Pharmacology & Pharmacy, 2011, 2, 109-115
doi:10.4236/pp.2011.23014 Published Online July 2011 (http://www.scirp.org/journal/pp)
109
A Study of Pungency of Capsaicinoid as Affected
by Their Molecular Structure Alteration
Junlian Wang1, Zhenghong Peng2, Shengze Zhou3, Jinxi Zhang4, Songfei Zhang1, Xiangfeng Zhou5,
Xiaobin Zhang1, Bixian Peng6*
1Department of Material Science and Engineering, Zhejiang University, Hangzhou, China; 2Chemistry Laboratory, M. D. Anderson
Cancer Center, Texas University, Houston, USA; 3Department of Pure and Applied Chemistry, University of Strachclyde, Glasgow,
England; 4Beijing Tiangonglongyuan Int’l Bio-Science & Technology Company Ltd., Beijing, China; 5Beijing Jiuzhoulongling
Hi-Tech Env. Prot. Mat. Company, Beijing, China; 6Technical Institute of Physics and Chemistry, CAS, Beijing, China.
Received October 17th, 2010; revised April 4th, 2011; accepted May 13th, 2011.
ABSTRACT
An attempt was made in an effort to synthesize a series of capsaicinoids, most of which are synthesized in our labora-
tory and characterized to be completely new members of capsaicinoids. The Structure-pungency dependence are pre-
sented and discussed.
Keywords: Capsaicinoid, Preparation, Structure, Pungency
1. Introduction
The research of capsaicinoid used in medical treatment
of various diseases has been attracting the attention of
medical scientists from various countries for many years
running. Bates T. E. et al. [1]. showed that capsaicin has
a remarkable effect, simultaneously with the morphologi-
cal.
Alteration of lung caner cells, to cause lung cancer
cell’s fading and necrosis. American and Japanese scien-
tists [2] reported capsaicin to be affectuated to kill the
most human’s prostate gland’s cancer cells. In addition
capsaicin has been shown to be of medical treatment
activities, Such as anticoagulation of blood platelet [3],
adjustment (regulation) of metabolite stimulation of
Chemical carcinogenic substances [4], restraining the
growth of transforming cell like Hela, Ovary malignant
tumour, mammary gland.
Malignant tumour and human promyelocytic lukemia
cells [5]. The induced antiproliferative effect through a
mechanism facilitated by ER stress in prostate PC-3 cells
[6], induced expression of androgen receptor via PI3k
MAPK pathways in prostate LNCaP cells [7], prostate
cancer cells’ suppressor [8], induced apoptosis of pros-
tate PC-3 cells [9], displayed anti-proliferative activity
against human small cell lung cancer in cell culture [10]
and the induced apoptosis in leukemic cells through oxi
dative stress [11]. The above accumulating evidence sup-
Figure 1. Essentical structural characteristics of capsaicin
which determine its pungency .
ports the notion that capsaicin exhibits antimutagenic,
anticarcinogenic and antioxidant activities in many cell
types and conditions and therefore sustained efforts are
made to understand the molecular mechanisms involved
in capsaicin action and to explore the potential therapeu-
ric use of capsaicin in cancer. In the above-mentioned
references most of them are dealt with capsaicin—one of
the main capsaicinoids, whose general structure is ex-
pressed in Figure 1.
Depending on the different chemical structures, such
as the length of acyl chain, the absence or presence of
double bond and its location along the numbered carbon
atom of acyl group, the side methyl group’s attachment
and its shift to the other numbered carbon atom, and the
nature of the substituted groups attached to 3 or 4 posi-
tions of ben zene ring of the v anillyl group, the capsaicin-

110 A Study of Pungency of Capsaicinoid as Affected by Their Molecular Structure Alteration
noids may differ and display greatly in their pungency,
probably hence the susceptible curative dose and the
finally optimized treatment effect. In present study an
attempt was made in an effort to synthesize a series of
capsaicinoids, some of which (No. 2, 3 and 7 in Table 1 .)
had been shown [12-14] to be known—either extracted
and separated from the natural pepper or prepared by
artificial synthesis from chemical laboratoryes, the others
of which are synthesized in our laboratory and charac-
terized to be completely new members of capsaicinoids.
The Structure-pungency dependence are presented and
discussed.
2. Experiment
2.1. Synthesis
The synthesis of 2 main intermediates, one is vanillyla-
mine designated as I-1 in Equation (1), the other is cor-
responding acid chloride designated as I-2 in Equation (1)
and used for capsaicinoid-making is conducted in a simi-
lar manner as described in our newly approved patent [15]
with some modification in choice of appropriate bromine
—substituted alkanes as starting raw material by reacting
the corresponding acid chlorides (in dry ether) with a
suspension of dry vanillylamine in dry ether under an
atmosphere of nitrogen as indicated by the following
Equation (1) being example for the capsaicin analogues
whose molecular have a double bond in the acyl chain.
