55
Saccharolipids are indispensable for assembly and functional regulation of PSII
(Mizusawa and Wada 2012 and the references therein). They play crucial roles
as markers for cellular recognition and stabilization of membrane bilayers and
during phosphate limitation in seaweeds (and in microalgae and plants) by
replacing phospholipids to combat the stress condition. Further, seaweed saccharolipids have notable anti- inflammatory, antimicrobial, antitumor, and antiviral properties, and a large number of saccharolipids have been isolated from
the species of Ulva, Chondria, Laurencia, Palmaria, Fucus, Sargassum, and
others (discussed in Maciel et al. 2016 and references therein).
4.2.3 Glycerolipids
Glycerolipids are characterized by glycerol backbone esterified with hydrophobic
acyl chains that may be saturated or unsaturated either at one, two, or all the three
positions (sn-1, sn-2, and sn-3) forming monoacylglycerol, diacylglycerol, and triacylglycerol, respectively. Triacylglycerol is the most prevalent glycerolipid accumulated in seaweeds as storage product and energy reservoirs. Its level is highly
plastic and ranges between 1% and 59.3% (Dembitsky et al. 1993; Dembitsky and
Rozentsvet 1996; Hofmann and Eichenberger 1997; Illijas et al. 2009; Khotimchenko
and Kulikova 1999; Kim et al. 1996; Kulikova and Khotimchenko 2000; Rozentsvet
et al. 1995).
4.2.4 Betaine Lipids
Betaine lipids are acylglycerolipids characterized by a betaine moiety (a quaternary
amine alcohol) instead of phosphorus or carbohydrate as a polar group linked to
sn-3 position of glycerol by an ether bond with fatty acids esterified in sn-1 and sn-2
positions. These betaine lipids are all zwitterionic at neutral pH due to their positively charged trimethylammonium group and a negatively charged carboxyl group.
The betaine lipids present in seaweeds are 1,2-diacylglyceryl-3-O-4′-(N,N,Ntrimethyl)-homoserine (DGTS) and 1,2-diacylglyceryl-3-O-2′-(hydroxymethyl)(N,N,N-trimethyl)-β-alanine (DGTA) (Fig. 4.1). Betaine lipids are widely distributed
in seaweeds and extensively reviewed by Dembitsky (1996) and Kato et al. (1996).
These two betaine lipids resemble PC due to their quaternary ammonium group and
hence replace PC in most of the seaweeds, even to traces such as in Ulotrichales,
Scytosiphonales, Desmarestiales, and others. DGTS abundantly occurs in
Chlorophyta with 5.2–56.5% of polar lipids and DGTA in brown algae with 7.3–
96.8% of polar lipids (Dembitsky and Rozentsvet 1996; Eichenberger et al. 1993;
Kulikova and Khotimchenko 2000; Makewicz et al. 1997; Muller and
Eichenberger 1994). DGTS in seaweeds contain long-chain PUFAs at both the sn-1
and sn-2 positions, while DGTA contain palmitic, myristic, oleic, LA, ALA, AA,
4 Seaweed Lipidomics in the Era of ‘Omics’ Biology: A Contemporary Perspective
Saccharolipids are indispensable for assembly and functional regulation of PSII
(Mizusawa and Wada 2012 and the references therein). They play crucial roles
as markers for cellular recognition and stabilization of membrane bilayers and
during phosphate limitation in seaweeds (and in microalgae and plants) by
replacing phospholipids to combat the stress condition. Further, seaweed saccharolipids have notable anti- inflammatory, antimicrobial, antitumor, and antiviral properties, and a large number of saccharolipids have been isolated from
the species of Ulva, Chondria, Laurencia, Palmaria, Fucus, Sargassum, and
others (discussed in Maciel et al. 2016 and references therein).
4.2.3 Glycerolipids
Glycerolipids are characterized by glycerol backbone esterified with hydrophobic
acyl chains that may be saturated or unsaturated either at one, two, or all the three
positions (sn-1, sn-2, and sn-3) forming monoacylglycerol, diacylglycerol, and triacylglycerol, respectively. Triacylglycerol is the most prevalent glycerolipid accumulated in seaweeds as storage product and energy reservoirs. Its level is highly
plastic and ranges between 1% and 59.3% (Dembitsky et al. 1993; Dembitsky and
Rozentsvet 1996; Hofmann and Eichenberger 1997; Illijas et al. 2009; Khotimchenko
and Kulikova 1999; Kim et al. 1996; Kulikova and Khotimchenko 2000; Rozentsvet
et al. 1995).
4.2.4 Betaine Lipids
Betaine lipids are acylglycerolipids characterized by a betaine moiety (a quaternary
amine alcohol) instead of phosphorus or carbohydrate as a polar group linked to
sn-3 position of glycerol by an ether bond with fatty acids esterified in sn-1 and sn-2
positions. These betaine lipids are all zwitterionic at neutral pH due to their positively charged trimethylammonium group and a negatively charged carboxyl group.
The betaine lipids present in seaweeds are 1,2-diacylglyceryl-3-O-4′-(N,N,Ntrimethyl)-homoserine (DGTS) and 1,2-diacylglyceryl-3-O-2′-(hydroxymethyl)(N,N,N-trimethyl)-β-alanine (DGTA) (Fig. 4.1). Betaine lipids are widely distributed
in seaweeds and extensively reviewed by Dembitsky (1996) and Kato et al. (1996).
These two betaine lipids resemble PC due to their quaternary ammonium group and
hence replace PC in most of the seaweeds, even to traces such as in Ulotrichales,
Scytosiphonales, Desmarestiales, and others. DGTS abundantly occurs in
Chlorophyta with 5.2–56.5% of polar lipids and DGTA in brown algae with 7.3–
96.8% of polar lipids (Dembitsky and Rozentsvet 1996; Eichenberger et al. 1993;
Kulikova and Khotimchenko 2000; Makewicz et al. 1997; Muller and
Eichenberger 1994). DGTS in seaweeds contain long-chain PUFAs at both the sn-1
and sn-2 positions, while DGTA contain palmitic, myristic, oleic, LA, ALA, AA,
4 Seaweed Lipidomics in the Era of ‘Omics’ Biology: A Contemporary Perspective