Synthesis and antifungal activity of oxygenated cholesterol derivatives

Article abstract of DOI:10.1016/j.steroids.2005.06.007

A series of oxygenated cholesterol derivatives were prepared from new synthetic methods and evaluated for their in vitro antimicrobial properties against human pathogens. The activity was highly dependent on the structure of the different compounds involved. The best results were obtained with hydroxy ketones 2, 4 and 5 and diketone 7 exhibiting activities against S. cerevisiae (ATCC 28383) and Candida albicans (CIP 1663-86). For example, compound 2 exhibited high activities against C. albicans (CIP 1663-86) and Amphotericine B and miconazole resistant strain C. albicans (CIP 1180-79) at a concentration of 1.5 μg/mL.

Full text of DOI:10.1016/j.steroids.2005.06.007

Steroids 70 (2005) 907–912
Synthesis and antifungal activity of oxygenated cholesterol derivatives
Jean Michel Brunela,∗, Celine Loncle , Nicolas Vidal ,
a
a
´
Michel Dherbomezb, Yves Letourneuxa,∗
a
Laboratoire Synthe`se et Etude de Substances Naturelles a` Activite´s Biologiques (SESNAB), IMRN INRA 1111, Faculte´ des Sciences et Techniques
de St Je´roˆme, Universite´ Paul Ce´zanne, Aix-Marseille III, Avenue Escadrille Normandie Nie´men, 13397 Marseille Cedex 20, France
b
IUT La Rochelle, 15 rue Francois de Vaux de Foletier, F-17026 La Rochelle, France
Received 7 March 2005; received in revised form 27 June 2005; accepted 30 June 2005
Available online 1 September 2005
Abstract
A series of oxygenated cholesterol derivatives were prepared from new synthetic methods and evaluated for their in vitro antimicrobial
properties against human pathogens. The activity was highly dependent on the structure of the different compounds involved. The best results
were obtained with hydroxy ketones 2, 4 and 5 and diketone 7 exhibiting activities against S. cerevisiae (ATCC 28383) and Candida albicans
(CIP 1663-86). For example, compound 2 exhibited high activities against C. albicans (CIP 1663-86) and Amphotericine B and miconazole
resistant strain C. albicans (CIP 1180-79) at a concentration of 1.5 ␮g/mL.
© 2005 Elsevier Inc. All rights reserved.
Keywords: Oxygenated sterols; Antifungal activity; Antimicrobial activity
1. Introduction
Ourisson et al. were the first to report preliminar results on the
cytotoxity of such compounds towards tumor cells [11–13].
In this area, recent results have been reported on the synthe-
sisandantiproliferative, anti-HIVandanti-Asthmaproperties
of various oxygenated sterol derivatives [14–16]. In contin-
uation of our work on biologically active sterol derivatives
[17–22], we report herein the synthesis of various new oxy-
genated cholesterol derivatives and their promising antifun-
galpropertiessincenobiologicalactivitiesofsuchderivatives
were described to date, even if numerous similar natural com-
pounds possessing interesting biological activities have been
isolated.
Oxygenated sterols, including both autoxidation products
and sterol metabolites, have many important biological activ-
ities mostly related to the physiological control of cholesterol
biosynthesis [1,2]. Several investigators have demonstrated
that oxygenated cholesterol such as 7-ketocholesterol and
25-hydroxycholesterol inhibit the activity of ␤-hydroxy-␤-
methylglutaryl CoA (HMG CoA) reductase, the rate-limiting
enzyme in the biosynthesis of cholesterol, in various in vitro
test system [1,3–6]. In 1995, two 4,4-dimethyl-ꢀ8,24-sterols
called FF-MAS (Follicular Fluid-Meiosis Activating Sterol)
were found to have a regulatory function in meiosis [7] and
since then numerous studies dealing with the design, synthe-
sis and derivation of structure-activity relation ships of FF-
MAS related sterol compounds have been reported [8–10].
