Steroids

steroid and its chemistry; nomenclature; stereochemistry; classification; sterol and its chemistry

1. STEROIDS PREAPRED BY : AZMIN MOGAL (M PHARM; SEM -1) GUIDED BY : Mr. STEPHEN AVVARU( Ph.d SCHOLER) DEPARTMENT: PHARMACEUTICAL CHEMISTRY

2. INTRODUCTION A steroid is an organic compound with four rings arranged in a specific molecular configuration. The steroid core structure is composed of seventeen carbon atoms(17), bonded in four "fused" rings. Three six-member cyclohexane rings (rings A , B and C in the first illustration) and one five-member cyclopentane ring (the D ring). Steroids vary by the functional groups attached to this four-ring core and by the oxidation state of the rings. Cyclopentanoperhydrophenanthrene ring

3. NOMANCLATURE Almost all steroids are named as derivatives of any one of the following basic steroidal ring. 5 ( α or β ) gonane (C =17) 5 ( α or β ) estrane (C=18)

4. 5 ( α or β ) andrastane (C=19) 4. 5 ( α or β ) pregnane (C=21)

5. 5 ( α or β ) cholestane (C=27) Solid line indicate groups above the plane of the nucleus (β-configuration) and dotted line denote groups below the plane ( α - configuration). The configuration of the hydrogen (-H) at C-5 position is always indicate in the name. Compounds with 5- α cholestrane belongs to the ‘ allo series’ while compounds derived from the 5- β - cholestane belongs to the ‘normal series’. If the double bond is not between sequencely numbered carbon, in that case both carbons are indicated in the name.

6. The symbol Δ(delta) is used to indicate C=C bond in steroids. When a methyl group is missing from the side chain , these is indicated by the prefix ‘nor’ with the number of the carbon atom which are disappear. Δ - Androstane 5

7. STEREOCHEMISTRY OF STEROIDS There are six asymmetric carbon atoms 5,8,9,10,13,14 in the nucleus, therefore 64 optically active forms are possible. Cholestane , enfrostane and pregnane exist in two conformations: 1. chair form 2. boat form 5-α- cholestane

8. Chair form is more stable then boat form due to less angle strength , therefore all cyclohexane ring in steroid nucleus exist in the chair form. The absolute stereochemistry of the molecule and any substituents is shown with solid bond ( β -configuration) and dotted bond ( α -configuration). The aliphatic side chain at C-17 position is always assumed to be β - configuration. The term cis and trans are sometimes used to indicate the backbone stereochemistry between the rings . example; 5- α - steroid are A/B TRANS. 5- β - steroids are A/B CIS. 5- α -Steroid A/B trans 5- β -Steroid A/B cis

9. If A/B fusion cis and trans both position possible or position is unknown ,it is indicated by waving lines/bonds. trans/cis

10. R

11. CLASSIFICATION OF STEROIDS 1.  Sterols :- where R is an aliphatic side chain. They contain usually one or more hydroxyl groups(-OH) attached in alicyclic linkage 2.  Sex Hormones :- where R bears a ketonic (C=O) or hydroxyl group(-OH) and mostly possess a two carbon side chain 3.Cardiac Glycoside  :where R is a lactone ring. The gylcosides also contains sugars linlked through oxygen in other parts of the molecule. Normally on hydrolysis it yields this sugar together with cardiac aglycon. 4.  Bile Acids  :- where R is essentially a five-carbon side chain ending with a carboxylic acid moiety 5. Sapogenins  :- where R contains an  oxacyclic ( etheral ) ring system.

12. cholesterol sterol Sex hormone Cardiac glycoside Bile acids Sapogenin

13. STEROL & ITS CHEMISTRY Sterols is also known as steroid alcohols, are a subgroup of the steroids and an important class of organic molecules. They occur naturally in plants, animals, and fungi, with the most familiar type of animal sterol being cholesterol. Cholesterol is vital to animal cell membrane structure and function and a precursor to fat-soluble vitamins and steroid hormones. Sterol chemical structure

14. Sterol is divided into three classes : 1. Zoosterol : sterol which is obtained from animal origin. Example; Cholesterol 2. Phytosterol : derived from the plant source. Example; Sitosterol 3. Mycosterol : obtained from fungi such as yeast. Example; Ergosterol - Sitosterol Cholesterol β