What Is a Glycoside?

S. Berger

Glycosides are unique molecules used by plants to safely store potentially dangerous compounds, and by animals to eliminate toxins. They consist of a sugar group, called a glycone, chemically attached to a non-carbohydrate compound. The non-carbohydrate is referred to as an aglycone, or a genin. These molecules have a variety of natural uses, such as defense mechanisms, as well as commercial ones, like medications, cleaning agents, and natural sweeteners.

Glycosides found in some stevia plants have sweeter tastes than sugar.
Glycosides found in some stevia plants have sweeter tastes than sugar.

The sugar group can be a single sugar, like glucose, or a group of sugars. Enzymes known as glycosyltransferases create bonds between the glycone and the aglycone in a process called glycosylation. The glycosidic bond can be broken by other enzymes called glycoside hydrolases.

Found in almonds, amygdalin is a type of toxic aglycone.
Found in almonds, amygdalin is a type of toxic aglycone.

Plants use glycosyltransferases to make a variety of glycoside compounds. These compounds often consist of potent chemicals, some of which include known medications and poisons. The glycoside structure renders the chemical inert until the plant must use it. Animals that have ingested these compounds may use their own enzymes to sequester it until it can be eliminated.

Some medications, like the steroids found in Digitalis plants, are present as glycosides, which in turn form the basis for heart medications. Other steroid-based glycosides can be used as the starting point to manufacture semi-synthetic drugs like glucocorticoids. Often the glycone groups are removed from the glycosides before their commercial use, but not in all cases. Glycosides found in some stevia plants have sweeter tastes than sugar, and are used as flavoring agents with the glycone kept intact.

Amygdalin, found in almonds, is an example of a poisonous aglycone. This contains cyanide that would normally harm the plant. The plant stores amygdalin as a glycoside to avoid harming itself. If the plant is damaged by another organism, enzymes break the glycoside bond and release the amygdalin. This process allows the plant to defend itself under the right conditions.

The pharmaceutical industry is making use of glycosides to manipulate the properties of drugs that contain natural sugars. Changing sugars can often change the pharmacological effects or properties of drugs. Chemicals or enzymes can be used for glycorandomization, which creates an array of natural product derivatives with different bound sugars.

Glycosylation generally occurs via enzyme catalysts in nature. A synthetic method known as chemical glycosylation allows this process to be performed in laboratories and manufacturing plants without requiring enzymes. A chemical known as an activator removes a group from a sugar, allowing it to accept a bond with the aglycone.

You might also Like

Readers Also Love

Discussion Comments


@David09 - Actually, I think that the almond tree plant renders it harmless. But even if it doesn't, I think it would be safe to eat the almonds.

I’ve never heard of anyone dying through eating almonds. My bet is that it would take a lot of almonds to get the amount of cyanide necessary to do you any permanent harm.

If you haven’t noticed any weird health problems already, you’re probably okay. You may want to do further research online to get a complete profile of almonds and their health effects.


@Charred - Does this mean that I can’t eat almonds? The article says that it contains Amygdalin and that this is poisonous.

I eat almonds a lot – I toss them on salads, eat them as snacks. I love almonds and have always been told that they are nutritious foods and a good source of protein. Now I’m reading that they have cyanide! Can anyone shed some light on this?


I notice that glycosidic bonds can function to sequester poisons. I would think then that perhaps these could be used for massive chemical spills, where the glycoside agents are released into the water and work to sequester the chemicals in a separate location.

If they can’t sequester them as such, maybe they can bond with them in such a way as to render them inert. Perhaps there are already such applications, I don’t know. It seems that it would make perfect sense to me.

I am always looking for environmentally friendly ways to solve ecological problems, and glycosides seem like the perfect solution from what I’m reading here.

Post your comments
Forgot password?