Nevertheless, few studies have been devoted to the possible
antifungal and antimicrobial activities against Gram-positive,
Gram-negative bacteria and yeast of such oxygenated sterols.
2. Experimental section
All solvents were purified according to reported proce-
dures, and reagents were used as commercially available.
Tetrahydrofuran (THF) was distilled from sodium-
benzophenone ketyl immediately prior to use. Ethylacetate
and petroleum ether (35–60 ◦C) were purchased from
SDS and used without any further purification. Column
∗
Corresponding authors. Tel.: +33 491288550; fax: +33 491288440.
E-mail address: bruneljm@yahoo.fr (J.M. Brunel).
0039-128X/$ – see front matter © 2005 Elsevier Inc. All rights reserved.
doi:10.1016/j.steroids.2005.06.007

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J.M. Brunel et al. / Steroids 70 (2005) 907–912
chromatography was performed on SDS silica gel (70–230
mesh). 1H NMR and 13C NMR spectra were recorded
in CDCl3 on a Bruker AC 300 spectrometer working at
300.00 and 75 MHz, respectively (the usual abbreviations
are used: s: singulet, d: doublet, t: triplet, q: quadruplet, m:
multiplet). Tetramethylsilane was used as internal standard.
All chemical shifts are given in ppm.
orationwasobserved. Theammoniawasallowedtoevaporate
overnight at room temperature. The residue was dissolved
in 100 mL of a toluene/EtOAc solution. The organic layer
was successively washed with a 0.1 N HCl solution, distilled
waterandbrine. TheorganiclayerwasdriedoverNa2SO4 and
concentrated in vacuo. The oily residue was purified by chro-
matography on a silicagel column using EtOAc/petroleum
ether as eluent (1/4–1/1) affording the expected diol 3 in 74%
yield.
2.1. Synthesis of 7-keto cholesterol 2
White solid; mp: 175 ◦C; 1H NMR: δ = 3.95–4.30 (m,
1H), 0.40–3.45 (m, 47H); 13C: δ = 75.21, 71.13, 55.80, 55.31,
52.55, 43.66, 43.48, 42.11, 40.05, 39.56, 38.13, 36.97, 36.26,
35.74, 35.00, 31.65, 31.50, 28.78, 28.07, 26.97, 23.91, 22.88,
22.62, 21.51, 18.86, 14.19, 12.51, 12.23. C27H48O2 calcd C
80.2, H 11.9; found C 80.4, H 10.9.
Compound 2 was prepared using a modified procedure
previously described by Kinney et al. [23,24]. Choles-
terol (50 g, 0.129 mol) and N-hydroxyphthalamide (22 g,
0.135 mol) were dissolved in EtOAc-acetone (1.5 L, 1:1
v/v) in a 2 L glass reactor equipped with a condenser and
a mechanical stirrer. Benzoyl peroxide (3 g) was added at
50–60 ◦C. Air was bubbled into the reaction solution and
stirring was maintained for 72 h at 50–60 ◦C. Additional
50/50 EtOAc-acetone was added to the reaction as needed
to replenish what was lost due to air flow through the sys-
tem. The reaction was followed by TLC on silicagel (50%
EtOAc in petroleum ether) and judged completed after 72 h.
After evaporation of all the solvents in vacuo, petroleum ether
was added and the organic phase was washed with sodium
carbonate solution until no orange coloration was observed.
The organic layers were washed with brine and dried over
MgSO4. The solvent was removed and the sterol dissolved
in pyridine (200 mL). The pyridine solution was cooled to
0 ◦C and CuCl2 (1 g) was added. The solution was stirred
overnight allowing the solution to warm to room temperature.
After addition of water (200 mL), the solution was extracted
with EtOAc (3 × 150 mL). The organic layer was washed
with saturated CuSO4 solution until no trace of pyridine
was observed. The organic layer was washed with a 0.1 M
HCl solution, dried over MgSO4 and concentrated in vacuo.
The oily residue was purified by chromatography on a sil-
icagel column using EtOAc/petroleum ether as eluent (50/50)
affording the expected hydroxy ketone 2 in 62% yield.
