The document covers natural product chemistry, focusing on the importance of naturally occurring compounds, their classification into primary and secondary metabolites, and the chemical methods for their isolation and structure elucidation. It discusses the biological significance of secondary metabolites, including their roles in medicine and ecology, as well as the biosynthesis of various classes of natural products like terpenoids. Additionally, it elaborates on analytical techniques used in characterizing these compounds and mentions historical uses and the development of pharmaceuticals from natural substances.

2. Aims
1. What is the natural product chemistry.
2. The important of natural product chemistry.
3. The distinction between primary and secondary
metabolites.
4. The structural characteristics of the major
classes of natural product and recognize their
biosynthetic building blocks.
5. The chemistry underlying the methods of
isolating natural products.
6. Structure elucidation of the natural product.

3. Introductio
n
Natural products are organic compounds that are
formed by living systems.
Naturally occurring compounds may be divided
into three broad categories:
Firstly: compounds which occur in all cells and
play a central role in the metabolism and
reproduction of those cells. These compounds
include the nucleic acids and the common amino
acids and sugars. “primary metabolites”

4. Introduction
Secondly, there are the high-molecular-weight
polymeric materials such as cellulose, the lignins
and the proteins which form the cellular structures.
Finally, compounds that are characteristic of a
limited range of species. “secondary metabolites”.
Most primary metabolites exert their biological
effect within the cell or organism that is responsible
for their production.
Secondary metabolites, on the other hand, have
often
attracted interest because of their biological effect
on other organisms.

5. Introduction
Many of the biologically active constituents of the
medicinal plants are secondary metabolites.
A number of screening programmes for bioactive
compounds exist and have led to new drugs, for
example taxol, which is used for the treatment of
various cancers.
They can be defensive substances, antifeedants,
attractants and pheromones.
Chemotaxonomy provides another reason for
examining the constituents of plants.

6. Introduction
A pheromone is a substance released by one
individual of a species which causes a change in
behaviour by another member of the same species.
Chemotaxonomy involves the use of natural
products in the classification of species.
A phytochemical is a natural product produced by
a plant.

7. NATURAL PRODUCTS
CHEMISTRY

12. Example 1: Water extract of
a sugar beet:
β-D-fructofuranosyl-(2→1)-α-D-glucopyranoside

13. Example 2: Water extract of
an apple

14. Example 3: GC chromatogram
of coffe volatiles

15. Analytical Natural Products
Chemistry

16. CLASSIFICATION OF NATURAL
PRODUCTS

17. WHY NATURAL PRODUCTS
CHEMISTRY?
Many natural products are important nutrients,
raw materials or pharmaceuticals.

18. Digitalis purpurea

19. OH
O
OAc
OCOPh
OH
AcO O
O
O
Ph
OTIPS
NH
O
Ph
Taxol
Cys1
Lys2
Gly3 Lys4
Gly5
Ala6
Lys7
Cys8
Ser9
Arg10
Leu11
Met12
Tyr13
Asp14
Cys15
Cys16
Thr17
Gly18
Ser19
Cys20
Arg21
Ser22
Gly23
Lys24
Cys25
H2N
H2N
Conus magus
Ziconotide
ω-conotoxin Taxus brevifolia (Pacific Yew)

20. Natural Products wich are slightly modified in order to improve their
activities or decrease the side-effects.
- 400 BC Use of the bark and leaves of willow
tree to releave pain and fever (Greece).
- 1758 Edward Stone (England) chew the
bark of a willow tree Þ bitter ÞÞ discovery of
Salicin and Salicilic acid (side effect: stomach
pain)
- 1897 Felix Hoffmann (BAYER, Germany)
synthesise
Aspirin.

21. Cinnamaldehyde (cinnamon)
diallyl disulfide (garlic)
n food industry, DADS is used to
mprove the taste of meat, vegetables
and fruits .

