Dehydrozingerone, chalcone, and isoeugenol analogues as in vitro anticancer agents

Article abstract of DOI:10.1021/np060252z

Twenty-eight compounds related to dehydrozingerone (1), isoeugenol (3), and 2-hydroxychalcone (4) were synthesized and evaluated in vitro against human tumor cell replication. Except for isoeugenol analogues 27-35, most compounds exhibited moderate or strong cytotoxic activity against KB, KB-VCR (a multidrug-resistant derivative), and A549 cell lines. In particular, chalcone 15 showed significant cytotoxic activity against the A549 cell line with an IC₅₀ value of 0.6 μg/mL. Furthermore, dehydrozingerone analogue 11 and chalcones 16 and 17 showed significant and similar cytotoxic activity against both KB (IC₅₀ values of 2.0, 1.0, and 2.0 μg/mL, respectively) and KB-VCR (IC₅₀ values of 1.9, 1.0, and 2.0 μ/mL, respectively) cells, suggesting that they are not substrates for the P-glycoprotein drug efflux pump.

Full text of DOI:10.1021/np060252z

J. Nat. Prod. 2006, 69, 1445-1449
1445
Dehydrozingerone, Chalcone, and Isoeugenol Analogues as in Vitro Anticancer Agents#
Jin Tatsuzaki,† Kenneth F. Bastow,‡ Kyoko Nakagawa-Goto,† Seiko Nakamura,† Hideji Itokawa,† and Kuo-Hsiung Lee*,†
Natural Products Research Laboratories, School of Pharmacy, UniVersity of North Carolina, Chapel Hill, North Carolina 27599-7360,
and DiVision of Medicinal Chemistry and Natural Products, School of Pharmacy, UniVersity of North Carolina,
Chapel Hill, North Carolina 27599-7360
ReceiVed June 5, 2006
Twenty-eight compounds related to dehydrozingerone (1), isoeugenol (3), and 2-hydroxychalcone (4) were synthesized
and evaluated in vitro against human tumor cell replication. Except for isoeugenol analogues 27-35, most compounds
exhibited moderate or strong cytotoxic activity against KB, KB-VCR (a multidrug-resistant derivative), and A549 cell
lines. In particular, chalcone 15 showed significant cytotoxic activity against the A549 cell line with an IC50 value of
0.6 µg/mL. Furthermore, dehydrozingerone analogue 11 and chalcones 16 and 17 showed significant and similar cytotoxic
activity against both KB (IC50 values of 2.0, 1.0, and 2.0 µg/mL, respectively) and KB-VCR (IC50 values of 1.9, 1.0,
and 2.0 µg/mL, respectively) cells, suggesting that they are not substrates for the P-glycoprotein drug efflux pump.
Dehydrozingerone (1), isolated from ginger (Zingiber offici-
nale),1,2 is a well-known phenolic natural product with anti-
inflammatory, antioxidant, and antitumor promoting activities.3 It
is the structural half analogue, as well as biosynthetic intermediate,4
of curcumin (2), which possesses various remarkable bioactivities
such as cytotoxic effects on cancer cell lines5-8 and induction of
apoptotic cell death in human promyelocytic leukemia HL-60 and
human oral squamous carcinoma HSC-4 cells.9 Dehydrozingerone
(1), isoeugenol (3), and 2-hydroxychalcone (4) (Figure 1) have
similar structures (acetyl, methyl, and benzoyl, respectively, attached
to a styrene skeleton). Both 3 and 4 are also prominent bioactive
compounds.10,11 Thus, we expected that 1-analogues should show
a wide range of pharmacological activities. In spite of the interesting
and simple structure of 1, we found only a few literature reports
on analogue syntheses and structure-activity relationships (SAR),12,13
although we recently reported the cytotoxic effects of curcumin
Figure 1. Structures of dehydrozingerone (1), curcumin (2),
isoeugenol (3), and 2-hydroxychalcone (4).
analogues.7,14,15
It is known that the presence of a prenyl or geranyl group on
flavonoids, including chalcones, can lead to a remarkable increase
in bioactivity.16,17 As dehydrozingerone (1) is structurally related
to chalcones, the introduction of a prenyl or geranyl group on any
position of 1 might also increase activity. In fact, most prenylflav-
onoids and geranylflavonoids as well as related compounds are
known to have potent cytotoxic effects.18-21 Furthermore, with
respect to cancer research, a prenyl moiety has been demonstrated
to be essential for chemopreventive activity in many compound
types.22-24 Therefore, we herein report the syntheses and cytotoxic
activities of dehydrozingerone analogues, including investigation
of prenyl substitution.
Derivatives 6-35 were evaluated as inhibitors of human tumor
cell replication using three human tumor cell lines: nasopharyngeal
carcinoma KB, multidrug-resistant expressing P-glycoprotein KB-
VCR, and lung carcinoma A549.26,27 Curcumin (2) and doxorubicin
were used as positive controls. The results are shown in Table 1.
Most analogues, except isoeugenol analogues 27-35, showed
moderate or strong cytotoxic activity against all three cell lines.
Comparison of the corresponding dehydrozingerone (1, 6-8) and
chalcone (14-17) analogues showed that the latter compounds were
more potent in each case. Because the chalcones have a phenyl
rather than methyl in the unsaturated ketone, these data suggest
that this phenyl group is important for optimal activity. Chalcone
15 showed significant activity against the A549 cell line with an
IC50 value of 0.6 µg/mL. Furthermore, the dehydrozingerone
analogue 11 and chalcones 16 and 17 showed significant cytotoxic
activity against both KB (IC50 values of 2.0, 1.0, and 2.0 µg/mL,
respectively) and KB-VCR (IC50 values of 1.9, 1.0, and 2.0 µg/
mL, respectively) cells. The similar potencies against the parental
and drug-resistant cell lines suggested that these compounds were
not substrates for the P-glycoprotein drug efflux pump.
