Types of Lipids II

Suaib Luqman

epgp books

 

  1. Objectives
  • v To know about the complex lipids
  • v What are their significance
  • v How they act in a system
  1. Concept Map
  1. Description

 

3.1 Types of Lipids II

 

 

Complex Lipids

 

 

Glycolipids

 

 

DGDG mono estolide from the kernel of oat

The estolide of DGDG include an avenolic acid (15-hydroxylated linoleic acid) and linoleic acid cluster. The di estolides of DGDG have also been isolated from the kernels of oat.

 

Structure of estolide of DGDG from the kernel of oat

 

 

A diminutive fraction of Tri and TetraGDG estolides were also noticed and overall the estolides include 10% of lipid fraction and ~29% of the total glycolipid fraction (extracted in methanol).

 

 

From the exudates of glandular trichome (secretory organ) of a cherry tree (Cerasu yedoensis) in Japan, 2-Acetoxy-1-(3-glycosyloxyoctadecanoyl) glycerol has been isolated and characterized. A 3-hydroxyoctadecanoic acid allied to disaccharide esterifies glycerol at sn 1 position, while sn 2 position being acylated.

Structure of 2-Acetoxy-1-(3-glycosyloxyoctadecanoyl) glycerol

Alkyl acyl glycosylglycerols

Cramerides (monoglycosyldiacylglycerol intermediate) was isolated from Pseudoceratina crassa, a sponge having a bizarre moiety of cyclitol, an alkyl chain (branched) and an acyl chain (saturated) with 14-16 carbon atoms (unbranched or branched). These compounds act as feeding deterrents in fish.

 

Dialkyl glycosylglycerols

 

 

Are diether lipids from bacteria containing glycosidic headgroups noticed in carbonated chimney of the hydrothermal field. These compounds have non-isoprenoid diethers and signify an exceptional permutation of archaeal distinctiveness in lipids of bacteria. A mono or a diglycosyl moiety is present at the polar head group and alkyl chains (14-18 carbon units) is either or monomethylated, monounsaturated or saturated. Since these glycolipids exist from the creation of life on earth, it was contemplated that they were the evolutionary precursor of phospholipids and their existence is interrelated to an incredibly squat level of phosphate in the utter atmosphere.

 

 

Myrmekiosides, a novel glyceroglycolipid have been reported from Myrmekioderma sp., a sponge possessing anti-tumor properties. At C1 position of glycerol, an O-alkyl ether chain (where R contains 16 carbon units/chain with or without a branched methyl group), at C2 position two moles of glucose and at C3 one mole of xylose were found.

 

 

Structure of Myrmekiosides

 

 

Trikentrion loeve, a Senegalese sponge revealed an exceptional ether lipid distinguished by the glycosylation (xylose) of two glycerol radicals and an O-alkenyl chain of ether (24 carbon units with lone double bond) at the third radical. In human brain, glyceroplasmalopsychosine (a plasmal conjugate of psychosine and glycerol), an additional ether lipid has been depicted.

 

 

Cyanobacterium, Synechocystis sp possess acylated forms of glycoglycerolipids bearing a palmitoyl group esterified at hydroxyl group of C-6 position of the terminal glycosyl moiety of either acylated DGMG or DGDG. The presence of acylated MGMG, MGDG and DGDG was also stated from nitrogen fixing cyanobacteria and leaf homogenates. Bacillus acidocaldarius, possess an extraordinary glucosamidyl glycolipids comprising ~64% of the total lipids (N-acyl derivative of Glucopyranosyl (1-> 4) Glucosamine (1->3)-diacylglycerol along with amide-

linked branched 13-cyclohexyltridecanoic acid, 11-cyclohexylundecanoic or heptadecanoic acid. In algae and bacteria, a hefty amount of glycolipids including diverse combinations of sugar have been reported.

 

 

Mycoloyl arabinosylglycerols

 

Are new glycolipids isolated from Mycobacterium avium-M. intracellulare complex, described by an arabinofuranosyl glycerol acylated on the C5 of the arabinose by an assorted mycolic acid structures (wax ester mycolic, mycolic, keto mycolic).

 

 

Alkyl galactosylglycerols amid acetal group

 

From the equine brain, a novel galactosylalkylglycerol named Plasmalogalactosylalkylglycerol was isolated consisting of a long chain cyclic acetal at the sugar moiety. The acetal and alkyl group chain lengths were C14 for the earlier and C16 and C18 for the last. The intact equine brain includes about 5 mg of plasmalogalactosylalkylglycerol.

