[CANCER RESEARCH 42. 1193-1198.
0008-5472/82/0042-OOOOS02.00
April 1982]
Isolation and Identification of Kahweol Palmitate and Cafestol
Palmitate äsActive Constituents of Green Coffee Beans That
Enhance Glutathione S-Transf erase Activity in the Mouse1
Luke K. T. Lam,2 Velta L. Sparnins, and Lee W. Wattenberg
Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis,
ABSTRACT
Glutathione (GSH) S-transferase is a major detoxification
enzyme system that catalyzes the binding of a variety of electrophiles, including reactive forms of chemical carcinogens, to
GSH. Green coffee beans fed in the diet induce increased GSH
S-transferase activity in the mucosa of the small intestine and
in the liver of mice. A potent compound that induces increased
GSH S-transferase activity was isolated from green coffee
beans and identified as kahweol palmitate. The corresponding
free alcohol, kahweol, and its synthetic monoacetate are also
potent inducers of the activity of GSH S-transferase. A similar
diterpene ester, cafestol palmitate, isolated from green coffee
beans was active but less so than was kahweol palmitate.
Likewise, the corresponding alcohol, cafestol, and its monoac
etate showed moderate potency as inducers of increased GSH
S-transferase activity. Kahweol palmitate and cafestol palmi
tate were extracted from green coffee beans into petroleum
ether. The petroleum ether extract was fractionated by prepar
ative normal-phase and reverse-phase liquid chromatographies
successively. Final purification with silver nitrate-impregnated
thin-layer chromatography yielded the pure palmitates of ca
festol and kahweol. The structures were determined by exam
ination of the spectroscopic data of the esters and their parent
alcohols and by derivative comparison.
INTRODUCTION
GSH3 S-transferase
has been studied extensively as a major
detoxification enzyme system that catalyzes the binding of a
wide variety of electrophiles to GSH (3,10). Since most reactive
ultimate carcinogenic forms of chemical carcinogens are elec
trophiles, GSH S-transferase may play a significant role in
carcinogen detoxification. Enhancement of the activity of this
system potentially could increase the capacity of the organism
to withstand the neoplastic effects of chemical carcinogens.
Experiments have been carried out to determine the correlation
between increased GSH S-transferase activity in a target organ
of chemical carcinogenesis and its response to the carcinogen.
For this purpose, the forestomach of the mouse was used.
Members of several classes of inhibitors of BP-induced neopla
sia of the mouse forestomach were studied for their effects on
the GSH S-transferase activity in that structure. Five of the
1 Supported
by USPHS Contract NOI-CP-85613-70
and Grant CA-09599.
Presented in part at the 182nd American Chemical Society National Meeting,
New York, N. Y., August 23 to 28, 1981 (14).
2 To whom requests for reprints should be addressed.
3 The abbreviations used are: GSH, glutathione: BP, benzo(a)pyrene; PE,
petroleum ether; LC, liquid chromatography; TLC, thin-layer chromatography;
NMR, nuclear magnetic resonance.
Received October 7, 1981 ; accepted January 4, 1982.
APRIL 1982
Minnesota 55455
compounds increased the GSH S-transferase activity of the
forestomach between 78 and 182%. They were p-methoxyphenol, 2-fe/t-butyl-4-hydroxyanisole,
coumarin, a-angelicalactone, and benzyl isothiocyanate (18). All 5 compounds
inhibited BP-induced neoplasia of the forestomach (13, 20,
21). These data suggest that the capacity to enhance GSH Stransferase activity might be used as a method of identifying
compounds or natural products likely to inhibit BP or other
carcinogens detoxified in a similar manner (18).
