Synthesis and bioactivity of resveratrol analogues

Article abstract of DOI:10.14233/ajchem.2014.16226

It has been reported that resveratrol enhanced SIRT1 expression and significantly mimicked calorie restriction by stimulating Sir2 which is the most homologic homologue of SIRT1 of mammalian. A series of novel resveratrol derivatives were designed and synthesized as novel SIRT1 activator candidates. These synthesized compounds were characterized by spectral (1H NMR) analysis and examined for their Sir2 activation against yeast parental strain-BY4743 at a concentration of 100 μM/L by Bioscreen C MBR machine. Several compounds showed a promising Sir2 activation activity compared with resveratrol. Meanwhile, the structure-activity relationships with Sirt2 activation activities were also discussed.

Full text of DOI:10.14233/ajchem.2014.16226

Asian Journal of Chemistry; Vol. 26, No. 7 (2014), 2092-2098
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2014.16226
Synthesis and Bioactivity of Resveratrol Analogues
1
1
2
1
1
1
1,*
JUNLI AO , YUANMOU CHEN , XIAOLING XU , XU ZHANG , YUE YU , PENG YU and ERBING HUA
1Key Laboratory of Industrial Microbiology of Ministry of Education, College of Biotechnology, Tianjin University of Science & Technology,
Tianjin, P.R. China
2Shanxi Medical University Clinical Training Center, Taiyuan, Shanxi Province, P.R. China
*Corresponding author: E-mail: huarb@tust.edu.cn
Received: 22 August 2013;
Accepted: 4 December 2013;
Published online: 22 March 2014;
AJC-14969
It has been reported that resveratrol enhanced SIRT1 expression and significantly mimicked calorie restriction by stimulating Sir2 which
is the most homologic homologue of SIRT1 of mammalian. A series of novel resveratrol derivatives were designed and synthesized as
novel SIRT1 activator candidates. These synthesized compounds were characterized by spectral (1H NMR) analysis and examined for
their Sir2 activation against yeast parental strain-BY4743 at a concentration of 100 µM/L by Bioscreen C MBR machine. Several compounds
showed a promising Sir2 activation activity compared with resveratrol. Meanwhile, the structure-activity relationships with Sirt2 activation
activities were also discussed.
Keywords: Resveratrol analogues, Synthesis, SIRT1 activator, Wittig-horner reaction, Structure-activity-relationship.
The budding yeast Saccharomyces cerevisiae is a widely
used model of cellular and organismal aging20-23. A role for
sirtuins in longevity determination was first suggested from
work showing that deletion of Sir2 shortens replicative life
span24, while overexpression increases replicative life span25.
We used a yeast-based screening to seek compounds for
activating Sir2, leading to optimizable lead compound for
SIRT1 activator. Here we report a novel yeast-based screening
for measuring yeast to detect the SIRT1 activators by moni-
toring outgrowth of yeast cells using a Bioscreen C MBR
machine. The aim of this work is to explore novel potent SIRT1
activators.
INTRODUCTION
In recent years, a number of papers have been published
on resveratrol (3,5,4'-trihydroxystilbene)1,2, which report a
wide range of novel discoveries, such as new extraction methods,
new applications3-5 and resveratrol analogs6-8. This intrigued
us to prepare its analoges and their derivatives. In order to
increase its stability and water-solubility, we designed and
synthesized some analogues of resveratrol. These changes will
influence bioavailability, susceptibility to metabolism and
possibly the pharmacological profile of the resulting analogue.
There have also been a large of reports about resveratrol exert
a variety of biological activities. Among the most significant
activities of resveratrol are its cancer chemo-preventive pro-
perties9,10, antioxidant11, antibacterial and antiinflammatory
activities12-14. Some of these has been reported to inhibit LDL
oxidation in human15, in addition to its blocking of platelet
aggregation16 and vasorelaxing activities17.
EXPERIMENTAL
The progress of the reaction is monitored by TLC and
product are purified through recrystallizationand or flash
chromatography. The purity of the compounds was checked
by thin layer chromatography (TLC) performed on E. Merck
silica gel 60 GF254 precoated plate of 0.5 mm thickness. Flash
chromatography was performed with 230-400 mesh silica gel.
1H NMR spectra was obtained at Bruker AM-400 NMR
spectrometer using CDCl3 or DMSO as the solvent except
where otherwise specified, the chemical shifts are reported in
δ values (ppm) relative to Me4Si line as internal standard and
J values are reported in Hertz. Unless otherwise stated, reagents
and solvents were of reagent grade and used as obtained from
commercial sources without further purification. Dichloro-
Especially resveratrol enhanced SIRT1 expression which
led to the effect on the proteins. SIRT1, an NAD+-dependent
sirtuin deacetylase, has emerged as potential therapeutic targets
for treatment of human illnesses such as type II diabetes, cancer,
cardiovascular and neurodegenerative diseases. The nuclear
SIRT1 is the closest homolog of yeast Sir218. In yeast assays,
resveratrol was also found to extended lifespan by 70 %19, a
mechanistic explanation has been proposed whereby calorie
restriction slows aging by activating Sir2.

Vol. 26, No. 7 (2014)
Synthesis and Bioactivity of Resveratrol Analogues 2093
methane was distilled from CaH2, THF from sodium prior
to use and DMF were dried over anhydrous sodium sulfate.