 

 

Glycophospholipids

 

 

Are primarily described in bacteria, however, in other living creatures, the glycosyl phosphatidylinositol anchors are present. The simplest forms of glycophospholipid consist of phospholipid, phosphatidic acid, linked to a glycosyl group. Glucosylated phosphatidic acid is the simplest compounds present in the erythrocytes of umbilical cord, human neutrophils, human epithelium, rat brain and might be a marker for lipid rafts.

 

Exclusively composed of a sole pair of fatty acids (saturated, 18:0 & 20:0), its task remains indefinite, however, carbonyl compounds and sugars interrelate with proteins or amino acids in Maillard reaction. Correspondingly, it has been depicted that phosphatidyl ethanolamine undergo Amadori rearrangement after reacting with glucose leading via an unstable Schiff base, formation.

 

 

 

Later, they were noticed in liver of rat, however its concentration increased in diabetic rats followed by establishment of their correct structure in human erythrocytes. It has also been observed that Amadori lipid products generate oxidative stress and accelerate membrane lipid peroxidation that amends cell survival and integrity. Concentration of Amadori PE has been found higher in erythrocytes and plasma of diabetic patients as compared to healthy individual. Phosphatidyl monoglucosyl diacylglycerol (PMDG) is found in many Gram-positive bacteria, however, its metabolism and structure elucidation was accomplished in Pseudomonas diminuta.

 

Phosphatidyl glucosaminyl glycerol (PGG) is found in Bacillus megaterium

 

From several species of Halomonas (halophilic Gram negative bacteria), Phosphatidylglycerol moiety has been isolated. It consist of a phosphatidic acid attached to glycerol residue that is alkylated by a glucose moeity. C16:0, C19:cyclopropane, oleic acid, palmitic acid are the most plentiful acyl chains attached to the phosphatidylglycerol moiety. The tetatnus causing microbe, Clostridium tetani, produces N-acetylglucosaminyl diacylglycerol where a phosphoethanolamine moeity is annexed to the C6 position of sugar.

N-Acetylglucosaminyl-phosphoethanolamine diacylglycerol

 

 

In phosphatidylinositol polymannoside (PIPM) established in Mycobacteria, at 2’position of inositol, a mannopyranoside cluster and at 6’ position, one to five mannoside groups are present. It was established that phosphatidylinositol mannosides from Mycobacterium tuberculosis wield effective anti inflammatory effects and inhibit the production of chemokines, cytokines and NO both in vitro and in vivo via Toll-like receptor inhibition. Mannophosphoinositides presence in phospholipid composition is a striking feature of some bacteria and Actinomycetes. Mono-mannosides have been delineated in Streptomyces, Propionibacteria and Mycobacterium species. Two types of dimannosides were identified from Streptomyces griseus with one extra fatty acid fastened to a mannose residue (tri & tetra acylmannoside). In Mycobacteria, Polymannosides, one of the most complexes with a number of fatty acids acylating the mannose chain were identified.

 

In Corynebacterium urealyticum, C16:0 or C18:1 (R3) acylated phosphatidylinositol dimannosides were also illustrated with acylating one of the two mannose groups.

  1. Summary

 

 

In this lecture we learnt about:

  • The Complex Lipid Types
  • Their Significance and Role in different organism

 

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Weblinks

 

 

Books

 

1.Chemistry Of Biomolecules by Bhutani SP. 2009. Page 258 https://books.google.co.in/books?isbn=8190840657

2.  Biochemistry by Berg JM, Tymoczko JL, Stryer L. 2002. 5th edition. New York: W H Freeman; 2002. http://www.ncbi.nlm.nih.gov/books/NBK22361/

3.Biochemistry by Thomas Briggs, ‎Albert M. Chandler. 1995. https://books.google.co.in/books?isbn=0387943986

4.Teaching Innovations in Lipid Science by Randall J. Weselake. 2007. Pages-216 https://books.google.co.in/books?isbn=1420012800

 

 

Journals

 

1.       Deuel HJ. Lipid metabolism. Calif Med. 1950 Apr; 72 (4): 197-200.

  1. Hartroft WS. Effects of various types of lipids in experimental hypolipotropic diets. Fed Proc. 1955 Jun; 14 (2): 655-660.