Results and Discussion
As shown in Scheme 1, dehydrozingerone (6-13) and chalcone
(14-17) analogues with various substitution patterns on the
benzylidene ring were easily obtained from substituted benzalde-
hydes (5) reacted with the appropriate ketone (acetone for 6-13,
acetophenone for 14-17) using an aldol condensation.12 Alkylation/
allylation of the phenol of 1 or 3 was achieved by a standard
procedure25 using an alkyl/allyl halide to give the corresponding
phenoxy analogues 18-26 and 27-35, respectively, as shown in
Scheme 2.
The substitution pattern on the benzylidene ring had some
influence on potency. In particular, among the dehydrozingerone
analogues, compounds with an ortho-hydroxy group were more
active than compounds with meta- or para-hydroxy substituents
[compare 6 (2′-OH, 3′-OMe), 8 (2′-OH, 4′-OMe), and 11 (2′-OH,
3′-OEt) with 1 (3′-OMe, 4′-OH), 7 (3′-OH, 4′-OMe), and 10 (3′-
OEt, 4′-OH)]. Compound 12 (2′-OH, 3′-F) also exhibited significant
activity, showing that fluorine could be substituted for an alkoxy
# Antitumor Agents 249. For part 248, see: Wei, L.; Brossi, A.; Morris-
Natschke, S. L.; Bastow, K. F.; Lee, K. H. Chemistry and Antitumor Activity
of Tylophorine-related Alkaloids. Stud. Nat. Prod. Chem., in press.
* Corresponding author. Tel: 919-962-0066. Fax: 919-966-3893. E-
mail: khlee@unc.edu.
† Natural Products Research Laboratories.
‡ Division of Medicinal Chemistry and Natural Products.
10.1021/np060252z CCC: $33.50
© 2006 American Chemical Society and American Society of Pharmacognosy
Published on Web 09/28/2006

1446 Journal of Natural Products, 2006, Vol. 69, No. 10
Tatsuzaki et al.
Table 1. Activities of Analogues against Human Tumor Cell
Replication
Scheme 1. Syntheses of Dehydrozingerone (6-13) and
Chalcone (14-17) Analogues
cell line/IC50 (µg/mL)a
compound
KBb
KB-VCRb
A549b
Dehydrozingerone Analogues
>10 >10
3.8 2.0
1
6
7
8
>10
2.5
>10
3.5
2.8
8.5
2.3
3.0
5.5
10.0
3.8
5.3
7.7
2.0
2.1
4.3
8.2
4.0
5.6
7.8
1.9
3.0
5.0
9
10
11
12
13
Chalcone Analogues
14
15
16
17
3.5
2.4
1.0
2.0
1.9
1.3
1.0
2.0
2.3
0.6
3.5
3.8
C-4-Alkylated Dehydrozingerone Analogues
18
19
20
21
22
23
24
25
26
5.7
6.8
4.8
2.2
6.5
8.6
5.5
6.5
3.6
3.5
5.0
3.4
3.3
7.4
7.8
8.0
4.2
3.2
3.8
5.8
6.8
3.4
7.4
8.0
>10
5.8
7.2
C-4-Alkylated Isoeugenol Analogues
>10 >10
27-35c
NDd
Controls
5.5
0.1
curcumin (2)
doxorubicin
3.1
2.7
5.2
0.1
a Cytotoxicity as IC50 values for each cell line, the concentration of
compound that caused 50% reduction in absorbance at 562 nm relative
to untreated cells using the sulforhodamine B assay. The average value
is from two independent determinations, and variation (SEM) was no
greater than 10%. b Human epidermoid carcinoma of the nasopharynx
(KB), multidrug-resistant expression P-glycoprotein (KB-VCR), and
Scheme 2. C-4′-Alkylated Dehydrozingerone (18-26) and
Isoeugenol (27-35) Analogues
c
d
human lung carcinoma (A549). 30 and 33 were not tested. ND )
not determined.
prenylated and/or geranylated flavonoids were more active than
farnesylated compounds.17,19 Derivative 26, which has a saturated
isoamyl rather than unsaturated prenyl group, showed equal and
significant activity against KB and KB-VCR cells with IC50 values
of 3.6 and 3.2 µg/mL, respectively. However, the prenylated
analogue (18) was about twice as potent against the drug-resistant
cell line (3.8 µg/mL, KB versus 2.0 µg/mL, KB-VCR).
In conclusion, chalcone 15 showed the highest in vitro potencies
with IC50 values ranging from 0.6 to 2.4 µg/mL. The ketone at the
C-3 and phenyl at the C-4 positions are necessary for optimal
cytotoxic activity. Compounds with hydroxyl at the ortho position
of the benzylidene moiety generally showed increased activity.
Among alkylated 1-analogues, alkylation of the phenolic OH with
prenyl or geranyl resulted in the highest potency.
Experimental Section
General Experimental Procedures. Melting points were mea-
sured with a Fisher Johns melting point apparatus without correction.
The proton nuclear magnetic resonance (1H NMR) spectra were
measured on a Varian Gemini 2000 (300 MHz) NMR spectrometer
with TMS as the internal standard. All chemical shifts are reported in
ppm. Mass spectra were obtained on a TRIO 1000 mass spectrometer.
Analytical thin layer chromatography (TLC) was performed on Merck
precoated aluminum silica gel sheets (Kieselgel 60 F 254). Column
chromatography was performed on a CombiFlash Companion system
using RediSep normal-phase silica columns (ISCO, Inc., Lincoln, NE).
Silica gel (200-400 mesh) from Natland (Durham, NC) was used for
column chromatography. All other chemicals were obtained from
Aldrich, Inc. unless otherwise noted.
group. In addition, substitution of 3′-fluoro for 3′-hydroxy (compare
13 with 7) was beneficial.