Reaction temperatures were controlled by oil bath with tempe-
rature modulator and dewars.
by recrystallization or flash column chromatography to afford
compounds 1c, 2c, 5c-8c, 1d, 2d, 5d-8d, 1e, 2e, 5e-8e, 7f, 8f.
General procedure for synthesis of the nitro groups
and stilbenes (3c, 4c, 3d, 4d, 4e): To a stirred suspension of
CH3ONa (3 eq.) in DMF (25 mL) was added dropwise to the
corresponding methoxylated diethyl benzylphosphonate
(1 eq.) at 0 °C in a round-bottomed flask and the mixture was
stirred for 1 h. Then the corresponding benzaldehyde (7-8)
(1 eq.) were added. The mixture was stirred at room tempera-
ture for 1 h, then heated to 100 °C under argon for 10 h. The
solution was poured into 150 mL ice-water, the precipitate
was filtered off and recrystallized from appropriate solvents
to afford the nitro groups and stilbenes 3c, 4c, 3d, 4d, 4e.
3,4,5-Trimethoxy-4'-bromo-trans-stilbene (1c): Yield
51.6 %. White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.48
(d, J = 8.8 Hz, 2H), 7.37 (d, J = 8.4 Hz, 2H), 7.02 (d, J = 16.4
Hz, 1H), 6.93 (d, J = 16.4 Hz, 1H), 6.73 (s, 2H), 3.92 (s, 6H),
3.87 (s, 3H).
General procedure for synthesis of aromatic esters (5a-
6a):To a well-stirred suspension of a mixture of hydroxybenzoic
acid (1a-2a) (1 eq.), anhydrous potassium carbonate (5 eq.)
and tetrabutylammonium bromide (0.5 eq.) in DMF (10 mL)
was added dimethyl carbonate (50 mL, 30 eq.) at room
temperature. After the mixture was stirred at 140 °C for 58 h.
The dimethyl carbonate was removed under reduced pressure
and water (80 mL) was added to the residue. The resulted
mixture was extracted with ethyl acetate and the organic layer
was washed with water and brine, dried over anhydrous sodium
sulfate. The solvent was concentrated in vacuo to yield the
pure product 5a-6a.
General procedure for synthesis of aromatic alcohol
(7a): LiAlH4 (0.5 eq.) was added slowly to a solution of aromatic
esters (3a-6a) (1 eq.) inTHF (50 mL) at 0 °C for 1 h. The reaction
mixture was stirred for 10 h at room temperature. Ice-water
(10 mL) was added slowly to the reaction mixture and stirred
for 10 min, followed by concentrated 2 M HCl to neutralize
the base. The reaction mixture was extracted with ethyl acetate
and the ethyl acetate layer was washed with water and brine,
dried over anhydrous sodium sulfate. The solvent was removed
in vacuo to yield the pure product 7a.
3,4,5-Trimethoxy-4'-chloro-trans-stilbene (2c): Yield
55.5 %. White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.43
(d, J = 8.4 Hz, 2H), 7.01 (d, J = 8.8 Hz, 2H), 7.01 (d, J = 16.4
Hz, 1H), 6.94 (d, J = 16.4 Hz, 1H), 6.73 (s, 2H), 3.92 (s, 6H),
3.87 (s, 3H).
3,4,5-Trimethoxy-3'-nitro-trans-stilbene (3c): Yield
58.7 %.Yellow solid: 1H NMR (400 MHz CDCl3): δ ppm 8.36
(s, 1H), 8.09 (d, J = 11.2 Hz, 1H), 7.79 (d, J = 8 Hz, 1H), 7.52
(t, J = 8 Hz, 1H), 7.17 (d, J = 16.4 Hz, 1H), 7.04 (d, J = 16.4
Hz, 1H), 6.77 (s, 2H), 3.93 (s, 6H), 3.89 (s, 3H).
General procedure for synthesis of benzyl bromine
(8a): A solution of tribromophosphine (3 eq.) in CH2Cl2 (15
mL) was added dropwise to a solution of aromatic alcohol
(7a) (1 eq.) in CH2Cl2 (30 mL) at 0 °C. The reaction mixture
was stirred for 2 h and then warmed up to room temperature.
After 4 h, the solution was poured into 80 mL ice-water and
stirred for 10 min. Then the organic layer was washed with
water and aq NaHCO3 (3 × 20 mL), dried over anhydrous sodium
sulfate and evaporated. The crude product on recrystallization
from appropriate solvents yield 8a.
3,4,5-Trimethoxy-4'-nitro-trans-stilbene (4c): Yield
1
55.5 %. Orange solid: H NMR (400 MHz CDCl3): δ ppm
8.22 (d, J = 8.8 Hz, 2H), 7.63 (d, J = 8.4 Hz, 2H), 7.20 (d, J =
16.4 Hz, 1H), 7.04 (d, J = 16.4 Hz, 1H), 6.78 (s, 2H), 3.93 (s,
6H), 3.89 (s, 3H).
3,4,5-Trimethoxy-trans-stilbene (5c): Yield 38.4 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.51 (d, J =
7.2 Hz, 2H), 7.36 (t, J = 7.6 Hz, 2H), 7.26 (t, J = 7.4 Hz, 1H),
7.05 (d, J = 16.4 Hz, 1H), 7 (d, J = 16.4 Hz, 1H), 6.74 (s, 2H),
3.92 (s, 6H), 3.87 (s, 3H).