22. HN
N
O
O
O
OH
HO-H2C
HO
HN
N
O
O
O
OH
HO-H2C
HO
HO-H2C
HO
O
OH
N
N
N
N
NH2
HO-H2C
N
N
N
N
O
H2N
O
H
Antiviral Compounds
1951 Bergmann and Feeney
Spongouridine and Spongothymidine
isolated from the sponge Cryptotethia crypta
Lead structures for the development of antiviral drugs
1980
Vidarabine and Aciclovir
Active against Herpes simplex virus and Vari-
zella – Zoster virus (chicken-pox, shingles)

23. Methods used in structure of
Compounds
1. Classical Methods
a. double bond
The compound should be pure
Br2/ CCl4
Br
Br
Br
Br
O
O
O
O
O
O
+
Diene Dienophile Adduct
Diels- Alder Reaction

24. H
H
NOCl
H
H
NO
Cl
Cl
NO
1. Classical Methods
a. double bond
O
O
O
O
O
O

25. Ozonylsis
CH3
H3C
O3
H
O
H
H
O
O
H3C
CH3
O
O
H
2
α-Ocymene
CH3
H3C CH3
O3
H
O
H H3C
O
CH3
O
O
CH3
O
O
H
β-Ocymene

26. Carbonyl: CO
O NH2OH NOH
Spectroscopic tools
1. MS, FABMS, ESIMS, HPLCMS, GCMS: Molecular formula
2. IR: Function groups.
3. UV: Chromophore.
4. NMR: 1H-NMR, 13C-NMR.
5. Optical rotation.

27. Terpenoids
Terpenoids are secondary metabolites synthesized by plants,
marine organisms, fungi by head to tail joining of isoprene
units.
1
2
3
4
Head
Tail
5
methylbuta-1,3-diene
Isopentenyl pyrophosphate
C C C C C C C C
C C
C C C C C C C C
C C
C C C C
C
head tail head tail

28. Terpenids
Terpenoids originate through the condensation of the universal
phosphorylated derivative of hemiterpene, isopentenyl
diphosphate (IPP) and dimethylallyl diphosphate (DMAPP)
giving geranyl pyrophosphate (GPP).

29. Biosynthesis of Isoprene from Mevalonic acid

30. GPP from IPP and DMAPP

31. Terpenoid classification
C5 Hemiterpenes C25 Sesterterpenes
C10 Monoterpenes C30 Triterpenes
C15 Sesquiterpenes C40 Tetraterpenes
C20 Diterpenes C > 40 Polyterpenes
1
2
3
4
Head
Tail
5

32. Terpenoids
 Mono-, sesqui-, di-, and sesterpenes contain the
isoprene units linked in a head to tail fashion. The
triterpenes and carotenoids (tetraterpenes) contain two
C15 and C20 units respectively linked head to head.
 Many terpenes are hydrocarbons, but oxygen-
containing compounds such as alcohols, aldehydes or
ketones are also found.
 Mono- and sesquiterpenes are the chief constituents
of the essential oils while the other terpenes are
constituents of balsams, resins, waxes, and rubber.

33.  A number of inducible terpenoid defensive compounds
(phytoalexins) from angiosperm species are well known
(Stoessl et al., Phytochemistry 1976, 15, 855).
 Isoprenoid units are also found within the framework of other
natural molecules.
Thus, indole alkaloids, several quinones (vitamin K), alcohols
(vitamin E, vitamin A formed from β-carotene), phenols,
isoprenoid alcohols (also known as terpenols or polyprenols)
also contain terpenoid fragments.
 According to Bohlmann J et al. (PNAS 1998, 95, 4126), there
are in excess of 1000 monoterpenes, more than 7000
sesquiterpenes and more than 3000 diterpenes.

34. Monoterpenes
Monoterpenes are major components of the aromas of
plants, obtained from leaves, flowers and fruits. These volatile
natural products, known as essential oils, form the basis of
the perfumery and flavouring industries.
GPP as the basic substance for Monoterpenes

35. bornane pinene
carane thujane
p- menthane
Monoterpenes
Open Chains
Cyclic
Monocyclic
Bicyclic
Bicyclic
6, 3
6, 4
6, 5

36. Acyclic Monoterpenes
 Defensive role of simple terpenes have been demonstrated as for more
complex compounds.
Experimentally, a study of Arabidopsis thaliana engineered to overexpress a
terpene synthase leading to the emition of large amounts of linalool, which is
normally produced only in trace levels.