In efforts at identifying dietary constituents that might protect
against chemical carcinogens, the effects of natural products
on GSH S-transferase activity were studied. During this inves
tigation, it was found that consumption of diets containing
powdered green coffee beans resulted in a very marked en
hancement of GSH S-transferase activity in the liver and mu
cosa of the small bowel of the mouse. The magnitude of
induction was as high as that obtained with any test compound
or natural material previously investigated. The coffee beans
used in the original study were from Guatemala. In subsequent
work, coffee beans from Brazil, Colombia, El Salvador, Mexico,
and Peru were all found to have a comparable enhancing effect
on GSH S-transferase activity (17). Roasted coffee and instant
coffee were found to have a weaker inducing activity than did
the green coffee beans studied, i.e., slightly less than 50% as
much. Decaffeinated instant coffee showed activity similar to
that of instant coffee. Investigations were then begun to identify
the constituents of green coffee beans having the capacity to
enhance GSH S-transferase activity. In the present study, it
was found that the coffee constituent kahweol palmitate is a
highly potent inducer of increased GSH S-transferase activity.
The palmitate of a closely related diterpene, cafestol, was
active as an inducer of GSH S-transferase but less so than was
kahweol palmitate.
MATERIALS
AND METHODS
Extraction of Green Coffee Beans. Powdered green coffee beans
(Guatemala) were placed in a large modified Soxhlet extractor and
were extracted with various solvents of increasing polarity (Chart 1).
PE (b.p. 60-70°) was used first, which was followed by benzene, ethyl
acetate, methanol, and water. Each solvent extraction was carried out
over a period of 7 days. The solvent of each extraction was removed
under reduced pressure. The crude extracts were dried under reduced
pressure until constant weights were obtained. The activities of the
extracts were monitored by the GSH S-transferase assay.
Fractionation of the PE Extract. The active PE extract was sepa
rated into 7 fractions by preparative LC using a Waters Associates
prepSOO liquid Chromatograph equipped with prepPak-500/silica
col
umns. The elution solvent was PE;ether (2:1, v/v). The active fraction
from preparative LC was further fractionated into 6 subfractions by
reverse-phase preparative LC. Two prep PAK-500/C18 columns in
series were used with 98% methanol as the eluting solvent. Silver
1193
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L. K. T. Lam et al.
GSH S-transferase activity. The inductive effects on the small bowel
mucosa under these conditions are about one-third of the magnitude
Green Coffee Beans
PE(8%)
0H
EtOAc
MeOH
H2O
Prep LC-silica
sÀ2
67PrepLC-C,sB
3(20%)45
l
C(38%)D7
|TLC-Sllica
Gel-AgNO 3
1Palmitic
as in the feeding procedure. Liver is much less responsive.
GSH S-transferase activity in the cytosol was determined according
to previously published procedures (18). All steps were done at 0-4°.
The tissues to be studied were homogenized in 0.1 M sodium phosphate
buffer (pH 7.5). The homogenate was centrifuged at 100,000 x g for
1 hr. The supernatant was used for the assay of GSH S-transferase
activity. The activity was determined spectrophotometrically
at 30°
with 1-chloro-2,4-dinitrobenzene
Isolation
Procedure
<2a>4
(2c)1Kahweol
Chart 1. Extraction and isolation scheme for kanweol and cafestol palmitates
0H, benzene; EtOAc, ethyl acetate. PrepPAK-500/silica
columns were used for
the normal-phase preparatory (Prep)LC. The eluting solvent was PE:ether (2:1,
v/v). PrepPAK-500/C18
columns were used for the reverse-phase preparatory
LC. The eluting solvent was 98% methanol (MeOH). The developing solvent for
silver nitrate-impregnated Silica Gel GF thin-layer plates was PEiether (2:1 ).
The activity of the enzyme GSH S-transferase in the liver and
mucosa of the small bowel of the mouse was enhanced by the
addition of 20% green coffee beans to the diet. The enhance
ment of enzyme activity in the liver was approximately 5 times
that of the control (Chart 28). A slightly smaller enhancement
1
TLC was used for the final purification of individual
active ingredients.
