Triterpenes

Terpenes
Terpenes is the generic name of a group of natural products,
structurally based on isoprene (isopentenyl) units
(branched five-carbon units).
The term may also refer to oxygen derivatives of these compounds
that are known as “Terpenoids”.
2

The five-carbon (isoprene) units that make up the terpenes are
often joined in a “head to-tail” fashion & head-to-head fusions are
common, and some products are formed by head-to-middle
fusions.
3
Head
Tail
Terpenes

Classifications of Terpenes
Types of Terpenes Empirical formula Isoprene units
Hemiterpenes C5H8 1
Monoterpenes C10H16 2
Sesquiterpenes C15H24 3
Diterpenes C20H32 4
sesterterpenes C25H40 5
Triterpenes C30H48 6
Tetraterpenes C40H64 8 4
Terpenes are normally classified into groups based on the number of isoprene
units from which they are biogenetically derived.

5
Terpenoid Biosynthesis
Chappell, J. (1995) Biochemistry and molecular biology of the isoprenoid biosynthetic pathway in plants. Annu. Rev. Plant
Physiol. Plant Mol. Biol. 46: 521–547.

6
Terpenoid Biosynthesis Con.
Isomerization

11
Pyruvate pathway
10
The details of the glyceraldehyde 3-phosphate/pyruvate pathway and the enzymes
responsible have not yet been fully defined.

3 Acetyl CoA MVA+ (mevalonate) IPP DMAPP
DMAPP + IPP GPP (C10) Geranyl diphosphate Monoterpenes
GPP + IPP FPP (C15) Farnesyl diphosphate
Sesquiterpenes
FPP + IPP GGPP (C20) Geranylgeranyl diphosphate Diterpenes
GPP + FPP GFPP (C25) Geranylfarnesyl diphosphate Sesterterpenes
FPP + FPP 2FPP (C30) Farnesyl diphosphate Triterpenes
GGPP + GGPP 2GGPP (C40) Geranylgeranyl diphosphate Tetraterpenes
12
11

Triterpenes C30H48
These are compounds containing thirty carbon atoms made from six
isoprene units. They are formed by head to head coupling of two
sesquiterpenoid units.
13

Triterpenoids classified
into two main groups
TetracyclicTriterpenes
Dammarane
C30H54
Tirucallane
C30H54
Pentacyclic Triterpenes
Friedelane
C30H52
Lupane
C30H52
Ursane
C30H52
Oleanane
C30H52
Serratane
C30H52
Taraxastane
C30H52
14

1-Tetracyclic Triterpenes
15
Dammarane Tirucallane

Friedelane Serratane Oleanane
16
2-Pentacyclic Triterpenes

Phytochemical Screening oF triterpenes
1- chemical test
Liebermann
Burchard reaction
red color
2- Thin layer chromatography:-
Without chemical
treatment
Under UV
With spray
reagents
18

2- Thin layer chromatography:-
The Most Frequently Used Solvents For TLC Performed On Silica Gel Include
Different Proportions Of Chloroform–methanol–water
19Source: From Oleszek, W., Bialy, Z., J. Chromatogr. A, 1112, 78, 2006. With Permission from Elsevier.

Detection on TLC
Without chemical treatment
Most of triterpenes are colourless substances, crystalline, and optically active.
They are not seen on the TLC plate either in natural light or under UV
exposure. The exceptions are glycyrrizic acid and its glycoside conjugates from
liquorice, These groups can be detected by exposure to UV-254 nm or UV-365
nm.
The other triterpenes, when developed on silica gel 60F254 precoated TLC, can
be observed under UV as a black quenching spots. These spots, however,
are not characteristic for any structural features.
21

With spray reagents
Detection and preliminary characterization of triterpenes on TLC plates can be performed using
different types of spray reagents. Over fifty spray reagents have been used.
1- Anisaldehyde–sulphuric acid reagent: Mix 0.5 mL anisaldehyde with 10 mL
of glacial acetic acid and add 85 mL of methanol and 5 mL of sulphuric acid.
Spray with the reagent and heat the plate for 5–10 min at 1000C. The reagent
has very limited stability time.
(Blue red-violet in visible light and reddish or blue in UV 365)
2- Antimony(III) chloride reagent (SbCl3): Prepare 20% solution of
antimony(III) chloride in chloroform. After spaying heat at 1000C for 5–10 min.
(Pink, purple in visible light, red-violet, green, blue in UV 365)
22

3- Blood reagent: 10 mL of 3.6% sodium citrate are mixed with 90 mL
of the fresh bovine blood. Two milliliters of this solution is mixed with 30
mL phosphate buffer pH 7.4. Spray over thoroughly dried TLC plate.
(White zones on the reddish background)
4- Liebermann–Burchard reagent: Add carefully 5 mL of acetic
anhydride and 5 mL of concentrated sulphuric acid into 50 mL of
absolute ethanol, while cooling in ice. Heat the plate at 1000C for 5 min.
(Blue, green, pink, brown, yellowish visible light also under UV)
23

