2016 3rd
International Conference on Engineering Technology and Application (ICETA 2016)
ISBN:
978-1-60595-383-0
Synthesis of a
New Pyridine Pharmaceutical Intermediate inPotential
Anti-cancer of HDACI
Xiaopan Zhang
& Zhiyi Yao*
College of
Chemical and Environmental Engineering, Shanghai Institute of Technology,
Shanghai, China
ABSTRACT: In
order to obtain better anti-cancer activity of HDACI, new HDCIs analog and a
pyridine pharmaceutical intermediate
were designed by comparing the molecule of FK228 and Largazole and introducing
the pyridine
intermediate to the cyclic tetrapeptide pharmacophore. The synthetic route of
HDCIs analog and the pyridine
intermediate were designed. The HDCIs analog and the pyridine intermediate were
all synthesized, and the optimum
conditions of synthesizing the pyridine intermediate were got by using parallel
test. The pyridine intermediate can
be used to manufacture new potential HDACIs by forming new structure of the
polypeptide. Due to the
special structure of the pyridine intermediate, it can also be widely used in
other medical field. Through our work
we have designed synthetic routes of the pyridine intermediate and discussed
the optimum conditions. And
we provide a new synthesis method of cyclopeptide HDCIs.
Keywords: FK228
analogue; HDACIs; pyridine; tetrapeptide
1 INTRODUCTION
Pyridine compound is a high value-added fine chemical product. Its
chemically active can participate in a variety of
chemical reactions. Pyridine compounds chlorinated,
fluoride and ammonia oxidation can be prepared for a
variety of intermediates in the pharmaceutical synthesis and
fine chemical industries that have been widely
used. Pyridine compounds are currently used in
medicine, pesticides, spices, feed additives, adhesives and
synthetic materials. Such compounds are being used
to develop the most widely used range of
fine chemical products global manufactures pyridine
compounds of $50 billion in annual sales. In the
field of medicine, pyridine can be used to produce
cephalexin, prednisone dexamethasone acetate, sulfa sulfuric
acid piperazine, hydrocortisone, idoxuridine,
progesterone, norfloxacin, vitamin A, D2 or D3, the
fourth generation of cephalosporins, and more than 40
kinds of synthetic materials of commonly used medicines.
For a long time,
cancer has been considered to be the result of a
wide variety of genetic and genomic alterations,
such as amplifications, translocations, deletions and
point mutations [1]. But recent research showed cancer
development is not only related to the genetic changes
but also involves epigenetic changes.
Epigenetics is
concerned with the inheritance of information based on
gene-expression levels. The main epigenetic
modifications in humans are DNA methylation and
posttranslational histone modifications.
2 MATERIALS AND
METHODS
Histones are small basic proteins that are rich in amino acids, lysine
and arginine [2]. Histone acetyltransferase (HAT) and
histone deacetylase (HDAC) can make histone
N-terminal amino acid residue be acetylated or deacetylated
in vivo, both enzymes work together to determine
histone acetylation levels, and they also
regulate expression of gene and some other cellular
processes, and studies have shown that acetylation and
deacetylation process and the occurrence of cancer are
closely linked. Therefore, histone deacetylase (HDACs) are
targets for anticancer drugs. Histone deacetylase
inhibitor (HDACi) has become a kind of hot areas of
research. Histone deacetylase inhibitor can improve the
level of p21 and other genes expression by increasing
cell level of histone acetylation. The process of
tumor cells proliferation has showed a very good
inhibitory effect, and the inhibitor can in-duce tumor cell differentiation
and/or the occurrence of apoptosis, so
it has the effect of inhibiting tumor [5,6]. Romidepsin
(Istodax), a cyclic peptide, has been recently
approved as an HDAC inhibitor against CTCL, indicating
that cyclic peptides are pharmacophores of interest in
this field. Histone deacetylases (HDACs) are
promising targets for such a novel NB therapy. HDACs catalyze the removal of acetul groups from the lysine
residues of proteins including the core nucleosomal
histones. Histone tails contain 40 lysine residues, which
are acetylated by HATs. Acetylation induces a
conformational change within chromation, allowing the
transcriptional machinery access to DNA thus promoting
gene expression. HDACs repress the gene expression
by deacetulating the lysine tails, allowing the positively
charged lysines to be tightly bound to the
negatively charged DNA and denying the transcriptional
machinery access to genes, thereby repressing gene
expression. Thus, these post- translational modifications
play a key role in directing gene expression, and
can create a phenotype that is unrelated to changes in
DNA. Histone deacetylases play a prominent role
in the regulation of gene transcription by histone
deacetylation. They are involved in the remodeling of
chromatin, and consequently, in the regulation of
gene expression. There is growing evidence that
perturbation of epigenetic balances promotes the initiation
and progression of cancer. HDAC inhibitors have
been found to have therapeutic properties in many
different human tumor cell lines, including those derived
from the bladder, breast, prostate, lung, ovary and
colon among others, indicating that the inhibition
of HDAC activity may be a viable strategy for the
treatment of cancers. HDAC inhibitors can be divided
into short-chain fatty acids, hydroxamic acids,
cyclopeptide HDCIs, benzamides, electrophilic ketones,
trithiocarbonate and other categories; however, in this
article we focus on the cyclic peptides. Cyclic peptides
were the most complex in all the HDACIs. Surface
recognition structure of macrocyclic inhibitors given
the complex structure, but also to ensure the
inhibitor with the enzyme molecule interactions more fully, this
may be one of the reasons to ensure cyclic
peptide inhibitor activity. Like most of other
inhibitors, the structure of cyclic peptide HDACIs is
divided into three domains [7], which are surface
recognition domain, linker domain and Zinc binding domain.
