Design, synthesis and biological evaluation of hydroxamic acid derivatives as potential high density lipoprotein (HDL) receptor CLA-1 up-regulating agents

Article abstract of DOI:10.3390/molecules16119178

Trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA) were reported in our recent publication as novel human high density lipoprotein (HDL) receptor CD36 and Lysosomal integral membrane protein-II Analogous-1 (CLA-1) up-regulators. As part of a

Full text of DOI:10.3390/molecules16119178

Molecules 2011, 16, 9178-9193; doi:10.3390/molecules16119178
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Design, Synthesis and Biological Evaluation of Hydroxamic Acid
Derivatives as Potential High Density Lipoprotein (HDL)
Receptor CLA-1 Up-Regulating Agents
Xiaofang Chen *,†, Li Wang †, Yu Du, Yanbin Wu, Xiaojian Jia, Yuan Yang and Bin Hong *
Institute of Medicinal Biotechnology, Chinese Academy of Medical Sciences & Peking Union Medical
College, Beijing 100050, China; E-Mails: capricornkey@163.com (L.W.);
duyu1983@hotmail.com (Y.D.); wyblily@sina.com (Y.W.); xiaojianjia@yahoo.cn (X.J.);
yangyuan78@hotmail.com (Y.Y.)
† These authors contributed equally to this work.
* Authors to whom correspondence should be addressed; E-Mails: chenchemistry@hotmail.com (X.C.);
binhong69@hotmail.com (B.H.); Tel.: +86-10-8315-5803 (X.C.); +86-10-6302-8003 (B.H.);
Fax: +86-10-6301-7302.
Received: 30 September 2011; in revised form: 20 October 2011 / Accepted: 28 October 2011 /
Published: 2 November 2011
Abstract: Trichostatin A (TSA) and suberoylanilide hydroxamic acid (SAHA) were
reported in our recent publication as novel human high density lipoprotein (HDL) receptor
CD36 and Lysosomal integral membrane protein-II Analogous-1 (CLA-1) up-regulators. As
part of a broader effort to more fully explore the structure-activity relationships (SAR) of
CLA-1 up-regulators, we synthesized a series of hydroxamic acid derivatives and evaluated
their CLA-1 up-regulating activities in HepG2 cells. Some compounds exhibited over
10-fold up-regulation of CLA-1 expression in HepG2 cells at 10 µg/mL concentration. The
compound 1g showed the best potency, with a lower EC50 than TSA (EC50 = 0.32 µM
versus 1.2 µM). These compounds provide early new CLA-1 up-regulators with potential
for treating atherosclerosis.
Keywords: high density lipoprotein receptor; up-regulator; CLA-1; trichostatin A (TSA);
suberoylanilide hydroxamic acid (SAHA); hydroxamic acid

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1. Introduction
Atherosclerosis is one of the leading causes of mortality in industrialized and developing nations. It
is a progressive disease that is characterized by the accumulation of lipid-rich plaques within the walls
of arteries [1]. Long-term clinical studies have shown that plasma concentrations of high density
lipoprotein (HDL) cholesterol (HDL-C) are inversely proportional to the risk for atherosclerotic
cardiovascular disease. One of the major atheroprotective actions of HDL particles involves the
transport of excess cholesterol from peripheral tissues to the liver for excretion, a process known as reverse
cholesterol transport (RCT) [2]. HDL-mediated RCT represents a major target for the development of
innovative antiatherogenic strategies to reduce the risk of atherosclerotic cardiovascular disease.
Scavenger receptor class B type I (SR-BI) is the first molecularly well-defined HDL receptor in
mice [3], and its human homologue is CD36 and Lysosomal integral membrane protein-II
Analogous-1 (CLA-1) [4]. SR-BI/CLA-1 plays an important role in RCT by mediating selective
uptake of cholesteryl ester from peripheral tissues to the liver. The discovery of up-regulators of CLA-1
expression may benefit the further study of the mechanism of action of CLA-1 in human atherosclerotic
cardiovascular diseases and might have pharmacologic applications [5].
To obtain active compounds that can increase CLA-1 transcriptional level in liver cells, we
developed a cell-based reporter assay applicable for high-throughput screening (HTS) [6]. Using this
assay trichostatin A (TSA) was found to prominently up-regulate CLA-1 transcriptional activity [7].
Suberoylanilide hydroxamic acid (SAHA), an analogue of TSA, was also found to up-regulate CLA-1
transcriptional activity [7]. TSA and SAHA have some common pharmacophore characteristics, which
can be segmented into four parts: (i) a terminal aromatic unit (TAU); (ii) a connecting unit (CU);
(iii) a linker domain; and (iv) the hydroxamic acid group (HAG) (Figure 1) [8,9]. Small molecular
structure changes have been found to have significant impact on up-regulating activity. When the
hydroxamic acid group was replaced by a carboxyl and an acylamide, the two corresponding analogues
of TSA showed a 10-fold and a 250-fold decrease in maximal up-regulating fold compared with TSA,
respectively [10]. To better understand the SAR of hydroxamic acid compounds, to lay out a
foundation for potential up-regulators of CLA-1 expression, and to further explore the mechanism of
CLA-1/SR-BI promoter up-regulation we embarked on the design and synthesis of analogues library
of TSA and SAHA.
Figure 1. Structures of TSA, SAHA and designed compounds.
Linker
HAG
TAU
Linker
CU
CU
HAG
TAU
O
O
O
H
N
OH
OH
N
H
N
H
O
N
SAHA
TSA
O
O
H
H
N
N
OH
OH
N
N
( )n
Ar
N
H
( )n
( )m
N
H
O
O
R
n=1, or 2
m=1, or2
1a-i
n=1, or 2
2a-e
O
O
H
N
Ar'
OH
N
H
( )n
N
H
n=1,or 2
3a-o

