Pharmacognosy - medicinal plants (herbs)
Pharmacognosy - medicinal plants (herbs)

Theme XIV: Lipids

Lipids

Definition of Lipids. Classification according to chemical structure. Fixed oils and fats, waxes, sterols, phospholipids and glycolipids.

What are lipids?

Lipids are fatty substances and similar which are found in plants and animals. Like carbohydrates and proteins constitute an important group of organic molecules with pharmacological use and form a heterogeneous range of chemical functions.

 

Initially, lipids are grouped based on its solubility characteristics, in general, are soluble in organic solvents such as ether and chloroform and are insoluble in water.

Classification of lipids

Lipids can be classified into five groups according to their chemical structure.

 

 

  1. Fixed Oils and Fats: Esters of glycerin with fatty acids. E.g.: The olive oil. The fixed oils which are solids at room temperature are commonly called greases. E.g.: lard.
  2. Waxes: esters of monohydric alcohols of high molecular weight with fatty acids of high molecular weight. E.g. the fat obtained from spermaceti.
  3. Sterols: Alcohols with the typical structure of cyclopentane phenanthrene (steroid). E.g. cholesterol and ergosterol.
  4. Phospholipids: Esters consisting of glycerin, fatty acids, phosphoric acid and some nitrogenous compounds. The most important of this group are the lecithins.
  5. Glycolipids: are substances isolated from brain and other sources which are based on the hydrolysis of fatty acids, galactose and nitrogenous compounds. Due to the most common sugar present in these compounds is galactose they are also called galactolipids. These compounds have no pharmaceutical application.

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Definition of Lipids. Classification according to chemical structure. Fixed oils and fats, waxes, sterols, phospholipids and glycolipids.