General procedure for synthesis of methoxylated di-
ethyl benzylphosphonates (9a) (Arbuzov rearrangement)26:
A mixture of bromide (8a) (1 eq.) and triethyl phosphate (2 mL
5 eq.) was stirred at 135 °C for 3 h. Triethyl phosphate (2 mL
5 eq.) was added again and stirred another 4 h. After the
reaction was completely finished, the mixture was purified
by distillation at 4 × 10-3 bar and 120 °C to yield yellow oils
methoxylated diethyl benzylphosphonates (9a). The crude
product was used directly for the next step without further
purification.
3,4,5,4'-Tetramethoxy-trans-stilbene (6c):Yield 34.2 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.44 (d, J =
8.4 Hz, 2H), 6.97 (d, J = 16.4 Hz, 1H), 6.89 (d, J = 16.4 Hz,
1H), 6.89 (d, J = 8.8 Hz, 2H), 6.71 (s, 2H), 3.91 (s, 6H) 3.86
(s, 3H), 3.82 (s, 3H).
3,4,5,2'-Tetramethoxy-trans-stilbene (7c):Yield 45.2 %.
1
White solid: H NMR (400 MHz CDCl3): δ ppm 7.57 (d,
J = 8.8 Hz, 1H), 7.36 (t, J = 16.4 Hz, 1H), 7.24 (q, J = 8.8 Hz,
1H), 7.04 (d, J = 16.4 Hz, 1H), 6.97 (t, J = 7.6 Hz, 1H), 6.91
(d, J = 8.4 Hz, 1H), 6.76 (s, 2H), 3.92 (s, 6H), 3.90 (s, 3H),
3.87 (s, 3H).
General procedure for synthesis of 1c, 2c, 5c-8c, 1d, 2d,
5d-8d, 1e, 2e, 5e-8e, 7f and 8f (Wittig-Hornor condensation)27:
Methoxylated diethyl benzylphosphonates (9a) (1 eq.) in the
round-bottomed flask was added dropwise a suspension of
NaH (4 eq.) in THF (20 mL) at 0 °C and stirred for 1 h. Then
the mixture was treated with aromatic carboxaldehyde (1-6)
(1 eq.) at 0 °C for 2 h. The reaction temperature was warmed
up to room temperature and further stirred for 15 h. The
solution was poured into 150 mL ice-water, neutralized with
2 M HCl and extracted with ethyl acetate. The ethyl acetate
layer was washed with water and brine, dried over anhydrous
sodium sulfate and concentrated. The crude product purified
3,4,5,2',3'-Pentamethoxy-trans-stilbene (8c): Yield
49.4 %. White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.34
(d, J = 16.4 Hz, 1H), 7.22 (d, J = 9.2 Hz, 1H), 7.06 (t, J = 8 Hz,
1H), 7.05 (d, J = 16.4 Hz, 1H), 6.84 (d, J = 9.2 Hz, 1H), 6.77
(s, 2H), 3.93 (s, 6H), 3.89 (s, 3H), 3.87 (s, 3H), 3.86 (s, 3H).
3,5-Dimethoxy-4'-bromo-trans-stilbene (1d):Yield 29.5
%. White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.47 (d,
J = 8.4 Hz, 2H), 7.36 (d, J = 8.4 Hz, 2H), 7.01(s, 2H), 6.65 (d,
J = 2.4 Hz, 2H), 6.41 (t, J = 2.2 Hz, 1H), 3.83 (s, 6H).

2094 Ao et al.
Asian J. Chem.
3,5-Dimethoxy-4'-chloro-trans-stilbene (2d): Yield
4-Methoxy-trans-stilbene (5e): Yield 23.4 %. White
solid: 1H NMR (400 MHz CDCl3): δ ppm 7.49 (d, J = 7.6 Hz,
2H), 7.45 (d, J = 8.8 Hz, 2H), 7.40 (t, J = 7.6 Hz, 2H), 7.21 (t,
J = 7.6 Hz, 1H), 7.06 (d, J = 16 Hz, 1H), 6.97 (d, J = 16 Hz,
1H), 6.90 (d, J = 8.4 Hz, 2H), 3.83 (s, 3H).
32.5 %. White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.42
(d, J = 8.4 Hz, 2H), 7.32 (d, J = 8.4 Hz, 2H), 7.01 (d, J = 1.6
Hz, 2H), 6.65 (d, J = 2.4 Hz, 2H), 6.41 (t, J = 2.4 Hz, 1H),
3.83 (s, 6H).
3, 5-Dimethoxy-3'-nitro-trans-stilbene (3d): Yield
40.3 %. Yellow solid: 1H NMR (400 MHz CDCl3): δ ppm 8.36
(s, 1H), 8.09 (d, J = 9.6 Hz, 1H), 7.79 (d, J = 8 Hz, 1H), 7.52
(t, J = 8 Hz, 1H), 7.16 (d, J = 16.4 Hz, 1H), 7.09 (d, J = 16.4
Hz, 1H), 6.69 (d, J = 2.4 Hz, 2H), 6.45 (t, J = 2.4 Hz, 1H),
3.84 (s, 6H).
4,4'-Dimethoxy-trans-stilbene (6e):Yield 40.2 %. White
solid: 1H NMR (400 MHz CDCl3): δ ppm 7.40-7.44 (m, 4H),
6.93 (s, 2H), 6.87-6.90 (m, 4H), 3.82 (s, 6H).