Saponification of Compounds 1 and 2. A sample of Compound 1
(or Compound 2), isolated from silver nitrate-impregnated
TLC plates,
X
was dissolved in 10% aqueous ethanolic potassium hydroxide at room
temperature. The reaction mixture was warmed to 50-60° for 0.5 hr.
It was then poured into ice, and the aqueous solution was extracted 3
times with ether. The organic layers were combined and dried over
anhydrous magnesium sulfate. The ether was removed under reduced
pressure. The neutral product was crystallized from PE:ether.
The aqueous layer after ether extraction was acidified with 6 N
hydrochloric acid and then extracted with 3 volumes of ether. The
ether was dried over anhydrous magnesium sulfate. The solvent was
removed under reduced pressure, and the acid thus obtained was
dried under reduced pressure overnight.
Spectroscopic
Studies. IR spectra were recorded on a Beckman
Acculab 5 spectrophotometer.
UV spectra were recorded on a Beck
man Model 25 spectrophotometer.
Proton NMR spectra were deter
mined on a Briiker WM 250 spectrometer at 250.13 MHz with tetramethylsilane as internal standard. Gas chromatography-mass
spectroscopy was determined on an LKB9000 spectrometer. High-resolu
tion mass spectroscopy were recorded on a double-beam AEI-MS-30
spectrometer. Melting points were determined on a Fisher-Johns MelTemp apparatus and were uncorrected.
Assay for in Vivo Enhancement of GSH S-Transferase
Activity.
Female ICR/Ha mice from the Harlan-Sprague-Dawley
Company (In
dianapolis, Ind.) were used in all experiments. Mice were randomized
by weight at 7 weeks of age into the groups to be used in a particular
protocol. In the initial stages of the fractionation, the extracts were
taken to dryness and added to a semipurified diet consisting of 27%
vitamin-free casein, 59% starch, 10% corn oil, 4% salt mix (U.S.P.
XIV), and a complete mixture of vitamins (Teklad, Inc., Madison, Wis.).
The amount of each extract added was such that the diets would
contain the equivalent of 20% powdered green coffee beans. In each
experiment, 20% crude powdered green coffee beans were included
as a positive control as well as a control in which there were no
additions. The diets were fed for 12 days at which time the mice were
killed. The mucosa of the proximal half of the small bowel and the liver
were taken for the determination of GSH S-transferase activity. In later
stages of the fractionation procedure in which smaller amounts of test
material were available, the assay technique was modified. The test
materials (2.5 mg), dissolved in cottonseed oil, were given by P.O.
intubation, 0.2 ml/mouse. The animals were killed 28 hr later. Mucosa
of the proximal half of the small bowel was taken for determinations of
1194
to the proce
RESULTS
Acid
Acid(1C)isaponificationCafestolPalmitic
nitrate-impregnated
as substrate according
dure of Habig ef al. (8).
I 2
GCB
3
PE
BZ
EA
ME
WA
RC
RS
CON
18
B
„
I
1 12 -
J,
10
»L
0
GCB
PE
BZ
EA
ME
WA
RC
RS
CON
Chart 2. Activity of green coffee beans (GCB) and their solvent extracts on
the enhancement effect of GSH S-transferase in the mucosa of the small bowel
(A) and in the liver (B) of mice. BZ, benzene; EA, ethyl acetate; ME, methanol;
WA, water; RC, reconstituted coffee beans; PS, residue of extraction; CON,
control. Bars, S.D.
CANCER
RESEARCH
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VOL.
42
Kahweol and Cafestol Palmitates in Green Coffee Beans
was found ¡nthe mucosa of the small bowel (Chart 2A). The
overall magnitude of enzyme activity in the latter organ, how
ever, was much lower than that in the former. PE extraction for
7 days successfully removed most of the ingredients that had
inducing activity. Subsequent extractions by benzene showed
activity that affected only the mucosa of the small bowel but
had little effect in the liver. The other solvent extracts were
inactive. When the extracts were combined with the residue of
extraction, a slight increase of activity was observed in com
parison with the original green coffee beans (Chart 2).
