1. P R E S E N T E D B Y :
H I M A N S H U S I N G H
M . P H A R M A 1 S T Y R .
( P H A R M A C E U T I C A L C H E M I S T R Y )
Structural elucidation of STEROIDS and
flavonoids
2. Content
1. Steroids
Introduction of steroids
Classification of steroids
Structural elucidation of steroids
2. Flavonoids
Introduction of flavonoids
Classification of flavonoids
Structural elucidation of flavonoids
3. Introduction
Steroids is a biologically active organic compound with four rings arranged in
a specific molecular configuration.
These arranged rings are core structure of steroids called as PERHYDRO-
CYCLO-PENTANOPHENANTHRENE NUCLEUS which consists of 17 carbon
atoms bonded in four fused rings.
Three six member cyclohexane rings (A, B & C) are in first illustration and
one five member cyclopentane ring (D) in second illustration.
4. Classification of steroids
1. Sterol:
Also called steroid alcohols, where R (C-17) is an aliphatic side chain.
They usually one or more hydroxyl groups attached in alicyclic linkage.
Sterol Source Examples
Zoosterol Animals Cholesterol,
Coprostanol
Phytosterols Plants Ergosterol,
Stigmasterol,
Sitisterol
Mycosterol Yeast or Fungi Ergosterol
5.
6. 2. Sex Hormones:
where R bears Ketonic or hydroxyl group and mostly posses a two
carbon side chain.
Ex-
1. Androgens (Male Hormones):
2.Oestrogens (Female Hormones):
a.Oestrone
b. Oestradiol
c. Stilbesterol
d. Hexesterol
7. 3.Gestogens ( The Carpus Luteum Hormone):
Ex- Progesterone
3. Bile acids:
where R is essentially a five carbon side chain ending with a carboxylic acid
moiety.
Ex-
Cholic acid
Deoxycholic
acid
8. 4. Cardiac glycoside: where R is a lactone ring.
Ex-
5. Sapogenin: where R contains an oxacylic (etheral) ring system.
Ex-
Digoxin
Digitonin
9. Classification On The Basis Of No. Of Carbon
Class No. of
carbons
Structure Example
Gogane 17
Estrane 18 Estradiol
11. Structural Elucidation of Steroids
Chemistry of sterol is explained by using cholesterol structure.
Molecular formula of cholesterol = C27H46O
The cholesterol structure have three regions:
1. A hydrocarbon tail
2. A ring structure region with 4 hydrocarbon rings
3. A hydroxyl group
12. Following steps for Elucidation of cholesterol:
1. Presence of double bond and hydroxyl group
2. Presence of ring system
3. Position of hydroxyl group.
13. 1. Presence of double bond and hydroxyl group:
a. The conversion of cholesterol into cholestanol show the presence
of double bond.
b. The oxidation of cholestanol with chromic acid into
cholestanone shows the presence of secondary alcoholic
group in cholesterol.
14. c. The clemmenson’s reduction of cholestanone yields a saturated
hydrocarbon called cholestane.
15. 2. Presence of a ring system:
The molecular formula of cholestane corresponds to the general
formula CnH2n-6 of a tetracyclic system. On distillation with
selenium atb360 degree celsius, cholesterol yields Diel’s
hydrocarbon.
Reaction shows the presence of
cyclopentanophenantherenenucleus in cholesterol.
16. 3. Position of the hydroxyl group:
The formation of 3,7-dimethylcyclopentanophenantherene from
cholesterol by the following step is possible only if –OH group is
consider at position C-3.
21. What are flavonoids?
Flavonoids are a group of plant Polyphenolic secondary metabolites
showing common three ring structure based upon a fifteen (15) carbon
skeleton consisting of two benzene rings (A & B as shown in figure)
linked via a heterocyclic pyrane ring( C).
22. Flavonoids named from the latin word-
“FLAVUS = YELLOW”
They are more common in higher plants being abundant in families:
1. Polygonaceae
2. Rutaceae
3. Leguminosae
4. Umbelliferae &
5. Compositae
23. Structure of flavonoids
The flavonoids are possessing 15 carbon atoms, two benzene rings
joined by a linear three carbon chain the skeleton can be
represented as the C6-C3-C6 system.
24.
25. Classification of flavonoids
Class Structure Subclass Sources
Flavone Apigenin
Luteolin
Tangeritin
Diosmetin
Celery,
Red pepper,
Ginkgo biloba,
Parsley.
Flavanone Naringin
Naringenin
Hesperitin
Eriodictiyol
Oranges
Lemons
Grapes
35. General Structure Elucidation of Flavonols
Molecular Formula of flavonol = C15H10O3
Flavonol shows characteristic band at 350-390 nm and 150-270 nm in
UV spectrum.
Presence of Hydroxyl group:
When flavonol acetylated to give an ester shows the presence of hydroxyl
group.
C15H9O2(OH) + CH3COCl C15H9O2(OCOCH3)+HCl
36. Presence of Methoxy group:
when methylation followed by fusion with KOH, flavonol yields
phenol and benzoic acid. Both these products do not possess methoxy
group. This shows that the methoxy group must be present atC3which
must have been lost in KOH fusion.
C15H10O3 C6H6O + C7H6O2
Methylation and
fusion with KOH Phenol Benzoic
acid
Flavonol
Position of hydroxyl group:
When flavanol is boiled with an ethanolic solution of Potassium
hydroxide, it yields a mixture of o-hydroxybenzoylmethanol and benzoic
acid.
The formation of these products reveals that flavonol contains a
hydroxy group at C3. hence flavanol must be 3-hydroxyflavone( 3-
hydroxy-2-phenyl-gamma-chromone).
