4202
W. Xu et al. / Bioorg. Med. Chem. Lett. 21 (2011) 4197–4202
4. Tarantino, P.; Zhi, C.; Wright, G. E.; Brown, N. C. Antimicrob. Agents Chemother.
Table 4
Antibacterial activity in micea
1999, 43, 1982.
5. Clements, J. E.; D’Ambrosio, J.; Brown, N. C. J. Biol. Chem. 1975, 250, 522.
6. Wright, G. E.; Brown, N. C. J. Med. Chem. 1980, 23, 34.
Treatment, IP 10 ml/kg
IP dose, mg/kg
% Survivors at 24 h
7. Zhi, C.; Long, Z.; Gambino, J.; Xu, W.-C.; Brown, N. C.; Barnes, M.; Butler, M.;
LaMarr, W.; Wright, G. E. J. Med. Chem. 2003, 46, 2731.
8. Wright, G. E.; Brown, N. C.; Xu, W.-C.; Long, Z.-Y.; Zhi, C.; Gambino, J. J.; Barnes,
M. H.; Butler, M. M. Bioorg. Med. Chem. Lett. 2005, 15, 729.
9. Cook, P. D.; Allen, L. B.; Streeter, D.; Huffman, J. H.; Sidwell, R. W.; Robins, R. K. J.
Med. Chem. 1978, 21, 1212.
10. De Bode, R.; Salemink, C. A. Recl. Trav. Chim. Pays-Bas 1974, 93, 3.
11. All new compounds were fully characterized by 1H NMR spectra and by
elemental or HR-MS analyses. Yields and properties of new compounds are in
Supplementary data.
Vehicleb
—
10
100
30
100
30
30
10
30
60
0
Daptomycinc
100
80
20
40
40
20
30
50
80
40
1
4a
‘
20a
8a
9a
‘
12. Rousseau, R. J.; Robins, R. K. J. Heterocycl. Chem. 1965, 2, 196.
13. All 9-isomers of isosteres were isolated and tested, but were weakly active as
enzyme inhibitors (Table 2) and inactive in antibacterial tests (results not
shown).
‘
23a
100
a
Groups of 10 mice were infected IP with S. a. (Smith) and treated IP 15 min post-
14. Mederski, W. W. K. R.; Dorsch, D.; Bokel, H. H.; Beier, N.; Lues, L.; Schelling, R.
J. Med. Chem. 1994, 37, 1632.
infection as described.
b
10% DMSO/peanut oil.
c
15. Recombinant pol IIIC and pol IIIE of Bacillus subtilis (B.s.) were prepared
according to Hammond, R.; Barnes, M.; Mack, S.; Mitchener, J.; Brown, N. Gene.
1991, 98, 29, and Ref. 2, respectively. E. coli (E. c.) pol IIIE was the three subunit
core enzyme purchased from Enzyco. The enzymes were assayed with
activated calf thymus DNA according to the method described by Barnes,
M. H.; Brown, N. C. Nucl. Acids Res. 1979, 6, 1203. Apparent inhibition
constants (Ki values) were obtained directly in a truncated assay lacking the
competitor dGTP [Wright, G. E.; Brown, N. C. Biochim. Biophys. Acta 1976, 432,
37.] or conventionally by variation of the concentration of dGTP. The standard
panel for determination of Minimum Inhibitory Concentration (MIC) values
included S. aureus 25923, S. aureus 13709 (Smith) and E. faecalis 29212, all
purchased from the American Type Culture Collection (ATCC, Manassas, VA).
Methicillin-resistant S. aureus (MRSA 1094), E. faecium 19434, and
vancomycin-resistant E. faecium (VRE) are clinical isolates provided by the
University of Massachusetts Medical School. B. subtilis BD54 [Love, E.;
D’Ambrosio, J.; Brown, N. C.; Dubnau, D. Molec. Gen. Genet. 1976, 144, 313.]
is a standard laboratory strain. E. coli (J-53) was provided by Professor Martin
Marinus, University of Massachusetts Medical School. Measurement of
Minimum Inhibitory Concentration (MIC) was done as described,7 by
incubating bacteria at 37 °C for 16–24 h in the presence of two-fold serial
dilutions of test compounds. Compounds were dissolved in and diluted from
DMSO stocks, and all assays contained 1% DMSO. MIC values are the lowest
concentrations of test compounds at which bacterial growth was not apparent
(<25% of the DMSO control, based on optical density at 600 nm). Pathogen-free
Swiss–Webster mice (males, 20–24 g) were purchased from Taconic Farms
(Germantown, NY). The animals were housed at the University of
Massachusetts Medical School (UMMS) Animal Medicine facility. All animal
experiments were approved by the UMMS institutional animal care and use
committee. Mice were allowed free access to food and water throughout the
studies. S. aureus (Smith) was grown at 37 °C to log-phase in Luria Broth (LB),
and the colony forming units (CFU) were determined using a nomogram
relating CFU to optical density at 600 nm. Bacteria were washed in fresh cold
broth, and given by intraperitoneal (IP) injection to mice as a suspension in
0.5 mL of broth. Groups of five or ten mice were treated via the IP route 15 min
post-infection with vehicle, test compound in vehicle, or daptomycin
(CubicinÒ, Cubist) in saline at 30 mg/Kg. Mice were returned to their cages
and monitored for mortality for 24 h.
5% dextrose/water.
from Gram+ bacteria, but weak inhibitors of the DNA polymerase
IIIE from the GramÀ E. coli (Table 2). Some isosteric compounds
were potent antibacterials against Gram+ bacteria (Table 3), gener-
ally paralleling their activity against the Gram+ DNA polymerases,
but weaker than the corresponding guanines. However, the isoster-
es showed weak activity against experimental S. aureus infection in
mice (Table 4), consistent with their moderate in vitro potencies
and low solubilities.
Acknowledgment
This work was supported by SBIR grant AI51103 from the Na-
tional Institutes of Health.
Supplementary data
Supplementary data (details of syntheses and characterization
of new compounds) associated with this article can be found, in
References and notes
1. Braithwaite, D.; Ito, J. Nucl. Acids Res. 1993, 21, 787.
2. Barnes, M. H.; Miller, S. D.; Brown, N. C. J. Bacteriol. 2002, 184, 3834.
3. Tarantino, P.; Zhi, C.; Gambino, J.; Wright, G. E.; Brown, N. C. J. Med. Chem. 1999,
42, 2035.
Xu, Wei-Chu