The dehydrozingerone derivatives 18-26 showed cytotoxic
activity, while the corresponding isoeugenol derivatives 27-35 were
inactive. This result supported the supposition that the ketone on
C-3 (numbering for dehydrozingerone) is important for anticancer
properties.28 Phenoxydehydrozingerone analogues 18 (C-4′-prenyl-
oxy) and 21 (C-4′-geranyloxy) showed higher activity than dehy-
drozingerone itself and were as or more active than the other
alkylated compounds 19, 20, and 22-26. With a longer farnesyl
group, analogue 22 showed decreased potency relative to 18 and
21. This result supported those of prior investigations showing that

Dehydrozingerone, Chalcone, and Isoeugenol Analogues
Journal of Natural Products, 2006, Vol. 69, No. 10 1447
General Procedure for Aldol Reaction.12 The appropriately
substituted benzaldehyde 5 was dissolved in acetone, and 1 N sodium
hydroxide was added to the solution with continuous stirring. Stirring
was continued overnight. Excess acetone was removed under reduced
pressure. Upon acidification with 1 N HCl, the reaction mixture was
extracted with CHCl3 or CH2Cl2, and then the solution was dried over
anhydrous Na2SO4. Solvent was removed, and the yellow solid obtained
was recrystallized from EtOAc to give 6-13. Similarly, for the
preparation of 14-17, benzaldehyde 5 was dissolved in MeOH with
acetophenone, and 5 N potassium hydride was added to the solution
with continuous stirring. Stirring was continued overnight. MeOH was
removed under reduced pressure. After acidification with 1 N HCl,
the crude mixture was extracted with CH2Cl2, and the solution was
dried over anhydrous Na2SO4. Solvent was removed, and the solid
obtained was purified with CombiFlash chromatography (EtOAc-
hexane) to provide 14-17.
(E)-1-(2-Hydroxy-3-methoxyphenyl)-3-phenylpropenone (15). Start-
ing with o-vanillin (128 mg, 0.85 mmol), acetophenone (100 µL, 0.85
mmol), MeOH (1 mL), and 5 N NaOH (1 mL); yield 80 mg (37%);
1
powder, mp 115 °C; H NMR (300 MHz, CDCl3) δ 8.05-8.02 (m,
2H, 2 × Ar-H), 8.04 (d, 1H, J ) 15.9 Hz, 1-H), 7.75 (d, 1H, J ) 15.9
Hz, 2-H), 7.61-7.47 (m, 3H, 3 × Ar-H), 7.20 (dd, 1H, J ) 3.3, 2.7
Hz, Ar-H), 6.92-6.86 (m, 2H, 2 × Ar-H), 6.27 (s, 1H, OH), 3.94 (s,
3H, OCH3); MS m/z 277 [M + Na]+.
(E)-1-(3-Hydroxy-4-methoxyphenyl)-3-phenylpropenone (16). Start-
ing with 3-hydroxy-4-methoxybenzaldehyde (128 mg, 0.85 mmol),
acetophenone (100 µL, 0.85 mmol), MeOH (1 mL), and 5 N NaOH (1
1
mL); yield 194 mg (90%); powder, 97-98 °C; H NMR (300 MHz,
CDCl3) δ 8.04-8.00 (m, 2H, 2 × Ar-H), 7.74 (d, 1H, J ) 15.7 Hz,
1-H), 7.61-7.47 (m, 3H, 3 × Ar-H), 7.41 (d, 1H, J ) 15.7 Hz, 2-H),
7.29 (d, 1H, J ) 2.0 Hz, Ar-H), 7.15 (dd, 1H, J ) 8.2, 2.0 Hz, Ar-H),
6.88 (d, 1H, J ) 8.2 Hz, Ar-H), 5.69 (br s, 1H, OH), 3.95 (s, 3H,
OCH3); MS m/z 255 [M + H]+.
(E)-1-(2-Hydroxy-3-methoxyphenyl)but-1-en-3-one (6). Starting
with o-vanillin (5 g, 0.03 mol), acetone (40 mL), and 1 N NaOH (50
(E)-1-(2-Hydroxy-4-methoxyphenyl)-3-phenylpropenone (17). Start-
ing with 2-hydroxy-4-methoxybenzaldehyde (128 mg, 0.85 mmol),
acetophenone (100 µL, 0.85 mmol), MeOH (1 mL), and 5 N NaOH (1
1
mL); yield 2.0 g (30%); powder, mp 79-80 °C; H NMR (300 MHz,
CDCl3) δ 7.84 (d, 1H, J ) 16.5 Hz, 1-H), 7.12 (dd, 1H, J ) 6.6, 2.7
Hz, 5′-H), 6.90-6.84 (m, 2H, 4′- and 6′-H), 6.81 (d, 1H, J ) 16.5,
2-H), 6.16 (s, 1H, OH), 3.92 (s, 3H, OCH3), 2.40 (s, 3H, 4-H); MS
m/z 277 [M + Na]+.
1
mL); yield 65 mg (30%); amorphous; H NMR (300 MHz, CDCl3) δ
8.14 (d, 1H, J ) 15.9 Hz, 1-H), 8.04-8.01 (m, 2H, 2 × Ar-H), 7.61
(d, 1H, J ) 15.9 Hz, 2-H), 7.61-7.47 (m, 4H, 4Ar-H), 6.53 (dd, 1H,
J ) 8.7, 2.4 Hz, Ar-H), 6.49 (d, 1H, Ar-H), 3.82 (s, 3H, OCH3); MS
m/z 277 [M + Na]+.
(E)-1-(3-Hydroxy-4-methoxyphenyl)but-1-en-3-one (7). Starting
with 3-hydroxy-4-methoxybenzaldehyde (1 g, 6.6 mmol), acetone (8
mL), and 1 N NaOH (10 mL); yield 1.2 g (94%); powder, mp 96-97
General Procedure for Alkylation.25 The mixture of dehydroz-
ingerone (2) or isoeugenol (3), an appropriate alkyl halide, and K2CO3
in acetone was heated to reflux overnight. The reaction mixture was
evaporated under vacuum. The crude mixture was extracted with CH2-
Cl2, and the organic phase was washed with brine, dried over NaSO4,
and concentrated to obtain the product as a solid. The crude solid was
purified with CombiFlash chromatography (EtOAc-hexane gradient)
to obtain the target materials (18-35).25
1
°C; H NMR (300 MHz, CDCl3) δ 7.42 (d, 1H, J ) 16.2 Hz, 1-H),
7.15 (d, 1H, J ) 1.5 Hz, 2′-H), 7.06 (dd, 1H, J ) 8.3, 2.1 Hz, 5′-H),
6.86 (d, 1H, J ) 8.3 Hz, 6′-H), 6.59 (d, 1H, J ) 16.2 Hz, 2-H), 5.70
(s, 1H, OH), 3.93 (s, 3H, OCH3), 3.36 (s, 3H, 4-H); MS m/z 193 [M
+ H]+.