37. Linalool has been the subject of numerous studies investigating its anxiolytic
(anti-stress) effects. Inhalation of Linalool, extracted from natural essential
oils, leads to decreased aggressive behavior, lessens stress response.
Linalool
Ruzicka
Synthesis of Linalool

38. 2.Thermal reaction
Acid catalysis convert Linalool into geraniol and nerol.
Geraniol
It is the primary part of rose oil,
palmarosa oil, and citronella oil.

39. H
CH2OH
dil H2SO4
OH
CH2OH
H
dil H2SO4
geraneol - terpineol nerol

40. CH2
+
C+ C
H
2
CH2OH
H+
CH2
OH - H2O
C+
H2O
OH
H+
OH
-
allylic rearrangement
- terpineol

41. 1H NMR Chemical shifts
Chemical shift d (or ppm )
0
2
4
6
8
10 d
CH3
CH2
CH
CH CH
COOH
CH
O
H

43. Hydrogen and Carbon Chemical Shifts
43
Chapter 13
=>

44. 0
1
2
3
4
5
PPM
H
OH
H
2.00
2.00
1.71
1.71 1.71
5.39
4.20
2.0
5.20

45. 0
20
40
60
80
100
120
140
PPM
H
OH
H
39.8
26.4
123.5
123.0
135.8
17.5
132.1
19.6 25.6
59.0

46. Is a constituent of lemon oil, is obtained commercially from lemon grass oil

47. MONOCYCLIC MONOTERPENES
They are derived from cyclohexane with an isopropyl
substituent.
IUPAC: 1-Isopropyl-
4-methylcyclohexan
p−Menthan

48. Acrylic acid methyl-ester
Synthesis of α-terpenol

49. Menthol
1. Simplest synthesis of menthol

50. 2. Synthesis from Myrcene
1. Allylic amine from myrcene, 2. asymmetric isomerisation in the presence of a
BINAP rhodium complex, 3. R-citronellal after hydrolysis, 4. cyclised by a
carbonyl-ene-reaction initiated by zinc bromide to isopulegol, 5.
hydrogenation .

51. ‫ثانوي‬ ‫كحول‬
‫كحول‬
P-cymene
OH
PCl5
P2O5
Cl
Se
CrO3
O
O
Reduction
Classical methods for structure determination

52. 0
1
2
3
PPM
OH
1.52;1.27
1.52;1.27
1.50
3.16
1.67;1.42
1.61
1.82
1.01 1.01
2.0
1.06
C10 H20O, [α]D = -50
IR: 3333, 1048, 1028, 994

53. 0
10
20
30
40
50
60
70
80
PPM
OH
34.2
22.1
50.4
72.2
42.9
28.3
25.5
21.3 21.3
21.0

54. BICYCLIC MONOTERPENES
Plants containing thujone are used in herbal medicine, mainly for their immune-system
stimulating effects.
Pinene is, as limonene, an allelochemichal emitted by the roots of Quercus ilex.
Camphor and pinene are allelochemicals emitted by Salvia leucophylla (Nishida N et al.,
J Chem Ecol , 2005, 31, 1187).

55. Camphor
O
Dried rosemary leaves, (Rosmarinus officinalis), in the mint family,
contain up to 20% camphor.
It is used for its scent, as an ingredient in cooking (mainly in
India), as an embalming fluid, for medicinal purposes, and in
religious ceremonies.

56. Synthesis of Camphor through Wagner-Meerwein rearrangement

57. Iridoids
 Iridoids are a class of bicyclic monoterpenes found in a wide variety of
plants and in some animals.
 Chemically, iridoids usually consist of a cyclopentane ring fused to a six-
membered oxygen heterocycle, as exemplified by nepetalactone.
Nepetalactone
 Iridoids are typically found in plants as glycosides,
most often bound to glucose.
 Iridodial is in equilibrium with its hemiacetal.
iridoids exhibit a wide range of bioactivities including cardiovascular, hypoglycemic,
anti-inflammatory, antispasmodic, antitumor, antiviral, immunomodulator and purgative
activities (Didna B et al., Chem Pharm Bull 2007, 55, 159).

