Cancer chemopreventive and antioxidant activities of pterostilbene, a naturally occurring analogue of resveratrol

Article abstract of DOI:10.1021/jf0116855

Pterostilbene, a natural methoxylated analogue of resveratrol, was evaluated for antioxidative potential. The peroxyl-radical scavenging activity of pterostilbene was the same as that of resveratrol, having total reactive antioxidant potentials of 237 ± 58 and 253 ± 53 μM, respectively. Both compounds were found to be more effective than Trolox as free radical scavengers. Using a plant system, pterostilbene also was shown to be as effective as resveratrol in inhibiting electrolyte leakage caused by herbicide-induced oxidative damage, and both compounds had the same activity as α-tocopherol. Pterostilbene showed moderate inhibition (IC₅₀ = 19.8 μM) of cyclooxygenase (COX)-1, and was weakly active (IC₅₀ = 83.9 μM) against COX-2, whereas resveratrol strongly inhibited both isoforms of the enzyme with IC₅₀ values of approximately 1 μM. Using a mouse mammary organ culture model, carcinogen-induced preneoplastic lesions were, similarly to resveratrol, significantly inhibited by pterostilbene (ED₅₀ = 4.8 μM), suggesting antioxidant activity plays an important role in this process.

Full text of DOI:10.1021/jf0116855

J. Agric. Food Chem. 2002, 50, 3453−3457 3453
Cancer Chemopreventive and Antioxidant Activities of
Pterostilbene, a Naturally Occurring Analogue of Resveratrol
AGNES M. RIMANDO,*,† MURIEL CUENDET,‡ CRISTIAN DESMARCHELIER,§
†
RAJENDRA G. MEHTA,| JOHN M. PEZZUTO,‡ AND STEPHEN O. DUKE
Natural Products Utilization Research Unit, Agricultural Research Service, U.S. Department of
Agriculture, P.O. Box 8048, University, Mississippi 38677; Department of Medicinal Chemistry and
Pharmacognosy, College of Pharmacy (m/c 877), University of Illinois at Chicago, 833 South Wood
Street, Chicago, Illinois 60612; IQUIMEFA-CONICET, School of Pharmacy and Biochemistry,
University of Buenos Aires, Jun´ın 956, Buenos Aires, Argentina; and Department of Surgical
Oncology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60612
Pterostilbene, a natural methoxylated analogue of resveratrol, was evaluated for antioxidative potential.
The peroxyl-radical scavenging activity of pterostilbene was the same as that of resveratrol, having
total reactive antioxidant potentials of 237 ( 58 and 253 ( 53 µM, respectively. Both compounds
were found to be more effective than Trolox as free radical scavengers. Using a plant system,
pterostilbene also was shown to be as effective as resveratrol in inhibiting electrolyte leakage caused
by herbicide-induced oxidative damage, and both compounds had the same activity as R-tocopherol.
Pterostilbene showed moderate inhibition (IC50 ) 19.8 µM) of cyclooxygenase (COX)-1, and was
weakly active (IC50 ) 83.9 µM) against COX-2, whereas resveratrol strongly inhibited both isoforms
of the enzyme with IC50 values of approximately 1 µM. Using a mouse mammary organ culture model,
carcinogen-induced preneoplastic lesions were, similarly to resveratrol, significantly inhibited by
pterostilbene (ED50 ) 4.8 µM), suggesting antioxidant activity plays an important role in this process.
