Glycosides and Glycoside Containing Drugs MD AHAD ALI KHAN DEPARTMENT OF PHARMACY SUB

Glycosides and Glycoside Containing Drugs MD AHAD ALI KHAN DEPARTMENT OF PHARMACY SUB

Glycosides Organic natural compounds present in a lot of plants and some animals, these compounds upon hydrolysis give one or more sugars (glycone) β_form and non sugar (aglycone) or called genin.

Aglyconeand Glycone Aglycone/ non-sugar compound After replacement of the glycosylgroup from a glycoside by a hydrogen atom Methyl alcohol, glycerol, a sterol, a phenol, etc. Glycones/ Sugars > Monosaccharides Glucose, Rhamnose, Fructose > Deoxysugars(more rare) Cymarose Those found in the cardiac glycosides

Physico-chemical properties of glycosides(general) 1) Colorless, solid, amorphous, nonvolatile (flavonoid- yellow, anthraquinone-red or orange. 2) Give positive reaction with Molisch'sand Fehling's solution test (after hydrolysis). 3) They are water soluble compounds, insoluble in organic solvents 4) Most of them have bitter taste (except: populin, glycyrrhizin, stevioside). 5) Odorless except saponin(glycyrrhizin).

6) When a glycosides has a lot of sugars its solubility in water decrease. 7) Glycosides hydrolyzed by using mineral acids and temperature or by using enzymes such as: a- Emolsin Bitter almond seeds. b-myrosinor Myrosinase black mustard seeds. c-rhamnase glycosides containing rhamnose as sugar part.

Hydrolysis of Glycoside

Glycosides +HCL Filtration Hydrolysis +HCL (dil) Neutralization by Using alkaline (H2O+G)+A (H2O+G)+(chloroform+A) glycone+aglycone G + A +salt+h2o chloroform We can separate them by using separating funnel The best solvent to extract aglyconeis Ethyl acetate because: -immiscible in water. -always presents in the upper layer.

Biosynthesis of glycosides (Oglycosides) UTP(UridineTriphoshate) +sugar-1-phoshate Uridylyl transferase Enzyme UDP-sugar + ppi(pyrophosphate inorganic). UDP-sugar +acceptor (aglycone) Glycosyl transferase Enzyme Acceptor-sugar +UDP Glycosyl transferase Enzyme

The function or the role of glycosides in the plant organism Converting toxic materials to non or less toxic. Transfer water insoluble substances by using monosaccharide. Source of energy(sugar reservoir). Storing harmful products such as phenol. Regulation for certain functions(growth). Some have beautiful colours(pollenation process).

Some glycosides have antibacterial activity, so they protect the plants from bacteria and diseases. bacteria kill Bitter almond Amygdalin hydrolysis HCN Eomlsin enzyme

In Nature Glycosides are formed by the interaction of the nucleotide of a sugar group with the alcoholic or Phenolic group of a 2nd compound. EC 2.3.1.173: flavonol-3-otriglucoside O- coumaroyltransferase EC 2.4.1.239: flavonol-3-oglucoside glucosyltransferase EC 2.4.1.240: flavonol-3-odiglycoside glucosyltransferase

GlycosidalReduction Glycosides themselves do not reduce Fehling s solution, But the simple sugars they produce on hydrolysis (aglycones) do (precipitate red cuprous oxide)

Terms used to Describe Glycosides A Glycoside is a Glucoside Has glucose as the sugar component Pentoside Has a sugar such as arabinose Rhamnosides Contains rhamnose Rhanmoglucosides Contains both rhamnose and glucose

Terms used for Aglycones Normally self-explantory E.g. Phenol Anthroquinone Sterol glycoside

Other GlycosidalTerms Saponin(soap-like) Cyanogenic(producing hydrocyanic acid) Cardiac (having an action on the heart) Terms: Are used to group glycosides together which have similar functions & chemical structure.

GLYCOSIDE STRUCTURE 2 types of geninare distinguished Based on the structure of the lactonering 5-membered ring bufanolides or bufadienilolides E.g. scillarenin 6-membered ring cardinolidesor cardiac active glycosides (medicinally more significant)