FK228 (formerly named FR901228), also known as
depsipeptide, is produced by Chromobacterium violaceum and
shows potent in vivo antitumor activity. FK228
received FDA approval in 2009 for the
treatment of cutaneous T-cell lymphoma. The naturally
occurring FK-228 displays impressive anticancer and
anti-angiogenesis activities through the HDAC inhibition,
and it is now approved as a cancer drug. FK228 is a
bicyclic depsipeptide with intramolecular disulfide
bridge, which is reductively activated after uptake
into the cells generating the sulfhydryl groups. Inspired
by the stability of FK228 due to its prodrug nature
[12], several HDAC inhibitors with the disulfide bond
have been proposed with more simplified structure for
the ease of synthetic study. In the past decade, a
considerable number of synthetic analogs have been
reported as cyclic-tetrapeptide HDAC inhibitors. Main
nucleus of 4-aniline quinazoline and hydroxylamine
part of histone acetyl off enzyme (HDAC) inhibitor
fragments are connected. By this way, they
developed an EGFR inhibitors, ErbB2 and HDAC targets,
the acetylation of EGFR phosphorylation and HDAC has
certain inhibitory effect. Predecessors by the way of
connecting hydroxylamine fragments at
site-6,7 of 4-aminoquinazolinone obtained good active
compound such as compound h1and h2,
therefore, we imagined that if at site-4 ' of 4 - aniline
quinazoline was substituted by different hydroxyl oxime
acid group to get some new compounds. Largazole is a
natural cyclic peptide which can selectively
inhibit Class I histone deacetylase and show remarkable
selectivity between transformed and non-transformed
cells. The design of these analogs has been done either
by changing the amino acids sequence in the cyclic
tetrapeptide framework to achieve high affinity of
the inhibitors with the enzyme surface or by the
introduction of different type of functional groups as zinc
ligands to achieve a strong binding affinity to the
enzyme’s active site. The functional groups
introduced are mostly full of electron. And more functional
groups have been introduced to the non-peptide HDAC
inhibitors. In order to develop HDAC inhibitors
with various functional groups, we replaced the
epoxyketone moiety of chlamydocin scaffold with a
pyridine ring. As the first part of this paper, we have
designed and synthesized 2 cyclic peptide
compounds as HDACi based on the structures of Largazole and
FK228. We tried to derive novel artificial amino
acids and a pyridine ring to introduce them into the
chlamydocin scaffold [9].
Figure 1.
Structural regions of cyclopeptide HDCIs.
By comparing the
structures of FK228 and Largazole, we designed and
synthesized other compounds. The cyclic
tetrapeptide structure in surface recognition domain was
changed by introducing an amino acid containing a
pyridine ring for a fuller contact with the surface and
enzymes. The pyridine intermediate has a similar
structure with amino acid, and it can be widely used in the
medical field, especially as cyclic peptide intermediate
fragment deacetylase inhibitors as FK228 analogues.
Details are shown as follows in Figure 1.1169 Since the
molecules have a cyclic tetrapeptide structure, we split the
molecule into three different fragments and then they are
connected end to end by a peptide bond or ester bond [14,
15]. Through the retrosynthesis the molecule can be split
into three different parts as Figure 2 shows by
breaking the amide bond and one ester bond. The zinc domain
and the linker can be synthesized by fragment 1. The
cyclic peptide was divided into valine and fragment 3.
So the amino acid containing the pyridinering becomes the
key intermediate in the total synthesis of molecule
DCE-3529415.
Details are shown as follows in
Figure 3.
Figure 2.
Retrosynthesis of DCE-3529415.
Figure 3. Design
of compound structure.
