General Introduction to Glycosides presentation

Glycosides general introduction

1. INTRODUCTION TO GLYCOSIDES Presented By, Dr. J. S. Suryawanshi, Asso . Professor, Dept. of Pharmacognosy, N.N.Sattha college of Pharmacy, Ahmednagar

2. Organic natural compounds present in a lot of plants and some animals, these compounds upon hydrolysis with acid or enzyme give one or more sugars ( glycone ) and non sugar ( aglycone ) or called genin . The sugar and non-sugar part is linked together by means of a linkage called Glycosidic linkage More important in medicine than a lot of drugs. Occur in higher plant tissues in very small amounts . Also fungal and bacterial cells (exuded in medium) and animals.

3. Sugar in glycosides is mostly beta-D glucose but other sugars like galactose , mannose, rhamnose , digitoxose can present. Glycosides have therapeutic effect in human and animals as they are used in traditional and modern medicines as cardio tonic, purgative, analgesic, anti- rheumatic, demulcent ,and many other uses. Glycosides end with suffix ‘in’ Ex- Digitoxin,Aloin,Hisperidine

4. Glycoside = sugar group+ nonsugar group ( glycone ) ( aglycone or genin ) Glycone and aglycone are linked by glycosidic linkage. Glycosidic linkage is formed between – OH group of sugar and –H group of non sugar moiety. Glycon - OH + H C – Aglycon Glycone —C— Aglycon + H2O

5. Classification of Glycosides 1) BASED ON THE CHEMICAL NATURE OF NON SUGAR MOIETY  Anthraquinone glycoside : - Anthraquinone moiety as aglycon . Ex: senna , Aloe ,Cascara Sterol or cardiac glycoside : - steroid molecule as aglycon portion Ex: Digitalis , Squill Saponin glycoside- Pentacyclic and Tetracyclic Triterpenoid as aglycone Ex: Liquorice , Dioscorea ,Ginseng Cyanogentic glycoside Ex : white cherry bark ,Bitter almond Isothiocynate glycoside Ex: black mustard. Flavonoid glycoside Ex : Ruta graveolens , Citrus bio flavonoid Coumarin glycoside or furano coumarine glycoside :- Ex : celery fruit Ammi majus Aldehyde glycosides Ex: vanilla pods Phenol glycosides Ex salcive Bitter glycosides Ex Bitter guard, Gentian root

6. Anthraquinone glycoside Sterol or cardiac glycoside Saponin glycoside Cyanogentic glycoside

7. Flavonoid glycoside - C 6 – C 3- C 6 Coumarin glycoside

8. 2) BASED ON THE NATURE OF SUGAR MOIETY:- Glucoside : sugar portion is glucose Rhamnoside : sugar portion is rhamnose Pentoside :sugar portion is pentose Fructoside :sugar portion is fructose Arabinoside :sugar portion is arabinose

9. 3) BASED ON LINKAGE BETWEEN GLYCON AND AGLYCON PORTION:- OH groups reacting with any of the following medicates like, OH, CH, SH, NH product in aglycon part   a) C-glycoside:- Glycon - OH + H C – Aglycon --> Glycone - C - Aglycon + H2O Ex.- Cascaroside in Cascara, Aloin in Aloes shows the –C- linkage.     b) O-glycoside Glycon - OH + H O – Aglycon --> Glycone - O - Aglycon + H2O      Ex- Sennosides in Senna

10. c) S-glycoside The example of this type is Isothiocyanate glycoside like Sinigirin in black mustard formed by the condensation of sulphohydryl group (SH) of aglycon to OH group of glycon . Glycon - OH + H S – Aglycon --> Glycone - S - Aglycon + H2O d) N-glycoside They most typical example of this is nucleoside where the amino group (NH 2 ) reacts with OH group of ribose or deoxyribose resulting into N-glycoside Glycon - OH + H N – Aglycon --> Glycone - N - Aglycon (Ribose/ Deoxyribose ) + H2O

11. GENERAL CHARACTERISTICS 1) Glycoside contains sugar but still the physical, chemical and therapeutic activity is based on aglycon portion. 2) Sugar facilitates the absorption of the glycoside ,helping it to reach the site of action 3) Glycoside are crystalline, amorphous substance which are soluble in water, and dilute alcohol but insoluble in the CHCl3 and ether. 4)The aglycon moiety is soluble in non-polar solvents like Chloroform, Ether, Benzene 5) Glycosides are easily hydrolyzed by mineral acids and enzyme. 6) Glycoside can not reduce fehling’s solution until they are hydrolyzed.