Glycosides and Their Biosynthesis

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Questions and Answers

What do glycosides yield upon hydrolysis?

One or more sugars (correct)

Only bitter substances

Only non-sugar components

Saturated solutions

What is the chemical structure of glycosides primarily characterized by?

Esters of fatty acids

Cetals formed from sugar and non-sugar components (correct)

Simple carbohydrates

A single sugar component

Which of the following characteristics is NOT typical of glycosides?

Soluble in water and diluted alcohol

Intensely sweet flavor (correct)

Crystalline or amorphous form

Usually colorless

Which of the following sources is NOT typically associated with glycosides?

Synthetic chemicals Signup and view all the answers

What is the role of glycosides in pharmacognosy?

They are important for pharmaceuticals and medicinal uses Signup and view all the answers

Which of the following flavonoids is commonly associated with the treatment of capillary bleeding?

Rutin Signup and view all the answers

What type of glycosides are hydrolyzed by emulsin?

Alcohol glycosides Signup and view all the answers

Which compound is the aglycone for vanilla?

Methylprotocatechuic acid Signup and view all the answers

Which of the following sources is NOT associated with vanillin?

Citrus fruits Signup and view all the answers

Which commercial variety of vanillin is known as Bourbon vanilla?

Bourbon vanilla Signup and view all the answers

What is a consequence of potassium depletion in patients taking cardiac glycosides?

Increased risk of cardiac glycosides toxicity Signup and view all the answers

Which of the following contains the active compound digitoxin?

Digitalis purpurea Signup and view all the answers

What effect can parenteral calcium have on patients taking cardiac glycosides?

It can potentiate the cardiac effect Signup and view all the answers

What process likely occurs after the formation of the anthraquinone nucleus in anthraquinone glycoside biosynthesis?

Transglycosylation to form a glycoside Signup and view all the answers

Which of the following is true regarding anthraquinone glycosides and their detection?

They are identified using Borntrager T.S. which shows a reddish color Signup and view all the answers

Which drug is associated with the anticoagulant dicumarol?

Coumarin Signup and view all the answers

What effect does methoxsalen have on patients with idiopathic vitiligo?

Facilitates repigmentation Signup and view all the answers

Which of the following drugs has been discontinued in the US due to potential toxicity?

Santonin Signup and view all the answers

What is the main action of allicin found in garlic?

Antimicrobial Signup and view all the answers

What type of compounds are psoralens classified as?

Furocoumarins Signup and view all the answers

What reaction occurs when arbutin is hydrolyzed?

Arbutin yields hydroquinone and glucose Signup and view all the answers

What caution should be taken when using methoxsalen for repigmentation therapy?

Limit exposure to ultraviolet radiation Signup and view all the answers

Which drug contains the active compound cantharidin?

Cantharides Signup and view all the answers

What is the primary end product formed from the breakdown of prunasin?

Benzaldehyde Signup and view all the answers

Which test is used to identify cyanogenic glycosides?

Guignard Test Signup and view all the answers

What is a common use of the wild cherry (Prunus virginiana)?

Flavored vehicle in cough remedies Signup and view all the answers

What compounds are primarily found in black mustard (Sinapis nigra)?

Sinigrin and allyl isothiocyanate Signup and view all the answers

Which group do glucosinolates belong to?

Isothiocyanate glycosides Signup and view all the answers

What is a property of allyl isothiocyanate from the hydrolysis of sinigrin?

Local irritant and emetic Signup and view all the answers

Which of the following vegetables is known to contain glucosinolates?

Cabbage Signup and view all the answers

What is the effect of indole 3-carbinol derived from the mustard family vegetables?

Reduces the risk of estradiol linked mammary cancer Signup and view all the answers

What are the two main components of glycosides?

Glycone and aglycone Signup and view all the answers

Which enzyme is obtained from almond kernels and is responsible for hydrolyzing glycosides?

Emulsin Signup and view all the answers

What physiological activities are examples of cellular functions associated with glycosides?

Osmosis and diffusion Signup and view all the answers

Which test would be used to identify the presence of cardiac glycosides?

Keller-Killiani test Signup and view all the answers

Which two enzymes hasten the biosynthesis of glycosides?

Uridyl transferase and glycosyl transferase Signup and view all the answers

What is the chemical structure classification of cardenolides?

C23 steroid with a 5-member lactone ring Signup and view all the answers

Which physiological mechanism is involved in the action of cardiac glycosides?