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Based on TSA and SAHA, primarily the hydroxamic acid group was retained and the lead change
program focused on the linker and terminal aromatic units. In TSA the chain length between the CU
and the hydroxamic acid group is five atoms and it is six atoms for SAHA. Firstly we adjusted the
length of the linker to 4–5 carbon atoms based on SAHA to obtain compounds 1a-i. TSA has two
methyl groups on the linker part, so piperazine ring was introduced in different locations in the linker
in 2a-e, mainly based on SAHA, to investigate space tolerance. Furthermore we introduced a
benzylamino group to the linker part to synthesize compounds 3a-o to investigate its effect on
up-regulating activity. Compounds 12a-d with a carboxyl group replacing the hydroxamic acid group
of 3a-d were also investigated.
1.1. Chemistry
Scheme 1 shows the synthetic routes used to prepare the three series of hydroxamic acid compounds
1a-i, 2a-e and 3a-o. Reactions of adipic acid monoethyl ester or pimelic acid monoethyl ester 4 with
relevant amines using 1-ethyl-3-(3-dimethyllaminopropyl)carbodiimide hydrochloride (EDC·HCl) as a
coupling agent gave acylamides 5 [11], which were then reacted with hydroxylamine in the presence of
NaOH, yielding the desired targets 1a-i [12]. Bromoacetic acid or 3-bromopropionic acid 6 were reacted
with relevant amines using EDC·HCl to obtain acylamides 7, which were in turn reacted with
1-BOC-piperazine in the presence of K2CO3 to give 8. The BOC groups of compounds 8 were
deprotected with 3 N HCl to afford 9 [13], which were reacted with ethyl bromoacetate or ethyl
3-bromopropionate in the presence of K2CO3 to give 10 [14]. Compounds 10 were finally converted into
2a-e in the same way as described for 1a-i. Acylamides 7 with methyl 4-(aminomethyl)benzoate
hydrochloride in the presence of KHCO3 furnished 11, which were then converted to 3a-o according to
the synthetic method used for 1a-i.
Scheme 1. The synthesis route of objective compounds.
O
O
O
H
N
H
N
OH
b
a
( )n
HO
( )n
Ar
O
Ar
N
( )n
O
H
O
c
O
n=1,2
n=1,2
O
n=1,2
5
4
1a-i
O
O
7
O
O
d
a
N
N boc
( )n
Br
N
NH
N
H
( )n
( )n
N
H
N
Br
( )n
HO
H
R
b
8
R
R
O
6
9
O
H
N
OC2H5
O
OH
c
N
N
( )m
( )n
N
N
N
H
( )n
10
( )m
N
H
O
R
n=1, or 2
m=1, or2
R
2a-e
O
O
O
O
H
N
a
c
Br
Ar'
Ar'
Br
O
( )n
N
H
( )n
( )n
N
H
HO
11
7
6
e
b
O
O
O
O
H
N
H
N
Ar'
Ar'
NHOH
OH
( )n
( )n
N
H
N
H
12a-d
3a-o
Reagents: (a) EDC, ArNH2, CH2Cl2; (b) NH2OH·HCl, NaOH, MeOH; (c) NaHCO3, relevant amine,
CH3CN, reflux; (d) 3N HCl, CH3OH; (e) NaOH, THF/CH3OH.

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2. Results and Discussion
As exploratory screening of the synthesized compounds, we first evaluated the up-regulating of
CLA-1 expression activities in HepG2 cells at 10 µg/mL concentration. Tables 1–3 summarize the
activity data and inhibition rates of HDAC at 500 nM for the synthesized compounds as well as the
known up-regulators TSA and SAHA as positive controls.
Table 1. Up-regulating activities of CLA-1 expression in HepG2 cells and inhibition rate of
HDAC of compounds 1a-i.
O
H
N
OH
( )n
Ar
N
H
O
n=1,2
Up-regulating fold b
(SD c)
Inhibition rate
of HDAC (%) d
Cpd. a
1a
Ar
n
5.4
(1.4)
1
8.8
Cl
9.4
(1.3)
1b
1c
1d
1e
1
1
1
2
18.8
18.8
9.6
5.9
(1.8)
Cl
3.6
(0.3)
MeO
13.8
(2.1)
34.9
Cl
9.2
(2.3)
1f
2
23.2
Cl
13.3
(3.4)
1g
1h
2
2
2
92.1
51.2
10.4
(1.4)
Cl
15.7
(2.5)
1i
39.9
72.9
95.0
MeO
15.5
(0.5)
SAHA
TSA
35.7
(1.8)
b
a
All compounds tested were >95% pure by HPLC; All compounds were tested at 10 µg/mL
except that SAHA was at 2.5 µM and TSA at 3.0 µM; c Standard deviation; d All compounds were
tested at 500 nM.

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Table 2. Up-regulating activities of CLA-1 expression in HepG2 cells and inhibition rate of
HDAC of compounds 2a-e.
O
H
N
OH
N
N
( )m
( )n
N
H
O
R
n=1, or 2
m=1, or2
Up-regulating fold Inhibition rate
Cpd.
2a
R
H
n
2
2
1
1
1
m
1
(SD)
1.2
of HDAC (%)
5.4
(0.1)
1.1
2b
2,4-(OCH3)
1
7.2
5.6
5.9
8.6
(0.08)
1.1
2c
H
4-N(CH3)2
H
1
(0.1)
1.1
2d
1
(0.2)
1.1
2e
2
(0.1)
Table 3. Up-regulating activities of CLA-1 expression in HepG2 cells and inhibition rate of
HDAC of compounds 3a-o, 12a-d.
O
O
H
N
Ar'
R'
( )n
N
H
n=1,or 2
Up-regulating fold Inhibition rate
(SD)
Cpd.
3a
Ar’
n
1
R’
of HDAC (%)
10.1
(0.8)
NHOH
23.3
Cl
6.6
(0.02)
3b
1
NHOH
23.7
Cl
Cl
0.89
(0.05)
3c
1
1
NHOH
NHOH
34.2
28.0
12.4
(1.1)
3d
10.5
(0.6)
3e
3f
1
1
NHOH
NHOH
28.3
21.3
CH3O
CH3O
2.9
(0.4)
CH3O