2,4'-Dimethoxy-trans-stilbene (7e):Yield 20.2 %. White
solid: 1H NMR (400 MHz CDCl3): δ ppm 7.55 (d, J = 8 Hz,
1H), 7.45 (d, J = 8.4 Hz, 2H), 7.34 (d, J = 16.4 Hz, 1H), 7.20
(t, J = 7.2 Hz, 1H), 7.05 (d, J = 16.4 Hz, 1H), 6.94 (t, J = 7.6
Hz, 1H), 6.87 (d, J = 8.4 Hz, 3H), 3.85 (s, 3H), 3.79 (s, 3H).
2,3,4'-Trimethoxy-trans-stilbene (8e): Yield 25.3 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.49 (d, J = 8
Hz, 1H), 7.32 (t, J = 16.4 Hz, 1H), 7.22 (d, J = 8 Hz, 1H), 7.08
(d, J = 16.4 Hz, 1H), 7.04 (t, J = 8 Hz, 1H), 6.90 (d, J = 8.8
Hz, 2H), 6.81 (d, J = 8.4 Hz, 1H), 3.89 (s, 6H), 3.84 (s, 3H),
3.83 (s, 3H).
3,5-Dimethoxy-4'-nitro-trans-stilbene (4d): Yield
38.5 %. Orange solid: 1 H NMR (400 MHz CDCl3): δ ppm
8.22 (d, J = 8.4 Hz, 2H), 7.63 (d, J = 8.8 Hz, 2H), 7.20 (d, J =
16.4 Hz, 1H), 7.11 (d, J = 16.4 Hz, 1H), 6.96 (t, J = 7.2 Hz,
1H), 6.70 (s, 2H), 6.46 (t, J = 2 Hz, 1H), 3.85 (s, 6H).
3,5-Dimethoxy-trans-stilbene (5d):Yield 22.5 %. White
solid: 1H NMR (400 MHz CDCl3): δ ppm 7.55 (d, J = 7.6 Hz,
2H), 7.40 (t, J = 7.6 Hz, 2H), 7.31 (t, J = 17.2 Hz, 1H), 7.14
(d, J = 16.4 Hz, 1H), 7.08 (d, J = 16.4 Hz, 1H), 6.73 (d, J = 2
Hz, 2H), 6.45 (t, J = 2.4 Hz, 1H), 3.87 (s, 6H).
3,4,2'-Trimethoxy-trans-stilbene (7f): Yield 23.9 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.58 (d, J =
9.2 Hz, 1H), 7.33 (d, J = 16.4 Hz, 1H), 7.21 (t, J = 4.8 Hz,
1H), 7.10 (d, J = 1.6 Hz, 1H), 7.06 (d, J = 16.4 Hz, 1H), 7.05
(d, J = 8.4 Hz, 1H), 6.96 (t, J = 7.6 Hz, 1H), 6.90 (d, J = 8 Hz,
1H), 6.85 (d, J = 8.4 Hz, 1H), 3.95 (s, 3H), 3.90 (d, J = 1.2 Hz,
6H).
3,5,4'-Trimethoxy-trans-stilbene (6d): Yield 18.5 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.44 (d, J =
8.4 Hz, 2H), 7.04 (d, J = 16 Hz, 1H), 6.91 (t, J = 6.4 Hz, 3H),
6.65 (s, 2H), 6.37 (s, 1H), 3.83 (s, 9H).
3,5,2'-Trimethoxy-trans-stilbene (7d): Yield 23.2 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.57 (d, J =
7.6 Hz, 2H), 7.45 (d, J = 16.4 Hz, 1H), 7.22-7.26 (m, 1H),
7.04 (d, J = 16.4 Hz, 1H), 6.96 (t, J = 7.2 Hz, 1H), 6.90 (d, J =
8.4 Hz, 1H), 6.69 (d, J = 2 Hz, 2H), 6.38 (t, J = 2.4 Hz, 1H),
3.88 (s, 3H), 3.83 (s, 6H).
3,4,2',3'-Tetramethoxy-trans-stilbene (8f): Yield
19.6 %. White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.31
(d, J = 16.4 Hz, 1H), 7.22 (d, J = 9.6 Hz, 1H), 7.09 (d, J = 16.4
Hz, 1H), 7.09 (s, 1H), 7.08 (t, J = 6.4 Hz, 1H), 7.04 (d, J = 8
Hz, 1H), 6.87 (d, J = 8.8 Hz, 1H), 6.83 (d, J = 9.6 Hz, 1H),
3.95 (s, 3H), 3.91 (s, 3H), 3.89 (s, 3H), 3.86 (s, 3H).
General procedure for the preparation of compounds
(2b): The mixture of hydroxybenzoic acid (1b) (1 eq.), acetic
anhydride (5 eq.) and pyridine (6 mL) was stirred at room
temperature for 12 h. Then the cold H2SO4 (10 %) was slowly
added into the reaction mixture, the precipitate was filtered
off to give 2b which was dried for the next step.
3,5,2',3'-Tetramethoxy-trans-stilbene (8d): Yield
24.8 %. White solid: 1 H NMR (400 MHz CDCl3): δ ppm
7.42 (d, J = 16.4 Hz, 1H), 7.23 (d, J = 9.2 Hz, 1H), 7.06 (t, J =
9.2 Hz, 1H), 7.05 (d, J = 16.4 Hz, 1H), 6.84 (d, J = 9.6 Hz,
1H), 6.70 (d, J = 2 Hz, 2H), 6.4 (t, J = 2.4 Hz, 1H), 3.88 (s,
3H), 3.85 (s, 3H), 3.84 (s, 6H).