The PE extract contained a small amount of caffeine which
could be removed by dissolving the dried extract in a small
volume of PE and filtering. The caffeine-free PE extract was
then fractionated by preparative LC to give 7 fractions. Fraction
3 contained materials that gave similar enhancement of activity
to that of the PE extract. The weight of Fraction 3 was 20%
that of the PE extract. The other fractions were all inactive in
the GSH S-transferase assay (Chart 3). All attempts to further
fractionate Fraction 3 with normal-phase preparative LC re
sulted in subfractions of mixtures of similar components. Anal
ysis of Fraction 3 by reverse-phase high-performance liquid
chromatography (Ci8-/iBondapak, eluted with methanol) indi
cated 6 peaks (Subfractions A to F) that were well separated.
Subfractions A to F were separated by preparative LC. All 6
subfractions were active in enhancing GSH S-transferase ac
tivity in the mucosa of the small bowel of the mouse (Chart 4).
Subfraction C, which constituted approximately 38% of Frac-
.8.6.4.2.0.6.4.2--------Axfeih:•:
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Õ
1|
1.4 -
o
Sk
1?
ëç
2 E
VB
W E
O
RC
AB
CON
Chart 4. Activities of the reverse-phase preparatory LC subtractions of Frac
tion 3 on the enhancement effect of GSH S-transferase in the mucosa of the
small bowel of mice. PC, reconstituted Fraction 3; CON, control. Bars, S.D.
65A•f1J*C5
ria--far-r
rin
2.01ÕE1¿
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1
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fÃ-Ã-Ã-j¡i::::::!K®25"5I
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2
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5
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7
CON
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Chart 3. Activities of the different fractions separated from the PE extract
(PE) on the enhancement effect of GSH S-transferase in the mucosa of the small
bowel (A) and in the liver (B) of mice. GCB, green coffee beans; CON, control.
Bars, S.D.
APRIL 1982
CON
CON4),
PA
C,fied
5. Activities of Subfraction saponi-7c)
components (| toB1A1and the
S-transferase
products of Compound 1 (|a.i\isits on the enhancement effect of GSH
acid;CON, in the mucosa of the small bowel of mice.i '/V authentic palmitic
S.D.tion
control. Bars,
andwas
3, showed the highestactivity
in theenzyme assay
purification.To
chosen for further
further separate Subfraction C intoits pure components,
TLC (Silica Gel G) plates impregnated with silver nitrate were
used (Chart 1). These silver nitrate-treated plates were able to
separate Subfraction C into 4 components, 3 of which were
active (Chart 5A). The activity of Compound 1 was similar to
1195
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L K. T. Lam et al.
that of the control level. Compound 2 showed the greatest
potency in enhancing the activity of GSH S-transferase. Ad
ministration of Compound 2 resulted in an increase of GSH Stransferase activity that was 4 times that of the control. Com
pounds 3 and 4 were able to induce the enzyme activity to
twice the control level. Compounds 1 and 2, the components
that had the highest R( values, were isolated on preparative
TLC plates impregnated with silver nitrate. Compound 1, which
was present in much higher quantity than were the other 3
components, was easily purified and characterized as a pure
compound. The behavior of this set of compounds during
fractionation and TLC separation indicated that they belonged
to the same class of organic compounds with only minor
structural differences. The structural determination of any one
of these compounds will facilitate the identification of the
remaining components. Since Compound 1 was isolated in its
pure form in sufficient quantity, structural determination was
started with this compound. Spectroscopic evidence and de
rivative comparison indicated that Compound 1 was the palmitate of cafestol (2). Component 2, which has a molecular weight
that is 2 mass units lower than that of Compound 1, was
identified to be the palmitate of kahweol (1). The previously
known coffee constituents, cafestol and kahweol, could be
isolated as the free alcohols from mild alkaline hydrolysis of
Compounds 1 and 2, respectively. While cafestol palmitate
showed very little activity as an enzyme inducer, cafestol and
its monoacetate showed activity that was approximately 1.5
times above control level (Chart 50) (see "Addendum"). Kah
weol and its monoacetate showed activity that was similar to
that of kahweol palmitate (Chart 6). Palmitic acid (Compound
1c) was inactive as an inducer of the activity of GSH S-trans
ferase (Chart 56).