(E)-1-(2-Hydroxy-4-methoxyphenyl)but-1-en-3-one (8). Starting
with 2-hydroxy-4-methoxybenzaldehyde (1 g, 6.6 mmol), acetone (8
mL), and 1 N NaOH (10 mL); yield 497 mg (39%); powder, mp 129-
(E)-1-[3-Methoxy-4-(3-methylbut-2-enyloxy)phenyl]but-1-en-3-
one (18). Starting with 1 (50 mg, 0.26 mmol), 4-bromo-2-methyl-2-
butene (48 µL, 0.39 mmol), and K2CO3 (252 mg, 1.82 mmol); yield
57 mg (87%); powder, mp 89-90 °C; 1H NMR (300 MHz, CDCl3) δ
7.46 (d, 1H, J ) 16.2 Hz, 1-H), 7.10 (dd, 1H, J ) 8.2, 2.1 Hz, 6′-H),
7.07 (d, 1H, J ) 2.1 Hz, 2′-H) 6.88 (d, 1H, J ) 8.2 Hz, 5′-H), 6.60 (d,
1H, J ) 16.2 Hz, 2-H), 5.51 (tt, 1H, J ) 6.6, 1.2 Hz, 2′-H), 4.63 (d,
1H, J ) 6.6 Hz, 1′′-H), 3.90 (s, 3H, OCH3), 2.37 (s, 3H, 4-H), 1.78 (br
s, 3H, CH3), 1.75 (br s, 3H, CH3); MS m/z 261 [M + H]+.
(E)-1-(4-Allyloxy-3-methoxyphenyl)but-1-en-3-one (19). Starting
with 1 (100 mg, 0.52 mmol), allyl bromide (68.1 mL, 0.78 mmol),
and K2CO3 (503 mg, 3.64 mmol); yield 115 mg (94%); needles, mp
1
130 °C; H NMR (300 MHz, CDCl3) δ 7.78 (d, 1H, J ) 16.3 Hz,
1-H), 7.34 (d, 1H, J ) 8.5 Hz, 6′-H), 7.01 (d, 1H, J ) 16.3 Hz, 2-H)
6.50 (dd, 1H, J ) 8.5, 2.1 Hz, 5′-H), 6.48 (d, 1H, J ) 2.1 Hz, 3′-H),
6.16 (s, 1H, OH) 3.82 (s, 3H, OCH3), 2.41 (s, 3H, 4-H); MS m/z 215
[M + Na]+.
(E)-1-Phenylbut-1-en-3-one (9). Starting with benzaldehyde (500
mL, 4.9 mmol), acetone (4 mL), and 1 N NaOH (5 mL); yield 241 mg
(34%); yellow oil; 1H NMR (300 MHz, CDCl3) δ 7.58-7.53 (m, 2H,
2 × Ar-H), 7.52 (d, 1H, J ) 16.2 Hz, 1-H), 7.42-7.40 (m, 3H, 3 ×
Ar-H), 6.73 (d, 1H, J ) 16.2 Hz, 2-H), 2.39 (s, 3H, 4-H); MS m/z 169
[M + Na]+.
(E)-1-(3-Ethoxy-4-hydroxyphenyl)but-1-en-3-one (10). Starting
with 3-ethoxy-4-hydroxybenzaldehyde (1 g, 6.0 mmol), acetone (8 mL),
and 1 N NaOH (10 mL); yield 1.1 g (42%); needles, mp 104-105 °C;
1H NMR (300 MHz, CDCl3) δ 7.44 (d, 1H, J ) 16.0 Hz, 1-H), 7.08
(br d, 1H, J ) 8.4 Hz, 6′-H), 7.05 (br s, 1H, 2′-H), 6.93 (d, 1H, J )
8.4 Hz, 5′-H), 6.57 (d, 1H, J ) 16.0 Hz, 2-H), 5.85 (s, 1H, OH), 4.16
(q, 2H, J ) 7.0 Hz, 1′-H), 2.36 (s, 3H, 4-H), 1.48 (t, 3H, J ) 7.0 Hz,
2′-H); MS m/z 229 [M + Na]+.
(E)-1-(3-Ethoxy-2-hydroxyphenyl)but-1-en-3-one (11). Starting
with 3-ethoxysalicylaldehyde (1 g, 6.0 mmol), acetone (8 mL), and 1
N NaOH (10 mL); yield 1.0 g (84%); powder, mp 77-78 °C; 1H NMR
(300 MHz, CDCl3) δ 7.84 (d, 1H, J ) 16.5 Hz, 1-H), 7.11 (dd, 1H, J
) 4.8, 2.1 Hz, 5′-H), 6.88-6.81 (m, 2H, 4′- and 6′-H) 6.21 (s, 1H,
OH), 6.81 (d, 1H, J ) 16.5 Hz, 2-H), 4.14 (q, 2H, J ) 6.9 Hz, 1′-H),
2.40 (s, 3H, 1-H), 1.47 (t, 3H, J ) 6.9 Hz, 2′-H); MS m/z 207 [M +
H]+.