White solid; mp: 116 ◦C; 1H NMR: δ = 5.45–5.75 (m, 1H),
4.34 (s, 1H), 3.47–3.75 (m, 1H), 0.45–2.12 (m, 41H); 13C:
δ = 202.81, 165.59, 126.49, 70.89, 55.17, 50.34, 45.80, 43.49,
39.87, 38.67, 36.57, 36.11, 28.40, 26.72, 24.22, 23.22, 22.96,
21.61, 19.26, 17.71, 12.37. C27H44O2 calcd C 80.9, H 11.1;
found C 81.0, H 10.8.
2.3. Synthesis of 7β-hydroxy cholestanone 4
A
suspension of 7␤-hydroxy cholestanol 3 (1 g,
1.9 × 10−3 mol) and silver carbonate on Celite (1 g) in
toluene (70 mL) was stirred under argon at reflux overnight.
The reaction mixture was filtered through a column of
Florisil and the filtrate was concentrated in vacuo. The
residuewaspurifiedbychromatographyonasilicagelcolumn
using petroleum ether/ethylacetate (100/0 (100 mL), 50/50
(100 mL), 0/100 (300 mL)) as eluent affording the expected
product 4 in 82% yield.
White solid; mp: 180 ◦C; 1H NMR: δ = 3.05–3.55 (m, 1H),
2.2–2.6 (m, 3H), 0.4–1.92 (m, 42H); 13C: δ = 211.55, 74.66,
55.61, 55.24, 51.83, 44.18, 43.94, 43.66, 39.90, 39.54, 38.12,
35.72, 35.16, 28.75, 28.06, 23.89, 22.87, 22.62, 21.80, 18.84,
12.22, 11.63. C27H46O2 calcd C 80.5, H 11.5; found C 81.6,
H 11.3.
2.4. Synthesis of 7α-hydroxycholestanone 5 and
3,7-cholestanedione 6
In a 250 mL two necked round flask were placed
under argon at −78 ◦C 7-ketocholesterol 2 (300 mg,
7.46 × 10−4 mol) dissolved in anhydrous THF (10 mL). L-
Selectride (2 equivalents) were slowly added at −78 ◦C
and stirred for 5 h before being quenched by the addition
of H2O2 and a solution of NaHCO3 (10 mL). The residue
was dissolved in 100 mL of ethylacetate, washed with brine
and dried over MgSO4. After filtration and evaporation of
the solvents, the crude residue of 7␣-hydroxy cholestanol
(196 mg, 4.85 × 10−4 mol) and silver carbonate on Celite
(631 mg) in toluene (70 mL) was stirred under argon at reflux
overnight. The reaction mixture was filtered through a col-
umn of Florisil and the filtrate was concentrated in vacuo. The
residuewaspurifiedbychromatographyonasilicagelcolumn
using petroleum ether/ethylacetate (70/30 → (80/20)) as elu-
ent affording the expected products 5 and 6 in, respectively,
13 and 17% yield.
2.2. Synthesis of 7β-hydroxy cholestanol 3
In a 250 mL two necked round flask were placed
under argon anhydrous THF (40 mL) at −78 ◦C and
40 mL of ammonia. Lithium wire (0.7 g, 0.14 mol) was
added to the solution with vigorous stirring. Once the
lithium was completely dissolved, 7-ketocholesterol 2 (3.5 g,
8.75 × 10−3 mol) was dissolved in 50 mL of anhydrous THF
and added to the flask in a steady stream from a 100 mL addi-
tion funnel. The reaction was stirred for 3 h at −78 ◦C before
being quenched by the addition of MeOH until no blue col-
Compound 5: white solid; mp: 115 ◦C; 1H NMR:
δ = 3.3–3.85 (m, 1H), 0.60–2.65 (m, 45H); 13C: δ = 211.36,

J.M. Brunel et al. / Steroids 70 (2005) 907–912
909
32H); 13C: δ = 202.76, 199.94, 161.50, 125.83, 56.94, 56.35,
51.37, 47.20, 42.92, 40.20, 39.85, 36.45, 36.06, 34.59, 28.39,
24.18, 23.20, 22.94, 21.26, 19.03, 17.98, 12.27. C27H44O2
calcd C 80.9, H 11.1; found C 81.0, H 10.8. C27H42O2 calcd
C 81.4, H 10.6; found C 81.2, H 10.7.