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Table 3. Cont.
Up-regulating fold Inhibition rate
of HDAC (%)
Cpd.
3g
Ar’
n
1
R’
(SD)
8.1
(0.3)
NHOH
9.8
N
4.6
(0.1)
3h
3i
1
1
NHOH
NHOH
29.8
16.5
CH3O
5.0
(0.4)
CH3O
CH3O
1.9
(0.4)
3j
1
2
NHOH
NHOH
10.9
35.0
Cl
8.2
(1.6)
3k
13.4
(4.8)
3l
3m
3n
2
2
2
NHOH
NHOH
NHOH
45.7
25.5
13.0
Cl
5.2
(1.1)
CH3O
CH3O
1.4
(0.3)
CH3O
7.2
(1.8)
3o
2
1
NHOH
COOH
27.7
-
CH3O
1.5
(0.3)
12a
Cl
1.1
(0.02)
12b
1
COOH
-
Cl
Cl
1.1
(0.1)
12c
12d
1
1
COOH
COOH
-
-
1.2
(0.1)
Compounds 1a-i with a linker chain of four or five carbon atoms showed promising up-regulating
activity. In general, compounds 1e-i with five carbon atoms chain showed more powerful activity than
1a-d with 9.2~15.7 fold up-regulation. From the structural perspective, the carbon chain length has
great influence on up-regulating activity; the longer chain with five carbon atoms is more active than the
shorter one. Compounds 1a-e, 1g, 1i were selected for further studies to obtain their activity EC50 values.
Similarly compounds with five carbon atoms chain showed better activities than those with four carbon

Molecules 2011, 16
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atoms chain. Figure 2 shows that compound 1g with a 3-chloro substituent on the phenyl ring exhibited
the best up-regulating activity in terms of EC50, suggesting that the substitution of the phenyl ring
seemed to have significant impact on the up-regulating activity. Compound 1g has an EC50 value of
0.32 µM, which is much lower than those of the reference compounds TSA (EC50 = 1.2 µM) and
SAHA (EC50 = 2.1 µM), and more importantly, it showed much better up-regulating activity than both
reference compounds at low concentrations (at and below 1 µM).
Figure 2. The dose-response curves of compound 1g and SAHA.
In contrast, 2a-e incorporating a piperazine group on the linker part exhibited no up-regulating
activity, suggesting that the position 1 to 2 carbon atoms away from hydroxamic acid can’t tolerate the
bulky piperazine ring group.
To determine if the CLA-1 expression level was increased by 1g due to the up-regulation of
transcriptional activity, flow cytometry was performed to investigate the abundance of CLA-1 protein
levels in HepG2 cells with and without 1g treatment. The result showed that with treatment of
0.3 µM 1g, the protein level of CLA-1 was increased by 224.6% (Figure 3A), which was higher than
0.3 µM SAHA (63.5%). To test whether 1g enhanced the selective uptake of lipids from HDL by
increasing the expression of CLA-1, fluorescence-labeled DiI-HDL uptake after 12 h incubation with
HepG2 cells was measured in the presence or absence of 1g. 0.3 µM 1g promoted the uptake of
DiI-HDL into the HepG2 cells by 62.5% which was higher than 0.3 µM SAHA (24.1%) (Figure 3B).
Figure 3. Effect of compound 1g on CLA-1 expression and DiI-HDL uptake.

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Figure 3. Cont.
TSA was reported as a potent specific reversible inhibitor of mammalian histone deacetylase
(HDAC), leading to hyperacetylation of chromatin-associated histones and thereby open promoter loci
to permit interaction with transcription factors to promote gene expression [15]. SAHA was the first
HDAC inhibitor approved for treating cutaneous T cell lymphoma by FDA in 2006. It was reported
that there was a 30-fold increase in HDAC inhibitory activity progressing from aceto- to benzoyl
hydroxamic acid, with IC50 values of 625 and 25 µM, respectively (Figure 4) [16,17]. In addition,
MS-275 is under clinical trials and K-182 is powerful as HDAC inhibitors [18]. They all possess a
benzylamino group on the linker part. We also tried to introduce a benzylamino moiety into the linker
part to synthesize compounds 3a-o. Compounds 3a-o showed moderate activity. When n = 1, phenyl
3a, p-chloro phenyl 3d, p-methoxyphenyl 3e showed activity, with over 10-fold up-regulation at
10 µg/mL concentration, while 3b and 3c with chloro group substitution in the ortho and meta
positions show a great decline in activity. Likewise, 3,4-dimethoxyphenyl compound 3f also displayed
reduced activity. Benzyl or phenylethyl compounds 3h-3j were inferior to those with phenyl groups.
When n = 2, p-chlorophenyl derivative 3l was more potent than the o-chlorophenyl one 3k. The
3,4-dimethoxy-phenyl compound 3n showed a fourfold decrease in activity compared with the similar
p-methoxy-phenyl analog 3m.
Figure 4. Structures of HDAC inhibitors.
O
H
N
H
N
N
OH
O
N
H
NH
H
N
H
N
OH
O
OH
N
O
O
O
OH
HDAC IC50=625 µM
25 µM
MS-275
K-182
For 12a-d, the most notable observation is the lack of activity of all the carboxylic acid derivatives
tested; conversely, nearly all hydroxamic acid analogs showed promising up-regulating activity.
Consistent with our previous results [10], these results indicated that the hydroxamic acid group is
indispensable. For this series of compounds, substitution at the para-position of the phenyl ring is
preferred for good activity.
At present, there are only some clues that several known HDAC inhibitors such as TSA, SAHA and
sodium butyrate are active on CLA-1 up-regulating activity [7]. However, TSA up-regulated CLA-1
transcription with EC50 = 1.2 µM, which is much higher than its HDAC inhibition IC50 values (usually