(E)-1-(3-Fluoro-2-hydroxyphenyl)but-1-en-3-one (12). Starting
with 3-fluorosalicylaldehyde (200 mg, 1.4 mmol), acetone (1.6 mL),
and 1 N NaOH (2 mL); yield 239 mg (93%); prisms, mp 167-168 °C;
1H NMR (300 MHz, CDCl3) δ 7.79 (d, 1H, J ) 16.5 Hz, 1-H), 7.29
(br d, 1H, J ) 8.1 Hz, 6′-H), 7.12 (br t, 1H, J ) 8.1 Hz, 5′-H), 6.91-
6.82 (m, 2H, 4′- and 2-H), 5.96 (br s, 1H, OH), 2.41 (s, 3H, 4-H); MS
m/z 203 [M + Na]+.
1
71-72 °C; H NMR (300 MHz, CDCl3) δ 7.48 (d, 1H, J ) 16.3 Hz,
1-H), 7.12-7.06 (m, 2H, 2′- and 6′-H), 6.88 (d, 1H, J ) 7.8 Hz, 5′-H),
6.60 (d, 1H, J ) 16.3 Hz, 2-H), 6.08 (ddt, 2H, J ) 17.4, 10.5, 5.1 Hz,
2′′-H), 5.42 (br d, 1H, J ) 17.4 Hz, 3′′-H), 5.32 (br d, 1H, J ) 10.5
Hz, 3′′-H), 3.91 (s, 3H, OCH3), 2.37 (s, 3H, 4-H); MS m/z 233 [M +
H]+.
(E)-1-(4-But-2-enyloxy-3-methoxyphenyl)but-1-en-3-one (20). Start-
ing with 1 (100 mg, 0.52 mmol), crotyl bromide (95 µL, 0.78 mmol),
and K2CO3 (503 mg, 3.64 mmol); yield 119 mg (93%); powder, mp
1
68-69 °C; H NMR (300 MHz, CDCl3) δ 7.48 (d, 1H, J ) 16.2 Hz,
1-H), 7.12-7.06 (d, 2H, 2′- and 6′-H), 6.88 (d, 1H, J ) 8.4 Hz, 5′-H),
6.60 (d, 1H, J ) 16.2 Hz, 2-H), 5.94-5.72 (m, 2H, 2′′- and 3′′-H),
4.56 (d, 1H, J ) 6.0 Hz, 1′′-H), 3.91 (s, 3H, OCH3), 2.37 (s, 3H, 4-H),
1.75 (d, 3H, J ) 5.1 Hz, 4′′-H); MS m/z 247 [M + H]+.
(E)-1-[4-(3,7-Dimethylocta-2,6-dienyloxy)-3-methoxyphenyl]but-
1-en-3-one (21). Starting with 1 (100 mg, 0.52 mmol), crotyl bromide
(149 µL, 0.78 mmol), and K2CO3 (503 mg, 3.64 mmol); yield 160 mg
1
(93%); powder, mp 56-57 °C; H NMR (300 MHz, CDCl3) δ 7.46
(d, 1H, J ) 16.2 Hz, 1-H), 7.10 (dd, 1H, J ) 8.2, 1.9 Hz, 6′-H), 7.07
(d, 1H, J ) 1.9 Hz, 2′-H), 6.87 (d, 1H, J ) 8.2 Hz, 5′-H), 6.60 (d, 1H,
J ) 16.2 Hz, 2-H), 5.51 (br t, 1H, J ) 6.6 Hz, 2′′-H), 5.07 (br t, 1H,
J ) 6.6 Hz, 6′′-H), 4.67 (d, 2H, J ) 6.6 Hz, 1′′-H), 3.91 (s, 3H, OCH3),
2.37 (s, 3H, 4-H), 2.16-2.05 (m, 4H, 4′′- and 5′′-H), 0.74 (br s, 3H,
CH3), 1.66 (br s, 3H, CH3), 1.60 (br s, 3H, CH3); MS m/z 351 [M +
H]+.
(E)-1-(3-Fluoro-4-methoxyphenyl)but-1-en-3-one (13). Starting
with 3-fluoro-4-methoxybenzaldehyde (500 mg, 3.24 mmol), acetone
(4 mL), and 1 N NaOH (5 mL); yield 139 mg (22%); needles, mp
(E)-1-[3-Methoxy-4-(3,7,11-trimethyldodeca-2,6,10-trienyloxy)-
phenyl]but-1-en-3-one (22). Starting with 1 (100 mg, 0.52 mmol),
farnesyl bromide (222.8 µL, 0.78 mmol), and K2CO3 (503 mg, 3.64
1
96-97 °C; H NMR (300 MHz, CDCl3) δ 7.42 (d, 1H, J ) 16.2 Hz,
1-H), 7.34-7.25 (m, 2H, 2 × Ar-H), 6.97 (t, 1H, J ) 8.7 Hz, 5′-H),
6.59 (d, 1H, J ) 16.2 Hz, 2-H), 5.85 (s, 1H, OH), 3.93 (s, 3H, OCH3),
2.37 (s, 3H, 4-H); MS m/z 217 [M + Na]+.
1
mmol); yield 182 mg (88%); powder, mp 66-67 °C; H NMR (300
MHz, CDCl3) δ 7.46 (d, 1H, J ) 16.2 Hz, 1-H), 7.10 (dd, 2H, J ) 7.8,

1448 Journal of Natural Products, 2006, Vol. 69, No. 10
Tatsuzaki et al.
2.0 Hz, 6′-H), 7.07 (d, 1H, J ) 2.0 Hz, 2′-H), 6.87 (d, 1H, J ) 7.8 Hz,
5′-H), 6.60 (d, 1H, J ) 16.2 Hz, 2-H), 5.51 (br t, 1H, J ) 6.0 Hz,
2′′-H), 5.12-5.04 (m, 2H, 6′′- and 10′′-H), 4.67 (d, 2H, J ) 6.3 Hz,
1′′-H), 3.91 (s, 3H, OCH3), 2.37 (s, 3H, 4-H), 2.18-1.92 (m, 8H, 4′′-,
5′′-, 8′′-, and 9′′-H), 0.75 (br s, 3H, 3′′- or 7′′-CH3), 1.68 (br s, 3H, 3′′-
or 7′′-CH3), 1.59 (br s, 6H, gem-diMe); MS m/z 397 [M + H]+.