71.08, 57.18, 56.53, 54.33, 47.13, 39.86, 38.32, 37.07, 36.49,
36.08, 31.10, 30.44, 28.43, 28.39, 24.38, 24.20, 23.20, 22.93,
21.92, 19.03, 13.53, 12.40. C27H46O2 calcd C 80.5, H 11.5;
found C 80.7, H 10.8.
Compound 6: white solid; mp: 181 ◦C; 1H NMR:
δ = 0.8–2.8 (m, 41H), 0.6–0.775 (m, 3H); 13C: δ = 211.66,
209.52, 57.91, 57.01, 56.52, 53.88, 47.02, 39.85, 39.79,
38.51, 38.43, 37.78, 37.39, 36.46, 36.08, 28.42, 28.39, 24.40,
24.19, 23.19, 22.93, 22.07, 19.02, 12.95, 12.41. C27H44O2
calcd C 80.9, H 11.1; found C 81.0, H 10.8.
2.7. Synthesis of 7α-hydroxycholesterol 9
To a stirred and cooled (−78 ◦C) solution of 7-keto
cholesterol 2 (300 mg, 6.78 × 10−4 mol) in dry THF (10 mL)
was added a 1 M solution of K-Selectride in THF (2 mL,
2 × 10−3 mol). The mixture was stirred overnight allowing
the solution to warm to room temperature. The organobo-
rane was oxidized by addition of H2O2 until the color of
the solution has disappeared and treated by a 1 N sodium
hydroxide solution (2 mL). Toluene (40 mL) was added and
the organic layer was successively washed with a solution
of 1 N HCl, Na2CO3 then dried over MgSO4. After filtra-
tion and removal of the solvents, the residue was purified
by chromatography on a silicagel column using petroleum
ether/ethylacetate (75/25) as eluent affording the expected
7␣-hydroxycholesterol 9 in 62% yield.
2.5. Synthesis of cholest-4-ene-3,6-dione 7
In a 250 mL two necked round flask cholesterol (5 g,
1.29 × 10−2 mol) was dissolved in anhydrous dichlorome-
thane (50 mL) and pyridinium chlorochromate (8.34 g,
3.87 × 10−2 mol) was added. The mixture was stirred at
room temperature for 3 days. Then an additional portion
of pyridinium chlorochromate (4.2 g, 1.93 × 10−2 mol) was
added. After further stirring at room temperature for 1 day,
dry diethylether (150 mL) was added and the liquid was
decanted from a brown gum. The insoluble residue was
washed three times with dry diethylether (3 × 50 mL). The
combined organic layers were washed with water, dried over
MgSO4, passed through a pad of Florisil and concentrated
in vacuo. The residue was purified by chromatography on
a silicagel column using petroleum ether/ethylacetate (5/2)
as eluent affording the expected cholest-4-ene-3,6-dione 7 in
72% yield.
White solid; mp: 185 ◦C; 1H NMR: δ = 5.60–5.71 (m, 1H),
3.80–3.95 (m, 1H), 3.40–3.72 (m, 1H), 2.15–2.50 (m, 2H),
0.60–2.10 (m, 41H); 13C: δ = 146.65, 124.25, 71.71, 65.75,
56.25, 49.81, 42.65, 42.54, 39.92, 37.91, 37.79, 36.16, 31.75,
28.67, 28.40, 24.69, 24.11, 23.20, 22.96, 21.10, 19.13, 18.64,
12.03. C27H46O2 calcd C 80.5, H 11.5; found C 80.0, H 11.4.
White solid; mp: 119 ◦C; 1H NMR: δ = 7.15 (s, 1H),
0.55–2.72 (m, 41H); 13C: δ = 202.38, 199.53, 161.13, 125.48,
56.59, 56.00, 51.01, 46.85, 42.58, 39.85, 39.50, 36.11, 35.72,
34.25, 34.02, 28.05, 24.01, 23.84, 22.86, 22.60, 20.92, 18.69,
17.55, 11.93. C27H42O2 calcd C 81.4, H 10.6; found C 81.2,
H 10.8.