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at nanomolar level). As the relationship between HDAC inhibition and CLA-1 transcriptional
upregulation is quite intriguing, we further detected the HDAC inhibitory activity of our compounds
using a HDAC Fluorimetric Assay kit (Enzo Life Science). At 10 nM, none of all 29 compounds
showed HDAC inhibition (<5% inhibition) except compound 1g (~25% inhibition), whereas TSA
exhibited ~60% inhibition at the same concentration (data not shown). At 500 nM, 1a-i and 3a-o
showed different HDAC inhibition rates ranging from 8.8% to 92.1% and compounds 2a-e showed
little inhibition (<8.6%) (Tables 1–3). Compound 1g showed the highest HDAC inhibition rate of
92.1% whereas TSA and SAHA exhibited 72.9% and 95.0% inhibition, respectively (Tables 1–3). The
HDAC inhibition activity of the compounds synthesized in the present study correlated positively to
their CLA-1 up-regulation activity on the whole, suggesting CLA-1 up-regulation may be dependent
on the HDAC inhibition. However, the activity of some compounds towards HDAC inhibition did not
correlate with the degree of up-regulation of CLA-1 promoter. This suggests that some of the
hydroxamic acid derivatives may affect CLA-1 transcription through mechanisms other than HDAC
inhibition in HepG2 cells. It will be interesting to determine the detailed relationship between HDAC
inhibition and the induction of CLA-1 transcription in future studies.
3. Experimental
3.1. General
All reagents and solvents were reagent grade or were purified by standard methods before use.
Melting points were determined in open capillaries on a RT-1 melting point apparatus (Tianjin Fenxi
Yiqichang, Tianjin, China) and are uncorrected. Column chromatography was carried out on flash MCI
GEL 20Y. 1H-NMR spectra analysis was performed on a Varian Inova 400 MHz spectrometer (Varian,
Palo Alto, CA, USA), using DMSO-d6 as solvent and Me4Si as the internal standard. Chemical shifts
(δ values) and coupling constants (J values) are given in ppm and Hz, respectively. ESI high-resolution
mass spectra (HRMS) analysis was recorded on an Autospec Ultima-TOF mass spectrometer (Micromass
UK Ltd., Manchester, UK). All the HRMS data were within 5 ppm of calculated values.
3.2. General Procedure for the Amide Bond Formation (Scheme 1, step a)
A solution of aniline (1.86 g, 20.0 mmol) in CH2Cl2 (10.0 mL) was added dropwise to a cooled (−5 °C)
solution of 3-bromopropionic acid (3.06 g, 20.0 mmol) and EDC·HCl (3.84 g, 20.0 mmol) in CH2Cl2
(20.0 mL). The mixture was allowed to warm at room temperature and stirred overnight. The progress of
the reaction was monitored by Thin-Layer Chromatography (TLC; eluent: dichloromethane/ethyl
acetate 5:1). After disappearance of the starting material, the mixture was washed with 1 mol/L
HCl (30 mL), 5% solution of Na2HCO3 (30 mL) and brine. The organic layer was dried over anhydrous
sodium sulfate and concentrated to give the crude material (about 60% yield) which was used for the
next reaction.
3.3. General Procedure for the Amine Bond Formation (Scheme 1, step c)
The corresponding bromide (10.0 mmol), methyl 4-(aminomethyl)benzoate hydrochloride (2.02 g,
10.0 mmol) and potassium bicarbonate (1.50 g, 15.0 mmol) were dissolved in CH3CN (100 mL). The

Molecules 2011, 16
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solution was stirred at reflux for 3–4 h, and then concentrated under reduced pressure. To the residue
was added water and ethyl acetate. HCl solution (1 mol/L) was added to organic layer and precipitate
was filtered. The sediment was dried (about 50% yield) and used for the next reaction.
3.4. General Procedure for Boc Deblocking (Scheme 1, step d)
Concentrated HCl (15 mL) was dropped into a solution of the corresponding BOC protected
compound (5.82 mmol) in ethyl alcohol (50 mL), and the mixture was stirred for 16 h at room
temperature. Saturated solution of NaHCO3 was added to pH > 8. The solution was concentrated under
reduced pressure and the residue was extracted with ethyl acetate. The organic layer was concentrated
under reduced pressure and provided the desired product as a yellow oil (about 80% yield).
3.5. General Procedure for the Synthesis of Hydroxamic Acids from Methyl Esters (Scheme 1, step b)
The corresponding methyl or ethyl esters 5, 10, 11 (5.0 mmol), hydroxylamine hydrochloride (280 mg,
4 mmol) were dissolved in MeOH (50 mL), and then 8 mol/L NaOH solution (10 mL) was added. The
solution was stirred at ambient temperature for 1~2 h. To the solution was added 1 mol/L HCl
(50 mL) at 0 °C until pH = 7~8, then the solution was concentrated under reduced pressure. The residue
was purified by flash chromatography MCI GEL 20Y (water/methanol) to get the target compounds
1a-i, 2a-e, 3a-o.
Adipoyl anilide hydroxamic acid (1a). A yellowish solid, 670 mg, yield: 59.2%; m.p. 180–181.5 °C;
1H-NMR: 1.52 (4H, m, 2CH2), 1.96 (2H, t, J = 6.8, CH2), 2.28 (2H, t, J = 6.8, CH2), 7.00 (1H, t, J = 8.0,
Ar-H), 7.27 (2H, t, J = 8.0, Ar-H), 7.55 (2H, d, J = 8.0, Ar-H), 8.65 (1H, s, CONHOH), 9.84 (1H, s,
NHCO), 10.34 (1H, s, CONHOH); MS (ESI) m/z: 237 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for
C12H17N2O3, 237.1234; found, 237.1227.
Adipoyl (3-chlorophenyl)amide hydroxamic acid (1b). A khaki solid, 712 mg, yield: 67.4%; m.p.
169–171 °C; 1H-NMR: 1.52 (4H, m, 2CH2), 1.96 (2H, t, J = 6.8, CH2), 2.29 (2H, t, J = 6.8, CH2), 7.07
(1H, d, J = 8.0, Ar-H), 7.30 (1H, t, J = 8.0, Ar-H), 7.42 (1H, d, J = 8.0, Ar-H), 7.81 (1H, s, Ae-H), 8.65
(1H, s, CONHOH), 10.05 (1H, s, NHCO), 10.34 (1H, s, CONHOH). MS (ESI) m/z: 271 (M+H)+; HRMS
(ESI) m/z: (M+H)+ calcd. for C12H16ClN2O3, 271.0849; found, 271.0839.
Adipoyl (4-chlorophenyl)amide hydroxamic acid (1c). A white solid, 543 mg, yield: 71.0%; m.p.
176–177 °C; 1H-NMR: 1.52 (4H, m, 2CH2), 1.96 (2H, t, J = 6.8, CH2), 2.28 (2H, t, J = 6.8, CH2), 7.32
(2H, d, J = 8.8, Ar-H), 7.60 (2H, d, J = 8.8, Ar-H), 8.65 (1H, s, CONHOH), 9.99 (1H, s, NHCO), 10.33
(1H, s, CONHOH); MS (ESI) m/z: 271 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C12H16ClN2O3,
271.0849; found, 271.0836.
Adipoyl (4-methoxybenzyl)amide hydroxamic acid (1d). A khaki solid, 398 mg, yield: 35.9%; m.p.
1
140–142 °C; H-NMR: 1.46 (4H, m, 2CH2), 1.93 (2H, t, J = 6.8, CH2), 2.09 (2H, t, J = 6.8, CH2), 3.71
(3H, s, OCH3), 4.16 (2H, d, J = 6.0, CH2NH), 6.86 (2H, d, J = 8.4, Ar-H), 7.14 (2H, d, J = 8.4, Ar-H),
8.21 (1H, t, J = 6.0, NHCO), 8.65 (1H, s, CONHOH), 10.34 (1H, s, CONHOH); MS (ESI) m/z: 281
(M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C14H21N2O4, 281.1496; found, 281.1487.