(E)-1-(3,4-Dimethoxyphenyl)but-1-en-3-one (23). Starting with 1
(100 mg, 0.52 mmol), bromomethane (50 µL, 0.78 mmol), and K2CO3
(503 mg, 3.64 mmol); yield 72 mg (78%); needles, mp 87-88 °C; 1H
NMR (300 MHz, CDCl3) δ 7.47 (d, 1H, J ) 16.2 Hz, 1-H), 7.13 (br
d, 1H, 6′-H), 7.08 (br s, 1H, 2′-H) 6.88 (d, 1H, J ) 8.2 Hz, 5′-H), 6.61
(d, 1H, J ) 16.2 Hz, 2-H), 4.08 (t, 2H, J ) 6.6 Hz, 1′′-H), 3.92 (s, 3H,
OCH3 × 2), 2.37 (s, 3H, 4-H); MS m/z 179 [M + H]+.
Hz, 1′′-H), 6.16-6.04 (m, 1H, 2′′-H), 3.89 (s, 3H, OCH3), 3.87 (s, 3H,
OCH3), 1.87 (d, 3H, J ) 6.3 Hz, 3′′-H); MS m/z 179 [M + H]+.
2-Methoxy-4-propenyl-1-propoxybenzene (34). Starting with 3
(100 µL, 0.65 mmol), 1-iodopropane (96 µL, 0.97 mmol), and K2CO3
1
(626 mg, 4.53 mmol); yield 129 mg (96%); pale yellow oil; H NMR
(300 MHz, CDCl3) δ 6.89-6.80 (m, 3H, 3-, 5-, and 6-H), 6.33 (d, 1H,
J ) 15.6 Hz, 1′′-H) 6.15-6.04 (m, 1H, 2′′-H), 3.96 (t, 3H, J ) 6.7 Hz,
1′-H), 3.87 (s, 3H, OCH3), 1.91-1.79 (m, 5H, 3′′- and 2-H), 1.03 (t,
3H, J ) 7.5 Hz, 3′-H); MS m/z 235 [M + H]+.
2-Methoxy-1-(3-methyl-butoxy)-4-propenylbenzene (35). Starting
with 3 (100 µL, 0.65 mmol), 1-methyl-3-bromobutane (127 µL, 0.97
mmol), and K2CO3 (626 mg, 4.53 mmol); yield 91 mg (59%); pale
1
yellow oil; H NMR (300 MHz, CDCl3) δ 6.89-6.78 (m, 3H, 3-, 5-,
(E)-1-(4-Ethoxy-3-methoxyphenyl)but-1-en-3-one (24). Starting
with 1 (100 µL, 0.65 mmol), bromoethane (59 µL, 0.97 mmol), and
K2CO3 (626 mg, 4.53 mmol); yield 70 mg (61%); needles, mp 108-
and 6-H), 6.33 (d, 1H, J ) 15.9 Hz, 1′′-H), 6.16-6.04 (m, 1H, 2′′-H),
4.03 (t, 2H, J ) 6.9 Hz, 1′-H), 3.87 (s, 3H, OCH3), 1.86 (d, 3H, J )
6.6 Hz, 3′′-H), 1.92-1.70 (m, 3H, 2′- and 3′-H), 0.97 (s, 3H, CH3),
0.95 (s, 3H, CH3); MS m/z 263 [M + H]+.
1
109 °C; H NMR (300 MHz, CDCl3) δ 7.46 (d, 1H, J ) 16.0 Hz,
1-H), 7.10 (br d, 1H, J ) 8.1, 6′-H), 7.08 (br s, 1H, 2′-H), 6.87 (d, 1H,
J ) 8.1 Hz, 5′-H), 6.60 (d, 1H, J ) 16.0 Hz, 2-H), 4.14 (q, 2H, J )
6.9 Hz, 1′′-H), 3.91 (s, 3H, OCH3), 2.37 (s, 3H, 4-H), 1.48 (t, 2H, 7.0
Hz, 2′′-H); MS m/z 221 [M + H]+.
Cytotoxic Activity Assay. The in vitro cytotoxicity assay was carried
out according to procedures described in Rubinstein et al.26 Drug stock
solutions were prepared in DMSO, and the final solvent concentration
was <1% DMSO (v/v), a concentration without effect on cell
replication. The human tumor cell line panel consisted of epidermoid
carcinoma of the nasopharynx (KB) and lung carcinoma (A-549). The
drug-resistant cell line was KB-VCR, an MDR variant selected for
growth in vincristine. It is cross-resistant to doxorubicin (Table 1).
Detailed characterization of this cell line is described elsewhere.27 Cells
were cultured at 37 °C in RPMI-1640 with 100 µg/mL kanamycin and
10% (v/v) fetal bovine serum in a humidified atmosphere containing
5% CO2. Initial seeding densities varied among the cell lines to ensure
a final absorbance of 1-2.5 A562 units. Drug exposure was for 2 days,
and the IC50 value, the drug concentration that reduced the absorbance
by 50%, was interpolated from dose-response data. Each test was
performed in duplicate, and absorbance readings varied no more than
5% between replicates.
(E)-1-(3-Methoxy-4-propoxyphenyl)but-1-en-3-one (25). Starting
with 1 (100 mg, 0.52 mmol), 1-iodopropane (77 µL, 0.78 mmol), and
K2CO3 (503 mg, 3.64 mmol); yield 57 mg (47%); needles, mp 101 °C;
1H NMR (300 MHz, CDCl3) δ 7.46 (d, 1H, J ) 16.2 Hz, 1-H), 7.10
(br d, 1H, 6′-H), 7.08 (br s, 1H, 2′-H) 6.87 (d, 1H, J ) 8.0 Hz, 5′-H),
6.60 (d, 1H, J ) 16.1 Hz, 2-H), 4.02 (t, 2H, J ) 6.9 Hz, 1′′-H), 3.90
(s, 3H, OCH3), 2.37 (s, 3H, 4-H), 1.89 (qt, 2H, J ) 7.3, 6.9 Hz, 2′′-H),
1.05 (t, 3H, J ) 7.3 Hz, 3′′-H); MS m/z 207 [M + H]+.