KEYWORDS: Cyclooxygenase; mouse mammary gland organ culture; total reactive antioxidant potential;
electrolyte leakage
INTRODUCTION
demonstrated in assays representing tumor initiation, promotion,
and progression of carcinogenesis (7). Epidemiological studies
found low incidence of coronary heart disease among wine-
drinking populations (8, 9) correlate such observations with
resveratrol present in wine. This seems to be supported by
studies in rats and mice which showed that resveratrol and its
glycoside piceid inhibited the accumulation of cholesterol and
triglycerides in rat liver, and reduced triglyceride synthesis in
mice liver (10). Furthermore, piceid reduced serum triglyceride
and low-density lipoprotein-cholesterol levels, and atherogenic
index (10). The antioxidant activity of resveratrol has been
studied to a great extent. Resveratrol prevented Fe2+-induced
lipid peroxidation in rat liver microsomes (11, 12), inhibited
Cu2+-catalyzed human low-density lipoprotein (LDL) peroxi-
dation (13) and porcine LDL peroxidation in the presence as
well as in the absence of CuSO4 (14), and tert-butylhydroper-
oxide-induced lipid peroxidation in human fibroblasts (12).
Resveratrol also inhibited the production of reactive oxygen
species in porcine platelets (15) and in murine macrophages
(16). The antioxidant property of resveratrol was also demon-
strated through its direct scavenging of 1,1-diphenyl-2-picryl-
hydrazyl (DPPH) free radical (12, 17) and inhibition of oxidation
of citronellal (12). The demonstrated biological and pharma-
cological activities of resveratrol are attributed to its antioxidant
property.
Pterostilbene, reported to be the only stilbene found in the
genus Pterocarpus, was first isolated from P. santalinus (red
sandalwood) (1). Together with resveratrol, it has also been
identified in Vitis Vinifera leaves (2), in infected grape berries
var. Chardonnay and Gamay (3), and in healthy and immature
berries var. Pinot Noir and Gamay (4). Pterostilbene has not
been detected in wine (5).
Pterostilbene was found to be one of the active constituents
in extracts of the heartwood of P. marsupium, used in Ayurvedic
medicine for the treatment of diabetes (6). When administered
to streptozotocin-induced hyperglycemic rats, pterostilbene and
marsupin, two of the major phenolic constituents in aqueous
decoctions of the heartwood of P. marsupium, significantly
decreased plasma glucose level by 42 and 33%, respectively,
with activities comparable to metformin (48% decrease), an oral
hypoglycemic agent (6).
Resveratrol has been the subject of numerous research
investigations. Its cancer chemopreventive activity has been
* Corresponding author [phone 662-915-1037, fax 662-915-1035, email
arimando@ars.usda.gov].
† U.S. Department of Agriculture.
‡ College of Pharmacy, University of Illinois at Chicago.
§ University of Buenos Aires.
| College of Medicine, University of Illinois at Chicago.
10.1021/jf0116855 CCC: $22.00 © 2002 American Chemical Society
Published on Web 05/10/2002

3454 J. Agric. Food Chem., Vol. 50, No. 12, 2002
Rimando et al.
Mouse Mammary Gland Organ Culture (MMOC) Model of
Carcinogenesis. The cancer chemopreventive activity of pterostilbene
was evaluated using MMOC following reported procedures (22).
Briefly, thoracic pairs of mammary glands from 4 to 5 weeks old Balb/c
female mice were incubated in serum-free medium supplemented with
5 µg/mL each of insulin and prolactin, and 1 µg/mL of aldosterone
and hydrocortisone as growth-promoting hormones. Incubations were
performed in the presence (10, 3, or 1 µM) or absence of pterostilbene
(15 glands/group). On the third day of culture the chemical carcinogen
7,12-dimethylbenz[a]anthracene (DMBA) was added to the culture dish
and incubated for 24 h. The medium was changed the following day,
and incubation was continued for 6 more days without DMBA. The
glands were then incubated for 14 more days in medium containing
only insulin. Finally, glands were fixed in 10% buffered formalin and
stained with alum carmine. The stained glands were evaluated
microscopically for the presence of mammary lesions and the incidence
of mammary lesions ((number of glands with lesions/total number of
glands) × 100) was calculated.
Figure 1. Structure of pterostilbene and resveratrol.