4.0-£5oa¡3.0|"5*>1
2.0in
coZ"wcoV
LOcoX8---mpia•m*TVATffijIMI•'.•'-•'.•
2a
la
CON
1b
2a
2b
CON
Chart 6. Activities of Compound 2 (2) and its derivatives and the derivatives
of Compound 1 (|) on the enhancement effect of GSH S-transferase in the
mucosa of the small bowel of mice. 7a, cafestol; lb, cafestol monoacetate; 2a,
kahweol; 20, kahweol monoacetate; CON, control. Bars, S.D.
CHzOR
Structural Identification
Compound 1. Compound 1 has been identified as the palmi
tate of cafestol (Chart 7). Mass spectrometry (70 eV) yielded:
m/e 554 (M +, 71.2). The precise mass for CseHseCXiwas
Calculated:
Found:
554.4335
554.4353
The loss of 18 mass units (-H2O) from 554 (m/e 536) clearly
1
indicated the presence of a hydroxy group. No other significant
mass fragments were observed between m/e 554 and m/e
298. The IR spectrum showed the presence of OH stretching
frequencies at 3600 and 3450 cm"'. Intense C—H stretching
frequencies around 2900 cm"1 indicated the presence of a
1a (Cafestol)
O
1b R=CCH3
large number of saturated carbon moieties. The carbonyl
stretching frequency at 1740 cm"1 together with the fragmen
tation pattern of the mass spectrum were indicative of an ester
function. The 250-MHz proton NMR spectrum confirmed the
presence of large numbers of protons on saturated carbons. A
triplet centered at 2.36 ppm was the result of the méthylène
protons adjacent to the carbonyl function of the ester (Com
pound 1). A singlet at 4.27 (2H) appeared to be the resonance
peak due to the 2 protons at C-17. Two doublets at 7.24 and
6.20 ppm (J < 0.01 Hz), respectively, are the resonances from
the protons at C-19 and C-18 on the furan ring.
Saponification of Compound 1 yielded an alcohol (Com
pound 1a) and an acid (Compound 1c). The acid was identified
1196
2
R = C(CH2)UCH3
9
R=C(CH2)14CH3
2a
(Kahweol)
O
2b R=CCH3
R=H
R=H
Chart 7. Structure of cafestol palmitate (1) and kahweol palmitate (2); their
parent compounds, cafestol (ia) and kahweol (2g), and their monoacetates
(lb, 20).
to be palmitic acid (M, 256) by mass spectroscopy and by
melting point.
Compound 1a. The molecular formula of the alcohol, Com
pound 1a, was determined by high-resolution mass spectros
copy to be C2oH28O3.
Calculated:
Found:
Gas chromatography-mass
316.2038
316.2027
spectroscopy
CANCER
of its trimethylsilane
RESEARCH
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VOL. 42
: K-' i'r -T
Kahweol and Cafestol Palmitates in Green Coffee Beans
derivatives revealed mono- and ditrimethylsilane derivatives
having molecular ions at m/e 388 and m/e 460, respectively.
The proton NMR spectrum at 250 MHz showed the absence of
aliphatic protons of the palmitic acid moiety. The resonances
at 7.24 and 6.20 ppm were unchanged. The singlet at 4.27,
however, has changed into an AB quartet with J = 13.5 Hz.