58. sesquiterpene
Some sesquiterpenes are found in the higher boiling
portions of essential oils.
The Conipositae are the largest family Of flowering plants Their flowers have characteristically a large number of petals Typical
examples are the daisy and the sunflower
Acyclic Sesquiterpene
HO
Farnesol
OH
Nerolidol

59. Monocyclic Sesquiterpenes
Hydration and /Or
dehydrogenation

60. The function of zingiberene and curcumene as insecticides,
repellents, and insect feeding deterrents.
The plant hormone abscisic acid, which stimulates leaf fall and
dormancy in plants.
Abscisic acid

61. Synthesis of β-Santalene
The asymmetric synthesis of Diels Alder reaction of Allene ester 18 with
cyclopentadiene, then selective reduction to yield 20 followed by oxidation”
Pyridinium chlorochromate” and Wolf-Kischner reduction.

62. Bicyclic Sesquiterpene
The classic bicyclic sesquiterpene is caryophyllene, from the
oil of cloves, which has a nine-membered ring and
cyclobutane ring.
Accumulation of rishitin as one of a major phytoalexin synthesis in tomato
plant was measured in leaves and stems after elicited by 1% of silver nitrate
at different plant ages.

63. Tricyclic Sesquiterpene
α-Santalol is an organic chemical compound and is a
principal constituent of oil of sandalwood.
α-cedren and β-cedrene and cedrol was detected in
Juniperus virginiana .
Juniperus virginiana

64. Sesquiterpenlactone
Santonin is a drug which was widely used in the past as an
anthelminthic a drug that expels parasitic worms.
Artemisinin
Artemisinin, obtained from Artemisia annua, have recently been
recommended by the World Health Organization for the treatment of resistant
strains of malaria.

65. Dry plant
Ethanol
39 g extract,
H2O/MeOH (7:3).
CHCl3/BuOH
CHCl3
CC
Hexane/ethyl acetate
1 2
Sesquiterpenes and a Phenylpropanoid from Cordia trichotoma
Z. Naturforsch, 59c, 19-22 (2004). , L. Pessoa et-al

66. IR (KBr): νmax = 3415, 2935, 2870, 1461, 1376, 1074, 1026.
EIMS: m/z (rel. int.) = 256 ([M]+, < 1), 241 ([M-CH3]+, 3.5), 223
([241- H2O]+, 3.8), 205 ([241D2H2O]+, 2.1).
Sesquiterpenes and a Phenylpropanoid from Cordia trichotoma
Z. Naturforsch, 59c, 19-22 (2004).

67. HO
OH
H
OH
3.18, dd, 10.7, 4.1
1.97, dt, 10.7, 10.7, 3.1
1.56, m
1.68, 1.58, m 1.07, d, 10.3
3.9, t, 10.3
1.33, m
1.52, 1.37, m
1.91, 1.04, m
2.35, m
0.98, d, 7.1
0.91, d, 6.9
1.02, s
1.46,s
HO
OH
H
OH
80.0
27.9
42.7
58.1 53.3
19.7
39.5
27.3
21.9
16.4
14.2
34.8
73.1 70.3
42.4
1H and 13C-NMR of (+)-1,4,6α-trihydroxyeudesmane

68. 2D 1H,1H – Homocorrelation NMR Spectra
Both F1 and F2 frequency axes denote 1H chemical shifts which are correlated
through spin-spin-coupling  homonuclear shift-correlation experiment.
1H,1H-COSY ("COrrelation SpectroscopY")
H
C
H
2JH-H
geminal
H
C C
H
vicininal
3JH-H
4JH-H
w-conformation
H H
C
C C
8.63, d, 2 Hz
8.87, d, 2 Hz
ppm
7.5
8.0
8.5
9.0 ppm
7.5
8.0
8.5
9.0
HO H
H
H
H
H
H
H
H
H
O
OH
H
K.S

