4244
W. J. Watkins et al. / Bioorg. Med. Chem. Lett. 13 (2003) 4241–4244
Table 2. Comparative tissue levels of analogues of 1
bacterial activity (MIC >40 mg/mL).
No.
logP
logD
AUC0À24 h (mg h/kg)a
Serum and tissue pharmacokinetics were measured in 5
male Sprague–Dawley rats with femoral and jugular
venous catheters. EPIs were administered alone or in a
cassette of up to five compounds as a 2 h constant rate
infusion into the femoral vein at doses varying from 1 to
10 mg/kg. Blood samples were collected for up to 8 h
from the jugular catheter. At 0.25, 2, 8, 16, and 24 h
after the start of the infusion, a single rat was sacrificed
and liver, kidney, and lung tissue were harvested. Serum
and tissue homogenates were assayed using HPLC/MS/
MS. Pharmacokinetic data were analyzed using com-
partmental and non-compartmental methods. Tissue
AUC0À24 h were normalized to a dose of 1 mg/kg for
comparison.
Kidney
Liver
Lung
1
3
4
6
2.3
1.4
1.8
2.3
1.2
2.8
ND
0.5
0.5
0.9
1.1
56
96
79
25
100
133
22
12
20
13
15
4
3
14
4
5
ND
7
À0.5
26
176
5.5
10b
11c
1.9
ND
8.5
aNormalized to 1 mg/kg dose; serum AUC0À24 for all compounds
References and Notes
h
was ca. 1 mg h/L.
bSynthesized as for 3, but coupling with amine C.
cSynthesized by coupling of BOC-d-Ala-OH with amine B (iPr2NEt,
PyBrop, CH2Cl2), followed by treatment with TFA.
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Nakayama, K.; Ishida, Y. J. Med. Chem. 1999, 42, 4928.
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Bioorg. Med. Chem. Lett. 2001, 11, 663.
ing that all dications accumulate regardless of structure
type, it is highly probable that no such EPIs fulfilling
this particular pharmacophore can be found.
3. Renau, T. E.; Leger, R.; Filonova, L.; Flamme, E. M.;
Wang, M.; Yen, R.; Cho, D.; Griffith, D.; Chamberland, S.;
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All analogues were purified by reverse-phase MPLC
and tested as their bis-TFA salts. The structural identity
of each compound was confirmed by 1H NMR and MS.
Levofloxacin was provided by Daiichi Pharmaceutical
Co., Ltd (Tokyo, Japan).
The ionization constants, partition coefficients and
lipophilicity profiles of the compounds were determined
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Æ0.15. LogD values are reported at physiological pH
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Levofloxacin MICs for P. aeruginosa strain PAM 1723
(MexAB-OprM
overexpressed;
DmexCD-oprJ,
DmexEF-oprN)11 were measured in the presence or
absence of varying concentrations of efflux pump inhi-
bitor (checkerboard format). Drugs were tested in
Mueller–Hinton broth according to NCCLSreference
methods. The in vitro potency of the EPI is expressed as
the minimum potentiation concentration (MPC8),
which is the lowest concentration required for an 8-fold
reduction in levofloxacin MIC. Assay controls estab-
lished the variability of the MPC8 as Æ2-fold. All the
compounds reported in this work had no intrinsic anti-