There is, evidently, a vast amount of research work done in
evaluating the activity of resveratrol using animal and microbial
systems. On the contrary, there is almost no work done to show
its effects using plant systems. The physiological function of
resveratrol in plants is, currently, not clearly known. One study
has shown that trans-resveratrol inhibited plant oxidative and
antioxidative enzymes, namely, superoxide dismutase, lipoxy-
genase, catalase, peroxidase, polyphenol oxidase, and 1-ami-
nocyclopropane-1-carboxylic acid oxidase (18).
There is no work known which demonstrates the antioxidant
effects of pterostilbene using a plant system. The antioxidative
activity of pterostilbene was first demonstrated in vitro by its
inhibition of methyl linoleate oxidation (19). More recently,
pterostilbene was reported to scavenge DPPH free radical and
to inhibit the oxidation of citronellal, and lipid peroxidation in
rat liver microsomes and in cultured human fibroblasts (12).
Pterostilbene isolated from Anogeissus acuminata (Fam. Com-
bretaceae) was also found to be cytotoxic against a number of
cancer cell lines including human breast cancer (ED50 13.6 µM)
and murine lymphoid neoplasma (ED50 10.1 µM) (20). Meth-
oxylated analogues of resveratrol, except pterostilbene, were
synthesized and were reported to demonstrate structure-activity
differences in their inhibitory activity against normal and
cancerous human diploid fibroblasts, and also against preneo-
plastic human mammary epithelial cells (21).
Evaluation of COX-1 and COX-2 Activity by Quantitation of
Prostaglandin E2 (PGE2). The effect of pterostilbene and resveratrol
on COX activity was determined by measuring PGE2 production (23).
Reaction mixtures were prepared in 100 mM Tris-HCl buffer, pH 8.0,
containing 1 µM heme, 500 µM phenol, 300 µM epinephrine, sufficient
amounts of COX-1 or COX-2 to generate 150 ng of PGE2/mL, and
various concentrations of test samples. The reaction was initiated by
the addition of arachidonic acid (final concentration, 10 µM) and
incubated for 10 min at room temperature (final volume 200 µL). The
reaction was then terminated by adding 20 µL of the reaction mixture
to 180 µL of 27.8 µM indomethacin, and PGE2 was quantitated by an
ELISA method. Samples were diluted to the desired concentration with
100 mM potassium phosphate buffer (pH 7.4) containing 2.34% NaCl,
0.1% bovine serum albumin, 0.01% sodium azide, and 0.9 mM Na4-
EDTA. Following transfer to a 96-well plate (Nunc-Immuno Plate
Maxisorp, Fisher) coated with a goat anti-mouse IgG (Jackson Immuno
Research Laboratories), the tracer (PGE2-acetylcholinesterase, Cayman
Chemical, Ann Arbor, MI) and primary antibody (mouse anti-PGE2,
Monsanto, St. Louis, MO) were added. Plates were then incubated at
room-temperature overnight, reaction mixtures were removed, and wells
were washed with a solution of 10 mM potassium phosphate buffer
(pH 7.4) containing 0.01% sodium azide and 0.05% Tween 20. Ellman’s
reagent (200 µL) was added to each well, and the plate was incubated
at 37 °C for 3-5 h, until the control wells yielded an OD ) 0.5-1.0
at 412 nm. A standard curve with PGE2 (Cayman) was generated on
the same plate, which was used to quantify the PGE2 levels produced
in the presence of test samples. Reactions were conducted in duplicate,
average values were expressed as a percentage relative to control
(solvent-treated) samples, and dose-response curves were constructed
for the determination of IC50 values. The variability of pterostilbene’s
IC50 values less than 10%.
Prompted by the close structural similarity of pterostilbene
and resveratrol (Figure 1), as well as pterostilbene’s presence
in grapes and its reported cytotoxic activities, we currently report
studies designed to investigate its cancer chemopreventive
potential and its activity against cyclooxygenase (COX). A
further objective was to investigate its antioxidant activity in
comparison with that of resveratrol.
