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DMSO
Flc
3
Flc (8 ug/mL)
+
AmpB
(8 ug/mL) (7.5 ug/mL)
(1 ug/mL)
3 (7.5 ug/mL)
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Figure 2. Viability of C. albicans SC5314 inoculums after 24 h treatment with
fluconazole (Flc), ML229 (3), and amphotericin B (AmpB). Average of 4 replicates.
16. Youngsaye, W.; Vincent, B.; Hartland, C. L.; Morgan, B. J.; Buhrlage, S. J.;
Johnston, S.; Bittker, J. A.; MacPherson, L.; Dandapani, S.; Palmer, M.; Whitesell,
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17. The results of the HTS campaign can be viewed free of charge at http://
(ML189) that sensitizes Candida albicans clinical isolates to fluco-
nazole.16 In this Letter, we report SAR studies on the structurally
distinct compound 2 that was also identified as a chemosensitizer
of C. albicans in the primary screen. The resulting small-molecule
probe 3 (ML229), along with 1 (ML189), should be useful tools
for interrogating the molecular mechanism by which C. albicans ac-
quires resistance against azole antifungals. To assist such efforts,
tetracyclic indole 3 has been registered with the NIH Molecular Li-
braries Program as probe ML229 and is available upon request.32
18. Redding, S.; Smith, J.; Farinacci, G.; Rinaldi, M.; Fothergill, A.; Rhine-Chalberg,
J.; Pfaller, M. Clin. Infect. Dis. 1994, 18, 240.
19. The fluconazole MIC for CaCi-2 and CaCi-8 was determined to be 2
(6.5 M) and 8 g/mL (26 M), respectively. For the CaCi-2 and CaCi-8 growth
inhibition assays, a fixed fluconazole concentration of 8 g/mL (26 M) was
lg/mL
l
l
l
l
l
used. In CaCi-2, this corresponded to a baseline growth inhibition of 60–80%
and was insufficient to suppress the trailing growth associated with this strain.
Complete details on the assays performed are provided in Ref. 16.
20. Sauter, F.; Fröhlich, J.; Chowdhury, A. Z. M. S.; Hametner, C. Monatsh. Chem.
1997, 128, 503.
Acknowledgments
21. Unangst, P. C. J. Heterocycl. Chem. 1983, 20, 495.
The authors are grateful to Patti Aha for assistance in manu-
script preparation. X-ray crystallography services were provided
by Dr. Peter Mueller and the Massachusetts Institute of Technology
X-ray diffraction facility. This work was funded by the NIH-MLPCN
program (1 U54 HG005032-1 awarded to S.L.S.). BV, LW, and SL are
grateful for funding from the NIH (1 R03 MH086456-01).
22. CCDC 858013 contains the supplementary crystallographic data for this paper.
23. Eagle, H.; Musselman, A. D. J. Exp. Med. 1948, 88, 99.
24. Fleischhacker, M.; Radecke, C.; Schulz, B.; Ruhnke, M. Eur. J. Clin. Microbiol.
Infect. Dis. 2008, 27, 127.
25. Wiederhold, N. P. Curr. Opin. Infect. Dis. 2007, 20, 574.
26. Cowen, L. E.; Lindquist, S. Science 2005, 309, 2185.
27. Cruz, M. C.; Goldstein, A. L.; Blankenship, J. R.; Del Poeta, M.; Davis, D.;
Cardenas, M. E.; Perfect, J. R.; McCusker, J. H.; Heitman, J. EMBO J. 2002, 21, 546.
28. Vu, K.; Gelli, A. Med. Mycol. 2010, 48, 255.
Supplementary data
29. Zhai, B.; Zhou, H.; Yang, L.; Zhang, J.; Jung, K.; Giam, C.-Z.; Xiang, X.; Lin, X. J.
Antimicrob. Chemother. 2010, 65, 931.
30. Sharma, M.; Manoharlal, R.; Negi, A. S.; Prasad, R. FEMS Yeast Res. 2010, 10, 570.
31. Marchetti, O.; Moreillon, P.; Glauser, M. P.; Bille, J.; Sanglard, D. Antimicrob.
Agents Chemother. 2000, 44, 2373.
Supplementary data (crystallographic data for compound 10k,
experimental protocols for the preparation of 3, and associated
spectroscopic data) associated with this article can be found, in
32. Compound 3 (probe ML229) is also available from commercial vendors.
References and notes
1. MacCallum, D. In New Insights in Medical Mycology; Kavanagh, K., Ed.; Springer:
Netherlands, Dordrecht, 2007; pp 99–129.