5- Vanillin–phosphoric acid reagent: One gram of vanillin
dissolve in 100 mL of 50% phosphoric acid. Spray and heat for 10
min at 1000C.
(Red-violet in visible light and reddish or blue in UV 365)
6- Vanillin–sulphuric acid reagent: Solution I—5% ethanolic
sulphuric acid; solution II—1% ethanolic vaniline. Spray the plate
with 10 mL of I, followed immediately by 10 mL of the solution II.
Heat at 1100C for 5–10 min.
(Blue, blue-violet, yellowish)
24

1H and 13C NMR spectra of triterpenes are crucial for the determination of their skeleton. In
general, the chemical shifts of olefinic carbons revealed on 13C NMR are used. This
information is completed by the number of methyl group observed on the 1H NMR
spectrum.
For the olean-12-ene type, the chemical Shifts of the double bond C12 and C13 are around
δ 122.0 and 144.0, respectively. While those of its isomer urs-12-ene are around δ 125.0
and 139.0, respectively, for the same carbons.
26olean-12-ene urs-12-ene

These olefinic carbon shifts differ from one class of triterpenoid to another
depending on their position in the skeleton.
27

Triterpenoid δ (ppm) Structure
Lup-20(29)-ene C29: 109.0 C20: 150.0
Taraxer-14-ene C14: 158.1 C15: 117.0
28
13C Shifts of Double Bond Carbons in Some
Triterpenoid

Dammarane
29
C N0. 13C-NMR C N0. 13C-NMR
1 33.7 16 27.6
2 24.8 17 49.6
3 76.4 18 16.6
4 37.7 19 16.1
5 50.5 20 75.5
6 18.3 21 25.4
7 35.2 22 40.6
8 40.7 23 22.6
9 50.5 24 124.8
10 37.3 25 131.6
11 21.5 26 25.8
12 25.4 27 17.8
13 42.3 28 28.4
14 49.8 29 22.2
15 31.2 30 15.6
3,20- dihydroxydammar-24-ene

30
oleanolic acid (3β-hydroxyolean-12-en-28-oic acid)
18
3
12

Green tea is produced from fresh leaves of camellia sinensis (L.) O.
Kuntze (theaceae) by steaming or panning just after harvest, followed by
systematic processes of kneading, crumpling, and drying.
Tea is produced by anaerobic microbial fermentation. In subsequent
chemical investigations of the characteristic post-fermented tea, we
isolated four triterpenes including two new compounds from a typical
tea produced by anaerobic fermentation.
35

Compounds 1
1- Name 13,26-Epoxy-3β,11α-dihydroxyolean-12-one
2- Color off-white amorphous powder
3- Molecular
Formula
C30H48O4
4- Mass data m/z: 495
4- IR absorptions arising from hydroxyl (3,462 cm−1) and carbonyl
(1,716 cm−1) functional groups.
6- 1H NMR signals corresponding to seven tertiary methyl groups at δ 0.77,
0.85, 0.87, 0.89, 0.99, 1.00, and 1.09. The spectrum also indicated
the presence of an oxygen bearing methylene group [δ 3.75 (1H,
dd, J = 9.2, 1.3 Hz) and 4.27 (1H, d, J = 9.2 Hz)] and two
oxymethine protons [δ 3.21 (1H, dd, J = 4.8, 11.6 Hz) and 4.30
(1H, d, J = 10.4 Hz)].
7- 13C NMR 30 carbon signals including four oxygen bearing carbons [δ71.8,
71.9, 78.4, and 89.2] and a carbonyl carbon [δ 208.4].
37

38
taraxastane-3β,20β-diol
C30H52O2
taraxastane-3β,20α-diol
C30H52O2
These NMR data and the unsaturation index (UI = 7) derived from the
molecular formula suggested that 1 is a pentacyclic triterpene with a ketone
group and an ether ring. Assignment of the signals with the aid of HSQC and
HMBC spectroscopy showed that the signals arising from the A and B ring
carbons were similar to those of compounds 3 and 4.

Compounds 2
1- Name 3β,11α,13β-Trihydroxyolean-12-one
2- Color yellow amorphous powder
3- Molecular
Formula
C30H50O4
4- Mass
data
m/z: 497
4- IR absorptions of hydroxyl (3,402 cm−1) and carbonyl (1,707
cm−1) groups.
6- 1H NMR
& 13C NMR
The 1H and 13C-NMR spectra were closely related to
those of 1,
except for
the appearance of eight methyl singlets and the
disappearance of the oxymethylene group (C-26) of 1.
39

New triterpene from the root of ricinus communis.
Purification of the n-hexane fraction led to the isolation and
characterisation of two triterpenes: one known compound
lupeol (1) and a new diketone pentacyclic triterpene named as
erandone (urs-6-ene-3,16-dione) (2), from the plant.
41