The main
challenges in the synthesis include the asymmetric
construction of the hydroxyl mercapto heptenoic acid
unit, the 16-membered cyclic depsipeptide ring itself (that
is, four amino acids and hydroxyl mercapto
heptenoic acid), and the intramolecular oxidative
coupling of the thiol moieties to produce the stable
prodrug form of the molecule. Using this method, Wen
et al. utilized a lactamization as an alternative
route to cyclization in 2008. Yurek-George et al. [13-16]
examined the importance of several features of the
romidepsin structure. To fragment 3, as the former
through breaking the amide bond, the molecule can be divided
to 2 parts, one is threonine. The hydroxyl of
threonine can react with MsCl and then be removed by
DABCO, so the double bond can form [14]. Details are
shown as follows in Figure 4.The other one is an amino
acids analogue with pyridine ring. The key to the amino
acids analogue is to introduce synthetic carboxyl and
amino functional groups. So we choose the 2,
6-dimethylpyridine as the raw material. Reacting with
KMnO4 the one methyl of 2,6-dimethylpyridine
can be oxidized to carboxyl and the other methyl
can stay the same [17]. Then the methyl can be
transferred into benzyl reacting with NBS by radical
reaction which is the material of Gabriel reaction in the
next step changing the benzyl to amino.
Details are
shown as follows in Figure 5.
O
NH
HO
O
N
NH
Boc
3
NH2
HO
O
+ N
HO NH2
O
N
HO Br
O
N
Figure 4.
Retrosynthesis of fragment 3 of DCE-3529415.
Figure 5.
Synthesis of fragment 3 of DCE-3529415.
3 EXPERIMENTAL
SECTION
All solvents
were A.R. grade and purchased from Shanghai
Chemical Reagent Company. Melting points were determined
on a WPS-2Acapillary apparatus and were
uncorrected. The 1HNMR and spectra were recorded on a Bruker
Avance III 500 NMR spectrometer using TMS as an
internal standard and chemical shifts were given in
ppm with tetramethylsilane (TMS). The HRMS spectra
were acquired on a Solari X-70FT-MS apparatus. TLC
was carried out on silica gel plates 1170 (GF254) with
visualization of components by UV light (254nm) or
exposure to I2. Column chromatography was carried out
on silica gel (300–400 mesh).
Compound 19
(21.43g, 0.2mol) dissolved in 1000mL H2O (not
completely dissolve and not affect the reaction)
was added KMnO4 47.41g. The solid was added in for ten
times, and the interval between two times is 30min.
After adding solid raising the temperature to 70°C, reflux
for 5h. After the material was completely
disappeared, the reaction solution was cooled to room
temperature, filtered. The filtrate was evaporated to
dryness, and then 200mL HCl (70%) was added to the
solid dissolved. Extract the solution with ethanol,
the solution was evaporated to be dryness and
recrystallization, giving product (17.3g).
Compound 19’
(15g, 0.11mol) was dissolved in 500mL methanol;
thionyl chloride was dropped into
methanol at 0°C.
After the dropwise addition the reaction apparatus was
brought to room temperature, reacting for 5 hours.
Methanol was removed by rotary evaporation to
give a white solid. The solid was dissolved in 200mL of
sodium hydroxide solution at a concentration of
1mol/L. The pH value was adjusted to 9. Ethyl
acetate was added to the solution and then was extracted.
The organic phase was collected and dried. The
solvent was evaporated under reduced pressure to give
the product 19’’ (10g).
Compound 19’’
(10g, 0.066mol) was dissolved in 60mL CCl4, NBS
14.1g (0.079mol) was added under stirring. AIBN
was added for 3 times about 5g (0.03mol). After
the addition reflux at 80°C for 6 hours, add a
certain amount of water and stir for 15min, the water
is separated from CCl4 then dried. The CCl4 was
removed under reduced pressure to give the crude
product. The crude product was recrystallized to give pure
product (6g).
Compound 20 (6g,
26.20mmol) dissolved in DMF (100mL) was
added with potassium phthalimide
(5.82g,
31.44mmol), and reaction was carried out at room temperature
for 5h. TLC showed the reaction was completed
and concentrated under reduced pressure. NaOH solution
was added with 0.2mol/L of washing. Water
was added, extracted with ethyl acetate, dried over
anhydrous sodium sulfate and finally concentrated to
give compound 21 (6.42 g, 83%).
Compound 21 (8g,
20.26mmol) dissolved in methanol (1/4, 200mL) was
added with hydrazine hydrate compound (2.9mL,
50mmol) and refluxed overnight. After the
reaction was completed, it was concentrated under reduced
pressure obtained compound 22 (2.59g,77%) by column
chromatography.