Peroxyl Radicals (ROO•) Scavenging Activity: Total Reactive
Antioxidant Potential (TRAP). The TRAP index was measured by
luminol-enhanced chemiluminescence (24). This method is based on
the inhibition of the generation of peroxyl radicals by the radical cation
2,2′-azo-bis(2-amidinopropane) (ABAP), which reacts with luminol
yielding chemiluminescence. The reaction medium consisted of 100
mM phosphate buffer (pH 7.4), 20 mM ABAP (Acros Organics,
Janssens Pharmaceuticalaan 3A, 2440 Geel, Belgium), 10 µM luminol
(Acros Organics), and increasing volumes (5-20 µL) of pterostilbene
or resveratrol (150 µM). Luminescence was measured at room
temperature in a WinSpectral (model 1414) liquid scintillation counter
(Turku, Finland) with the circuit coincidence out of mode. The system
was calibrated using 150 µM of the synthetic R-tocopherol analogue
Trolox (Sigma-Aldrich). Induction times, the period during which
luminescence remained reduced after addition of the samples indicating
the presence of free-radical scavengers, were determined by measure-
ment of chemiluminescence intensity (total counts). A comparison of
the induction times after addition of known concentrations of Trolox
and antioxidants (shown later in Figure 3) allows TRAP values to be
obtained as equivalents of Trolox concentration necessary to suppress
the emitted luminescence (25) by employing the following equation:
MATERIALS AND METHODS
Preparation of Pterostilbene. Pterostilbene was prepared by partial
methylation of trans-resveratrol (Sigma-Aldrich, St. Louis, MO). To a
solution of trans-resveratrol [150 mg in 3.0 mL of 20% (v/v) MeOH],
5 mL of 38% NaOH and 2.5 mL of dimethyl sulfate were added
dropwise, with agitation, under nitrogen. The mixture was heated to
40 °C for an additional hour, and then cooled to room temperature.
The partially methylated products were extracted with CHCl3 and dried
with Na2SO4. Pterostilbene was obtained by preparative TLC (develop-
ing solvent, hexane/EtOAc, 8:2, Rf 0.6), yield 11%. Its structure and
identity were confirmed by comparison of 1H- and 13C NMR data
(obtained on a Bruker Avance DPX 300 instrument; Billerica, MA)
with published values (20). 1H NMR (CDCl3, 300 MHz): δ 7.40 (2H,
d, J ) 8.50 Hz; H-2′and H-6′), 7.03 (1H, d, J ) 16.20 Hz; H-â), 6.89
(1H, d, J ) 16.20 Hz; H-R), 6.83 (2H, d, J ) 8.51 Hz; H-3′and H-5′),
6.65 (2H, d, J ) 1.88 Hz; H-2 and H-6), 6.38 (1H, t, J ) 1.88 Hz;
H-4), 4.96 (1H, br s; OH), 3.83 (6H, s, 2 × OCH3). 13C NMR (CDCl3,
75.5 MHz): δ 160.92 (C-2 and C-5), 155.31 (C-4′), 139.61 (C-1),
130.10 (C-1′), 128.63 (C-â), 127.99 (C-2′), 126.60 (C-R), 115.60 (C-
3′ and C-5′), 104.31 (C-6), 99.59 (C-4), 55.35 (OCH3).

Antioxidant Activities of Pterostilbene
J. Agric. Food Chem., Vol. 50, No. 12, 2002 3455
TRAP (µM Trolox) ) (µLtotal/µLsample) × (δi sample/δi Trolox) ×
δi Trolox (1µM)
where µLtotal is the final volume (3000 µL), µLsample is the volume of
the sample added to the reaction (5, 10, 15, and 20 µL of a 150 µM
solution), δi
volumes of the sample, δi
is the induction time observed for the different
sample
is the induction time observed for the
Trolox
reference compound (Trolox), and δi
is the induction time
Trolox (1µM)
observed for the reference compound at a 1 µM final concentration.
