Novel CoA-polyamine conjugates for effective inhibition of spermine/spermidine-N1-acetyltransferase

Article abstract of DOI:10.1080/15257770701528214

New mimics of the transition state of spermine/spermidine-N1- acetyltransferase reaction were prepared starting from aminooxy analogues of spermidine or spermine and SH-CoA. The activity depended on the structure of polyamine fragment of the conjugate and best of the synthesized compounds were active at micromolar concentrations. Copyright Taylor & Francis Group, LLC.

Full text of DOI:10.1080/15257770701528214

Nucleosides, Nucleotides, and Nucleic Acids, 26:1245–1248, 2007
Copyright ꢀ Taylor & Francis Group, LLC
C
ISSN: 1525-7770 print / 1532-2335 online
DOI: 10.1080/15257770701528214
NOVEL CoA-POLYAMINE CONJUGATES FOR EFFECTIVE INHIBITION
OF SPERMINE/SPERMIDINE-N1-ACETYLTRANSFERASE
Alina Simonian and Alex Khomutov
Russian Academy of Sciences, Moscow, Russia
Engelhardt Institute of Molecular Biology,
2
Tapani Hyvonen
A.I. Virtanen Institute for Molecular Sciences, University of
2
Kuopio, Kuopio, Finland
Nikolay Grigorenko
Engelhardt Institute of Molecular Biology, Russian Academy of
2
Sciences, Moscow, Russia
Tuomo Keinanen
A.I. Virtanen Institute for Molecular Sciences, University of
2
Kuopio, Kuopio, Finland
Jouko Vepsalainen
Department of Chemistry, University of Kuopio, Kuopio,
2
Finland
Leena Alhonen and Juhani Janne
A.I. Virtanen Institute for Molecular Sciences,
2
University of Kuopio, Kuopio, Finland
New mimics of the transition state of spermine/spermidine-N1 -acetyltransferase reaction were
2
prepared starting from aminooxy analogues of spermidine or spermine and SH-CoA. The activ-
ity depended on the structure of polyamine fragment of the conjugate and best of the synthesized
compounds were active at micromolar concentrations.
Keywords Polyamines; coenzyme A; SSAT; coenzyme-substrate inhibitors
INTRODUCTION
The biogenic polyamines spermidine (Spd) and spermine (Spm)
occur in significant amounts in all mammalian cells and are essential
for their normal growth. Key enzymes of polyamine biosynthesis are
This work was supported by the Russian Foundation for Basic Research, project No. 06-04-49638
and Academy of Finland, project no. 117436.
N. Grigorenko present address: Department of Chemistry & Biochemistry, University of Bern, Bern,
Switzerland.
Address correspondence to Alex Khomutov, Engelhardt Institute of Molecular Biology, Russian
Academy of Sciences, Vavilov St. 32, Moscow 119991, Russia. E-mail: alexkhom@list.ru.
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A. Simonian et al.
FIGURE 1 Mimic of the transition state of spermine/spermidine-N 1-acetyltransferase reaction.
ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase
(AdoMetDC), while acetyl-CoA-dependent spermine/spermidine-N1-
acetyltransferase (SSAT) is the rate-controlling enzyme of polyamine
catabolism. Tumor cells have elevated levels of polyamines as compared
with normal cells and this stimulated design of specific and powerful
inhibitors of ODC and AdoMetDC. However, the most efficient strategy to
deplete the polyamine pool is the activation of SSAT. Biosynthesis and activ-
ity of SSAT is regulated by intracellular content of polyamines and/or their
properly designed analogues. Hence, a big family of terminally bis-alkylated
derivatives of Spm and Spd, which turned to be effective inductors of the
enzyme in vitro and in vivo, were synthesized.[1] However, the family of
SSAT inhibitors is far too limited.[2−5]
Spm/Spd-acetyl transferase reaction does not involve an acetylated
enzyme intermediate and this was the reason to design CoA-substrate
conjugates derived from Spm, nor-Spd or their symmetric homologues
which turned to be effective (IC50) toward isolated enzyme at 0.5–5 µM
concentrations.[2] Later, regioselective, but overly complicated, synthesis of
the adducts of CoA to either N1 or N8 positions of Spd were suggested.[3]
Here we present a simple synthesis of two novel types of the analogues of
transition acetyl-CoA-substrate complex derived either from HS-CoA or D-
N-pantothenylamidoethyl mercaptane (Figure 1).
RESULTS AND DISCUSSION
Having hydroxylamine-containing analogues of spermine and spermi-
dine with a terminal aminooxy group,[6] it was obvious to use an acetone
linker to bind the polyamine analogue together and CoA. This was the key
point of a simple and convenient two-step synthesis of the required conju-
gates derived either from HS-CoA or D-N-pantothenylamidoethyl mercap-
tane (D-Pant) and afforded an opportunity to attach the CoA easily to the
required terminus of the polyamine analogue (Scheme 1). At the first step
of the synthesis the free thiol group was alkylated with equimolar amount of
chloroacetone at slightly basic pH. Thus obtained ketone was reacted with

Novel CoA-Polyamine Conjugates
1247
SCHEME 1 i - ClCH2COCH3; ii - RONH2.
equimolar amount of corresponding O-substitution hydroxylamines that re-
sulted in required conjugates 2a–5a and 2b–5b with quantitative yield.
Compound (3a) turned to be the most effective inhibitor of SSAT
(Table 1). This substance (IC50 1 µM) formally may be considered as an
analogue of the intermediate of N8-acetyltransferase reaction, while com-
pound 2a, which initially was design as the most exact mimic of the interme-
diate of N1-acetyltransferase reaction was found to be less active (IC50 6 µM).
The observed dependence of the activity of the conjugate with oxime linker
on the structure of the polyamine group of the conjugate was quite oppo-
site as compared with that for earlier inhibitors with the acetate linker.[2]
Hence, the nature of the linker at least must be taken into consideration.
The significant contribution of the polyamine fragment into the inhibition
was proved with lower activity (IC50 22 µM) of the ketone 1a. The existence
of adenosine group was crucial for effective inhibition, since none of the
conjugates of D-N-pantothenylamidoethyl mercaptane family exhibited IC50
better than 100 µM.
Synthesized set of novel effective inhibitors of SSAT is of obvious interest
for x-ray investigations of the enzyme and also for studying the peculiarities
of the organization of the active sites of different forms of SSAT.
TABLE 1 Inhibition of SSAT by the synthesized coenzyme-substrate
conjugates. Substrate mixture was the same as published [7] but contained
3 µM [1-14C]-Acetyl-CoA
Compound
1a
2a
3a
4a
5a
2b
3b
4b
5b
IC50, µM
22
6
1
17
5
>100
>100
>100
>100

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