In case of hydrocapsaicin analogues an unique differ-
ence is to use the corresponding saturated fatty acid chlo-
ride to replace the unsaturated ones. The structure for-
mula characterized by element analysis. IR. HNMR are
listed in Appendix 1.
2.2. Pungency Determination [16]
Scoville’s sensory assessment method is widely acknow-
ledged domestically and internationally to be used to
determine the pungency of capsaicinoid.
The basic principle of this method is based on 1) the
first step is to prepare and purify a capsaicinoid (extract
or artificial product), 2) an extract or product is weighed
accurately (in general 0.050 g), 3) To dilute a solution of
weighed sample with sucrose aquatic solution continu-
ously and stepwise by multifold to an appropriate ex-
treme degree by which the pungency of a capsaicinoid
can be just tasted by sensory organs of individual’s group.
4) the experimentally found diluted limit (extreme dilu-
tability) is considered to be scoville Index, expressed as
Scoville Heat Unit (simply SHU). The pungency of all
the capsaicinoids synthesized in present study are deter-
mined in Nutrition and Food Safety Detection Centre of
Hunan Agricultural University, Changsha city, Hunan,
China.
3. Results and Discussion
All the chemical structural formula of capsaicinoids are
listed in Table 1. The experimental data needed to char-
acterize individual capsaicinoid such as melting point,
elemental analysis HNMR.CNMR, are summarized in
Appendix 1. The determined value of capsaicinoid’s
pungency expressed as SHU are collected in the last
column of Table 1 for systematic comparisonas well.
3.1. Synthesis
From data listed in Appendix 1, it is shown that the ex-
perimentally found data of elemental analysis for each
capsaicinoid is coincided with the calculated ones for
C.H.N content (%) within an allowed deviation. HNMR
data for each capsaicinoid are in good agreement with
the assigned chemical
Shift typical for each functionalized groups contained
in new compound s involved. All th e above-stated figur es
tell in flavour that the synthesis of all the members of
capsaicinoids we have developed in present study is to be
successful.
3.2. Pungency-Structure Dependence
A group of systematic and comparative results listed in
Table 1 and regarding the pungency—structure depen-
dence, permitted us to reveal the following basic laws
governing the heading of pungency alternation.
Firstly among the many factors affecting the pungency
of capcaicinoids, the mutuality of hydroxy and methoxy
attached to benzene ring of vanilly group have a decisive
influence on the pungency, which is clearly demonstrated
by comparing the structure and pungency of capsaicinoid
No. 10 as one positive side with that of No. 8 and 9 as
opposite side. Keeping methoxy group to be unchanged
but eliminating the hydroxy (case No. 8) lead to remark=
able dropping of the pungency of No.10, leaving only
one third of the originol pungency (1.6 > 0.6 × 106 SHU)
alternatively sustaining hydroxy but omitting methoxy
enable the pungency continuously dropped to be zero,
high lighting the 1-st extreme importance of methoxy
and hydroxy mutuality, neither of two groups can be
dispensed with, Neith er should be overemphasized at the
xpense to the neglect of the other. The two groups e
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A Study of Pungency of Capsaicinoid as Affected by Their Molecular Structure Alteration
111
Table 1. The Chemical Structural formula Charac terized in present study and the pungency (SHU) of capsaicinoids.
No. Structural formula SHU reference
1 3 × 106 ours
2
9.1 × 106 [15, 16]
3
16.1 ± 0.6 × 106 [15, 16]
4 12 × 106 ours
5 0.65 × 106 ours
6
1.1 × 106 ours
7
16.1 ± 0.6 × 106 [15, 16]
8
0.6 × 106 ours
9 0 ours
10 1.55 × 106 ours

112 A Study of Pungency of Capsaicinoid as Affected by Their Molecular Structure Alteration
depend on each other for existence, restrict and interact
each other to give full play to the pungency functionality.
Secondly, one of the major factors affecting the pun-
gency is the length of acyl chain. Neither too long, for
example, chain with more than 9 carbon atoms, nor too
short for instance, chain with less than 9 carbon atoms
can promote to further upgrade the pungency of capsai-
cin (case No. 7) and dihydrocapsaicin (case No. 3),whose
acyl chain is constituted just from 9 carbon atoms.