Using Trolox as a reference inhibitor that removes two radicals per
added molecule (25), it is possible to obtain the number of radicals
removed per molecule of additive.
In WiWo Antioxidant Assay in Plant Tissue. Cucumber seedlings
(Cucumis satiVus L. cv. Long Green Improved) were used for plant
oxidative damage experiments. Seeds were planted in Miracle Gro
potting soil and grown in a chamber maintained at 25 ( 2 °C with
continuous 200 µmol m-2‚s-1 photosynthetically active radiation (PAR).
Oxidative damage to plant tissues was monitored by measurement of
herbicide-induced electrolyte leakage, as previously described (26). Fifty
4-mm cucumber cotyledon disks (∼0.1 g fresh weight) from 6-day-
old seedlings were placed in a 6-cm-diameter disposable Petri dish
containing 5 mL of 1% (w/v) sucrose and 1 mM 2-(N-morpholino)-
ethanesulfonic acid (MES; pH 6.5). Acifluorfen (5-[2-chloro-4-(tri-
fluoromethyl)phenoxy]2-nitro-benzoic acid; Sigma-Aldrich Laborchemi-
kalien GmbH, D-30918 Seelze, Germany) was dissolved in this media
to make a 10 mM stock solution. Resveratrol, pterostilbene, and
R-tocopherol were dissolved in methanol, which was placed into the
Petri dish and allowed to dry before the buffer media was added (control
contained media only). This method was used because of the relative
insolubility of these compounds in water. All treatments were performed
in triplicate and the experiment was replicated in time. The Petri dishes
were placed in darkness at 25 °C for 18 h and then exposed to 525
µmol m-2‚s-1 PAR for the remainder of the experiment. Cellular
damage was determined by measuring electrolyte leakage in the bathing
solution with a conductivity meter capable of assaying 1 mL of bathing
medium (27). Conductivity was measured for 18 h in darkness, followed
by continuous light. Because of differences in background conductivity
between different treatments, results are expressed as change in the
conductivity after exposure to light.
Figure 2. Effect of pterostilbene on the development of DMBA-induced
mammary alveolar lesions in organ culture. Data from groups treated with
pterostilbene were compared with those from control (DMBA only) groups
and results were expressed as a percentage.
that pterostilbene has cancer chemopreventive activity similar
to that of resveratrol. The activity of pterostilbene against COX-1
and -2 was then further investigated, because COX-1 and -2
enzymes are implicated in the tumor promotion stage of
carcinogenesis (23, 29). Pterostilbene was found to only
moderately inhibit COX-1 (IC50 19.8 µM) and weakly inhibit
COX-2 (IC50 83.9 µM) as compared to resveratrol (IC50 1.1
and 1.3 µM for COX-1 and COX-2, respectively). Results from
earlier studies (7), using O2 consumption as the endpoint for
measuring inhibition, showed resveratrol to inhibit the hydro-
peroxidase activity of COX-1 and -2 with IC50 values of 3.7
µM and 85 µM, respectively. In the present study the endpoint
was inhibition of prostaglandin production. Inhibition of syn-
thesis progtaglandins (PGs) is a possible mechanism for cancer
chemoprevention, as PGs enhance growth of malignant cells
by increasing cell proliferation (30).