(E)-1-[3-Methoxy-4-(3-methylbutoxy)phenyl]but-1-en-3-one (26).
Starting with 1 (100 mg, 0.52 mmol), 1-methyl-3-bromobutane (102.3
µL, 0.78 mmol), and K2CO3 (503 mg, 3.64 mmol); yield 32 mg (23%);
needles, mp 77-78 °C; 1H NMR (300 MHz, CDCl3) δ 7.45 (d, 1H, J
) 16.1 Hz, 1-H), 7.10 (br d, 1H, J ) 8.4 Hz, 6′-H), 7.07 (br s, 1H,
2′-H) 6.88 (d, 1H, J ) 8.4 Hz, 5′-H), 6.60 (d, 1H, J ) 16.1 Hz, 2-H),
4.08 (t, 2H, J ) 6.6 Hz, 1′′-H), 3.90 (s, 3H, OCH3), 2.37 (s, 3H, 4-H),
1.92-1.70 (m, 1H, 3′-H), 1.77 (br t, 2H, J ) 6.6 Hz, 2′′-H), 0.98 (br
s, 3H, CH3), 0.96 (br s, 3H, CH3); MS m/z 263 [M + H]+.
Acknowledgment. This investigation was supported by a grant from
the National Cancer Institute (CA 17625) awarded to K.H.L.
2-Methoxy-1-(3-methylbut-2-enyloxy)-4-propenylbenzene (27).
Starting with 3 (100 µL, 0.65 mmol), 4-bromo-2-methyl-2-butene (118
µL, 0.97 mmol), and K2CO3 (626 mg, 4.53 mmol); yield 45 mg (30%);
References and Notes
1
(1) De Bernardi, M.; Vidari, G.; Vita-Finzi, P. Phytochemistry 1976,
15, 1785-1786.
yellow oil; H NMR (300 MHz, CDCl3) δ 6.89-6.78 (m, 3H, 3-, 5-,
and 6-H), 6.33 (d, 1H, J ) 15.6 Hz, 1′′-H), 6.16-6.04 (m, 1H, 2′′-H),
5.89-5.71 (m, 2H, 2′- and 3′-H), 4.50 (d, 2H, J ) 5.4 Hz, 1′-H), 3.87
(s, 3H, OCH3), 1.86 (d, 3H, J ) 6.3 Hz, 3′′-H), 1.76 (s, 3H, CH3),
1.72 (s, 3H, CH3); MS m/z 233 [M + H]+, 255 [M + Na]+.
(2) Motohashi, N.; Ashihara, Y.; Yamagami, C.; Saito, T. Mutat. Res.
1997, 377, 17-25.
(3) Motohashi, N.; Yamagami, C.; Tokuda, H.; Konoshima, T.; Okuda,
Y.; Okuda, M.; Mukainaka, T.; Nishino, H.; Saito, Y. Cancer Lett.
1998, 134, 37-42.
1-Allyloxy-2-methoxy-4-propenylbenzene (28). Starting with 3
(100 µL, 0.65 mmol), allyl bromide (85 µL, 0.97 mmol), and K2CO3
(4) Roughley, R. J.; Whiting, A. W. Org. Bio-Org. Chem. 1973, 20,
2379-2388.
1
(626 mg, 4.53 mmol); yield 78 mg (59%); pale yellow oil; H NMR
(5) Matthes, H. W. D.; Luu, B.; Ourisson, G. Phytochemistry 1980, 19,
2643-2650.
(300 MHz, CDCl3) δ 6.89-6.78 (m, 3H, 3-, 5-, and 6-H), 6.33 (d, 1H,
J ) 16.2 Hz, 1′′-H) 6.16-6.02 (m, 1H, 2′′-H), 5.42 (br d, 1H, J )
17.4 Hz, 3′-H), 5.27 (br d, 1H, J ) 9.6 Hz, 3′-H), 4.60 (d, 2H, J ) 5.7
Hz, 1′-H), 3.88 (s, 3H, OCH3), 1.86 (d, 3H, J ) 6.3 Hz, 3′′-H); MS
m/z 205 [M + H]+.
(6) Adams, B. K.; Ferstl, E. M.; Davis, M. C.; Herold, M.; Kurtkaya,
S.; Camalier, R. F.; Hollingshead, M. G.; Kaur, G.; Sausville, E. A.;
Rickles, F. R.; Snyder, J. P.; Liotta, D. C.; Shoji, M. Bioorg. Med.
Chem. 2004, 12, 3871-3883.
1-But-2-enyloxy-2-methoxy-4-propenylbenzene (29). Starting with
3 (100 µL, 0.65 mmol), crotyl bromide (118 µL, 0.97 mmol), and K2-
(7) Ishida, J.; Ohtsu, H.; Tachibana, Y.; Nakanishi, Y.; Bastow, K. F.;
Nagi, M.; Wang, H. K.; Itokawa, H.; Lee, K. H. Bioorg. Med. Chem.
2002, 10, 3481-3487.
(8) Syu, W. J.; Shen, C. C.; Don, M. J.; Ou, J. C.; Lee, G. H.; Sun, C.
M. J. Nat. Prod. 1998, 61, 1531-1534.
(9) Nogaki, A.; Satoh, K.; Iwasaka, K.; Takano, H.; Takahama, M.; Ida,
Y.; Sakagami, H. Anticancer Res. 1998, 18, 3487-3491.
(10) Rajakumar, D. V.; Rao, M. N. Biochem. Pharmacol. 1993, 46, 2067-
2072.