69. HMQC (“Heteromolecular Multiple Quantum Coherence") and
HSQC (“Heteromolecular Single Quantum Coherence")
2D 1H,13C – Heterocorrelation NMR Spectra
H
C
H
C
H
H C
H
H
• Indirect detection of 13C through magnetisation transfer
from 1H to 13C  enhanced sensitivity in comparison with 13C NMR
• Correlation between 1H and 13C through 1 bond (1JCH).
ppm
3
4
5
6
7
8 ppm
50
100
OH
O
O
OH
HO
1J1H-13C
3.90, s
56.9, s
3.90, s
56.9, s
23.3
3.23, d
Xanthohumol
K.S

70. HMBC
ppm
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5 ppm
40
60
80
100
120
140
160

O 

O
HO
HO
H
OH
COOH
5.17, dd
CH2: 38.0
C-1‘: 129.4
COOH: 173.5
CO: 168.5
2JH-C
2JH-C
3JH-C
3JH-C
Example:
2JH-C and 3JH-C correlations
of H-2 of rosmarinic acid
K.S

71. 5
HO
OH
H
HO
H
H
H
H
H
H
H
H
H H
H
H
1
2
3
4 6
7
8
9
10
11
12
13
14
15
COSY
HMBC

72. Norsesquiterpene
Antidepressant,
antifungal
antiinflammatory,
antiseptic
Chamomile
Vitispirane is an important
norisoprenoid odorant that
occurs in many wines.

73. They have 20 carbon atoms and are derived from
geranylgeraniol pyrophosphate
Diterpene
They are found in the resinous high-boiling fractions
remaining after distillation of essential oils.
The rosin remaining after distilling pine turpentine, for
instance, is rich in diterpenoids

74. Diterpenoid groups that are physiologically active include:
Vitamin A activity (retinol)
Phytohormones that regulate plant growth and germination,
e.g. gibberellin, fungal hormones that stimulate the switch from
asexual to sexual reproduction.
Disease resistance agents (phytoalexins) e.g. trisporic acid;
the anticancer drug, taxol, from the bark of the yew tree.
Phytol is a partially saturated diterpene, a monounsaturated
derivative of geranylgeraniol which is part of the chlorophyll
molecule.

75. Acyclic Diterpene
Plaunotol is the active ingredient of a commercial drug named
Kelnac®, is a mucosal protective factorenhancing antiulcer agent.
Science Asia 32 (2006): 17-20, Wanchai De-Eknamkul et-al
Furanoditerpenes are found in Compositea family.

76. Monocyclic Diterpene, Vitamin A
Syntheis of β-Ionon

77. β-Ionon react with acetylene in base, partial hydrogenation and
Grinard reaction with vinyl metal organometallic, then Wittig
reaction with 3-formylcrotylacetate to afford Vitamine A acetate.
Syntheis of Viatmine A from β-Ionon

78. Cafestol
Anticancer activity
Kahweol

79. The steviol glycosides are responsible for the sweet taste of the leaves of the
stevia plant (Stevia rebaudiana, Asteraceae). These compounds are 40 to 300
times sweeter than sucrose.
Phorbol ester is phorbol-12-myristate-13-acetate (PMA), which is used as a
research tool in models of carcinogenesis.
Tetrahydrocannabinol, also known as Δ9-THC or Δ9-tetrahydrocannabinol, is the
main psychoactive substance found in the plant.
Tetrahydrocannabinol
PMA
Steviol

80. Ent-Kuarane Diterpenes Cembrane
Abietane Labdane

81. 3.6 Paclitaxel semisynthesis
N
O
PITSO
Ph
O
Ph
+
OSiEt3
O
OAc
OCOPh
OH
AcO O
O
O
Ph
OTIPS
NH
O
OH
O
OAc
OCOPh
OH
AcO O
O
O
Ph
OTIPS
NH
O
Ph
DMPA, Pyridine
HCl
OR2
O
OAc
OCOPh
OH
R1O O
HO
R1, Ac, R2: SiEt3
10-deacetylbaccatin III

82. Sesterterpenes
Variously unsaturated and branched sesterpenes, known as
Haslenes, were found in species of diatomaceous algae.
They are derived from geranylfarnesol pyrophosphate and have
25 carbon atoms.