4-Methoxy-4'-bromo-trans-stilbene (1e):Yield 24.9 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.45 (d, J =
6.4 Hz, 2H), 7.43 (d, J = 6 Hz, 2H), 7.34 (d, J = 8.4 Hz, 2H),
7.04 (d, J = 16.4 Hz, 1H), 6.89 (d, J = 8.8 Hz, 2H), 6.89 (d,
J = 16.4 Hz, 1H), 3.83 (s, 3H).
General procedure for the preparation of compounds
(4b)28: To a stirred solution of 4-acetoxybenzoic acid (2b)
(1 eq.) was added thionyl chloride (10 mL 5 eq.). Then the
mixture was heated to reflux for 3 h. The reaction mixture
was removed the excessive thionyl chloride under reduced
pressure. The crude product (4b) was used directly for the
next step without further purification.
4-Methoxy-4'-chloro-trans-stilbene (2e):Yield 31.8 %.
White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.43 (d, J =
8.8 Hz, 2H), 7.40 (d, J = 8.4 Hz, 2H), 7.30 (d, J = 8.4 Hz, 2H),
7.02 (d, J = 16.4 Hz, 1H), 6.90 (d, J = 16.4 Hz, 1H), 6.89 (d,
J = 8.8 Hz, 2H), 3.83 (s, 3H).
General procedure for the preparation of compounds
(1f, 2f, 4f-6f): In a microwave reactor vial (20 mL), to solution
of styrene (9-12) (1.5 eq.) and reagent (3b-5b) (1 eq.) were
added tetrabutylammonium bromide (2 eq.), anhydrous
potassium carbonate (2.5 eq.) and Pd(OAc)2 (0.05 eq.) in DMF
(15 mL) under argon. The vial was placed into the microwave
cavity. The reaction mixture was irradiated at high level for
4 h at 100 °C then cooled to room temperature. The solution
was poured into 100 mL H2O and then extracted with ethyl
acetate. The organic layers were combined and washed with
water and brine, then dried with sodium sulphate anhydrous.
The removal of the solvent under reduced pressure provided
the crude which was purified by flash column chromatography
4-Methoxy-3'-nitro-trans-stilbene (3e): Yield 24.3 %.
Yellow solid: 1H NMR (400 MHz CDCl3): δ ppm 8.32 (s, 1H),
8.07 (t, J = 9.6 Hz, 1H), 7.75 (d, J = 8 Hz, 1H), 7.49 (t, J = 8.8
Hz, 1H), 7.48 (d, J = 8.8 Hz, 2H), 7.18 (d, J = 16.4 Hz, 1H),
6.98 (d, J = 16.4 Hz, 1H), 6.92 (d, J = 8.8 Hz, 2H), 3.84 (s,
3H).
4-Methoxy-4'-nitro-trans-stilbene (4e): Yield 17.1 %.
Orange solid: 1H NMR (400 MHz CDCl3): δ ppm 8.20 (d, J =
8.8 Hz, 2H), 7.60 (d, J = 8.4 Hz, 2H), 7.50 (d, J = 8.8 Hz, 2H),
7.23 (d, J = 16.4 Hz, 1H), 7.01 (d, J = 16.4 Hz, 1H), 6.95 (d,
J = 8.8 Hz, 2H), 3.85 (s, 3H).

Vol. 26, No. 7 (2014)
Synthesis and Bioactivity of Resveratrol Analogues 2095
(ether/ethyl acetate 40:1) and recrystallization from appropriate
solvents to afford compounds (1f, 2f, 4f-6f).
that was 1/10 th of the total volume of the Erlenmeyer growth
flask. These conditions provide maximal aeration for cell growth.
Inoculum titers were chosen to allow overnight incubation (16-
18 h) and harvesting of cells in mid-logarithmic phase;
balanced growth was attained at a titer of 1 × 107 cells/mL.
Only the starting flask culture that had been in balanced
exponential growth for at least three generations and that had
a budding frequency of 65-75 % were used to inoculate
microculture experiments.
3,5-Dimethoxy-4'-amino-trans-stilbene (1f): Yield
49.6 %. Yellow solid: 1H NMR (400 MHz CDCl3): δ ppm 7.33
(d, J = 8.4 Hz, 2H), 7 (d, J = 16.4 Hz, 1H), 6.84 (d, J = 16.4
Hz, 1H), 6.67 (d, J = 8.4 Hz, 2H), 6.63 (d, J = 2.4 Hz, 2H),
6.36 (t, J = 2.4 Hz, 1H), 3.82 (s, 6H), 3.75 (br, 2H).
4-Amino-trans-stilbene (2f):Yield 40.3 %.Yellow solid:
1H NMR (400 MHz DMSO): δ ppm 7.50 (d, J = 8 Hz, 2H),
7.32 (t, J = 7.6 Hz, 2H), 7.28 (d, J = 8.4 Hz, 2H), 7.18 (t, J =
7.2 Hz, 1H), 7.06 (d, J = 16.4 Hz, 1H), 6.89 (d, J = 16.4 Hz,
1H), 6.57 (d, J = 8.8 Hz, 2H), 5.32 (br, 2H).