Molecules 2011, 16
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Pimeloyl anilide hydroxamic acid (1e). A khaki solid, 666 mg, yield: 75.8%; m.p. 148–150 °C;
1H-NMR: 1.26 (2H, m, CH2), 1.53 (4H, m, 2CH2), 1.93 (2H, t, J = 7.2, CH2), 2.27 (2H, t, J = 7.2, CH2),
7.00 (1H, t, J = 8.0, Ar-H), 7.26 (2H, t, J = 8.0, Ar-H), 7.57 (2H, d, J = 8.0, Ar-H), 8.64 (1H, s,
CONHOH), 9.83 (1H, s, NHCO), 10.31 (1H, s, CONHOH); MS (ESI) m/z: 251 (M+H)+; HRMS (ESI)
m/z: (M+H)+ calcd. for C13H18N2O3, 251.1390; found, 251.1385.
Pimeloyl (2-chlorophenyl)amide hydroxamic acid (1f). A white solid, 359 mg, yield: 43.8%; m.p.
1
62–64 °C; H-NMR: 1.28 (2H, m, CH2), 1.47 (4H, m, 2CH2), 1.92 (2H, m, CH2), 2.33 (2H, m, CH2),
7.17 (1H, m, Ar-H), 7.30 (1H, t, J = 7.2, Ar-H), 7.47 (1H, m, Ar-H), 7.65 (1H, d, J = 7.2, Ar-H), 8.64
(1H, s, CONHOH), 9.43 (1H, s, NHCO), 10.32 (1H, s, CONHOH); MS (ESI) m/z: 285 (M+H)+; HRMS
(ESI) m/z: (M+H)+ calcd. for C13H18ClN2O3, 285.1001; found, 285.0995.
Pimeloyl (3-chlorophenyl)amide hydroxamic acid (1g). A white solid, 723 mg, yield: 77.2%; m.p.
138–140 °C; 1H-NMR: 1.25 (2H, m, CH2), 1.53 (4H, m, 2CH2), 1.93 (2H, t, J = 7.2, CH2), 2.29 (2H, t,
J = 7.2, CH2), 7.06 (1H, dd, J = 8.0, 2.0, Ar-H), 7.30 (1H, t, J = 8.0, Ar-H), 7.42 (1H, d, J = 8.0, Ar-H),
7.81 (1H, t, J = 2.0, Ar-H), 8.64 (1H, s, CONHOH), 10.04 (1H, s, NHCO), 10.31 (1H, s, CONHOH);
MS (ESI) m/z: 285 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C13H18ClN2O3, 285.1001;
found, 285.0994.
Pimeloyl (4-chlorophenyl)amide hydroxamic acid (1h). A white solid, 219 mg, yield: 53.3%; m.p.
161–162 °C; 1H-NMR: 1.25 (2H, m, CH2), 1.53 (4H, m, 2CH2), 1.93 (2H, t, J = 7.6, CH2), 2.28 (2H, t,
J = 7.6, CH2), 7.32 (2H, d, J = 8.8, Ar-H), 7.60 (2H, d, J = 8.8, Ar-H), 8.63 (1H, s, CONHOH), 9.98 (1H,
s, NHCO), 10.31 (1H, s, CONHOH); MS (ESI) m/z: 285 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for
C13H18ClN2O3, 285.1001; found, 285.0995.
Pimeloyl (4-methoxybenzyl)amide hydroxamic acid (1i). A white solid, 441 mg, yield: 41.7%; m.p.
133–135 °C; 1H-NMR: 1.20 (2H, m, CH2), 1.47 (4H, m, 2CH2), 1.91 (2H, t, J = 7.2, CH2), 2.08 (2H, t,
J = 7.2, CH2), 3.71 (3H, s, OCH3), 4.16 (2H, d, J = 5.6, CH2NH), 6.86 (2H, d, J = 8.8, Ar-H), 7.14 (2H,
d, J = 8.8, Ar-H), 8.22 (1H, t, J = 5.6, NHCO); MS (ESI) m/z: 295 (M+H)+; HRMS (ESI) m/z: (M+H)+
calcd. for C15H23N2O4, 295.1657; found, 295.1645.
N-Hydroxy-2-(4-phenylcarbamoylethyl-piperazin-1-yl)-acetamide (2a). A white solid, 35 mg, yield:
1
62.4%; m.p. 75–77 °C. H-NMR: 2.42–2.61 (12H, m, 6CH2), 3.28 (2H, s, CH2), 7.01 (1H, t, J = 7.6,
Ar-H), 7.26 (2H, m, Ar-H), 7.55 (2H, d, J = 8.0, Ar-H), 10.06 (1H, m, NHCO); MS (ESI) m/z: 307
(M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C15H23N4O3, 307.1765; found, 307.1754.
N-Hydroxy-2-{4-[(3,4-dimethoxyphenylcarbamoyl)-ethyl]piperazin-1-yl}acetamide (2b). A yellowish
solid, 21 mg, yield: 54.9%; m.p. 69–71 °C; 1H-NMR: 2.39–2.58 (12H, m, 6CH2), 3.28 (2H, s, CH2),
3.69 (3H, s, OCH3), 3.70 (3H, s, OCH3), 6.85 (1H, d, J = 8.8, Ar-H), 7.04 (1H, m, Ar-H), 7.27 (1H, d,
J = 2.0, Ar-H), 9.94 (1H, m, NHCO); MS (ESI) m/z: 367 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for
C17H27N4O5, 367.1976; found, 367.1966.
N-Hydroxy-2-(4-phenylcarbamoylmethylpiperazin-1-yl)acetamide (2c). A yellowish solid, 13 mg, yield:
79.8%; m.p. 56–58 °C; 1H-NMR: 2.41–2.73 (8H, m, 4CH2), 3.09 (2H, s, CH2), 3.10 (2H, s, CH2), 7.04