Thirdly the methyl group attached to the 8- numbered
carbon atom is concluded not to be dispensable, hence
might be nonessential or neglectful. Let us have a paral-
lel comparison on the pungency of two members of cap-
saicinoid, one is norddihydrocapsaicin (case No. 7), whose
pungency is 12.1 ± 0.6 × 106, the other is (E)-N-vanilly-
(4-hydroxy-3-methoxy benzyl-) nonylamide (case No.
10), whose pungency is declined as low as 1.5 × 106
SHU, being one of eighth of the original pungency of
capsaicinoid No. 7.
Fourthly It has been known that capsaicin and dihy-
drocapsaicin differ from each other in the presence(case
No. 3) and absence (case No. 7) of do uble bond at the 8 -
numbered carbon atom, such a structural distinction
failed to create a difference in pungency. However it
doesn’t imply that it is of secondary or even no signifi-
cance for a factor of double bond. Nothing in chemistry
would is invariable. If a double bond’s locatio n is shifted
and headed for th e dire ction toward the amide planarity,
for example, from 6-nonen-(case No. 3) to 4-nonen am-
ide (case No. 4), the pungency value had been lowered
from 16.1 × 106 SHU for capsaicinoid No. 3 to 12 × 106
SHU for No. 4.
Finally the effect of Carbon atom number by which
the benzene ring and amide plane is separated should
also considered to be not ignored, which can be clearly
seen when the carbon atom number is increased from one
(case No. 10) to two (case No. 5). In response to such a
increased carbon atom (-CH2-), the pungency is Less-
ened from 1.5 × 106 (Case 10) to 0.65 × 106 SHU.
4. Summary
1) A series of capsaicinoids with different structures
have been synthesized and characterized.
2) The pungency of different capsaicinoids has been
determined by sensory method expressed as SHU.
3) The pungency is found to be very sensitive an d de-
pendent upon the molecular structure alteration occurred
within the capsaicinoids.
4) The structure pungency dependence discovered in
present study has provided a preliminary basis to further
study the structure-curative effect dependence of capsai-
cinoids with respect to various cancer cells and dis-
eases.
5. References
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[7] S. Malagarie-Cazenave, N. Olea-Herrero, I. Diaz-Laviada,
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[9] A. M. Sanchez, S. Malagarie-Cazenave, I. Diaz-Laviada
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[10] K. C. Brown, T. R. Witte, P. Dasgupta, et al., “Capsaicin
Displays Anti-Proliferative Activity against Human Small
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[11] K. Ito, T. Nakazato, M. Kizaki, et al., “Induction of
Apoptosis in Leukemic Cell by Homovanillic Acid De-
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A Study of Pungency of Capsaicinoid as Affected by Their Molecular Structure Alteration 113
[12] P. M. Gannett , D. L. Na gel, P. J. Re illy, et al., “The Cap-
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[13] H. Kaga, M. Masakatsu and K. Orito, “A Facile Proce-
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A Study of Pungency of Capsaicinoid as Affected by Their Molecular Structure Alteration
114
Appendix 1
Capsaicinoid No. 1
1HNMR of capsaicinoid No. 1 is more complicated than
that of capsaicin [8] due to the presence of a unsymmet-
ric carbon atom, HNMR of hydrogen attached to benzene
ring is similar to capsaicin [8]. Chemical shift of 3 methy
groups is 1.6, 1.7 and 0.96 ppm respectively.
Capsaicinoid No. 2
All the 1HNMR data are totally coincided with that of
nordcapsaici n i n p aper [8].
Capsaicinoid No. 3
All the 1HNMR data are totally coincided with that of
capsaicin in paper [8].
Capsaicinoid No. 4
Elementary analysis (%) Calculated: C, 70.79; H, 8.91;
N, 4.59. Found: C, 70.84; H, 9.06; N, 4.41.
1HNMR (CDCl3) δ (ppm): 0.856 (6H, CH3), 1.183
(2H, CH2), 1.514 (1H, CH), 1.953 (2H, C=C-CH 2), 2 .254
(2H, O=C-CH2), 2.341 (2H, CH2-C=C), 3.884 (3H,
OCH3), 4.351 (2H, ArCH2), 5.428 (2H, CH=CH), 5.579
(1H, OH), 5.673 (1H, NH), 6.763 (1H, 6-ArH), 6.808
(1H, 2-ArH) , 6.864 (1H, 5-ArH) .
DEPT 135˚ δ (ppm): 22.493 (+, CH3), 27.494 (+, CH),
28.663 (–, CH2), 30.379 (–, CH2), 36.719 (–, CH2),
38.619 (–, CH2), 43.565 (–, CH2), 55.954 (+, OCH3),
110.708 (+, CH), 114.362 (+, CH), 120.835 (+, CH),
127.985 (+, CH), 132.306 (+, CH).