83. Triterpenes
They form a large group of natural substances which includes
steroids and consequently sterols. Squalene is the immediate
biological precursor of all triterpenoids.

84. Squalane is a completely saturated derivative of squalene. it is largely used as
a component in many cosmetic products. It is obtained by hydrogenation of
squalene extracted from olive oil.
The common tetracyclic triterpene lanosterol is a major constituent of wool
fat and its esters are found in lanolin cream.
Other triterpenes,such as the α- and β-amyrins are found in wood resin and
the bark of many trees.
HO
18
19
20 21
22
23
24 25
26
27
28
29
30
1
3
5
7
9
11
13
15
17
β-amyrins
α- amyrins
lanosterol
Olean
Ursane

85. Lupane
Pentacyclic triterpenoids based on the lupane skeleton are found vegetables
and fruit.
Lupeol was shown to have various pharmacological properties, inducing anti-
inflammatory and anti-arthritic responses and inhibition of tumor growth
(Saleem M et al., Cancer Res 2005, 65, 11203) in animal cells.
The traditional medicine ginseng (Panax ginseng) contains glycosides of
triterpenes such as protopanaxadiol Chinese.
O
H
HO
H
HO
H
H
OH
H
O
OH
Saponins: Glycosidic compounds which could be triterpenes or steroidal or
steroidal alkaloids.
OH
HO
H
OH
H
H
protopanaxadiol Saponins

86. Ursolic acid is found at high concentration in coffee seeds and in apple fruit.
It is used in cosmetics as an anti-inflammatory, antibacterial and antifungal
drug. Ursolic acid is also able to inhibit some form of cancer, particularly
multiple myeloma (Pathak AK et al, Mol Cancer Res 2007, 5, 943).
Although limonin was first isolated by Bernay in 1841, Its
structure was finally established in 1987 by the work of three
groups, those of Ley, Nakanishi and Kraus.

87. Tetraterpenes
It consist of eight isoprenoid units “Carotenoids “
Carotenoids can be considered derivatives of lycopene, found in
tomatoes, fruits and flowers.
Lycopene is a bioactive red colored pigment naturally occurring in
plants.
Interest in lycopene is increasing due to increasing evidence proving its
antioxidant activities and its preventive properties toward numerous
diseases.
In vitro, in vivo and ex vivo studies have demonstrated that lycopene-
rich foods are inversely associated to diseases such as cancers,
cardiovascular diseases, diabetes, and others. A review of all these
aspects may be consulted (Kong KW et al., Molecules 2010, 15, 959).

88. Carotenoids may be acyclic (seco-carotenoids) or cyclic (mono- or bi-,
alicyclic or aryl). Oxyfunctionalization of various carotenoids leads to a
large number of xanthophylls in which the function may be a hydroxyl,
methoxyl, carbonyl, oxo, formyl or epoxy group.

89. Dietary phytoene is accumulated in human skin where it can
potentially protect the skin (UV absorber, antioxidant, anti
inflammatory).
β-carotene is probably the most important as a precursor of
vitamin A.
In human serum several carotenes and xanthophylls have been
detected “(lutein, zeaxanthin, cantaxanthin and β-cryptoxanthin”.
Fucoxanthin, as an allenic carotenoid with a 5,6-monoepoxide
group, is one of the most abundant carotenoid in brown algae and
diatoms.
Fucoxanthin

90. Steroids
Steroids form an important group of compounds based on the
fundamental saturated tetracyclic hydrocarbon : 1,2-
cyclopentanoperhydrophenanthrene (sterane or gonane).
This nucleus, partially or completely hydrogenated, is generally
substituted by methyl groups at C10 and C13. A chemical group
(ketone, hydroxyl...) or an alkyl side-chain may also be present at
C17.

91. According to their chemical structure, the wide array of steroid
molecules may be divided into several groups:
Sterols, Bufadienolides, Cardenolides, Cucurbitacins,
Sapogenins, Steroidal alkaloids, Bile acids, Hormonal steroids.