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(1H, t, J = 7.6, Ar-H), 7.26 (2H, m, Ar-H), 7.55 (2H, d, J = 8.0, Ar-H), 9.64 (1H, s, NHCO); MS (ESI)
m/z: 293 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C14H21N4O3, 293.1608; found, 293.1598.
N-Hydroxy-2-{4-[(4-dimethylaminophenylcarbamoyl)methyl]piperazin-1-yl}acetamide (2d). A white
1
solid, 33 mg, yield: 44.4%; m.p. 217–219 °C; H-NMR: 2.48 (4H, m, 2CH2), 2.83 (10H, m, 2CH2,
2CH3), 3.03 (2H, s, CH2), 3.30 (3H, s, OCH3), 6.67 (2H, d, J = 9.2, Ar-H), 7.39 (2H, d, J = 9.2, Ar-H),
9.33 (1H, s, NHCO); MS (ESI) m/z: 336 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C16H26N5O3,
336.2030; found, 336.2018.
N-Hydroxy-3-(4-phenylcarbamoylmethylpiperazin-1-yl)propionamide (2e). A white solid, 29 mg, yield:
65.1%; m.p. 55–57 °C; 1H-NMR: 2.23 (2H, m, CH2), 2.51–2.64 (10H, m, 5CH2), 3.18 (2H, s, CH2), 7.06
(1H, t, J = 7.6, Ar-H), 7.31 (2H, m, Ar-H), 7.55 (2H, d, J = 7.6, Ar-H), 8.77 (1H, s, CONHOH), 9.75
(1H, s, NHCO), 10.46 (1H, s, CONHOH); MS (ESI) m/z: 307 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd.
for C15H23N4O3, 307.1765; found, 307.1753.
N-Hydroxy-4-{[(phenylcarbamoylmethyl)amino]methyl}benzamide (3a). A white solid, 67 mg, yield:
1
47.7%; m.p. 124–126 °C. H-NMR: 3.26 (2H, s, CH2CO), 3.77 (2H, s, NHCH2), 7.01–7.71 (9H, m,
Ar-H), 9.80 (1H, s, CONH); MS (ESI) m/z: 300 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for
C16H18N3O3, 334.0953; found, 334.0952.
N-Hydroxy-4-{[(2-chlorophenylcarbamoylmethyl)amino]methyl}benzamide (3b). A white solid, 72 mg,
1
yield: 57.0%; m.p. 160–162 °C; H-NMR: 3.31 (2H, s, CH2CO), 3.82 (2H, s, NHCH2), 7.12 (1H, m,
Ar-H), 7.33 (1H, m, Ar-H), 7.45 (2H, d, J = 8.0, Ar-H), 7.50 (1H, m, Ar-H), 7.71 (2H, d, J = 8.0, Ar-H),
8.24 (1H, m, Ar-H), 8.98 (1H, s, CONHOH), 10.05 (1H, s, NHCO), 11.15 (1H, s, CONHOH); MS (ESI)
m/z: 334 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C16H17ClN3O3, 334.0953; found, 334.0952.
N-Hydroxy-4-{[(3-chlorophenylcarbamoylmethyl)amino]methyl}benzamide (3c). A yellowish solid, 45 mg,
1
yield: 66.4%; m.p. 127–129 °C; H-NMR: 3.27 (2H, s, CH2CO), 3.76 (2H, s, NHCH2), 7.09 (1H, d,
J = 8.0, Ar-H), 7.32 (1H, t, J = 8.0, Ar-H), 7.41 (2H, d, J = 8.0, Ar-H), 7.48 (1H, d, J = 8.0, Ar-H), 7.70
(2H, d, J = 8.0, Ar-H), 7.84 (1H, s, Ar-H), 9.99 (1H, s, NHCO); MS (ESI) m/z: 334 (M+H)+; HRMS
(ESI) m/z: (M+H)+ calcd. for C16H17ClN3O3, 334.0953; found, 334.0957.
N-Hydroxy-4-{[(4-chlorophenylcarbamoylmethyl)amino]methyl}benzamide (3d). A white solid, 67 mg,
1
yield: 31.9%; m.p. 162–163 °C; H-NMR: 3.26 (2H, s, CH2CO), 3.77 (2H, s, NHCH2), 7.34 (2H, d,
J = 8.4, Ar-H), 7.42 (2H, d, J = 8.0, Ar-H), 7.64 (2H, d, J = 8.4, Ar-H), 7.70 (2H, d, J = 8.0, Ar-H), 8.97
(1H, s, CONHOH), 9.94 (1H, s, NHCO), 11.14 (1H, s, CONHOH); MS (ESI) m/z: 334 (M+H)+; HRMS
(ESI) m/z: (M+H)+ calcd. for C16H17ClN3O3, 334.0953; found, 334.0953.
N-Hydroxy-4-{[(4-methoxyphenylcarbamoylmethyl)amino]methyl}benzamide (3e). A white solid, 38 mg,
1
yield: 68.9%; m.p. 156–157 °C; H-NMR: 2.79 (1H, brs, NH), 3.22 (2H, s, CH2CO), 3.71 (3H, s,
OCH3), 3.76 (2H, s, NHCH2), 6.86 (2H, d, J = 8.8, Ar-H), 7.42 (2H, d, J = 8.0, Ar-H), 7.50 (2H, d,
J = 8.8, Ar-H), 7.70 (2H, d, J = 8.0, Ar-H), 8.96 (1H, s, CONHOH), 9.66 (1H, s, NHCO), 11.14 (1H, s,
CONHOH); MS (ESI) m/z: 330 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C17H20N3O4, 330.1448;
found, 330.1448.