This quartet is the result of hydrogen bonding of the hydroxy
groups on C-1 6 and C-1 7 which makes the protons on C-1 7
magnetically nonequivalent. These spectral data and the IR
spectrum of Compound 1a are consistent with the structure of
cafestol (4, 6, 15).
The monoacetate of Compound 1a, which was synthesized
by the treatment with acetyl chloride in pyridine, had an IR
spectrum identical to that of cafestol monoacetate, Compound
1b, reported by Djerassi ef a/. (5).
Compound 2. Compound 2 was found to be very similar in
structure to Compound 1 and was identified as the palmitate of
kahweol (Chart 7). The molecular weight was determined to be
552 by mass spectroscopy. The precise mass for CaeHgeC^
was
Calculated: 552.4178
Found:
552.4203
The IR spectrum of Compound 2 was almost identical to that of
Compound 1 except for a small peak at 3050 cm"1 which is
the stretching
frequency
of C—H bond on a carbon-carbon
double bond. The proton spectrum had 2 sets of doublets at
7.26 and 6.25, respectively. These resonances are due to the
2 vinyllic protons of the double bond at C-1 and C-2 of Com
pound 2. Saponification of Compound 2 yielded palmitic acid
and an alcohol Compound 2a.
Compound 2a. Compound 2a has been identified as kah
weol. Mass spectrometry yielded m/e 314 (M+ 10.4). The
molecular formula of Compound 2a was determined by highresolution mass spectroscopy
to be
Calculated: 314.1882
Found:
314.1872
Compound 2a is easily oxidized in the presence of air. Its
monoacetate, Compound 2b, melts at 133.5-136°, which is
similar to the melting point of the monoacetate
reported by Kaufman and Sen Gupta (11,1 2).
of kahweol
DISCUSSION
In the present investigation, a potent inducer of increased
GSH S-transferase activity has been isolated from green coffee
beans. This compound is kahweol palmitate. A related com
pound, cafestol palmitate, was also active as an inducer of
GSH S-transferase activity but less so than kahweol palmitate.
The active ingredients from green coffee beans were almost
totally extracted into PE when the extraction was carried out
for 7 days or more. The PE extract was able to induce increased
GSH S-transferase activity in both the mucosa of the small
intestine and the liver of the mouse. On an equivalent weight
basis, the activity of the PE extract was approximately 40%
higher than that of the green coffee beans. This increase in
activity was probably due to the greater availability of the
APRIL 1982
inducing compounds resulting from their extraction. Benzene,
the second solvent used in the extraction scheme, was able to
extract substances that had inducing activity for the mucosa of
the small bowel but were inactive in the liver of the mouse.
The first fractionation of the PE extract by normal-phase
preparative LC was able to eliminate 80% of the inactive
substances. Attempts to manipulate the solvent composition to
further separate the components in the active Fraction 3 were
not successful. Reverse-phase high-performance liquid chromatography, however, was able to resolve this fraction into 6
distinct peaks. Peak C, which constitutes approximately 38%
of Fraction 3, was isolated in the preparative scale using prep
PAK-500/Ci8
columns. Preliminary UV spectral data on
Subfraction C indicated the presence of conjugated double
bonds in the molecules. Since silver nitrate-impregnated TLC
had been used successfully to separate olefins, it was antici
pated that the technique might be applied to further separate
components in Subfraction C (19). At least 4 well-separated
components were found by this method which led to the final
identification of the active ingredients.
The diterpenes, cafestol and kahweol, were isolated from
the unsaponifiable portion of the PE extract of green coffee
beans in 1938 and 1932, respectively (1, 16). The structure of
cafestol was elucidated in the reports of Djerassi ef a/. (4, 6)
and others (15). In the present investigation, Compound 1a
obtained by the saponification of Compound 1 was identical to
cafestol by spectroscopic and derivative comparison. The
structure of kahweol was elucidated by Kaufmann and Sen
Gupta (11,12). Compound 2a obtained by the saponification
of Compound 2 was shown to have the same structure as that
of kahweol. The exact location of the double bond was ques
tioned recently by Gershbein and Baburao (7). Our NMR data
favor the double bond at C-1 and C-2 which is consistent with
the structure proposed by Kaufmann and Sen Gupta. Although
the existence of these 2 diterpenes has been known since
1932, their palmitate esters have not been well characterized.