Compounds 2
1- Name urs-6-ene-3,16-dione (erandone)
2- Color white crystalline powder
3- Molecular
Formula
C30H46O2
4- Mass data m/z: 439
6- 1H NMR δ 1.25 (br, s, H-5) 5.14 (m, d, H-6-7), 1.63 (dd, J ¼ 6.2 Hz, H-18)
1.02 (3H, s, H-23), 1.15 (3H, s, H-24), 1.04 (3H, s, H-25), 0.96 (3H,
s, H-26), 1.09 (3H, s, H-27) and 1.19 (3H, s, H-28) and two
secondary methyl proton signals at δ 0.85 (d, J ¼ 6.4 Hz, H-29),
0.83 (d, J ¼ 6.0 Hz, H-30).
7- 13C NMR δ 39.7 (C-1), 37.3 (C-2), 209.5 (C-3), 57.1 (C-4), 56.4 (C-5), 138.3
(C-6), 130.1 (C-7), 41.6 (C-8), 51.6 (C-9), 43.4 (C-10), 22.1 (C-11),
26.5 (C-12), 40.1 (C-13), 41.6 (C-14), 47.1 (C-15), 211.6 (C-16),
57.9 (C-17), 53.8 (C-18), 32.2 (C-19), 38.4 (C-20), 37.7 (C-21),
29.1 (C-22), 21.5 (C-23), 21.4 (C-24), 12.4 (C-25), 19.3 (C-26),
12.5 (C-27), 24.4 (C-28), 12.6 (C-29), 19.3 (C-30) 42

Two novel triterpene dilactones, kadsuphilactones A (1) and B (2), were
isolated from medicinal plant kadsura philippinensis, Fam.Schizandraceae
(The leaves and stems).
The isolation of two novel triterpene from the EtOA.
44C32H46O8 C30H42O5

1H NMR Spectrum
An acetyl methyl singlet, five methyl singlets,
and a methyl doublet.
45

Comp.1 contained four carbonyl groups of one
ketone and three esters,
Five quarternary carbons, including one
olefinic carbon and one oxygenated carbon.
Seven methines, including one olefinic carbon,
and three oxygenated carbons
Nine methylenes, and seven methyl groups.
Among them, the oxygenated carbons appeared
at δ 81.3 (C-1), 84.1 (C-4), 94.9 (C-10), 75.5 (C-
11) and 80.3 (C-22).
46
The 13C NMR spectrum and DEPT

possessing partial structures of ring A and ring B, was observed from its
HMBC studies, which indicated
Correlations of H-2 (δ 2.83, dd, J ) with C-1,
C-3 (δ 174.9), and C-10 (δ 94.9),
 H-5 (δ 1.93 m) with C-10 and C-4.
C-4 was also found to correlate with H-29
(δ H 1.26) and H-30 (δ H 1.09).
47Li, R. T.; Li, S. H.; Zhao, Q. S.; Lin, Z. W.; Sun, H. D.; Lu, Y.; Wang, C.; Zheng, Q. T. Tetrahedron lett. 2003, 44, 3531-3534.

The six-membered α-methyl, α,β- unsaturated lactone was elucidated
from mass fragment at m/z 111 ([C6H7O2]+), as well as HMBC correlations
of H-22 (δ 4.44, d, J ) 12.9 Hz) with C-20 (δ 39.9) and C-24 (δ 139.6) and
correlations of the methyl singlet (H-27, δ 1.88) with C-24, C-25, and C-
26 (δ 166.6).
48Chen, D. F.; Zhang, S. X.; Wang, H. K.; Zhang, S. Y.; Sun, Q. Z.; Cosentino, L. M.; Lee, K. H. L. J. Nat. Prod. 1999, 62, 94-97.

The relative stereochemistry of kadsuphilactone A (1) was disclosed from the
NOESY correlations, which indicated cross-peaks between H1 and Me-29 and
between H-11 and Me-28 (δ 0.82s).
The location of the acetyl was revealed from HMBC correlation (H-11/ COCH3).
Ring D is five-membered, while ring C reveals an unusual Eleven-
membered system with a carbonyl group at C-9.
The 1H and 13C NMR assignment of rings C and D
was further determined by detailed analysis of COSY,
HMQC, and HMBC.
49

50
Plausible Biogenetic
Relationships
kadsulactone
schisanlactone B
intermediatesA-F
Kadsuphilactone A
Kadsuphilactone B

The DEPT spectra showed six methyl singlets (δ 16.8, 19.1, 19.2, 20.8,
22.1, and 29.2).
The location of a tertiary hydroxyl group was revealed by HMBC, in which
H-22 (δ 4.25, dd, J ) 4.5, 12.0 Hz), H-17 (δ 1.94 m), and Me-21 (δ 1.27 s)
were correlated with C-20 (δ 75.4).
The complete structure and stereochemistry of 2 were established from
NOESY and X-ray crystallographic analysis.
53

References
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54

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55

14- Anjaneyulu, V.; Ravi, K.; Prasad, K.H.; Connolly, J.D. Triterpenoids from Mangifera indica.
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19- Chen, D. F.; Zhang, S. X.; Wang, H. K.; Zhang, S. Y.; Sun, Q. Z.; Cosentino, L. M.; Lee, K.
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Triterpenes