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N-Hydroxy-4-{[(3,4-dimethoxyphenylcarbamoylmethyl)amino]methyl}benzamide (3f). A white solid,
35 mg, yield: 57.3%; m.p. 175–177 °C; 1H-NMR: 3.16 (2H, s, CH2CO), 3.70 (3H, s, OCH3), 3.71 (3H,
s, OCH3), 3.78 (2H, s, NHCH2), 6.86 (1H, d, J = 8.8, Ar-H), 7.12 (1H, dd, J = 8.8, 2.0, Ar-H), 7.30 (1H,
d, J = 2.0, Ar-H), 7.43 (2H, d, J = 8.0, Ar-H), 7.71 (2H, d, J = 8.0, Ar-H), 8.97 (1H, s, CONHOH), 9.65
(1H, s, NHCO), 11.15 (1H, s, CONHOH); MS (ESI) m/z: 360 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd.
for C18H22N3O5, 360.1554; found, 360.1543.
N-Hydroxy-4-{[(4-dimethylaminephenylcarbamoylmethyl)amino]methyl}benzamide (3g). A white solid,
17 mg, yield: 21.0%; m.p. 116–118 °C; 1H-NMR: 2.83 (6H, s, 2NCH3), 3.20 (2H, s, NHCH2), 3.76 (2H,
s, NHCH2), 6.67 (2H, d, J = 9.2, Ar-H), 7.41 (4H, m, Ar-H), 7.70 (2H, d, J = 8.0, Ar-H), 8.97 (1H, s,
NHCO), 9.50 (1H, s, CONHOH), 11.19 (1H, s, CONHOH); MS (ESI) m/z: 343 (M+H)+; HRMS (ESI)
m/z: (M+H)+ calcd. for C18H23N4O3, 343.1765; found, 343.1777.
N-Hydroxy-4-{[(4-methoxybenzylcarbamoylmethyl)amino]methyl}benzamide (3h). A white solid,
31 mg, yield: 60.2%; m.p. 71–73 °C; 1H-NMR: 3.09 (2H, s, CH2CO), 3.69 (2H, s, NHCH2), 3.71 (3H, s,
OCH3), 4.22 (2H, d, J = 6.0, CH2), 6.86 (2H, d, J = 8.4, Ar-H), 7.16 (2H, d, J = 8.4, Ar-H), 7.38 (2H, d,
J = 8.4, Ar-H), 7.68 (2H, d, J = 8.4, Ar-H), 8.22 (1H, t, J = 6.0, NHCO), 8.96 (1H, s, CONHOH), 11.14
(1H, s, CONHOH); MS (ESI) m/z: 344 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C18H22N3O4,
344.1605; found, 344.1605.
N-Hydroxy-4-{[(phenethylcarbamoylmethyl)amino]methyl}benzamide (3i). A yellow solid, 53 mg,
yield: 57.7%; m.p. 114–116 °C; 1H-NMR: 2.72 (2H, t, J = 7.2, NHCH2CH2), 3.02 (2H, s, CH2CO), 3.31
(2H, t, J = 7.2, CH2CH2Ph), 3.62 (2H, s, NHCH2), 7.15–7.40 (7H, m, Ar-H), 7.68 (2H, d, J = 8.0, Ar-H),
7.84 (1H, m, NH), 8.97 (1H, s, CONHOH), 11.15 (1H, s, CONHOH); MS (ESI) m/z: 328 (M+H)+;
HRMS (ESI) m/z: (M+H)+ calcd. for C18H22N3O3, 328.1656; found, 328.1651.
N-Hydroxy-4-{[(3,4-dimethoxyphenethylcarbamoylmethyl)amino]methyl}benzamide (3j). A white solid,
21 mg, yield: 37.9%; m.p. 123–125 °C. 1H-NMR: 2.65 (2H, t, J = 7.2, NHCH2), 3.02 (2H, s, CH2CO),
3.30 (2H, t, J = 7.2, ArCH2), 3.61 (2H, s, NHCH2), 3.69 (3H, s, OCH3), 3.71 (3H, s, OCH3), 6.69 (1H, m,
Ar-H), 6.80 (2H, m, Ar-H), 7.31 (1H, d, J = 2.0, Ar-H), 7.80 (1H, t, J = 5.6, NHCO); MS (ESI) m/z: 388
(M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C20H26N3O5, 388.1867; found, 388.1856.
N-Hydroxy-4-{[(2-chlorophenylcarbamoylethyl)amino]methyl}benzamide (3k). A white solid, 29 mg,
1
yield: 71.5%; m.p. 57–59 °C; H-NMR: 2.48 (2H, t, J = 6.0, COCH2CH2), 2.79 (2H, t, J = 6.0,
CH2CH2NH), 3.80 (2H, s, NHCH2), 7.11 (1H, t, J = 7.6, Ar-H), 7.29 (1H, t, J = 7.6, Ar-H), 7.41 (2H, d,
J = 8.0, Ar-H), 7.45 (2H, d, J = 8.0, Ar-H), 7.69 (2H, d, J = 8.0, Ar-H), 7.98 (2H, d, J = 8.0, Ar-H), 8.96
(1H, s, CONHOH), 10.51 (1H, s, CONH), 11.14 (1H, s, CONHOH); MS (ESI) m/z: 348 (M+H)+; HRMS
(ESI) m/z: (M+H)+ calcd. for C17H19ClN3O3, 348.1110; found, 348.1123.
N-Hydroxy-4-{[(4-chlorophenylcarbamoylethyl)amino]methyl}benzamide (3l). A khaki solid, 47 mg,
1
yield: 66.0%; m.p. 161–163 °C; H-NMR: 2.46 (2H, t, J = 6.8, COCH2CH2), 2.76 (2H, t, J = 6.8,
CH2CH2NH), 3.72 (2H, s, NHCH2), 7.34 (4H, m, Ar-H), 7.59 (2H, d, J = 8.8, Ar-H), 7.69 (2H, d, J = 8.0,

