T. Uchida et al. / Bioorg. Med. Chem. Lett. 19 (2009) 2013–2017
2017
Table 5
MICs of 23d, fluconazole and itraconazole
Strainb
MIC (l
g/mL)a
Cmpd.
23d
CS-758
Fluconazole
Itrazonazole
C. albicans ATCC24433
C. albicans SANK51486
C. albicans TIMM3164
C. albicans ATCC64550
C. parapsilosis ATCC90018
C. glabrata ATCC90030
C. krusei ATCC6258
C. tropicalis ATCC750
C. neoformans TIMM1855
A. fumigatus ATCC26430
A. fumigatus SANK10569
A. flavus SANK18497
60.008
60.008
60.008
0.25
60.008
2
0.063
0.016
0.031
0.031
0.031
0.125
0.016
60.008
0.063
0.5
0.016
1
0.25
0.25
0.016
0.063
0.063
0.25
0.5
0.25
>4
>4
0.5
>4
>4
2
>4
>4
0.125
0.031
0.25
1
0.125
1
0.5
0.5
0.25
0.25
0.25
0.5
>4
>4
a
MICs were determined at 35 °C (30 °C for Aspergillus spp.) in RPMI1640 medium (yeast nitrogen base for C. neoformans) at pH 7.0. MICs were defined as the minimum
concentration of the test compounds that inhibit the growth of the fungi by 80%.
b
C. albicans, Candida albicans; C. parapsilosis, Candida parapsilosis; C. glabrata, Candida glabrata; C. krusei, Candida krusei; C. tropicalis, Candida tropicalis; C. neoformans,
Cryptococcus neoformans; A. fumigatus, Aspergillus fumigatus; A. flavus, Aspergillus flavus.
4. (a) Oida, S.; Tajima, Y.; Konosu, T.; Nakamura, Y.; Somada, A.; Tanaka, T.; Habuki,
fungal activity of compound 24a, which has a meta phenylene
group, was drastically weakened, whereas the MICs of compound
24b, in which a fluorine atom was introduced to the inner benzene
ring were almost comparable to or slightly higher than those of
23d.
S.; Harasaki, T.; Kamai, Y.; Fukuoka, T.; Ohya, S.; Yasuda, H. Chem. Pharm. Bull.
2000, 48, 694; (b) Konosu, T.; Oida, S.; Nakamura, Y.; Seki, S.; Uchida, T.; Somada,
A.; Mori, M.; Harada, Y.; Kamai, Y.; Harasaki, T.; Fukuoka, T.; Ohya, S.; Yasuda,
H.; Shibayama, T.; Inoue, S.; Nakagawa, A.; Seta, Y. Chem. Pharm. Bull. 2001, 49,
1647; (c) Kamai, Y.; Harasaki, T.; Fukuoka, T.; Ohya, S.; Uchida, K.; Yamaguchi,
H.; Kuwahara, S. Antimicrob. Agents Chemother. 2002, 46, 367.
Finally, the MICs of 23d were determined against 12 fungal
strains and compared with those of CS-758, fluconazole, and
itrazonazole (Table 5). The MICs of 23d surpassed those of fluco-
nazole, and itrazonazole, and were almost comparable to those of
CS-758.
In a stability test under acidic conditions, the half-life (t1/2) of
23d in HCl (0.007 mol/L) solution in CH3CN–H2O (3:7, v/v at
37 °C) was over 160 min, whereas that of CS-758 was 6.40 min.
Thus, compound 23d showed dramatic improvement in its acid-
stability compared with CS-758.10
In conclusion, efficient routes were found for the synthesis of
our novel aryl-amide analogs of antifungal dioxane–triazole deriv-
atives. Compound 23d, which has a cyano group at the C4 position
on the benzene ring, exhibited higher in vitro activities than fluco-
nazole or itraconazole. Furthermore, compound 23d has a much
longer half-life under acidic conditions than CS-758. Further eval-
uations of this class of compounds are currently proceeding.
5. Though itraconazole has a ketal moiety, it is stable under acidic conditions and
used for oral administration.
6. The stereochemistry of the 1,3-dioxane ring was elucidated by the coupling
constants in the 1H NMR spectra. The trans isomers showed characteristic
signals of the axial methylene protons on the C4 and C6 positions in the 1,3-
dioxane ring with large coupling constants (triplet, J = ca. 11 Hz). In contrast,
the corresponding signals of cis isomers appeared as multiplets.
7. Maiti, A. K.; Bhattacharyya, P. Tetrahedron 1994, 50, 10483.
8. MICs were determined by the broth microdilution methods in accordance with
the guidelines in the National Committee for Clinical Laboratory Standards
(NCCLS) documents. 1997. M27-A; 1995. M27-T; 1998. M38-P. National
Committee for Clinical Laboratory Standards, Wayne, PA.
9. Data for 23d: mp 185–187 °C; 1H NMR (270 MHz, CDCl3) d: 1.22 (d, 3H,
J = 7 Hz), 3.36 (q, 1H, J = 7 Hz), 3.4–3.6 (m, 1H), 3.76 (t, 1H, J = 11 Hz), 3.79 (t,
1H, J = 11 Hz), 4.42 (ddd, 1H, J = 11, 5, 2 Hz), 4.55 (ddd, 1H, J = 11, 5, 2 Hz), 4.85
(d, 1H, J = 14 Hz), 5.05 (d, 1H, J = 1 Hz), 5.05 (d, 1H, J = 14 Hz), 5.55 (s, 1H), 6.7–
6.8 (m, 2H), 7.3–7.4 (m, 1H), 7.65 (d, 2H, J = 8 Hz), 7.68 (d, 2H, J = 8 Hz), 7.80 (s,
2H), 7.80 (d, 2H, J = 8 Hz), 7.89 (d, 2H, J = 8 Hz), 7.93(s, 1H); IR (m
max/cmꢀ1, KBr):
3371, 2225, 1679, 1512, 1319, 1139; MS (FAB) m/z: 592 [M+H]+; ½a D25
ꢀ52° (c
ꢁ
0.60, AcOEt); HRMS: calcd for C30H28F2N5O4S [M+H]+ 592.18301, found
592.18186; Anal. Calcd for C30H27F2N5O4S: C, 60.90; H, 4.60; N, 11.84; S,
5.42; F, 6.42. Found: C, 61.14; H, 4.35; N, 11.58; S, 5.30; F, 6.39.
10. Contrary to expectation, the absolute bioavailability (BA) of 23d in rats after
oral administration (20 mg/kg) of its polyethylene glycol 400 solution was only
31.7%, whereas that of CS-758 was 113%. Though the reason for the low
bioavailability of 23d was not determined, we reason that hydrolysis of the
amide moiety presumably contributed. CS-758 is a compound that can be
hydrolyzed in acidic conditions faster than 23d, but the acid-stability to this
degree seems to be sufficient for use in oral administration.
References and notes
1. Georgopapadakou, N. H.; Walsh, T. J. Antimicrob. Agents Chemother. 1996, 40,
279.
2. Sheehan, D. J.; Hitchcock, C. A.; Sibley, C. M. Clin. Microbiol. Rev. 1999, 12, 40.
3. Aoyama, Y.; Yoshida, Y.; Sato, R. J. Biol. Chem. 1984, 259, 1661.