It has been suggested that cancer-inducing damage to cells
might be prevented by antioxidants through the scavenging of
excess free radicals that are byproducts of many normal
metabolic functions, or by reducing the adverse effects of
carcinogens or radiation (31). Thus, to further evaluate the
cancer chemopreventive potential of pterostilbene, its free radical
scavenging property was investigated. Preliminary information
on the antioxidant activity of pterostilbene was gathered from
its inhibition of the oxidation of methyl linoleate (19), but this
test was not a direct measure of its free radical scavenging
activity. Pterostilbene was tested together with resveratrol for
direct radical scavenging capacity through inhibition of ABAP-
derived peroxyl radicals. This test allows the definition of a
TRAP index, relative to Trolox (25). Trolox is a reference
inhibitor that removes two radicals per molecule (32). As
illustrated in Figure 3, induction times with pterostilbene and
resveratrol were proportional to the test concentrations. The
numbers of radicals (N) removed per molecule of pterostilbene
and resveratrol are summarized in Table 1. Both compounds
were more effective than Trolox as free radical scavengers, and
pterostilbene was as effective as resveratrol in this system. These
results parallel those obtained by Stivala et al. (12) who found
pterostilbene (EC50 30.1 ( 2.1 µM) to have activity comparable
to that of resveratrol (EC50 24.5 ( 1.5 µM) in DPPH radical
scavenging assay.
RESULTS AND DISCUSSION
Pterostilbene used in the studies reported here was synthesized
in a one-step reaction by permethylaton of trans-resveratrol.
The product obtained was identical with the naturally occurring
pterostilbene as confirmed from its NMR data.
The cancer chemopreventive property of pterostilbene was
investigated using a mouse mammary gland culture model of
carcinogenesis. This model mimics the morphologic and
biochemical changes observed in animals during various physi-
ologic stages of the gland in transition from virgin to pregnancy
and lactation, and it is the closest adaptation of the mammary
gland in vivo (22). The entire cycle of mammary gland
morphology and physiology can be simulated with appropriate
hormonal supplementation of a chemically defined medium (28).
The validity of this model has been proven in the assay of known
chemopreventive agents (29). The glands show largely ductal
structures and very few end buds when observed under the
microscope. However, in the presence of the chemical carcino-
gen DMBA, mammary alveolar precancerous lesions develop.
The incidence of mammary alveolar formation (number of
glands with lesions/number of total glands in the group) is
compared between treated and control groups and the percent
inhibition is calculated. For pterostilbene, an ED50 of 4.8 µM
(Figure 2) was obtained. The potential of resveratrol to function
as a cancer chemopreventive agent was previously evaluated
using this system and was found to inhibit preneoplastic lesions
induced by DMBA with an ED50 of 3.2 µM (7). It appeared
The antioxidant activity of pterostilbene and resveratrol was
also evaluated using a plant system. Inhibitors of protoporphy-
rinogen oxidase, such as the herbicide acifluorfen, cause
oxidative damage to plant cells through accumulation of the
photodynamic compound protoporphyrin IX (33). Oxidative
damage was initiated when tissue that had been incubated in
darkness with the herbicide was exposed to light. Protoporphyrin

3456 J. Agric. Food Chem., Vol. 50, No. 12, 2002
Rimando et al.
Figure 3. Induction time (min) as a function of the concentration of Trolox
(150 µM initial concentration) (9), pterostilbene (b), and resveratrol (2)
(150 µM initial concentration). Induction times determined as the period
during which luminescence remained reduced after addition of the samples.
Values are the means of two determinations.
Table 1. Total Reactive Antioxidant Potential (TRAP) Expressed in µM
Trolox Equivalents, and Number of Radicals (N) Trapped Per Molecule
of Additive
sample
Trolox
pterostilbene
resveratrol
TRAP (µM)a
N
144 ± 16
237 ± 58
253 ± 53
2
3.16
3.37
Figure 4. Effects of antioxidants on aciflourfen-caused, photooxidative
cellular leakage in cucumber cotyledon disks. Control (b), 50 µM
acifluorfen (O), 60 µg/mL R-tocopherol (3), 50 µM acifluorfen + 60 µg/
mL R-tocopherol (1), 30 µg/mL resveratrol (9, panel A), 30 µg/mL
resveratrol + 50 µM acifluorfen (0, panel A), 30 µg/mL pterostilbene (9,
panel B), 30 µg/mL pterostilbene + 50 µM acifluorfen (0, panel B).
a Average values, measured in the volume range of 5−20 µL, starting with
initial solution at a concentration of 150 µM.