Molecules 2011, 16
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Ar-H), 10.17 (1H, s, CONH); MS (ESI) m/z: 348 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for
C17H19ClN3O3, 348.1109; found, 348.1102.
N-Hydroxy-4-{[(4-methoxy-phenylcarbamoyl-ethyl)-amino]methyl}benzamide (3m). A white solid,
13 mg, yield: 59.9%; m.p. 173–175 °C; 1H-NMR: 2.43 (2H, t, J = 6.4, COCH2CH2), 2.76 (2H, t, J = 6.4,
CH2CH2NH), 3.71 (3H, s, OCH3), 3.75 (2H, s, NHCH2), 6.85 (2H, d, J = 9.2, Ar-H), 7.39 (2H, d, J = 8.0,
Ar-H), 7.47 (2H, d, J = 9.2, Ar-H), 7.69 (2H, d, J = 8.0, Ar-H), 8.97 (1H, s, CONHOH), 9.87 (1H, s,
CONH), 11.14 (1H, s, CONHOH); MS (ESI) m/z: 344 (M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for
C18H22N3O4, 344.1605; found, 344.1594.
N-Hydroxy-4-{[(3,4-dimethoxyphenylcarbamoylethyl)amino]methyl}benzamide (3n). A white solid,
1
26 mg, yield: 44.3%; m.p. 175–176 °C; H-NMR: 2.72 (2H, t, J = 7.2, NHCH2CH2), 3.02 (2H, s,
CH2CO), 3.31 (2H, t, J = 7.2, CH2CH2Ph), 3.62 (2H, s, NHCH2), 7.15–7.40 (7H, m, Ar-H), 7.68 (2H, d,
J = 8.0, Ar-H), 7.84 (1H, m, NH), 8.97 (1H, s, CONHOH), 11.15 (1H, s, CONHOH); MS (ESI) m/z: 374
(M+H)+; HRMS (ESI) m/z: (M+H)+ calcd. for C19H24N3O5, 374.1711; found, 374.1713.
N-Hydroxy-4-{[(4-methoxybenzylcarbamoylethyl)amino]methyl}benzamide (3o). A khaki solid, 32 mg,
1
yield: 52.9%; m.p. 152–154 °C; H-NMR: 2.28 (2H, t, J = 6.8, COCH2CH2), 2.69 (2H, t, J = 6.8,
CH2CH2NH), 3.70 (2H, s, NHCH2), 3.71 (3H, s, OCH3), 4.17 (2H, d, CH2NHCO), 6.84 (2H, d, J = 8.8,
Ar-H), 7.15 (2H, d, J = 8.8, Ar-H), 7.34 (2H, d, J = 8.0, Ar-H), 7.68 (2H, d, J = 8.0, Ar-H), 8.32 (1H, t,
J = 5.6, CONH),8.96 (1H, s, CONHOH), 11.14 (1H, s, CONHOH); MS (ESI) m/z: 358 (M+H)+; HRMS
(ESI) m/z: (M+H)+ calcd. for C19H24N3O4, 358.1761; found, 358.1771.
3.6. CLA-1 Up-Regulating Activity
CLA-1 up-regulating activity was analyzed as described previously [14]. Briefly, HepG2 cells
stably transfected with pGL3-CLAP containing CLA-1 promoter region were seeded in 96-well plates
at 5 × 104 number/well in MEM (Hyclone, Logan, UT, USA) (100 µL) containing 10% FBS (Hyclone)
and 600 µg/mL G418 (Invitrogen, Carlsbad, CA, USA). With ~80% confluence, the cells were washed
once with PBS (pH 7.3, 137 mM NaCl, 2.7 mM KCl, 4.3 mM Na2HPO4, 1.4 mM KH2PO4), followed by
incubation with MEM (200 µL) containing 0.1% vehicle (DMSO), positive control (2.5 µM SAHA or
3.0 µM TSA) or 10 µg/mL compounds. After 18 h incubation at 37 °C, cells were washed with PBS, and
then the luciferase activity was detected using the Luciferase Assay System (Promega, Madison, WI,
USA). EC50 values of the compounds were determined by a dose-response assay. Briefly, the above
mentioned HepG2 cells were treated with the indicated concentrations of the compounds and detected
by luciferase assay. The does-response curves were obtained and the apparent EC50 value for each
compound was calculated using Sigma Plot 9.0.
3.7 Analysis for Cell Surface Expression by Flow Cytometry
Cell surface expression of CLA-1 was analyzed by flow cytometry as described previously [7].
Briefly, HepG2 cells were plated in 24-well dishes at 50,000 cells/well, followed by treatment for 24 h
with 0.3 µM compounds or vehicle (0.1% DMSO). Then HepG2 cells were trypsinized from the plate,
washed and resuspended in 4% paraform fixing solution, incubated overnight at 4 °C. After fixing,

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cells were blocked for 15 min at 4 °C in PBS containing 5% FBS. Cells were then incubated with
monoclonal antibody to CLA-1 (BD Biosciences, San Jose, CA, USA) at a final dilution of 1:50 (4 °C,
1 h), followed by washing and staining with FITC-conjugated goat antibody to mouse IgG (1:100
dilution, 4 °C, 1 h). The cell suspension was centrifuged (800 × g, 3 min, 4 °C), the pellet was
resuspended in PBS, and fluorescence intensity was analyzed using a BD FACSCalibur flow cytometer
(BD Biosciences).
3.8 Analysis of Cellular Uptake of DiI-labeled HDL by Flow Cytometry
For the cellular DiI-HDL uptake by HepG2 cells assays, the cell pretreatment was the same as for
the cell surface expression assay. Cells were incubated with DiI-HDL (2 µg/mL) and 0.3 µM
compounds or vehicle for 12 h at 37 °C, then washed with PBS and incubated with PBS containing 0.5%
bovine serum albumin (BSA) and 2 mM EDTA for 1 h at 4 °C, detached from the plate by gentle
pipetting. The cell suspension was centrifuged (3 min, 800 g, 4 °C), the obtained pellet was resuspended
in PBS, and DiI fluorescence was analyzed using a BD FACSCalibur flow cytometer (BD Biosciences).
4. Conclusions
A small library of hydroxamic acid compounds was constructed and the compounds were assessed
for their up-regulating activity on CLA-1 expression in HepG2 cells. Among them, compound 1g
showed the best potency, with EC50 = 0.32 µM.
Acknowledgments
This work was supported by the National Natural Science Foundation of China (90813027 and
30801401) and the Key New Drug Creation and Manufacturing Program (2009ZX09302-004 and
2009ZX09301-003).
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Sample Availability: Samples of the compounds 1a-i, 2a-e, 3a-o are available from the authors.
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