Synthesis and activity of selective MMP inhibitors with an aryl backbone

Article abstract of DOI:10.1016/S0960-894X(00)00584-9

A series of novel, MMP-1 sparing arylhydroxamate sulfonamides with activity against MMP-2 and -13 is described. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0960-894X(00)00584-9

Bioorganic & Medicinal Chemistry Letters 10 (2000) 2815±2817
Synthesis and Activity of Selective MMP Inhibitors
with an Aryl Backbone
Thomas E. Barta,a,* Daniel P. Becker,a Louis J. Bedell,a Gary A. De Crescenzo,b
Joseph J. McDonald,b Grace E. Munie,b Shashi Rao,c Huey-Sheng Shieh,b
Roderick Stegeman,b Anna M. Stevensb and Clara I. Villamila
aPharmacia, Department of Medicinal Chemistry, 4901 Searle Parkway, Skokie, IL 60077, USA
bPharmacia, Department of Medicinal Chemistry, 700 North Chester®eld Parkway, St. Louis, MO 63198, USA
cMolecular Simulations, Inc., 736 Bellerive Manor Dr., St. Louis, MO 63141, USA
Received 1 September 2000; accepted 9 October 2000
AbstractÐA series of novel, MMP-1 sparing arylhydroxamate sulfonamides with activity against MMP-2 and -13 is described.
# 2000 Elsevier Science Ltd. All rights reserved.
Individual members of the matrix metalloproteinase
(MMP) family of zinc-dependent enzymes catalyze a
variety of important physiological processes, such as
tissue regeneration, angiogenesis, and growth and
development (Fig. 1).
synovium in arthritis, and the loss of tone of cardiac
tissue post myocardial infarction. Considerable research
has been devoted towards identifying small-molecule
MMP inhibitors with the hope that such compounds
might prove clinically useful in attenuating excessive
remodeling and improving the outcome of the above
conditions and others.
Broad-spectrum inhibitors, such as British Biotech's
marimastat, have been found to induce over the course
of treatment a dose-limiting joint-sti€ening, which must
be reversed by putting the patient on a `drug holiday'.1
Since MMP-1 is ubiquitous2 and is used in constitutive
tissue housekeeping, there is keen interest in exploring
inhibitors that spare MMP-13 while blocking those
MMPs that have been associated with disease states,
such as MMP-13 in arthritis4 and MMP-2 in cancer
metastasis.4
This paper describes a novel series of aryl hydroxamic
acid derivatives that inhibit MMP-2 and -13 and spare
MMP-1. The series was conceived de novo, upon con-
sideration of the bond distances and geometry of the
active site of these enzymes. Speci®cally, we felt that,
with a hydroxamate bound to the zinc in the catalytic
site, a two-carbon sp2 linker joined to a sulfonamide
should position an oxygen of that sulfonamide su-
ciently close to the Leu 160 in the enzyme backbone to
form a hydrogen bond. Such a bond is a key feature of
essentially all published inhibitors.5 The other planned
design feature was to install a relatively long substituent
Figure 1. Structures of some reported MMP inhibitors.
Excessive MMP activity and the concomitant increased
remodeling of the extracellular matrix is thought to
exacerbate a number of pathologies, for example, the
in®ltration and metastasis of tumors, the erosion of the
*Corresponding author. Tel.: +1-847-985-4639; fax: +1-847-982-
4714; e-mail: barta@netmug.org
0960-894X/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(00)00584-9

2816
T. E. Barta et al. / Bioorg. Med. Chem. Lett. 10 (2000) 2815±2817
into P10, to favor selectivity against MMP-1, as MMP-1
has a relatively more shallow pocket.
Chemistry
The requisite ester-sulfonyl chloride aryl sca€old (1 or
2) was prepared by the method of Nagasawa6 or pur-
chased7 (Scheme 1) and was allowed to react with the
requisite amines. The resulting sulfonamide esters (3a±
k) were saponi®ed to the corresponding acids (4a±k)
and coupled with O-(tetrahydro-2H-pyran-2-yl)hydrox-
ylamine using EDC. Acid hydrolysis yielded the desired
hydroxamates.
Scheme 2. (a) (BOC)2O, THF, 0 ꢀC; (b) Cs2CO3, 120 ꢀC, DMF 2 days;
(c) 4 N HCl, dioxane.
Crystallography
Figure 2 shows compound 7h bound to the MMP-8
enzyme.9 The complex was solved at 1.8 A with an
R=0.26 and an Rfree=0.33. The sulfonyl group of the
inhibitor makes a single hydrogen bond to the protein
through the pro-S sulfonamide oxygen to the backbone
amide hydrogen of Leu 160. In addition to the three
zinc ligands derived from the histidine sidechains at
positions 197, 201, and 207, the inhibitor ligates the zinc
atoms through the oxygens of the hydroxamate moiety.
The -OH group of the hydroxamate makes a hydrogen
bond with the Glu 198 side chain. The piperidine-O-
phenyl moiety extends into the S10 subsite and makes
van der Waals contact with the protein. Interestingly,
the sulfonyl group sits axial to the piperidine ring; the cis
conformation around the phenyl-SO2 group, and the
spatial constraints imposed by hydrogen bonding and
the S10 subsite do not allow steric-free positioning with
an equatorial con®guration. The selectivity against
MMP-1 was achieved by making P10 moieties of su-
cient length to sterically interfere with the Arg residue in
MMP-1 that is positionally equivalent to Leu 193 in
MMP-8.
Results and Discussion
The aryl hydroxamates were assayed in vitro using pre-
viously described protocols.10
As shown in Table 1, it is clear that we were able to
prepare compounds with potent inhibition of MMP-2
and -13 from a variety of di€erent amines. The entries
with very short P10 subunits (6a and 6b) showed poorer
Table 1. IC 50's of the studied hydroxamates, in nM
Compound
MMP-2
MMP-13
MMP-1
Scheme 1. (a) HNRR0, triethylamine, acetonitrile; (b) KOH, EtOH
(aq); (c) EDC, HOBT, THPONH2, DMF; (d) AcCl, MeOH.
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
ND
ND
148
70
>10,000
>10,000
1000
520
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
2.9
35
900
3500
2300
1.3
9000
2200
28
The non-commercial amines leading to 6h±k were pre-
pared by routine protect/deprotect sequences or as
shown in Scheme 2, by nucleophilic displacements of
aryl ¯uorides.8 The cesium carbonate conditions
worked well in the example shown, but less reactive
2.0
33
1800
1000
3.3
0.75
0.3
2000
6700
12.2
2.0
0.5
0.6
7h
Marimastat
AG-3340
RS-130830
starting
¯uoromethoxybenzene required more forcing conditions
materials,
such
as
1-¯uoro-4-tri-
23.5
800
0.4
(NaH/N-methylpyrrolidinone).