Bioscreen C MBR Outgrowth: A Bioscreen C MBR
(Growth Curves USA, Piscataway, NJ) machine was used for
all outgrowth assays. For outgrowth of aged cells, 5 µL of the
starting flask culture was inoculated into 295 µL of richYPD
(2 % glucose, 2 % bactopeptone, 1 % yeast extract) medium
in a Bioscreen honeycomb 100-well plate (cat no. 9502550).
Incubation of the plate is kept constant at 30 °C, with the
shaking module set to high continuous shaking. Absorbance
readings at 600 nm (wideband range) are taken every 0.5 h for
24 h. OD data were normalized for background prior to
presentation by subtracting the initial OD value at t = 0 from
each subsequent OD reading.
General procedure for the preparation of compounds
3f: Sodium methoxide (0.1 eq.) was added to a solution of
compound (4f) (1 eq.) in THF (20 mL). The reaction mixture
was stirred for 10 h, followed by concentrated 2 M HCl to
acidification and evaporation in vacuo. The residue was
purified by silica gel column chromatography, eluting with a
solution of 1 % methanol in dichloromethane. Then the
compound 3f was obtained in 75.8 % yield. White solid: 1H
NMR (400 MHz CDCl3): δ ppm 7.51 (d, J = 7.2 Hz, 2H), 7.44
(d, J = 8 Hz, 2H), 7.37 (t, J = 7.6 Hz, 2H), 7.26 (t, J = 7.2 Hz,
1H), 7.08 (d, J = 16.4 Hz, 1H), 6.99 (d, J = 16.4 Hz, 1H), 6.86
(d, J = 8.8 Hz, 2H), 6.77 (br, 1H).
Yeast-based drug screening assay: The synthesized
compounds 1c-8f were screened for SIRT1 activators against
Yeast Parental strain-BY4743 at a concentration of 100 µM/L
by Bioscreen C MBR machine. For comparison, resveratrol
was used as the standard drugs. Compounds were added to
corresponding number of well to a final concentration of 100
µM/L. DMSO served as control and there was no visible change
in yeast growth due to this. The doubling time for each well in
a Bioscreen assay, δw was determined by the maximal slope
of the semilog plot of OD as a function of time. This value
was defined as the median of the three lowest δ values obtained
for every consecutive pair of OD measurements for that
well in that experiment (Fig. 1). The cell doubling times (in
hours) are measured at the maximal growth rate (µm), µ = Ln
(ODn/ODn-1)/tn-tn-1, µm is maximum, doubling time (δw) = Ln
(2)/µm (Fig. 2). The OD24h value show the total biomass in
stable phase (Fig. 3).
4-Acetoxy-trans-stilbene (4f):Yield 48.8 %. White solid:
1H NMR (400 MHz CDCl3): δ ppm 7.54 (d, J = 8.8 Hz, 2H),
7.53 (d, J = 8.4 Hz, 2H), 7.39 (t, J = 7.6 Hz, 2H), 7.29 (t, J =
7.6 Hz, 1H), 7.13 (d, J = 8.8 Hz, 2H), 7.12 (d, J = 16.4 Hz,
1H), 7.08 (d, J =16.4 Hz, 1H), 2.34 (s, 3H).
3,4-Methylenedioxy-4'-acetoxy-trans-stilbene (5f):
Yield 48.2 %. White solid: 1H NMR (400MHz CDCl3): δ ppm
7.40 (d, J = 8 Hz, 2H), 7.18 (d, J = 8 Hz, 2H), 7.08 (s, 1H),
7.00 (d, J = 16 Hz, 1H), 6.95 (d, J = 8 Hz, 1H), 6.93 (d, J = 16
Hz, 1H), 6.81 (d, J = 8 Hz, 1H), 6 (s, 2H), 2.38 (s, 3H).
3,4-Methylenedioxy-4'-methyl-trans-stilbene (6f):Yield
44.2 %. White solid: 1H NMR (400 MHz CDCl3): δ ppm 7.40
(d, J = 8 Hz, 2H), 7.18 (d, J = 8 Hz, 2H), 7.08 (s, 1H), 7.00 (d,
J = 16.4 Hz, 1H), 6.95 (d, J = 8 Hz, 1H), 6.93 (d, J = 16.4 Hz,
1H), 6.81 (d, J = 8 Hz, 1H), 5.99 (s, 2H), 2.38 (s, 3H).
Strains and media: Yeast strains used throughout this
study were Yeast Parental strain-BY4743 (Yeast Gene Sir2)
ordered from Thermoscientific, USA. Rich YPDA medium
was used for liquid culture of yeast strains, which were incu-
bated at 30 °C and handled by standardized methods of yeast
genetics15,16. Permanent stocks of yeast strains are maintained
in 50 % (v/v) glycerol at -80 °C. For routine use, an aliquot of
the frozen stock was streaked onto a YPDA agar plate and
incubated for 2 days to form single colonies. The genotype of
one independent colonies was tested by replica plating to
selective drop-out media and a single verified clonal isolate to
be used as a working stock was maintained on a YPDA agar
plate at 4 °C for no longer than 2 week. A loop full of cells
was taken from the working stock (agar plate), resuspended
in a small volume of medium and titered by hemacytometer
count for inoculation of a shake flask culture. Shake flask
cultures were incubated with orbital shaking at 300 rpm in an
Innova Model refrigerated, shaking incubator from New
Brunswick Scienti Wc Co. (New Brunswick, NJ) in a volume
RESULTS AND DISCUSSION
In this work, we use the Wittig-Horner and Heck reaction
to synthesis of resveratrol derivatives.A series of novel resvera-
trol analogues were synthesized. Compounds 1c-8e,7f, 8f.
