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A. Pérez-Gálvez and J. Fontecha
by many cultures, current demands of an increasing human population to face challenges related with new food supplies, climate change, health claims, and sustainable economy have driven the traditional use of marine stores to the application of
state-of -the-art analytical procedures and technologies for (i) systematic screening
of marine organisms to yield unraveled novel compounds, (ii) new drugs development, and (iii) green production of crude biomass for fractionation in target bioactive compounds. Among marine resources with a high socioeconomic impact factor,
microalgae comprise a large group of species with enormous biochemical diversity
and high plasticity and adaptability to different cultivation conditions and biological
stimuli. Hence, microalgae-based products encompass food applications as sources
of proteins (Becker 2007), polyunsaturated fatty acids (Singh et al. 2005), algal
pigments (Prasanna et al. 2007), and minerals (Gouveia et al. 2009), or directly
as dietary supplements; animal feed (Borowitzka 1997); fertilizers and soil conditioners; cosmetics (Bedoux et al. 2014); and health products (Cornish and Garbary
2010).
The isoprenoids represent more than 50% of the total secondary metabolism
in algal organisms, including terpenes, steroids, prenylated quinones and hydroquinones, and carotenoid pigments. However, the key role of some of the latter as
accessory pigments in photosynthesis makes them become primary metabolites associated with the cellular photosynthetic apparatus, while other carotenoid species are
molded by the local environment or cultivation conditions and even some of them are
biosynthesized to counteract external harmful stimuli. These different biosynthetic
aims are determining factors for both the intracellular distribution and accumulation rate of primary and secondary carotenoids (Orosa et al. 2000; Huang et al.
2017). The occurrence and biosynthesis of carotenoids are out of the scope of this
chapter and the reader is referred to the chapters in this handbook dealing with
this topic (Chaps. 2, 4, and 5). Nevertheless, some points related to microalgae
as source of carotenoids deserve attention in this chapter focused in the analytical
protocols. The first one is the feasibility of microalgae to biosynthesize a relatively
simple carotenoid profile under certain culture conditions. This is the case of the
unicellular microalgae Dunaliella salina and Dunaliella bardawil, which are the
common sources of β-carotene that reaches almost 12% in dry cell weight (Saini
and Keum 2018). Other examples are the freshwater green algae Haematococcus
pluvialis that in environmentally stressful conditions produces astaxanthin, reaching
5% in dry weight (Boussiba et al. 1999), and Coelastrella striolata and Coelastrella
zofingiensis that under salt stress and nitrogen-deprivation cultivation conditions
accumulate canthaxanthin (Abe et al. 2007). In these examples, the processing of
the biomass for extraction concentrates most of the effort, either for analytical or
commercial purposes, while the strains accumulating a complex carotenoid profile
would require a comprehensive strategy for both processing for exhaustive extraction, and application of an analytical method for pigment characterization. Another
issue with a potential impact on the performance of the analytical protocols is the
intracellular location of carotenoids in microalgae. Those primary pigments accumulating in subcellular structures, i.e., light-harvesting complexes or membranes, are
firmly attached to the membrane (Okulski et al. 2000; Sujak et al. 2000) performing
A. Pérez-Gálvez and J. Fontecha
by many cultures, current demands of an increasing human population to face challenges related with new food supplies, climate change, health claims, and sustainable economy have driven the traditional use of marine stores to the application of
state-of -the-art analytical procedures and technologies for (i) systematic screening
of marine organisms to yield unraveled novel compounds, (ii) new drugs development, and (iii) green production of crude biomass for fractionation in target bioactive compounds. Among marine resources with a high socioeconomic impact factor,
microalgae comprise a large group of species with enormous biochemical diversity
and high plasticity and adaptability to different cultivation conditions and biological
stimuli. Hence, microalgae-based products encompass food applications as sources
of proteins (Becker 2007), polyunsaturated fatty acids (Singh et al. 2005), algal
pigments (Prasanna et al. 2007), and minerals (Gouveia et al. 2009), or directly
as dietary supplements; animal feed (Borowitzka 1997); fertilizers and soil conditioners; cosmetics (Bedoux et al. 2014); and health products (Cornish and Garbary
2010).
The isoprenoids represent more than 50% of the total secondary metabolism
in algal organisms, including terpenes, steroids, prenylated quinones and hydroquinones, and carotenoid pigments. However, the key role of some of the latter as
accessory pigments in photosynthesis makes them become primary metabolites associated with the cellular photosynthetic apparatus, while other carotenoid species are
molded by the local environment or cultivation conditions and even some of them are
biosynthesized to counteract external harmful stimuli. These different biosynthetic
aims are determining factors for both the intracellular distribution and accumulation rate of primary and secondary carotenoids (Orosa et al. 2000; Huang et al.
2017). The occurrence and biosynthesis of carotenoids are out of the scope of this
chapter and the reader is referred to the chapters in this handbook dealing with
this topic (Chaps. 2, 4, and 5). Nevertheless, some points related to microalgae
as source of carotenoids deserve attention in this chapter focused in the analytical
protocols. The first one is the feasibility of microalgae to biosynthesize a relatively
simple carotenoid profile under certain culture conditions. This is the case of the
unicellular microalgae Dunaliella salina and Dunaliella bardawil, which are the
common sources of β-carotene that reaches almost 12% in dry cell weight (Saini
and Keum 2018). Other examples are the freshwater green algae Haematococcus
pluvialis that in environmentally stressful conditions produces astaxanthin, reaching
5% in dry weight (Boussiba et al. 1999), and Coelastrella striolata and Coelastrella
zofingiensis that under salt stress and nitrogen-deprivation cultivation conditions
accumulate canthaxanthin (Abe et al. 2007). In these examples, the processing of
the biomass for extraction concentrates most of the effort, either for analytical or
commercial purposes, while the strains accumulating a complex carotenoid profile
would require a comprehensive strategy for both processing for exhaustive extraction, and application of an analytical method for pigment characterization. Another
issue with a potential impact on the performance of the analytical protocols is the
intracellular location of carotenoids in microalgae. Those primary pigments accumulating in subcellular structures, i.e., light-harvesting complexes or membranes, are
firmly attached to the membrane (Okulski et al. 2000; Sujak et al. 2000) performing