Triglyceride
Triglycerides, triglycerides, and glycerol triester, rare obsolete neutral fats, are triple esters of trivalent alcohol glycerol with three acid molecules and should be named according to the IUPAC recommendation given as triacylglycerols, short tags, (or more accurately Tri-O- acylglycerols ). The prefix tri refers to three acyl- acid residues that are esterified with glycerol.
Triacylglycerols with three fatty acids are the compounds in fats and fatty oils. Natural fats consist predominantly of Triglycerolen with three long chain fatty acids, which usually consist of unbranched chains of 4 to 26, typically 12 to 22 carbon atoms. They are liquid at room temperature, they are also referred to as oils, or in order to distinguish them from mineral oils or essential oils, fatty oils. Pure triacylglycerols of fatty acids are also known as neutral fats.
Substance groups and naming
One can distinguish between medium and long chain triglycerides. Here, have medium-chain triglycerides (English: medium - chain triglycerides, MCT) fatty acids of medium length (6 to 12 carbon atoms) and long-chain triglycerides (English: long- chain triglycerides, LCT) fatty acids great length (14 to 24 carbon atoms ) bound.
In addition, there are two types of triacylglycerols: simple and mixed triacylglycerols. Triacylglycerols with simple side chains ( that is, the fatty acid residues ) are identical, they are different in mixed.
The reason that fat is solid and oil is liquid, is located in the much higher proportion of unsaturated fatty acids in oils. The unsaturated fatty acids generally having cis double bonds, which complicates the formation of crystals and thus down the set melting point.
In a triacylglycerol Are the side chains of different R1 and R3, there is a chiral molecule before and one can observe optical activity, ie, the mirror image of the molecule is not identical to the original and a solution of the molecule is able to to rotate polarized incident light.
Phosphoglycerides such as lecithins are triacylglycerols from two fatty acids and an organic phosphoric acid compound. Both types of compounds belonging to the class of lipids. In addition to plant and animal triacylglycerols there are also synthetic.
Of chiral derivatives of glycine, there is also the sn- nomenclature.
Analysis of triglycerides
The comments in groups of substances and names indicate that native triglyceride mixtures can have a high complexity. In the presence of different fatty acid types n n ³ various isomers (including the position isomers and of the optic isomers) are possible. Because now are known more than 100 relatively common naturally occurring fatty acids, it is evident that only very powerful analytical methods are suitable, the different triglycerides characterize clearly and quantify.
For qualitative and quantitative analysis of triglycerides therefore preferred chromatographic methods are used. Depending on the to be examined matrices adequate sample preparation methods are required. So it must be insulated from physiological matrices ( eg, serum or cerebrospinal fluid ) or from foods, the triglycerides prior to analysis by suitable extraction method. Native oils and fats can usually be studied as eluent without elaborate sample preparation with the help of Argentations chromatography, or HPLC with propionitrile. The high-temperature gas chromatography, is used in the determination of the individual triglycerides.
Medical importance
In the medical field, the TG levels are measured in the blood in the preparation of a blood analysis. Elevated levels ( greater than 150 mg per dL or 1.7 mmol per liter ) indicate a lipid metabolism disorder ( hypertriglyceridemia ), or overweight. Also in other diseases such as hypothyroidism or kidney disease, these values are increased. Elevated triglyceride levels are a risk because they may promote the formation of thrombosis or atherosclerosis of the blood vessels, especially if they are accompanied by an elevated cholesterol level.
Examples
Examples of some of triacylglycerols and the underlying acid:
- Tristearate ( tristearin ): stearic acid
- Tripalmitate ( tripalmitin ): palmitic acid
- Trioleate ( triolein ): oleic acid
- Trilinolein: linoleic acid
- Triricinoleat ( triricinolein ): ricinoleic acid