Galactolipid

Galactolipids are a type of glycolipid whose sugar group is galactose. They differ from glycosphingolipids in that they do not have nitrogen in their composition.[1]

General chemical structure of a monogalactosyl diacylglycerol (MGDG), a prevalent type of galactolipid. R1 and R2 are fatty chains.

They are the main part of plant membrane lipids where they substitute phospholipids to conserve phosphate for other essential processes. These chloroplast membranes contain a high quantity of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG).

They probably also assume a direct role in photosynthesis, as they have been found in the X-ray structures of photosynthetic complexes.[2]

Galactolipids are more bioavailable than free fatty acids, and have been shown to exhibit COX mediated anti-inflammatory activity.[3] Bio-guided fractionation of spinach leaves (Spinacia oleracea) revealed alpha-linolenic acid galactolipids (18:3, n-3) were responsible for inhibitory effects on tumor promoter-induced Epstein-Barr virus (EBV) activation.[4] Recently, it has been demonstrated that this same galactolipid, 1,2-di-O-α-linolenoyl-3-O-α-D-galactopyranosyl-sn-glycerol,[5] may be important for the anti-inflammatory activity of Dog Rose (Rosa canina), a medicinal plant with documented effect on inflammatory diseases such as arthritis.

The galactosphingolipid galactocerebroside (GalC) and its sulfated derivative sulfatide is also in abundance present (together with a small group of proteins) in myelin, the membrane around the axons in the nervous system of vertebrates.[6]

It is galactolipids, rather than phlorotannins, that act as herbivore deterrents in Fucus vesiculosus against the sea urchin Arbacia punctulata.[7]

References
  1. "Galactolipids". Genetics Home Reference. U.S. National Library of Medicine. 21 December 2009. Retrieved 25 December 2009.
  2. Dörmann, Peter; Christoph Benning (1 March 2002). "Galactolipids rule in seed plants". Trends in Plant Science. 7 (3): 112–118. doi:10.1016/S1360-1385(01)02216-6. PMID 11906834.
  3. Christensen, L. Galactolipids as Potential Health Promoting Compounds in Vegetable Foods Recent Patents on Food, Nutrition & Agriculture, 2009; 1, 50-58.
  4. Wang R, Furomoto T, Motoyama K, Okazaki K, Kondo A, Fukui H. Possible anti-tumor promoters in Spinacia oleracea (spinach) and comparison of their contents among cultivars. Biosci Biotechnol Biochem 2002; 66(2): 248-254.
  5. Block G, Patterson B, Subar A. Fruit, vegetables, and cancer prevention: A review of the epidemiological evidence. Nutr Cancer 1992; 18(1): 1-29.
  6. Coet, Timothy; Kunihiko Suzukia; Brian Popkoa; Kunihiko Suzukib; Brian Popkoc; Kunihiko Suzukid; Brian Popko (1 March 1998). "New perspectives on the function of myelin galactolipids". Trends in Neurosciences. 21 (3): 126–130. doi:10.1016/S0166-2236(97)01178-8. PMID 9530920.
  7. Galactolipids rather than phlorotannins as herbivore deterrents in the brown seaweed Fucus vesiculosus. Michael S. Deal, Mark E. Hay, Dean Wilson and William Fenical, Oecologia, June 2003, Volume 136, Issue 1, pages 107-114, doi:10.1007/s00442-003-1242-3
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