Transport of sodium out and potassium into the cell Signup and view all the answers

Which group does isothiocyanate belong to in glycoside classification?

Other organosulfur drugs Signup and view all the answers

Study Notes

Glycosides

Glycosides are components that, upon hydrolysis, yield one or more sugars
Chemically, they are cetals where a sugar's hydroxyl group bonds with a non-sugar component's hydroxyl group, creating an oxide ring.
Physcially, they are often crystalline or amorphous, typically colorless and bitter, dissolving readily in water and diluted alcohol.
Glycosides consist of a glycoside (sugar portion) and an aglycone (non-sugar portion)
Glycosides can be hydrolyzed by mineral acids or enzymes.

Biosynthesis of Glycosides

Glycosides are synthesized through the action of uridyl transferases and glycosyl transferases.
Uridyl transferases transfer a uridyl group from uridine triphosphate to a sugar, forming a uridyl sugar.
Glycosyl transferases transfer the sugar from uridine diphosphate to an acceptor molecule, forming a glycoside.

Classification of Glycosides

Glycosides are classified into groups based on their specific components and activities: cardioactive, anthraquinone, saponin, cyanophore, isothiocyanate, flavonol, alcohol, aldehyde, lactone, phenol groups and others.
Some examples of specific glycosides include digitoxin, digoxin, emodin, anthraquinone compounds, cardioactive glycosides, sennosides, and others.

Steroid Glycosides

Steroid aglycones are characterized by a cyclopentanoperhydrophenanthrene nucleus.
Cardenolides (C23 steroids) have a 5-member lactone ring.
Bufadienelides (C24 steroids) have a 6-member lactone ring.
Tests for identifying cardiac glycosides include the Keller-Killiani test.

Anthraquinone Glycosides

Anthraquinone glycosides are anthracene derivatives, and their detection is done using Borntrager test.
Cascara sagrada and Frangula are examples of drugs containing anthraquinone glycosides.

Saponin Glycosides

Saponin glycosides are compounds that form colloidal solutions in water, are bitter, and act as hemolytic agents.
They're classified as neutral or acid-forming, and contain steroid or triterpenoid sugar portions and sapogenins.
The saponin glycosides are vital for their biosynthesis, with acetate and mevalonate units coupling to form different glycosides.

Cyanophore Glycosides

These glycosides release hydrocyanic acid upon hydrolysis, and are commonly found in Rosaceae plants.
Amygdalin and prunasin are examples, both yielding D-mandelonitrile as the aglycone.
Reactions yielding benzaldehyde and hydrocyanic acid occur during the hydrolysis of amygdalin.
Guignard test is used for detecting cyanogenic glycosides.

Isothiocyanate Glycosides

Found in the mustard family and are pungent and odorless, containing allyl isothiocyanate and benzyl isothiocyanate.
Myrosin converts the glucosinolates to the pungent isothiocyanate compounds.
White and black mustard are examples of plants containing isothiocyanate glycosides.

Flavonol Glycosides

Flavonol glycosides, or flavonoids, frequently contain rutin, quercitrin, hesperidin, hesperetin, diosmin, and others.
They're considered vitamin P or permeability factors, involved in capillary bleeding and fragility.

Alcohol Glycosides

Alcohol glycosides include salicin, populin, and coniferin.
Mineral acids and enzymes may hydrolyze them.

Aldehyde Glycosides

Aldehyde glycosides include vanillin, and the aglycones can be aldehydes.

Lacione Glycosides

Lacione glycosides include a group of coumarin molecules which is used as an anticoagulant.
Cantharides (Spanish flies) are an example, along with anthoxanthum odoratum

Phenol Glycosides

Examples include uva ursi, containing arbutin, corilagin, pyroside, quercitin, and more.
Arbutin, upon hydrolysis, yields hydroquinone and glucose.

Other Organosulfur Drugs

Garlic contains alliin, which, when cells are crushed, converts into allicin through the alliinase enzyme.
Allicin has potent antibacterial properties and is responsible for garlic's distinctive odor.

Check for Understanding (Sample Questions)

Questions from the provided document are summarized below. The provided text contains a series of questions on various aspects of glycosides. These questions evaluate understanding of specific glycosides, their properties, and related concepts.

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Description

Explore the fascinating world of glycosides, which are crucial components yielding sugars upon hydrolysis. This quiz covers their chemical structure, physical properties, biosynthesis, and classification. Test your knowledge on how they are formed and classified within biological systems!