At 0 °C, the
compound 22 (1.7g, 10.24mmol) in THF was added
with DIPEA (2.0mL) and Boc2O
(2.79g), and
reacted at room temperature overnight. TLC showed the
reaction was complete, concentrated under reduced
pressure, water was added, with ethyl ester
extraction, dried over anhydrous sodium sulfate, and concentrated
by column chromatography to obtain the product
compound 23 (2.3g, 86%)
The compound 23
(2.0g, 7.93mmol) and H-Thr-Ome (1.6g,
9.52mmol) in DCM (40mL) was added PyBop
(4.13g, 7.93mmol) and DIPEA (5.3mL), Reaction was
carried out at room temperature overnight, quenched with
saturated ammonium chloride and extracted
with dichloromethane, washed with water and
saturated brine, and concentrated, dried over anhydrous sodium
sulfate, and concentrated by column chromatography
to give compound 6 (1.48 g, 51%).
At 0 °C, under
the protection of Ar gas, the compound 24 (1.0 g,
2.72mmol) in DCM (10mL) were sequentially
added DMAP (16.6 mg), TEA (1.13 mL), MsCl (0.63 mL),
Reaction was carried out at room temperature for
2 hours, quenched with saturated ammonium
chloride, extracted with dichloromethane, washed with
water and saturated brine, concentrated, dried over
anhydrous sodium sulfate, and concentrated to give a pale
yellow compound 980.8mg. At 0 °C, the pale yellow
compound (900mg, 2.02mmol) in DCM (10mL) was added
with DABCO (2.27g), and reaction was carried out
at room temperature 2h, quenched with saturated
ammonium chloride, extracted with dichloromethane,
washed with water and saturated brine,
concentrated, dried over anhydrous sodium
sulfate, and
concentrated by column chromatography to give compound
25 (620.1mg, 95%).
Compound 25
(600mg, 1.72mmol) dissolved in methanol was
added with LiOH (123.5mg,). Reaction
was carried out
at room temperature for 10 hours. After completion
of the reaction, the solution was
filtered to
remove LiOH and concentrated to give compound 3
(547.6mg, 95%).
6-Methyl-2-pyridinecarboxylic
acid
1HNMR(501MHz,CDCl3)δ13.17(s,1H),8.20(d,J=7.4Hz,1H),8.11(d,J=7.6Hz,1H),7.78(D,J=8.3Hz,1H),2.17(s,3H)ESI-HRMS
calcd for C7H7NO2 [M + H]+,138.06
6-Methylpicolinic
acid methyl ester
1HNMR(501MHz,CDCl3)δ8.20(d,J=7.4Hz,1H),8.13(d,J=7.8Hz,1H),7.77(D,J=8.3Hz,1H),3.23(s,3H),2.50(s,3H)ESI-HRMS
calcd for C8H9NO2 [M + H]+,152.07
6-(Bromomethyl)picolinic
acid methyl ester
1HNMR(501MHz,CDCl3)δ8.20(d,J=7.4Hz,1H),8.13(d,J=7.8Hz,1H),7.77(D,J=8.3Hz,1H),5.3(s,2H),3.3(s,3H)ESI-HRMS calcd
for C8H8BrNO2[M+H]+, 229. 98
2-Pyridinecarboxylicacid,6-[(1,3-dihydro-1,3-dioxo-2H-isoindol-2-yl)methyl]-,methyl ester
1HNMR(501MHz,CDCl3)δ8.83(d,J=7.6Hz,1H),8.27(d,J=12.3Hz,2H),8.10(d,J=7.6Hz,1H),7.74(d,J=8.9Hz,1H),7.11(d,J=8.9Hz,1H),5.75(s,3H),3.90(s,3H)ESI-HRMS calcd for
C16H16N2O4[M + H]+,297.09
2-Pyridinecarboxylicacid,
6-(aminomethyl)-, methyl ester
1HNMR(501MHz,CDCl3)δ8.42(d,J=8.8Hz,1H),8.35(d,J=8.3Hz,1H),7.87(d,J=6.3Hz,1H),4.76(s,2H),3.58(s,3H) ESI-HRMS
calcd for C8H10N2O2[M + H]+,167.08
6-[[(tert-Butoxycarbonyl)amino]methyl]pyridine-2-1171carboxylic acid
1HNMR(501MHz,CDCl3)δ12.1(s,1H),8.52(d,J=8.3Hz,1H),8.35(d,J=8.6Hz,1H),7.99(d,J=6.9Hz,1H),4.55(s,2H),1.33(s,9H)
ESI-HRMS calcd for C12H16N2O4 [M+ H]+,253.12
Threnine,N-[[6-[[[(1,1-dimethylethoxy)carbonyl]amino]methyl]-2-pyridinyl]carbonyl]-,
methyl ester
1HNMR(501MHz,CDCl3)δ8.55(d,J=8.7Hz,1H),8.50(d,J=8.7Hz,1H),8.01(d,J=9.7Hz,1H),7.81(m,2H),5.1(d,J=6.1Hz,1H),
4.7(d, J=6.1Hz,1H),4.4(s,2H), 3.3(s,3H),2.3(m,1H),1.3(s,9H)ESI-HRMS
calcd for C17H25N3O6[M + H]+,368.18
2-Butenoicacid,2-[[[6-[[[(1,1-dimethylethoxy)carbonyl]amino]methyl]-2-pyridinyl]carbonyl]amino]-,
methyl ester
1HNMR(501MHz,CDCl3)δ8.12(d,J=7.4Hz,1H),7.85(s,1H),7.83(d,J=8.7Hz,1H),7.02(s,1H),4.48(d,J=5.6Hz,2H),1.89(s,3H),1.57(s,3H),1.43(d,J=29.6Hz,9H)ESI-HRMS calcd for
C17H23N3O5[M + H]+,350.17
2-Butenoicacid,2-[[[6-[[[(1,1-dimethylethoxy)carbonyl]amino]methyl]-2-pyridinyl]carbonyl]amino]
1HNMR(501MHz,CDCl3)δ9.50(d,J=72.4Hz,1H),8.12(d,J=7.4Hz,1H),7.85(s,1H),7.43(d,J=50.9Hz,1H),7.02(s,1H),4.48(d,J=22.2Hz,2H),1.89(s,3H),1.43(d,J=29.6Hz,9H). ESI-HRMS
calcd for C16H21N3O5[M+H]+,336.16
4 RESULTS AND
CONCLUSION
During the process for preparing compound 19’, we found that the
equivalent of KMnO4 has a greater impact on the
yield of the product. So we carried out experiments at
different equivalents, and the results are shown in
Table 1.
Table 1 showed
the yield of 19’ declining with theincreasing
equivalent of KMnO4. However, in the actual process,
the reaction time is shortened with the increase of
KMnO4 equivalents. Balance based on efficiency and
productivity, the 1.5 equiv. of KMnO4 at 80°C is the
optimum condition.
During the
process for preparing compound 20, we found that
the equivalent of NBS have a greater impact on the
yield of the product. So we carried out experiments at
different equivalents, the results are shown as
follows. The chart showed the yield of 19’ declining with
the increasing equivalent of NBS. Because, the
dibromide increases very quickly with the increasing
equivalent of NBS, the 1.2 equiv. of NBS was chosen
to be the optimum condition.
Data in Table 1
showed the equivalent of KMnO4 are the key to
control yield of 6-Methyl-2-Prydinecarboxylic acid. With the
increasing equivalent of KMnO4, more and
more 6-Methyl-2-Pyridinecar boxylic acid are
transfered into 2,6-pyridinedicarboxylic acid. With the
increasing equivalent of NBS, more and
more 6-Methylpicolinic acid methyl ester r are
transfered into 2-pyri-dinecarboxylic acid, 6-(dibromomethyl)-methyl
ester and 2-pyridinecarboxylic acid,6-(trbromomethyl)-
methyl ester. Accoding to
Figure 7, the A point which is 1.2 equivalent of
NBS was chosen to be the optimum condition.
In summary, by
means of comparing the structures of FK228 and
Largazole, we designed and synthesized several
compounds. The cyclic tetrapeptide structure in surface
recognization domain was changed by introducing an
amino acid containing a pyridine ring for a fuller
contact with the surface and enzymes. Through the
retrosynthesis analysis, a pyridine pharmaceutical
intermediate was designed and synthesized. The
pyridine intermediate has a similar structure with
amino acid, it can be widely used in the medical field,
especially as cyclic peptide intermediate fragment
deacetylase inhibitors as FK228 analogues. The key
intermediate fragment for the entire molecule
cyclic
tetrapeptide structure plays an important role in the surface
recognization domain. Through continuous improvement and
exploration of the conditions, we
Table 1.
Equivalent of KMnO4 effect on yield.
No. Material(g)
Equivalent(KMnO4) Product(19’g) Yield(%)
1 11.3 1.1 10.3
71
2 11.3 1.3 10.5
72
3 11.7 1.5 9.7
67
4 11.3 1.7 8.1
56
5 11.1 1.9 6.6
46
6 11.3 2.1 5.0
35
Table 2.
Equivalent of NBS effect on yield.
No. Material(g)
Equivalent(NBS) Product(g) Yield(%)
1 10.1 1.0 5.5
36
2 10.0 1.1 6.3
41
3 10.1 1.2 6.7
44
4 10.0 1.3 4.1
27
5 10.0 1.4 4.1
27
6
7
10.0
10.0
1.5
1.6
5.0
4.5
33
30
1172
found more
optimal conditions. And this has important
implications for the synthesis of analogues
of FK228, and
the development of new drugs is also important.
ACKNOWLEDGMENTS
This work was
supported by Shanghai Institute of Technology.
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(ISTN)
KIMIA MEDISINAL
Dosen Pembimbing : Lia Puspitasari,
S.Farm, M.Si,Apt.
Mahasiswa
Nama : Suyatno
NIM : 17330730
Kelas A
Synthesis of a New Pyridine
Pharmaceutical Intermediate in
Potential Anti-cancer of HDACI
Abstrak : Untuk mendapatkan aktivitas anti kanker yang
lebih baik dari HDACI, analog HDACI baru dan dari sedian farmasi piridin
intermediate dirancang dengan membandingkan molekuk FK228 dan Largazole dan
mengenalkan piridin dengan farmakofor tetrapeptida siklik. Jalur sintesis
analog HDCI dan piridin mulai dirancang. HDCIs analog dan intermediate piridin
semuanya disintetis, pada kondisi optimum untuk mensintesis piridin
intermediate didapat dengan menggunakan uji paralel. Piridin intermediate dapat
digunakan untuk memproduksi HDACIs potensi baru dengan membentuk struktur baru
polipeptida. Karena struktur khusus piridin intermediate, juga dapat digunakan
secara luas dibidang medis lainya. Melalui pekerjaan kami, kami telah merancang
rute sintetik piridin intermediate dan membahas yang optimum kondisi. Dan kami
menyediakan metode sintesis baru dari HDCIs siklopeptidin.
Latar Belakang
Senyawa piridin adalah produk kimia halus bernilai tambah tinggi. Piridin
dapat berpatisiasi dalam berbagai reaksi kimia. Senya piridin
terklorinasi,oksidasi fluorida dan amonia dapat disiapkan untuk berbagai zat
antara dalam sintesis farmasi dan industri kimia. Senyawa piridin saat ini
digunakan dalam pengobatan, pestisida, rempah-rempah, aditif pakan, perekat dan
bahan sintetis. Dibidang kedokteran, piridin dapat digunakan untuk memproduksi
cephalexin, prednisone, dexamethason acetat, sulfo sulfur sulfat, pipozet,
hydrokortison, idoksuridin, progesteron, norfloksasin, vitamin A, D2 atau D3,
generasi keempat sefalosporin, dan lebih dari 40 jenis bahan sintetis obat yang
biasa digunakan.
Untuk waktu yang lama, kanker telah dianggap sebagai hasil dari beragam
peubahan genetik dan genomik, seperti amplifikasi, translokasi, delesi dan
mutasi titik. Namun penelitian terbaru menunjukan perkembangan kanker tidak
hanya terkait dengan perubahan genetik namun juga melibatkan perubahan
epigenetik.
Epigenetika berkaitan dengan pewarisan informasi berdasarkan tingkat
ekspresi gen.
Modifikasi epigenetik utama pada manusia adalah metilasi DNA dan modifikasi
histone posttranslasional.
Metode Penelitian yang Digunakan
Histones adalah protein dasar kecil yang kaya akan
asam amino, lisin dan arginin. Histone acetyltransferase (HAT) dan histone
deacetylase (HDAC) dapat membuat residu asam amino n-terminal histon menjadi
asetilasi atau deasetilasi invivo, kedua enzim bekerja sama untuk menentukan
tingkat asetilasi histon, mereka juga mengatur ekspresi gen dan beberapa proses
seluler lainya, penelitian telah menunjukkan bahwa proses asetilasi dan
deasetilasi dan terjadinya kanker terkait erat. Oleh karena itu, histone
deacetylase (HDACs) menjadi target obat antikanker.
Histone deacetylase inhibitor (HDACi) telah
menjadi semacam daerah penelitian yang panas. Histone deacetylase inhibitior
dapat memperbaiki tingkat p21 dan ekspresi gen lainya dengan meningkatkan
tingkat aset asetone histon. Proses proliferasi sel tumor telah menunjukkan
efek penghambatan yang sangat baik, dan inhibitor dapat menyebabkan
diferensiasi sel tumor dan atau terjadinya apoptosis, sehingga memiliki efek
menghambat tumor.
Romidepsin (Istodax), peptida siklik, baru-baru
ini disetujui sebagai penghambat HDAC melawan CTCL, yang menunjukan bahwa
peptida siklik adalah farmakope yang menarik dalam bidang ini. Histone
deacetylase (HDACs) merupakan target yang menjanjikan untuk terapi NB yang
baru. HDAC mengkatalisis penghapusan gugus asetat dari residu lisin protein
termasuk hambatan inti nukleosom.
Ekor
histone mengandung 40 residu lisin, yang dilarutkan dengan HAT. Asetilasi
menginduksi perubahan konformasi dalam kromasi, memungkinkan akses mesin
trankripsi ke DNA sehingga mendorong ekspresi gen. HDACs menekan ekspresi gen
dengan deasetilasi ekor lisin, yang memungkinkan lisin bermuatan positif
terikat erat dengan DNA bermuatan negatif dan menolak akses mesim transkripsional
terhadap gen, sehingga menepis eksprsi gen. Dengan demikian, modifikasi pasca
translasi ini memainkan peran kunci dalam mengarahkan ekspressi gen, dan dapat
menciptakan fenotipe yang tidak terkait dengan perubahan DNA. Histone
deacetylases memainkan peran penting dalam pengaturan transkripsi gen denga
deasetilasi histone. Mereka terlibat dalam remodeling kromatin, dan akibatnya,
dalam regulasi ekspresi gen. Ada bukti yang berkembang epigenetik mendorong
inisiasi dan perkembangan kanker. Penghambat HDAC telah ditemukan memiliki
sifat terapeutik pada banyak sel tumor manusia yang berbeda termasuk yang
berasal dari kandung kemih, payudarah, prostat, paru-paru, ovarium dan usus
besar antara lain, menunjukan bahwa penghambatan aktivitas HDAC dapat menjadi
strategi yang tepat untuk pengobatan kanker.
Penghambat HDAC dapat dibagi menjadi asam lemak
rantai pendek, asam hidroksamat, HDACls siklopeptida, benzamida, keton
elektrofilik, tritokarbonat dan kategori lainnya; Namun, dalam artikel ini kita
fokus pada peptida siklik.
Peptida siklik adalah yang paling komplek di semua
HDACI. Struktur pengenalan permukaan penghambat macrocyclic mengingat struktur
kompleks, tetapi juga untuk memastikan penghambat inteaksi enzim secara lebih
penuh, ini mungkin salah satu alasan untuk memastikan aktivitas inhibitor
peptida siklik. Seperti kebanyakan penghambat lainya, struktur HDACI peptida
siklik dibagi menjadi tiga domain, yaitu domain pengenalan permukaan, domain
linker dan domain pengikat seng. FK228 (dahulu bernama FR901228), juga dikenal
sebagai depsipeptide, diproduksi oleh Chromobacterium violaceum dan menunjukkan
aktivitas antitumor in vivo yang manjur. FK228 menerima persetujuan FDA pada
tahun 2009 untuk pengobatan limfoma sel T kutaneous. FK-228 yang terjadi secara
alami menampilkan aktivitas antikanker dan anti-angiogenesis yang mengesankan
melalui penghambat HDAC, dan sekarang disetujui sebagai obat kanker.
FK228 adalah depsipeptida bicyclic dengan jembatan
disulfida intramolekul, yang diaktifkan secara reduksi setelah dilakukan
pengambilan ke dalam sel yang menghasilkan gugus sulfhidril. Terinspirasi oleh
stabilitas FK228 karena produg nature, beberapa penghambat HDAC dengan ikatan
disulfida telah diusulkan dengan struktur yang lebih sederhana untuk memudahkan
studi sintetis.
Dalam dekade terakhir, sejumlah besar analog
sintetis telah dilaporkan sebagai inhibitor HDAC siklik-tetrapeptida. Inti inti
dari 4-anilin quinazoline dan bagian hidroksilamina fragmen inhibitor enzim
histone acetyl off enzyme (HDAC) dihubungkan. Dengan cara ini, mereka
mengembangkan inhibitor EGFR, target ErbB2 dan HDAC, asetilasi fosforilasi EGFR
dan HDAC memiliki efek penghambat tertentu. Pendahulunya dengan cara
menghubungkan fragmen hidroksilamina di tempat-6,7 dari 4-aminoquinazolinone
memperoleh senyawa aktif yang baik seperti senyawa h1 dan h2, oleh karena itu,
kita membayangkan bahwa jika di tempat-4 ‘anina 4-anilin diambil dari hidroksil
oksimena yang berbeda kelompok asam untuk mendapatkan beberapa senyawa baru.
Largazole adalah peptida siklik alami yang secara
selektif dapat menghambat deasetilase histone Kelas I dan menunjukkan
selektivitas yang luar biasa antara sel yang berubah dan tidak berubah.