IX accumulates harmlessly in darkness, but generates singlet
oxygen when exposed to light. In turn, membrane lipids are
rapidly peroxidized, resulting in plasma membrane dysfunction.
This effect is easily monitored by measuring electrolyte leakage
from plant tissues treated with herbicide (26). In previous similar
studies, the antioxidant R-tocopherol was shown to protect
cucumber tissue from this type of oxidative damage (27).
Employing this model, we found that resveratrol (Figure 4A)
and pterostilbene (Figure 4B) gave similar results at ap-
proximately equimolar concentrations, reducing the oxidative
damage by 30-50%, depending on the point in the time course.
Both compounds had antioxidative activity approximately equal
to that of R-tocopherol. Results obtained in this assay are in
agreement with that obtained from the assay using ABAP,
confirming that the antioxidant activity of pterostilbene is similar
to that of resveratrol. Additionally, this assay provided clues as
to the physiological function of pterostilbene and resveratrol in
plants other than as phytoalexins. Furthermore, the results can
be extrapolated to animal systems, but taking into consideration
that the mechanisms of antioxidant activity are independent of
tissue type.
the 4′-hydroxyl group in both compounds was determined to
be required for the antiproliferative activity.
Results reported herein indicate that pterostilbene effectively
scavenges peroxyl radicals (ROO•) and reduces singlet-oxygen-
induced peroxidation at levels similar to those of resveratrol.
These data suggest that the antioxidant activity observed could
be responsible, in part, for its capability to reduce mouse
mammary gland culture carcinogenesis, and mediation of
inflammatory processes shown by its weak inhibition of COX
activity is possibly a less important mechanism for its chemo-
preventive activity. Reported cytotoxic activity of pterostilbene
may also play a role in its chemopreventive property, but further
investigations are needed to examine in more depth the
mechanisms underlying its apparent cancer chemopreventive
activity. Studies to establish in vivo efficacy would also be of
value. This is the first report to demonstrate the antioxidant
activity of pterostilbene, as well as resveratrol, using a plant
system, and further studies to determine the physiological
function of these stilbenes in the plant are warranted.
The powerful antioxidant properties of resveratrol (34) and
its ability to modulate redox-sensitive cell signaling pathways
(35) may relate to the multitude of biological effects exhibited
by this compound. Pterostilbene was demonstrated in these
studies to have antioxidant activity similar to that of resveratrol,
and it may also exert many biological effects similar to
resveratrol. In fact, Stivala and co-workers (12) found that
among the derivatives they tested, only pterostilbene inhibited
the growth of normal fibroblasts in a dose-dependent manner
similar to resveratrol (IC50 60 µM for both), and pterostilbene
also caused cell cycle imbalance in a manner similar to that of
resveratrol. Furthermore, only pterostilbene inhibited DNA
synthesis in an extent similar to resveratrol. The presence of
ABBREVIATIONS USED
COX, cyclooxygenase; DMBA, 7,12-dimethylbenz[a]anthra-
cene; DPPH, 1,1-diphenyl-2-picrylhydrazyl radical; LDL, low-
density lipoprotein; MMOC, mouse mammary gland organ
culture; NMR, nuclear magnetic resonance; TRAP, total reactive
antioxidant potential; Trolox, 6-hydroxy-2,5,7,8-tetramethoxyl-
chroman-2-carboxylic acid; ABAP, 2,2′-azo-bis(2-amidinopro-
pane).
ACKNOWLEDGMENT
The technical assistance of Robert Johnson is gratefully
acknowledged.

Antioxidant Activities of Pterostilbene
J. Agric. Food Chem., Vol. 50, No. 12, 2002 3457
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Received for review December 20, 2001. Revised manuscript received
March 27, 2002. Accepted April 2, 2002. This work was supported in
part by P01 CA48112 funded by the National Cancer Institute.
JF0116855