T. E. Barta et al. / Bioorg. Med. Chem. Lett. 10 (2000) 2815±2817
2817
Therapeutic Applications; Greenwald, R. A., Zucker, S.,
Golub, L. M., Eds.; The New York Academy of Sciences: NY,
1999; pp 583±586.
3. The hypothesis that sparing MMP-1 is necessary and su-
cient to prevent the musculoskeletal sti€ening has been called
into question in view of recent clinical results where it is
observed that certain inhibitors that inhibit MMP-1 never-
theless do not appear to show the side e€ect. See Shaw, T.;
Nixon, J. S.; Bottomley, K. M. Exp. Opin. Invest. Drugs 2000,
9, 1469.
4. Shalinsky, D. R.; Brekken, J.; Zou, H.; McDermott, C. D.;
Forsyth, P.; Edwards, D.; Margosiak, S.; Bender, S.; Truitt,
G.; Wood, A.; Varki, N. M.; Appelt, K. In Inhibition of
Matrix Metalloproteinases: Therapeutic Applications; Green-
wald, R. A., Zucker, S., Golub, L. M., Eds.; The New York
Academy of Sciences: NY, 1999; pp 236±270.
5. Lovejoy, B.; Welch, A. R.; Carr, S.; Luong, C.; Broka, C.;
Hendricks, R. T.; Campbell, J. A.; Walker, A. M.; Martin, R.;
Van Wart, H.; Browner, M. F. Nat. Struct. Biol. 1999, 6, 217.
6. Nagasawa, H. T.; Kawle, S. P.; Elberling, J. A.; DeMaster,
E. G.; Fukoto, J. M. J. Med. Chem. 1995, 38, 1865.
7. Sulfonyl chloride 2 is available from Lancaster, but in our
hands reactions involving the ethyl ester seemed cleaner.
8. (a) Analogue 7h was prepared by ortholithiation of the
corresponding 3-¯uorosulfonamide, followed by a carbon
dioxide quench. The acid was transformed to the hydroxamate
by making the acid chloride and reacting with tetra-
hydropyranhydroxylamine. Full details will be reported in a
subsequent communication. (b) Sindelar, K.; Hrubantova, M.;
Svatek, E.; Matousova, O.; Metysova, J. Collect. Czech.
Chem. Commun. 1989, 54, 2240
Figure 2. X-ray crystal structure of 7h bound to hMMP-8.
potency across the board. Perhaps any van der Waals
stabilization of P10 from the pocket is minimal for these
analogues. The most active analogues (6h±i, and 7h)
have P10 subunits which reach down to the bottom of
the pocket, having a length and volume similar to what
is seen in, for example, Ag-3340 and RS-130630.
The potency of 6h and 6i towards the target enzymes
and the extraordinary level of selectivity against MMP-1
has encouraged us to pursue this aryl series further.
9. Compound 7h had an IC50 of 33 nM against this enzyme.
10. Assays were conducted at six dilutions with an N at least
equal to 2. Inhibitors were tested against puri®ed hMMP-13,
hMMP-1 and hMMP-2 using an enzyme assay based on clea-
vage of the ¯uorogenic peptide MCA-Pro-Leu-Gly-Leu-Dpa-
Ala-Arg-NH2. This is similar to conditions described by
Knight, C. G.; Willenbrock, F.; Murphy, G. in FEBS Lett.
1992, 296, 263, except that 0.02% ®nal concentration of 2-
mercaptoethanol was used in the MMP-13 and MMP-1
assays.
Additional results will be reported in due course.11
References and Notes
1. Steward, W. P. Cancer Chemother. Pharmacol. 1999, 43,
S56±S60.
2. Yocum, S. A.; Lopresti-Morrow, L. L.; Reeves, L. M.;
Mitchell, P. G. In Inhibition of Matrix Metalloproteinases:
11. Barta, T. E.; Becker, D. P.; Bedell, L. J.; Freskos, J. N.;
McDonald, J. J.; Mischke, B. V.; Rao, S. N. WO 9838859,
1998; Chem. Abstr. 1998, 129, 260344.