Capsaicinoid No. 5
Elementary analysis (%) Calculated: C, 70.32; H, 9.51;
N, 4.56. Found: C, 70.69; H, 9.41; N, 4.68.
1HNMR (CDCl3) δ (ppm): 0.876 (3H, t, -CH3), 1.1 ~
1.4 (10H, -(CH2)5-Me), 1.588 (2H, m, -CH2-), 2.121 (2H,
t, CO-CH2-), 2.743 (2H, t, Ar-CH2-), 3.489 (2H, q,
N-[2-(4-hydroxy-3-methoxybenzyl)]-8-methyl-4-nonenami-
de
N-[2-(4-hydroxy-3-methoxyphenyl)ethyl]nonanamide
N-(3,4-dimethoxybenzyl)nonanamide
N-(3-methoxybenzyl) nonanamide
N-(4-hydroxybenzyl) nonanamide
-CH2-N), 3.880 (3H, s, Ar-OCH3), 5.430 (2H, s, -NH-CO,
Ar-OH), 6.665 ~ 6.860 (3H, Ar-H).
DEPT 135˚ (CDCl3) δ (ppm): 14.094 (+, CH3), 22.646
(–, CH2), 25.795 (–, CH2), 29.144 (–, CH2), 29.297 (–,
CH2), 29.321 (– , CH2), 31 .827 ( –, CH2) , 35.399 (– , CH2),
36.905 (–, CH2), 40.672 (–, CH2), 55.916 (+, OCH3).
Capsaicinoid No. 6
Elementary analysis (%) Calculated: C, 70.32; H, 9.51;
N, 4.56. Found: C, 69.93; H, 9.59; N, 4.57.
1HNMR (CDCl3) δ (ppm): 0.880 (3H, t, -CH3), 1.1 ~
1.4 (10H, -(CH2)5-Me), 1.656 (2H, m, -CH2-), 2.207 (2H,
t, CO-CH2-), 3.071 (6H, s, 2Ar-OCH3), 4.377 (2H, d,
Ar-CH2-), 5.7 3 6 (1 H, s, -N H-CO), 6.820 (3H, s, Ar-H).
DEPT 135˚ (CDCl3) δ (ppm): 14.069 (+, CH3), 22.630
(–, CH2), 25.804 (–, CH2), 29.148 (–, CH2), 29.319 (–,
CH2), 31.805 (– , CH2), 36 .852 ( –, CH2) , 43.426 (– , CH2),
55.885 (+, OCH3), 55.953 (+, OCH3).
Capsaicinoid No. 7
All the 1HNMR data are totally coincided with that of
dihydrocapsaicin in paper [8].
Capsaicinoid No. 8
Elementary analysis (%) Calculated: C, 73.61; H, 9.81;
N, 5.05. Found: C, 73.75; H, 9.93; N, 5.13.
1HNMR (CDCl3) δ (ppm): 0.876 (3H, t, -CH3), 1.1 ~
1.4 (10H, -(CH2)5-Me), 1.655 (2H, m, -CH2-), 2.210 (2H,
t, CO-CH2-), 3.796 (3H, s, Ar-OCH3), 4.415 (2H, d,
Ar-CH2-), 5.727 (1H, s, -NH-CO)，6.809 ~ 7.243 (4H,
Ar-H).
DEPT 135˚ (CDCl3) δ (ppm): 14.077 (+, CH3), 22.638
(–, CH2), 25.787 (–, CH2), 29.148 (–, CH2), 29.309 (–,

A Study of Pungency of Capsaicinoid as Affected by Their Molecular Structure Alteration
115
CH2), 29.328 (– , CH2), 31 .807 ( –, CH2) , 36.832 (– , CH2),
43.557 (–, CH2), 55.232 (+, OCH3).
Capsaicinoid No. 9
Elementary analysis (%) Calculated: C, 72.97; H, 9.57;
N, 5.32. Found: C; H; N.
1HNMR (CDCl3) δ (ppm): 0.876 (3H, t, -CH3), 1.1 ~
1.4 (10H, -(CH2)5-Me), 1.646 (2H, m, -CH2-), 2.202 (2H,
t, CO-CH2-), 4. 359 (2H, d, Ar-CH2-).
DEPT 135˚ (CDCl3) δ (pp m): 14.081 (+, CH3), 22.629
(–, CH2), 25.774 (–, CH2), 29.127 (–, CH2), 29.258 (–,
CH2), 29.273 (– , CH2), 31 .794 ( –, CH2) , 36.856 (– , CH2),
43.268 (–, CH2).
Capsaicinoid No. 10
Except methyl group at 8-numbered carbon atom for
No.7 all the 1HNMR data are totally coincided with that
of dihydrocapsaicin in paper [8].