B. S. Jursic et al. / Bioorg. Med. Chem. Lett. 20 (2010) 7372–7375
7375
intermediate alcohol 3 was later oxidized by chromic acid by fol-
lowing standard procedures (Scheme 1).17 From this point, we then
branched the synthetic scheme into two different paths; the first
This present work describes the synthesis and preliminary anti-
fungal evaluation of 2,3-functionalized androstane and cholestane
derivatives, which were prepared by simple and efficient synthetic
methods using readily available starting material. Several of the
derivatives from the androstane and cholestane groups showed
reasonable antifungal activity (as measured spectroscopically by
a >25% reduction in fungal growth compared to control wells)
against at least one species of fungus. Further, the 2,3-functional-
ized derivatives can further be used as building blocks for the syn-
thesis of novel fatty-acid esters of steroids with potential
antimicrobial activities.
involved the direct introduction of an acetyl group into the 2a po-
sition of 4 with lead tetraacetate to generate 7 (Scheme 1, step vii);
while the second approach generated the same compound 7 using
a three-step procedure (Scheme 1, steps iv–vi). The first step of the
alternative preparation of 7 is the synthesis of vinyl acetate 5
(Scheme 1, step iv), followed by epoxidation of 5 with MCPBA to
yield epoxide 6 (Scheme 1, step v). Finally, epoxide 6 ring opening
occurs following treatment with acetic acid to yield the desired
compound 7. Although longer, the alternative route through the
preparation of vinyl ester 5 and epoxide 6 has an added advantage
with respect to the purification of the product, and this method
gave us comparable yields of 7 (Scheme 1). Finally, to generate
the 2,3-functionalized steroids, we followed a straightforward
NaBH4/CeCl3 reduction of the carbonyl group of 7, followed by
the acetate ester hydrolysis to produce 8 and 9, respectively
(Scheme 1).
The preparation of 2,3-functionalized cholestane derivatives
follows an almost identical synthetic route using cholesterol as
the starting material (10, Scheme 2). Ketoacetate 15 and ester 16
were prepared by following a previously described procedure for
Pb(OAc)4 acetyl group introduction and NaBH4/CeCl3 keto group
reduction.18 One notable exception is the two additional steps that
were taken to prepare succinic acid derivatives 18 and 19 from the
corresponding alcohols 16 and 17, respectively (Scheme 2). These
reactions were adapted from the classical alcohol esterification
by succinic acid anhydride. The antifungal activity of the synthe-
sized stereoisomers of the 2,3-functionalized steroids evaluated
in vitro.
Acknowledgments
This work was supported in part by P30EY002377 (LSU Eye
Center Core), funding from the Louisiana Lions Eye Foundation,
and by an unrestricted grant from Research to Prevent Blindness,
New York, NY (LSU Department of Ophthalmology-LSUHSC). We
also thank the National Science Foundation for financial support
(CHE-0611902) for this work (B.S.J.).
Supplementary data
Supplementary data associated with this article can be found, in
References and notes
1. Chakrabarti, A.; Chatterjee, S. S.; Shivaprakash, M. R. Nippon Ishinkin Gakkai
Zasshi 2008, 49, 165.
2. Chandesris, M. O.; Lanternier, F.; Lecuit, M.; Lortholary, O. Rev. Prat. 2007, 57,
1653.
3. Cornely, O. A. Infection 2008, 36, 296.
4. Brunel, J. M.; Loncle, C.; Vidal, N.; Dherbomez, M.; Letourneux, Y. Steroids 2005,
70, 907.
5. Shamsuzzaman; Khan, M. S.; Alam, M.; Tabassum, Z.; Ahmad, A.; Khan, A. U.
Eur. J. Med. Chem. 2010, 45, 1094.
6. Loncle, C.; Brunel, J. M.; Vidal, N.; Dherbomez, M.; Letourneux, Y. Eur. J. Med.
Chem. 2004, 39, 1067.
The susceptibility studies and minimal inhibitory concentra-
tions (MIC) values for C. albicans (ATCC no. 10231), C. neoformans
(ATCC no. 36556), C. glabrata (ATCC no. 48435), and the filamen-
tous fungus A. fumigatus (ATCC no. 16424) were determined by
the broth dilution technique in accordance with NCCLS reference
documents M27-A.19 Dilution panels ranged from 0.01 to 128
lg/
7. Rauf, A.; Gangal, S. J. Oleo. Sci. 2008, 57, 453.
mL. Master stock concentrations of drugs (soluble in DMSO) were
prepared to ensure that the maximum final concentration of DMSO
in tested antifungal solutions was 1% or less. Subsequent twofold
serial dilutions were made using RPMI 1640 broth or sterile water
to a final concentration of 1280–0.1 lg/mL. A final 10-fold dilution
of each drug was made by aliquotting 0.1 mL of each dilution to
8. Banday, M. R.; Farshori, N. N.; Ahmad, A.; Khan, A. U.; Rauf, A. Eur. J. Med. Chem.
2010, 45, 1459.
9. Moss, G. P. Eur. J. Biochem. 1988, 178, 277.
10. Marston, A.; Hostettmann, K. Planta Med. 2009, 75, 672.
11. Marston, A.; Potterat, O.; Hostettmann, K. J. Chromatogr. 1988, 450, 3.
12. Hostettmann, K.; Marston, A.; Maillard, M.; Wolfender, J. L. Adv. Exp. Med. Biol.
1996, 404, 117.
13. Banday, M. R.; Farshori, N. N.; Ahmad, A.; Khan, A. U.; Rauf, A. Eur. J. Med. Chem.
2010, 45, 1459.
0.9 mL of inoculating media, giving final drug concentrations
14. Kaskiw, M. J.; Tassotto, M. L.; Mok, M.; Tokar, S. L.; Pycko, R.; Th’ng, J.; Jiang, Z.
H. Bioorg. Med. Chem. 2009, 17, 7670.
15. Dixon, R. A. Nature 2001, 411, 843.
16. Reyes-Moreno, M.; Ruiz-Garcia, J.; Jauregui-Haza, U.; Lora-Garcia, J.; Aguero-
Aguero J. Revista CENIC Ciencias Quimicas 2001, 32, 51.
17. Mamlok, L.; Jaques, J. Bull. Soc. Chim. Fr. 1960, 484.
18. Cruz Silva, M. M.; Riva, S.; Sa’eMelo, M. L. Tetrahedron 2005, 61, 3065.
19. Clinical Laboratory and Standards Institute. M27-A3 2010, 28.
tested in the range of 128–0.01
used for these studies were Amphoteracin B and Itraconazole (Sig-
ma–Aldrich). All controls used were diluted to 1.0 g/mL concen-
trations, according to the manufacturer’s instructions and run in
parallel to each in vitro screening of the 2,3-functionalized steroid
analogs. The results of these screenings are summarized in Table 1.
lg/mL. Antifungal drug controls
l