1
CO3 (626 mg, 4.53 mmol); yield 98 mg (69%); pale yellow oil; H
NMR (300 MHz, CDCl3) δ 6.89-6.78 (m, 3H, 3-, 5-, and 6-H), 6.33
(d, 1H, J ) 15.3 Hz, 1′′-H) 6.16-6.04 (m, 1H, 2′′-H), 5.51 (m, 1H,
2′-H), 4.55 (d, 2H, J ) 6.6 Hz, 1′-H), 3.87 (s, 3H, OCH3), 1.86 (d, 3H,
J ) 6.3 Hz, 3′′-H), 1.71 (d, 3H, J ) 5.1 Hz, 4′-H); MS m/z 219 [M +
H]+.
2-Methoxy-4-propenyl-1-(3,7,11-trimethyldodeca-2,6,10-trieny-
loxy)benzene (30). Starting with 3 (100 µL, 0.65 mmol), farnesyl
bromide (277 µL, 0.78 mmol), and K2CO3 (626 mg, 4.53 mmol); yield
(11) Ogata, M. Aroma Res. 2004, 5, 259-262.
(12) Elias, G.; Rao, M. N. A. Eur. J. Med. Chem. 1988, 23, 379-380.
(13) Motohashi, N.; Yamagami, C.; Tokuda, H.; Okuda, Y.; Ichiishi, E.;
Mukainaka, T.; Nishino, H.; Saito, Y. Mutat. Res. 2000, 464, 247-
254.
1
215 mg (90%); yellow oil; H NMR (300 MHz, CDCl3) δ 6.88-6.78
(m, 3H, 3-, 5-, and 6-H), 6.33 (d, 1H, J ) 15.3 Hz, 1′′-H) 6.16-6.04
(m, 1H, 2′′-H), 5.51 (m, 1H, 2′-H), 5.10 (m, 2H, 6′- and 10′-H), 4.60
(d, 2H, J ) 6.3 Hz, 1′-H), 3.87 (s, 3H, OCH3), 2.15-1.90 (m, 8H, 4′-,
5′-, 8′-, 9′-H), 1.86 (d, 3H, J ) 6.3 Hz, 3′′-H), 1.77 (s, 3H, CH3), 1.72
(s, 3H, CH3), 1.59 (s, 6H, gem-diCH3); MS m/z 369 [M + H]+.
1,2-Dimethoxy-4-propenylbenzene (32). Starting with 3 (100 µL,
0.65 mmol), bromomethane (61 µL, 0.97 mmol), and K2CO3 (626 mg,
4.53 mmol); yield 101 mg (88%); pale yellow oil; 1H NMR (300 MHz,
CDCl3) δ 6.89-6.78 (m, 3H, 3-, 5-, and 6-H), 6.34 (d, 1H, J ) 15.9
(14) Ohtsu, H.; Xiao, Z.; Ishida, J.; Nagai, M.; Wang, H. K.; Itokawa,
H.; Su, C. Y.; Shih, C.; Chiang, T.; Chang, E.; Lee, Y.; Tsai, M. Y.;
Chang, C.; Lee, K. H. J. Med. Chem. 2002, 45, 5037-5042.
(15) Ohtsu, H.; Itokawa, H.; Xiao, Z.; Su, C. Y.; Shih, C. C.; Chiang, T.;
Chang, E.; Lee, Y.; Chiu, S. Y.; Chang, C.; Lee, K. H. Bioorg. Med.
Chem. 2003, 11, 5083-5090.
(16) Wang, Y.; Tan, W.; Li, W. Z.; Li, Y. J. Nat. Prod. 2001, 64, 196-
199.
(17) Huang, C.; Zhang, Z.; Li, Y. J. Nat. Prod. 1998, 61, 1283-1285.

Dehydrozingerone, Chalcone, and Isoeugenol Analogues
Journal of Natural Products, 2006, Vol. 69, No. 10 1449
(18) Tanaka, N.; Takaishi, Y.; Shikishima, Y.; Nakanishi, Y.; Bastow,
K. F.; Lee, K. H.; Honda, G.; Ito, M.; Takeda, Y.; Kodzhimatov, O.
K.; Ashurmetov, O. J. Nat. Prod. 2004, 67, 1870-1875.
(19) Kanokmedhakul, S.; Kanokmedhakul, K.; Nambuddee, K.; Kong-
saeree, P. J. Nat. Prod. 2004, 67, 968-972.
(24) Ito, C.; Itoigawa, M.; Otsuka, T.; Tokuda, H.; Nishino, H.; Furukawa,
H. J. Nat. Prod. 2000, 63, 1344-1348.
(25) Katritzky, A. R.; Long, Q.; He, H. Y.; Qiua, G.; Wilcox, A. L.
ARKIVOC 2000, 1, 868-875.
(26) Rubinstein, L. V.; Shoemaker, R. H.; Paull, K. D.; Simon, R. M.;
Tosini, S.; Skehan, P.; Scudiero, D. A.; Monks, A.; Boyd, M. R. J.
Natl. Cancer Inst. 1990, 82, 1113-1118.
(27) Ferguson, P. J.; Fisher, M. H.; Stephenson, J.; Li, D. H.; Zhou, B.
S.; Cheng, Y. C. Cancer Res. 1988, 48, 5956-5964.
(28) Ducki, S.; Hadfield, J. A.; Lawrence, N. J.; Liu, C. Y.; McGown, A.
T.; Zhang, X. Planta Med. 1996, 62, 185-186.
(20) van Der Kaaden, J. E.; Hemscheidt, T. K.; Mooberry, S. L. J. Nat.
Prod. 2001, 64, 103-105.
(21) Nkengfack, A. E.; Azebaze, A. G.; Waffo, A. K.; Fomum, Z. T.;
Meyer, M.; van Heerden, F. R. Phytochemistry 2001, 58, 1113-1120.
(22) Itoigawa, M.; Ito, C.; Tokuda, H.; Enjo, F.; Nishino, H.; Furukawa,
H. Cancer Lett. 2004, 214, 165-169.
(23) Ito, C.; Itoigawa, M.; Furukawa, H.; Ichiishi, E.; Mukainaka, T.;
Okuda, M.; Ogata, M.; Tokuda, H.; Nishino, H. Cancer Lett. 1999,
142, 49-54.
NP060252Z