2.8. Synthesis of 7β-hydroxycholesterol 10
To a stirred solution of 7-keto cholesterol 2 (445 mg,
10−3 mol) in dry THF (10 mL) was added a 0.4 M solution of
CeCl3·H2O in THF/CH3OH (2/1, 2.5 mL). NaBH4 (38 mg,
10−3 mol) was then slowly added and stirring was maintained
for 1 h at room temperature. The reaction was quenched by
addition of 5% HCl (1 mL) and 7␤-hydroxy cholesterol was
extracted with CH2Cl2. The organic layer was dried over
MgSO4, filtered and the solvents were removed in vacuo. The
crude product was purified by chromatography on a silicagel
column using ethylacetate as eluent affording the expected
7␤-hydroxycholesterol 10 in 75% yield.
2.6. Synthesis of cholest-5-ene-3,7-dione 8
Compound 8 was prepared using a modified procedure
previouslydescribedbyCoreyetal. forthecatalyticoxidation
of secondary alcohols to ketones [25].
Into a 25 mL round-bottom flask, which had been flame
dried and filled with argon, was placed CH2Cl2 (2 mL) and
a dark orange CCl4 solution of a cyclic chromate ester
(3.0 × 10−3 mol) prepared from 2,4-dimethylpentane-2,4-
diol and chromium trioxide. After cooling the mixture to
0 ◦C in an ice bath a solution of peroxyacetic acid (3 mL)
and cholesterol (235 mg, 0.61 mmol) dissolved in 2 mL of
dry CH2Cl2 were slowly added. The mixture was stirred at
0 ◦C for 48 h. Removal of the solvents in vacuo afforded a oily
brown residue which was purified by chromatography on a
silicagel column using petroleum ether/ethylacetate (75/25)
as eluent affording the expected cholest-5-ene-3,7-dione 8 in
45% yield.
White solid; mp: 77 ◦C; 1H NMR: δ = 5.27 (s, 1H),
3.82–3.84 (m, 1H), 3.50–3.57 (m, 1H), 0.67–2.31 (m, 43H);
13C: δ = 144.25, 126.22, 74.13, 72.20, 56.73, 56.24, 59.04,
43.70, 41.68, 40.27, 37.71, 37.21, 36.98, 36.50, 32.35, 29.31,
28.78, 27.15, 24.61, 2..58, 23.32, 21.85, 19.93, 19.55, 12.60.
C27H46O2 calcd C 80.5, H 11.5; found C 80.5, H 11.5.
2.9. Synthesis of cholest-4-ene-3,6-diol 11
To a stirred solution of LiAlH4 (210 mg, 5.52 × 10−3 mol)
in dry THF (10 mL) was slowly added at 0 ◦C a solution of
cholest-4-ene-3,6-dione 7 (550 mg, 1.38 × 10−3 mol) in dry
THF. Stirring was maintained for 24 h allowing the solution
Red solid; mp: 91 ◦C; 1H NMR: δ = 5.90 (s, 1H), 3.10 (s,
2H), 2.27–2.77 (m, 2H), 1.75–2.20 (m, 5H), 0.50–1.71 (m,

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J.M. Brunel et al. / Steroids 70 (2005) 907–912
to warm to room temperature. The reaction was quenched by
addition of water (397 ␮L, 2.20 × 10−2 mol). After filtration
through a pad of Celite, the organic layer was dried over
MgSO4, filtered and the solvents were removed in vacuo. The
crude product was purified by chromatography on a silicagel
column using petroleum ethylacetate as eluent affording the
expected compound 11 in 72% yield.
