Products
Polysaccharides are present as excipients and active ingredients in numerous pharmaceuticals. They play a fundamental role in foods for nutrition. Polysaccharides are also known as glycans (glycans).
Structure and properties
Polysaccharides are polymeric carbohydrates composed of hundreds to thousands of sugar units (monosaccharides). As few as 11 monosaccharides are referred to as polysaccharides. They belong to the macromolecules and biopolymers and have a high molecular mass. Polysaccharides can contain only one type of monosaccharide or two or more. Accordingly, they are called homopolysaccharides (homoglycans) or heteropolysaccharides (heteroglycans). Polysaccharides can be linear or branched. This is in contrast to other biopolymers such as proteins. Polysaccharides are usually of natural origin and come, for example, from plants (e.g. celluloses, starch, tragacanth), algae (e.g. carrageenan, agar, alginic acid), fungi, microorganisms (e.g. xanthan gum), lichens or animals (chitin). They can also be produced and modified synthetically. With the help of acids, bases, heat or enzymes, polysaccharides can be broken down into smaller polysaccharides as well as mono-, di- and oligosaccharides. Humans can digest only some polysaccharides, mainly starch and glycogen. Many others are indigestible and enter the intestine as dietary fiber. The simple sugars in polysaccharides are linked by glycosidic bonds. In starches and glycogen, the α(14) and α(16) bonds are present, and in celluloses, the β(14) bond is present.
Representative
Known polysaccharides are:
- Celluloses
- Chitin
- Chitosan
- Fructans
- Glycogen
- Glycosaminoglycans such as chondroitin sulfate, the hyaluronic acid and keratan sulfate.
- Hemicelluloses, xylan
- Pectin
- Starch (amylose, amylopectin)
Effects
Polysaccharides are essential for life on Earth. They have structural functions like celluloses, store energy like starches and glycogen, and they have gel-forming properties like glycosaminoglycans (mucopolysaccharides).
Areas of application
In pharmacy:
- For the preparation of gels, solutions, syrups and suspensions.
- As a binder, filler, carrier and disintegrant for tablets and partially for capsules.
- As thickeners, stabilizers and viscosity enhancers.
- As active ingredients, such as heparins, chondroitin sulfate, hyaluronic acid, phytopharmaceuticals.
- For tear substitutes.
- As dietary fiber.
- For the production of oligo-, di- and monosaccharides.
Food: