Bioorganic & Medicinal Chemistry Letters
Discovery of S-adenosyl-L-homocysteine hydrolase inhibitors based
on non-adenosine analogs
b
a
a
a
Akira Nakao a, , Hiroko Suzuki , Hiroaki Ueno , Hiroshi Iwasaki , Tomofumi Setsuta
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a Medicinal Chemistry Research Laboratories II, Research Division, Mitsubishi Tanabe Pharma Corporation, 2-2-50, Kawagishi, Toda-shi, Saitama 335-8505, Japan
b Pharmacology Research Laboratories I, Research Division, Mitsubishi Tanabe Pharma Corporation, 1000, Kamoshida-cho, Aoba-ku, Yokohama 227-0033, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
High throughput screening using Automated Ligand Identification System (ALIS) resulted in the discovery
Received 11 May 2014
Revised 1 June 2014
Accepted 5 June 2014
Available online 21 June 2014
of a new series of S-adenosyl-L-homocysteine hydrolase inhibitors based on non-adenosine analogs. The
optimization campaign led to very potent and competitive compound 39 with a Ki value of 1.5 nM. Com-
pound 39 could be a promising lead compound for research to reduce elevated homocysteine levels.
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
Homocysteine
S-Adenosyl-L-homocysteine hydrolase
inhibitors
Competitive
Homocysteine (Hcy) is a sulfur-containing amino acid, which is
an intermediate metabolite of an essential amino acid, methionine
One of the strategies to lower the Hcy levels10 is the inhibition
of the Hcy synthetic enzyme, S-adenosyl- -homocysteine hydro-
L
(Met). Met is condensed with ATP to form S-adenosyl-
(AdoMet), and AdoMet utilized as a methyl donor for methylation
reactions is converted to S-adenosyl- -homocysteine (AdoHcy).
L-methionine
lase (AdoHcyase; EC 3.3.1.1.).11 Almost all of the known AdoHcyase
inhibitors are adenosine analogs.12–14 Some of them inhibit the
enzyme irreversibly, and many of them lack selectivity against
related enzymes for producing adenosine, suggesting that there
could remain concerns about adverse side effects.12 A reversible
inhibitor 4 has only a weak potency for the enzyme (ꢀ10À6 M)
(see Fig. 2).12 We hypothesize that reversible, competitive AdoHcy-
ase inhibitors based on non-adenosine analogs can provide some
distinct advantages in terms of selectivity and toxicity.
L
AdoHcy is hydrolyzed to Hcy and adenosine. There are two meta-
bolic pathways of Hcy: (i) remethylation through methionine syn-
thase into Met, and (ii) degradation to cysteine thorough
cystathionine beta-synthase. Intracellular Hcy is highly regulated
at low levels and redundant Hcy is released into the blood (see
Fig. 1).
About forty years ago, McCully reported that Hcy caused vascu-
lar pathology such as arteriosclerosis and myocardial infarction.1
Thereafter, clinical tests verified that patients having arteriosclero-
sis in the peripheral or cerebral vessel showed high Hcy levels.2 In
most clinical tests, a correlation between increased Hcy levels and
cerebral infarction has been reported.3–8 In a large-scale study, it
has been reported that when the blood Hcy levels increases by
To explore the ligands of AdoHcyase, high-throughput screen-
ing, utilizing Automated Ligand Identification System (ALIS),15 an
affinity-based system for rapidly screening disease-associated tar-
gets, was employed.16 ALIS screening technology based on size
exclusive chromatography identifies non-covalent chemical
ligands to protein targets from large combinatorial mixtures, sug-
gesting that the ligands acquired from the system could be revers-
ible inhibitors. Fortunately, we discovered a series of several lead
candidate molecules (5a–f) illustrated in Figure 3.
The structural features of the compounds are that they contain
two amides: a hydrophobic amide and a hydrophilic amide with an
amine group. We addressed the replacement of the two amide
moieties to improve the inhibitory activity. The general synthetic
routes are described in Scheme 1.
25% (3 lM in absolute level), the risk of coronary artery disease
increases by 10%, and the risk of cerebral infarction increases by
20%;9 and it is now suggested that Hcy is an independent risk fac-
tor. Therefore, lowering the Hcy levels could be one of the possible
approaches to prevent and treat diseases such as coronary artery
disease or ischemic stroke.
Reaction of 1,4-dichloro-2-nitrobenzene (6) with 4-chlorophe-
nol in the presence of NaH in DMF provided biphenylether 7.
Reduction of the nitro group of 7 to 8 was performed by using
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Corresponding author. Tel.: +81 48 433 2685; fax: +81 48 433 2650.
0960-894X/Ó 2014 Elsevier Ltd. All rights reserved.