Starting from hydroxybenzoic acid and methoxybenzoic acid,
the aromatic esters were prepared in moderate yield, followed
by reduction with LiAlH4. Subsequent treatment of aromatic
alcohol with tribromophosphine afforded benzyl bromine.
Using Wittig-Horner reaction, methoxylated diethyl benzyl-
phosphonates were obtained by refluxing benzyl bromine with
P(OEt)3, which were condensed withArCHO in CH3ONa/DMF
or NaH/THF (Scheme-I). Compounds 1f-6f were prepared
by aromatic alkenes was reacted with the benzonic acid chloride
or halogenated aromatic under palladium acetate catalysis with
Heck reaction (Scheme-II). Wittig-Horner and Heck reaction
reaction is considered as the key route to prepare a series of
resveratrol analogues, only the trans isomer was obtained, the
coupling constants of the vinylic protons of the trans-stilbenes
were about 16.4 Hz. Structures of these compounds were listed
in Table-1.

2096 Ao et al.
Asian J. Chem.
1.6
yeast (a)
(b)
1.6
1.4
1.2
yeast
Res
1d
Res
1c
2c
3c
4c
5c
6c
7c
8c
1.4
1.2
2d
1
3d
1
4d
0.8
0.6
0.4
0.2
5d
0.8
0.6
0.4
0.2
6d
7d
8d
0
0
0
2
4
6
8
10
12
14
16
18
20
22
24
0
2
4
6
8
10
12
14
16
18
20
22
24
Time (h)
Time (h)
1.6
1.6
1.4
1.2
yeast
Res
1f
yeast
Res
1e
(c)
(d)
1.4
1.2
2f
3f
2e
4f
3e
1
5f
1
4e
6f
5e
0.8
0.6
0.4
0.2
7f
0.8
0.6
0.4
0.2
6e
8f
7e
8e
0
0
0
2
4
6
8
10
12
14
16
18
20
22
24
0
2
4
6
8
10
12
14
16
18
20
22
24
Time (h)
Time (h)
Fig. 1. Exponentially growing cells were resuspended in yeast parental strain-BY4743 media containing all compounds concentration (100 µM/L) and
incubated for 24 h at 30 °C. Analysis of cell concentration by OD600, in the honeycomb 100-well plate, cells were deposited in triplicate and cell
growth was measured every 0.5 h for 24 h; (a) Growth curve of compound 1c -8c; (b) Growth curve of compound 1d -8d; (c) Growth curve of
compound 1e-8e; (d) Growth curve of compound 1f-8f
3
1.6
1.4
1.2
2.5
2
1
0.8
0.6
0.4
0.2
1.5
Res
yeast
f
1
e
c
d
d
0.5
c
e
Res
f
0
yeast
0
1
2
3
4
5
Tested compounds
6
7
8
1
2
3
4
5
6
7
8
Tested compounds
Fig. 3. OD value of 24h of tested compounds compared to the resveratrol
and yeast measured at the total biomass
Fig. 2. Cell doubling times of tested compounds compared to the resveratrol
and yeast measured at the maximal growth rate
COOH
R4
R1
R2
R5
CH2Br
CH2P(O)(OEt)2
(OCH3)n
CH2OH
V
R3
R1
R6
1c,2c,5c~8c
3 1d,2d,5d~8d
1e,2e,5e~8e
7f,8f
CHO
R6
IV
R2
3a-4a
II
III
R
4 R5
1~6
R
(OCH3)n
(OCH3)n
7a
n=1~3
COOCH3
9a
COOH
8a
R4
R5
1 R5,R6=H R4=Br
2 R5,R6=H R4=Cl
3 R4,R5,R6=H
4 R5,R6=H R4=OCH3
5 R6=OCH3 R4,R5=H
6 R5,R6=OCH3 R4=H
7 R4,R6=H R5=NO2
8 R5,R6=H R4=NO2
I
1a R2,R3=OH R1=H
2a R1,R3=OH R2=H
3a R1,R3=H R2=OCH3
4a R1,R2,R3=OCH3
5a R2,R3=OCH3 R1=H
6a R1,R3=OCH3 R2=H
R1
R3
R1
R3
R1
VI
CHO
R2
5a-6a
R6
R2
1a-2a
3c,4c
3d,4d,4e
R2
R4 R6
R5
R3
7~8
Scheme-I: Synthesis of stilbenes 7f, 8f and 1c-8e. Reagents and conditions: (i) (CH3O)2CO, Bu4NBr, DMF, K2CO3, 140 °C; (ii) LiAlH4, THF, 0 °C; (iii) PBr3,
CH2Cl2, rt; (iv) P(O)(OEt)3, 135 °C; (v) NaH, ArCHO, THF, 0 °C; (vi) CH3ONa, ArCHO, DMF, 100 °C

Vol. 26, No. 7 (2014)
Synthesis and Bioactivity of Resveratrol Analogues 2097
I
NH2
R1
NH2
3b
R2
1f,2f
OH
OAc
R3
COOH
COOH
COCl
IV
III
II
I
3f
4f
R2
R1
R3
OH
1b
OAc
2b
OAc
4b
R2
9~12
9
R ,R =OCH R =H
1
10 R ,R ,R =H
2
3
2
1
11 R ,R =H R =OAc
2
3
Br
O
1
3
2
O
5f,6f
12 R ,R =H R =CH
1 3 2 3
O
O
5b
Scheme-II: Synthetic pathway for compounds 1f-6f. Reagents and conditions: (i) Ac2O, pyridine, rt, 1.5 h; (ii) SOCl2, 80 °C, 3h; (iii) Bu4NBr, K2CO3,
Pd(OAc)2, DMF, 80 °C, 4h; (iv) NaOMe, THF, rt, 10h
TABLE-1
CHEMICAL STRUCTURES OF COMPONUD 1c-8f
This method provides growth curves comparable to traditional
one. If compounds can activate Sir2, leading to increase repli-
R6
R5
cative life span which could be measured through the visible
light absorption of cultural yeast strain, the results could be
recorded and showed by its growth curves.
