disorders (Luo, Su, and Zhang 2015). Microalgae produce several types of phytosterols, like brassicasterol, sitosterol and stigmasterol, based on the taxonomic classification (Volkman 2003). The amounts of sterols can vary depending on the physiological condition (Fábregas et al. 1997). Microalgae of the members of Chlorophyceae (green algae), Phaeophyceae (brown algae) and Rhodophyceae (red algae) are known to produce sterols (Lopes et al. 2013). Recently, Pavlova lutheri, Tetraselmis sp. M8 and Nannochloropsis sp. BR2 were identified as the highest microalgal phytosterol producers (0.4%—2.6 % DW). Further, a two-fold increase (5.1% w/w) in phytosterol accumulation was achieved in P. lutheri by modifying salinity, nutrient and cultivation duration (Ahmed, Zhou, and Schenk 2015). The plant sterols that are reduced to the stanols (sterols saturated at C-5) are commonly used in vegetable oils and are considered effective in lowering plasma cholesterol (Piironen et al. 2000). Studies suggest that the production of phytosterols by microalgae is comparable to or higher than plant sources, and hence it may be more advantageous to use microalgae as an alternative phytosterol source.
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.