Perencanaan analog ini telah dilakukan baik dengan mengubah urutan asam amino
dalam kerangka tetrapeptida siklik untuk mencapai afinitas tinggi inhibitor
dengan permukaan enzim atau dengan pengenalan berbagai jenis gugus fungsional
sebagai ligan seng untuk mencapai afinita ikatan yang kuat, kesitus aktif
enzim. Kelompok fungsional yang diperkenalkan sebagai besar penuh dengan
elektron. Dan kelompok yang lebih fungsional telah diperkenalkan pada inhibitor
HDAC non-peptida. Untuk mengembangkan penghambat HDAC dengan berbagai kelompok
fungsional, kami mengganti bagian epoxyketone perancah chlamydocin dengan cicin
piridin. Sebagai bagian pertama dari jurnal ini, kami telah merancang dan
mensintesis 2 senyawa siklik peptida sebagai HDACi berdasarkan struktur
Largazole dan FK228. Kami mencoba untuk mendapatkan asam amino buatan baru dan
cincin piridin untuk mengenalkannya ke perancah chlamydocin.
Dengan membandingkan struktur FK228 dan Largazole, kami merancang dan
mensintesis senyawa lainnya. Struktur tetrapeptida siklik dalam domain
pengenalan permukaan diubah dengan memasukan asam amino yang mengandung cincin
piridin untuk kontak lebih penuh dengan permukaan dan enzim. Piridin
intermediate memiliki struktur yang sama dengan asam amino, dan dapat digunakan
secara luas di bidang medis, terutama sebagai penghambat deacetylase fragmen
siklik peptida sementara sebagai analog FK228. Rincian ditunjukkan seperti
Figure 1 karena molekul memiliki struktur tetrapeptida siklik, kita membagi
molekul menjadi tiga fragmen yang berbeda dan kemudian terhubung ujungnya
dengan ikatan peptida atau ikatan ester. Melalui retrosynthesis, molekul dapat
dibagi menjadi tiga bagian yang berbeda seperti di tunjukkan pada figure 2
dengan memecah ikatan amida dan satu ikatan ester.
Domain seng dan linker dapat disintesis dengan
fragmen 1. Cincin menjadi kunci antara sintesis total molekul DCE-3529415
Rincian ditunjukan pada Figure 3. Desain struktur majemuk.
Tentang utama dalam sintesis meliputi kontruksi
asimetris unit asam heptenoat hidroksil merkapto, cincin depsipeptida siklik
beranggota 16 itu sendiri (yaitu empat asam amino dan asam hidroksil merkapto
heptenoat), dan kopling oksidatif intramolekul dari bagian tiol untuk
menghasilkan bentuk prodrug stabil dari molekul. Dengan menggunakan metode ini,
Wen et al. memanfaatkan laktamisasi sebagai jalur alternatif untuk siklisasi
pada tahun 2008. Yurek-George et al. meneliti pentingnya beberapa ciri struktur
romidepsin. Untuk fragmen 3, sebagai bekas ikatan amida, molekul dapat di bagi
menjadi 2 bagian, satu adalah treonin. Hidroksil dari treonin dapat bereaksi
dengan MsCI dan kemudian dikeluarkan oleh DABCO, sehingga ikatan rangkap dapat
terbentuk.
Rincian ditunjukan pada Figure 4.
Yang lainnya adalah asam amino yang analog dengan
cincin piridin. Kunci untuk asam amino analog adalah mengenalkan gugus fungsi
karboksil dan amino sintetis. Jadi kita memilih 2,6-dimetilpiridin sebagai
bahan baku. Bereaksi dengan KMnO4 satu metil 2,6-dimetilpiridin dapat
dioksidasi menjadi karboksil dan metil lainya bisa tetap sama. Kemudian metil
dapat di pindahkan ke benzil yang bereaksi dengan NBS melalui reaksi radikal
yang merupakan bahan reaksi Gabriel pada langkah selajutnya untuk mengubah
benzil menjadi amino.
Rincian ditunjukkan pada Figure 5.
Hasil dan Analisis
Mereka membandingkan struktur FK228 dan Largazole,
dan merancang mensintesis beberapa senyawa. Struktur tetrapeptida siklik di
domain pengenalan permukaan diubah dengan memperkenalkan asam amino yang
mengandung cincin piridin untuk kontak lebih penuh dengan permukaan dan enzim
Melalui analisis Retrosynthesis intermediate
farmasi piridin dirancang dan disintesis. Piridin intermediate memiliki
struktur yang sama dengan asam amino, dapat digunakan secara luas di bidang
medis, terutama sebagi penghambat deakeetylase fragmen siklik peptida sementara
sebagai analog FK228.
Saran karena memiliki struktur yang sama dengan asam amino dan dapat digunakan
secara luas di bidang medis dan ini memiliki implikasi penting untuk sintesis
analog dari FK228 dan pengembangan obat-obat baru.