Previous work has not established any biological effects of
cafestol or kahweol (2, 7, 9, 22).
The concentration of kahweol palmitate in the active Fraction
3 is estimated at 10 to 15%. The remaining active constituents
in Subfractions A, B, and D to F are most probably due to fatty
acid esters of kahweol. Preliminary TLC data indicated the
presence of cafestol and kahweol in all the active fractions in
the isolation scheme.
Several compounds that are potent inducers of increased
GSH S-transferase activity inhibit carcinogen-induced neopla
sia (18). 3-ferf-Butyl-4-hydroxyanisole
is among the most po
tent of these compounds and inhibits a wide variety of chemical
carcinogens. When compared under the same experimental
conditions, i.e., a single p.o. administration 24 hr prior to
sacrifice, kahweol palmitate is more than 3 times as potent in
enhancing GSH S-transferase activity of the mucosa of the
small intestine as 3-ferf-butyl-4-hydroxyanisole.
It remains to
be determined whether kahweol palmitate and related diter
pene esters will have carcinogen-inhibitory
capacities. The
constituents of green coffee are complex mixtures of a very
large number of chemicals. The composite biological effects of
coffee on occurrence of neoplasia may not be the result of one
or 2 discrete components alone. Thus, it is not possible at the
present time to assume a dominant biological significance of
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L. K. T. Lam et al.
the diterpene esters in the complex mixture of coffee constit
uents.
ADDENDUM
During the isolation procedure, the activity of cafestol palmitate as an inducer of GSH S-transferase activity was deter
mined using a single p.o. administration of 2.5 mg/mouse.
Under these conditions, cafestol palmitate showed only mar
ginal activity (Chart 5). A subsequent experiment using 4
administrations of 2.5 mg cafestol palmitate (once a day for 4
days with mice killed 24 hr after the last administration) resulted
in a GSH S-transferase activity of the small bowel mucosa 41 %
greater than that of the control. Further experiments were
carried out using cafestol and kahweol palmitates obtained
from the esterification of the alcohols with palmitoyl chloride.
The semisynthetic esters used in these experiments were iden
tical to the naturally occurring compounds by TLC, mass spectroscopy, and NMR. With the use of 4 daily administrations and
a dose level of 5.0 mg/mouse, the GSH S-transferase activity
of the small bowel mucosa of mice receiving cafestol palmitate
was 3.9 times that of the controls, and the corresponding GSH
S-transferase activity of mice receiving kahweol palmitate was
5.6 times that of the controls. These data indicate that cafestol
palmitate enhances GSH S-transferase activity but is less po
tent than kahweol palmitate.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
ACKNOWLEDGMENTS
17.
We thank Gerald Bratt for the NMR and Thomas Krick for the mass spectra
determinations. The technical assistance of Chester Yee is gratefully acknowl
edged.
18.
REFERENCES
1. Bengis. R. O.. and Anderson. R. J. The chemistry of the coffee bean. I.
Concerning the unsaponifiable matter of the coffee-bean oil. Extraction and
properties of kahweol. J. Biol. Chem., 47: 99-113, 1932.
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CANCER
RESEARCH
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VOL.
42
Isolation and Identification of Kahweol Palmitate and Cafestol
Palmitate as Active Constituents of Green Coffee Beans That
Enhance Glutathione S-Transferase Activity in the Mouse
Luke K. T. Lam, Velta L. Sparnins and Lee W. Wattenberg
Cancer Res 1982;42:1193-1198.
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