Glycomics

Description

The non-sugar group or genin part of the glycoside.

Discussion

Glycosides are often classified according to the chemical nature of the aglycone. For purposes of biochemistry and pharmacology, this is the most useful classification. These include:[1]

• Anthraquinone glycosides: These glycosides contain a glycone group that is a derivative of anthraquinone. They are present in senna, rhubarb and aloes; they have a laxative effect.
• Simple phenolic glycosides: Here the aglycone is a simple phenolic structure. An example is arbutin found in the Common Bearberry Arctostaphylos uva-ursi. It has a urinary antiseptic effect.
• Alcoholic glycosides: An example of an alcoholic glycoside is salicin which is found in the genus salix. Salicin is converted in the body into salicylic acid, which is closely related to aspirin and has analgesic, antipyretic and antiinflammatory effects.
• Thioglycosides: As the name implies, these compounds contain sulfur. Examples include sinigrin, found in black mustard, and sinalbin, found in white mustard.
• Flavonoid glycosides: Here the aglycone is a flavonoid. This is a large group of glycosides; examples include apiin, hesperidin (found in citrus fruits), rutin, quercetin and silymarin. Among the important effects of flavonoids are their antioxidant effect. They are also known to decrease capillary fragility.
• Steroidal glycosides or cardiac glycosides: Here the aglycone part is a steroidal nucleus. These glycosides are found in the plant genera Digitalis, Scilla, and Strophanthus. They are used in the treatment of heart diseases e.g. congestive heart failure and arrhythmia.
• Saponins: These compounds give a permanent froth when shaken with water. They also cause haemolysis of red blood cells. Saponin glycosides are found in liquorice. Their medicinal value is due to their expectorant effect.
• Coumarin glycosides: Here the aglycone is coumarin. An example is apterin which is reported to dilate the coronary arteries as well as block calcium channels.
• Cyanogenic glycosides: In this case, the aglycone is a contains a cyanide group, and the glycoside can release the poisonous hydrogen cyanide if acted upon by some enzyme. An example of these is amygdalin from almonds. Cyanogenic glycosides can be found in the fruits (and wilting leaves) of the rose family (including cherries, apples, plums, almonds, peaches, apricots, rasberries, and crabapples). Cassava, an important food plant in Africa and South America, contains cyanogenic glucosides and therefore has to be washed and grinded under running water prior to consumption.

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