R1
R4
R2
We found that the lag time of most of the yeast is about 4
h from the growth curve. The lag phase of resveratrol was
significantly faster than blank control. Compound 5d, 1e, 2e,
4e, 6e, 7e, 7f and 5f exerted a stronger promoting effect than
blank control respectively, indicating that these compounds
can shorten the lag time of the yeast, but much slower than
resveratrol; Compound 1c, 2c, 3c, 4c, 5c, 6c, 8c, 1d, 2d, 4d,
6d, 7d, 8d, 4e, 6f and 8f showed no activity than blank control,
respectively. Compound 7c, 3d, 3e, 8e, 2f, 4f, 3f and 1f
obviously inhibited the growth of yeast, significantly prolon-
ging the lag time of yeast, respectively.
1c-8f
R3
R3
Comp.
R1
R2
R4
Br
R5
R6
1c
2c
3c
4c
5c
6c
7c
8c
1d
2d
3d
4d
5d
6d
7d
8d
1e
2e
3e
4e
5e
6e
7e
8e
1f
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
H
OCH3 OCH3
OCH3 OCH3
OCH3 OCH3
OCH3 OCH3
OCH3 OCH3
OCH3 OCH3
OCH3 OCH3
OCH3 OCH3
H
H
H
H
H
H
H
H
Cl
H
NO2
H
NO2
H
H
OCH3
H
H
H
OCH
OCH3
H
H
Br
OCH3
H
H
H
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
H
Cl
H
H
H
H
NO2
H
H
Most of the tested compounds began to enter the logari-
thmic phase after 4 h. Each compound influenced the doubling
time of yeast shown in Fig. 2. The doubling time of resveratrol
obviously was less than blank control. Compound 7c, 1d, 2d,
6d, 7d, 8d and 8e was less than blank but faster than resveratrol,
respectively, indicating that these compounds exerted a
stronger promoting effect than resveratrol; Compounds 8c,
3d, 5d, 1e, 2e, 3e, 6e, 5f and 6f exerted moderate effect but
less activity compared to resveratrol, respectively. Compound
1c, 2c, 3c, 4c, 5c, 6c, 4d, 4e, 5e, 7e, 7f, 8f, 2f, 4f, 3f and 1f
restrained the growth of logarithmic phase of yeast, respec-
tively.
H
NO2
H
H
H
H
H
H
OCH3
H
H
H
H
H
OCH3
OCH3
H
H
H
Br
OCH3
H
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
H
H
H
H
Cl
H
H
H
H
H
NO2
H
H
H
H
NO2
H
H
H
H
H
H
H
H
OCH3
H
H
OCH3
OCH3
H
H
H
H
H
H
H
OCH3
H
OCH3
H
OCH3
H
NH2
NH2
OH
AcO
H
2f
H
H
Most of compounds came into stationary phase after 12 h.
OD value of between 12 and 24 h show stationary phase (Fig.
3). It was shown that the OD24 h value of resveratrol was higher
than blank. The microbial content within compound 2c, 4c,
5c, 2e, 7e and 7f was more than blank while the microbial
content of 5c, 2e, 7e and 7f was a little more than resveratrol,
respectively. Compound 3d, 4e, 8f, 1f, 2f, 4f, 5f and 6f showed
a stronger suppressive effect than blank control, respectively
as the microbial content of yeast was obviously less than blank.
The rest of the compound exerted moderate activities compared
to blank since the microbial count was about equal with the
blank control.
H
3f
H
H
H
H
H
4f
H
H
H
H
5f
H
AcO
CH3
OCH3
OCH3
H
—OCH2—
—OCH2—
H
H
6f
H
H
7f
OCH3
OCH3
H
H
H
H
OCH3
OCH3
OCH3
8f
H
Biological activities: Yeast as model of drug screening
for SIRT1actovators is convenient based on homology of yeast
Sir2 and human SIRT1. Here we reported a novel yeast-based
method for measuring yeast growth curves by monitoring
outgrowth of yeast cells using a Bioscreen C MBR machine.

2098 Ao et al.
Asian J. Chem.
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Compound 5d and 2e indeed significantly improved
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position of A ring except compound 4d shorten the doubling
time most over the blank control. In the B ring: amino, acetyl
and hydroxyl group strongly inhibited the yeast growth while
nitro group played weaker inhibition activity. The chloride
and methoxy at 1',2' positions promoted the yeast growth. In
view of a and b ring, the a ring may affect a certain period of
yeast but b ring may influence the whole period of yeast.
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ACKNOWLEDGEMENTS
Funding for this study was provided by National Natural
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