92. In 5 α-cholstane, all rings are trans and substituted groups are in β-position.
in 5 β- (A/B cis-, B/C und C/D trans). The presence of OH group at C-3 in β-
position is common while the configuration of substituent at positon 5,10 / 8,9 /
13,14 is different .
α- and β- cholstane

93. Sterols may be found either as free sterols, acylated (sterol esters), alkylated
(steryl alkyl ethers), sulfated (sterol sulfate), or linked to a glycoside moiety
(steryl glycosides) .
Sterols
Cholesterol is found in high concentrations in animal cell
membranes.
Cholesterol has numerous functions, as a precursor to hormones
and vitamins, to providing mechanical strength and a control of
the behavior of membranes (Rog T et al., Biochim Biophys Acta
2009, 1788, 97).

94. Sulfated sterols isolated from the sponge Pseudoaxinissa digitata
(Demospongia, order Axinellida) and showing anti-HIV activity.

95. Bufadienolides
They are typically polyhydroxy C24
steroids with a pentadienolide ring at
C-17. They are important for their
cardiotonic activity..
Cardenolides
Their structure is closely related to
bufadienolides but these C23 steroids
possess a butenolide ring located at C-17.
They are widely distributed in plants mainly
as glycosides and are either toxic or insect
deterrents.

96. Sapogenins
They form the aglycon part of saponins which have well known
detergent properties. They are oxygenated C27 steroids with an
hydroxyl group in C-3.
These steroids can regulate steroid hormones.
Thus, diosgenin can be chemically converted into corticosteroids,
estrogens and progesterone.

97. They form a large group of molecules where a nitrogen atom is
integrated into a ring or in a substituent.
The steroid nucleus can contain double bonds and hydroxyls in
various positions.
Steroid alkaloids
These alkaloids are only distributed in Solanaceae (potato,
tomato, eggplant ...). Fortunately, their toxic properties disappear
by structural transformation during ripening.

98. Bile acids
Bile acids are the end products of cholesterol utilization,
synthesized in the liver.
The most common bile acids are C24 steroids with a carboxyl
group at C-24 and up to three hydroxyl groups on the steroid
nucleus, one being at C-3.

99. Bile acids have long been known to be essential in dietary lipid
absorption and cholesterol catabolism.
Bile acids have been discovered to activate specific nuclear
receptors.
They regulate the increase in energy expenditure in adipose
tissue, preventing obesity and resistance to insulin (Watanabe M
et al., Nature 2006, 439, 484).
‫النبات‬ ‫طريق‬ ‫عن‬ ‫الربو‬ ‫مرض‬ ‫تثبيط‬ ‫في‬ ‫دولية‬ ‫اختراع‬ ‫براءة‬ ‫يحققان‬ ‫سعوديان‬
,
‫بروقيري‬ ‫فغونيا‬

100. Vertebrate hormonal steroids
Sexual hormones Corticosteroids Neurosteroids
Andostenedione Aldosterone Pregnenolone

101. HO
18
19
20 21
22
23
24 25
26
27
28
29
30
1
3
5
7
9
11
13
15
17
Triterpenes
Steroids
30
27 / 29
No. of Carbons
6 or 8
4 or 5
No. of methyl
groups
Two methyl groups
One methyl group
May contains one methyl
group
No methyl group
C-4 Position
C-14 Position
Difference between Steroids and Triterpenes

102. Total Synthesis of steroid
Vinyl allylether undergo γ-δ rearrangement to afford aldehyde. Reaction with
propargylmagnesium bromide then reaction with methyl lithium and bromide reagent in
acid medium to afford triene diketone, followed by intraldol-condensation to give tetra-en
then oxidation with osmium oxide and finally aldol cyclization .

103. Total Synthesis of steroid
TORGOV-Reaction

104. OPP
H
Macro and Polycyclic diterpenes
Cembranes
Taxanes
Tiglianes
GGPP
Biosynthesis of some Diterpenes

105. The initial isopropylidene unit of the GGPP chain leads to two perhydronaphtalene
bicyclic intermediates resulting in the two enantiomeric series that differ from each other
in their inverted configurations of the carbons C-5, C-9 and C-10.
Molecules 2007, 12, 456