35.4, 31.4, 30.4, 28.7, 27.9, 24.6, 23.5, 23.2,21.1, 19.4, 16.5,
12.1. C27H48O2 calcd C 80.2, H 11.9; found C 80.0, H 11.1.
3. Results and discussion
3.1. Chemistry
White solid; mp: 157 ◦C; H NMR: δ = 5.75–6.925 (m,
1
1H), 5.45–5.2 (m, 1H), 3.7–4.35 (m, 3H), 0.45–2.6 (m, 41H);
13C: δ = 149.61, 120.25, 69.02, 68.33, 56.53, 56.21, 54.61,
42.91, 39.88, 38.31, 36.51, 36.14, 34.74, 28.53, 28.40, 24.22,
23.21, 22.95, 20.08, 19.04, 12.35. C27H46O2 calcd C 80.5, H
11.5; found C 80.3, H 11.2.
In the present study, various oxygenated cholesterol
derivatives 1–13 were prepared from new synthetic meth-
ods or literature modified procedures as outlined in
Schemes 1 and 2. All these oxygenated derivatives were pre-
pared in only one or two steps in high scale synthesis from
commercial and inexpensive reagents. It is noteworthy that all
these compounds were previously isolated as byproducts in
low chemical yields from numerous oxidation processes but
no methods were reported to date for their efficient synthesis.
According to a modified procedure described by Kinney
et al. the high scale synthesis of 7-keto cholesterol 2 has
been performed from cholesterol 1 in the presence of N-
hydroxyphtalamide in a continuously aerated EtOAc/acetone
(1/1) solution at 50–60 ◦C for 72 h [23,24]. Subsequent treat-
ment of the crude mixture with CuCl2 in pyridine afforded
the expected product 2 as a white solid in 62% yield. 7␤-
hydroxy cholestanol 3 was easily prepared in 74% isolated
yield from derivative 2 by lithium–ammonia reduction at
−78 ◦C. Oxidation of compound 3 in refluxing toluene with
silver carbonate on Celite afforded 7␤-hydroxy cholestanone
4 in 82% yield. On the other hand, parent compounds 7␣-
hydroxy cholestanone 5 and 3,7-cholestanedione 6 were
2.10. Synthesis of 6β-hydroxy cholestanol 13
To a stirred solution of commercial 6-ketocholestanol
12 (444 mg, 10−3 mol) in dry THF (10 mL) was added a
0.4 M solution of CeCl3·H2O in THF/CH3OH (2/1, 2.5 mL).
NaBH4 (38 mg, 10−3 mol) was then slowly added and stir-
ring was maintained for 1 h at room temperature. The reaction
was quenched by addition of 5% HCl (1 mL) and the product
was extracted with CH2Cl2. The organic layer was dried over
MgSO4, filtered and the solvents were removed in vacuo. The
crude product was purified by chromatography on a silicagel
column using ethylacetate as eluent affording the expected
6␤-hydroxycholestanol 13 in 60% yield.
White solid; mp: 168 ◦C; 1H NMR: δ = 7.25–7.36 (m, 1H),
3.61–3.94 (m, 2H), 0.65–2.36 (m, 45H); 13C: δ = 71.9, 71.3,
57.1, 56.9, 53.9, 47.2, 42.5, 40.6, 39.8, 39.4, 37.2, 36.1, 35.7,
Scheme 1. (i) PCC CH2Cl2, 20 ◦C, 96 h. (ii) Peracetic acid, C5H10O4Cr, CH2Cl2, 20 ◦C, 48 h. (iii) (a) O2, acetone/ethylacetate, N-hydroxyphtalimide, ben-
zoylperoxide, 50 ◦C, 72 h; (b) CuCl2, pyridine, 0 ◦C, 24 h. (iv) (a) L-Selectride, THF, −78 ◦C, 24 h; (b) Ag2CO3-Celite, toluene, 110 ◦C, 12 h. (v) (a) Li, NH3,
THF, −78 ◦C, 1 h. (vi) Ag2CO3-Celite, toluene, 110 ◦C, 12 h.

J.M. Brunel et al. / Steroids 70 (2005) 907–912
911
Scheme 2. (i) L-Selectride, THF, −78 ◦C, 24 h. (ii) AlLiH4, THF, 0 ◦C, 24 h. (iii) AlLiH4, THF, 20 ◦C, 24 h. (iv) NaBH4, MeOH, 20 ◦C, 24 h.
easily synthesized in a one step sequence from derivative
2 by L-Selectride reduction at −78 ◦C in THF for 5 h and
subsequent oxidation with silver carbonate on Celite in
refluxing toluene. Purification of the crude residue on a sil-
icagel column afforded the expected products 5 and 6 in
respectively 13 and 17% yield. Moreover, cholest-5-ene-
3,7-dione 8 was prepared from cholesterol 1 according to
a modified procedure reported by Corey et al. involving a
cyclic chromate ester/peroxyacetic acid oxidant reagent [25].
7␣ and 7␤-hydroxy cholesterol 9 and 10 were obtained in
62 and 75% yield involving, respectively, K-Selectride and
NaBH4/CeCl3·H2O reducing agents. On the other hand, diol
compounds 11 and 13 came from the corresponding keto
derivatives 7 and 12 according to modified well known pro-
cedures.
the 3,7-cholestane structure positions seems to be necessary
to improve the biological activity of the molecule against
fungi. Thus, most antifungal drugs are sterol biosynthesis
inhibitors (SBIs) acting as site-specific inhibitors at different
steps of the ergosterol biosynthesis, the predominant sterol in
most fungi [27]. These SBIs compounds 2, 4 and 5 are mimics
of the carbocationic intermediates involved in ꢀ8–ꢀ7 sterol
isomerase reaction since this process is conducted by the ini-
tial addition of a proton to the ␣ face of C-9 giving a stabilized
carbonium ion at C-8. This high energy intermediate is con-
verted into ꢀ7 by removal of the 7␤ or 7␣ hydrogen atom.
Thus, in our case, these compounds seem to inhibit ꢀ8–ꢀ7
isomerase and to arrest cell proliferation. On the other hand,
compound 2 has exhibited activities against Candida albi-
cans (CIP 1663-86) and Amphotericine B and miconazole
resistant strain C. albicans (CIP 1180-79) at a concentration
of 1.5 ␮g/mL. In all other cases, moderate results have been
All these compounds were isolated in satisfactory yields
(13–82%) and both chemical structures were consistent with
both analytical and spectroscopic data (1H and 13C NMR).
Table 1
Antimicrobial activity of oxygenated cholesterol derivatives 2–13
3.2. Biological investigation
Sample CIP Antimicrobial activity (IC50) (␮g/mL)
All the synthesized compounds were screened for antimi-
crobial activity against several yeast strains, Gram-positive
and Gram-negative bacteria strains [26]. Six out of eleven
oxygenated cholesterol derivatives tested in the present study
were found to have no activity against the micro-organisms
listed in Table 1.
Results of the remaining five compounds showed that they
have some antifungal activities but no antibacterial activi-
ties. The best results have been encountered using hydroxy
ketones 2, 4–5 showing activities against S. cerevisiae (ATCC
28383) at a concentration of 1.5, 0.4, and 0.4 ␮g/mL, respec-
tively. The presence of a keto group and an hydroxy moiety on
S. cerevisiae
(ATCC 28383) (53-154)
S. aureus
C. albicans
(1180-79)
C. albicans
(1663-86)
2
4
5
6
7
8
9
10
11
12
13
1.5
0.4
0.4
>50
>50
>50
>50
>50
>50
>50
>50
>50
1.5
12.5
12.5
>50
3.1
>50
>50
>25
>25
12.5
6.2
1.5
>50
>50
>50
25
>50
>50
>50
12.5
>50
>25
0.8
>50
>50
>50
12.5
–
>25
6.2
–

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J.M. Brunel et al. / Steroids 70 (2005) 907–912
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