Synthesis of 3-aroyl-4-aryl-1-isopropylamino-4-piperidinols and evaluation of the cytotoxicities of the compounds against human hepatoma and breast cancer cell lines

Article abstract of DOI:10.3109/14756366.2014.951350

Some 4-piperidinol derivatives were synthesized and their cytotoxicity was tested against human hepatoma (Huh7) and breast cancer (T47D) cells. Aryl part was changed as phenyl in 2a, 4-methylphenyl in 2b, 4-methoxyphenyl in 2c, 4-chlorophenyl in 2d, 4-fluorophenyl in 2e, 4-bromophenyl in 2f, 4-nitrophenyl in 2g and 2-thienyl in 3. Compounds were synthesized and reported for the first time by this study except 2a and 2d. Chemical structures were confirmed by ¹H NMR, ¹³C NMR, IR, MS and elemental analyses. Compounds 2a (3.1 times), 2c (3.8 times), 2f (4.6 times), 2g (1.3 times) and 3 (3.2 times) had 1.3-4.6 times higher cytotoxic potency than the reference compound 5-FU against Huh7 cell line while all the compounds synthesized had shown lower activities against T47D cell line than 5-FU. In the light of these results, compounds 2a, 2c, 2f, 2g and 3 may serve as model compounds for further studies.

Full text of DOI:10.3109/14756366.2014.951350

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ISSN: 1475-6366 (print), 1475-6374 (electronic)
J Enzyme Inhib Med Chem, 2015; 30(4): 564–568
2014 Informa UK Ltd. DOI: 10.3109/14756366.2014.951350
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ORIGINAL ARTICLE
Synthesis of 3-aroyl-4-aryl-1-isopropylamino-4-piperidinols and
evaluation of the cytotoxicities of the compounds against
human hepatoma and breast cancer cell lines
Kaan Kucukoglu1, Ebru Mete2, Rengul Cetin-Atalay3, and Halise Inci Gul1
1Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Ataturk University, Erzurum, Turkey, 2Department of Chemistry, Faculty of Science,
3
Ataturk University, Erzurum, Turkey, and Department of Molecular Biology and Genetics, Faculty of Science, Bilkent University, Ankara, Turkey
Abstract
Keywords
Some 4-piperidinol derivatives were synthesized and their cytotoxicity was tested against
human hepatoma (Huh7) and breast cancer (T47D) cells. Aryl part was changed as phenyl in 2a,
4-methylphenyl in 2b, 4-methoxyphenyl in 2c, 4-chlorophenyl in 2d, 4-fluorophenyl in 2e,
4-bromophenyl in 2f, 4-nitrophenyl in 2g and 2-thienyl in 3. Compounds were synthesized and
reported for the first time by this study except 2a and 2d. Chemical structures were confirmed
by 1H NMR, 13C NMR, IR, MS and elemental analyses. Compounds 2a (3.1 times), 2c (3.8 times),
2f (4.6 times), 2g (1.3 times) and 3 (3.2 times) had 1.3–4.6 times higher cytotoxic potency than
the reference compound 5-FU against Huh7 cell line while all the compounds synthesized had
shown lower activities against T47D cell line than 5-FU. In the light of these results, compounds
2a, 2c, 2f, 2g and 3 may serve as model compounds for further studies.
Cytotoxicity, Huh7 cells, isopropylamine,
Mannich bases, T47D cells
History
Received 29 June 2014
Revised 26 July 2014
Accepted 29 July 2014
Published online 1 September 2014
Introduction
4-Piperidinol derivatives have been investigated for their
biological activities especially in the last decade. Anti-tubercu-
losis23, anti-inflammatory24, H3 antagonist25, sodium and calcium
channel blocker26, anti-leukemia27, estrogen receptor modula-
Today, breast cancer is the most common cancer in women and is
one of the five common cancers. In the treatment of breast cancer,
chemotherapy, endocrine and radiation therapy, and surgery are
used in general but emergence of side effects of cytotoxic
chemotherapeutics and drug resistance to these drugs are often
problems in the course of therapy1. Similarly, hepatocellular
carcinoma (HCC) is the fifth most common and the third most
deadly cancer disease worldwide2. For most patients with HCC,
surgery is the only curative treatment procedure because HCC
cells have high resistance to the chemotherapeutic agents3. In the
light of these information mentioned above, novel approaches and
cytotoxic agents are urgently needed in the treatment of breast
cancer and HCC.
28
29
¨
tor , liver glycogen phosphorylase inhibitor , map kinase
inhibitor30 and dopamine D2 receptor antagonist31,32 activities
were reported in the literatures. Since Mannich bases were known
with their remarkable cytotoxic activities in literature4,13,33, it
could be useful to synthesize new chemicals having Mannich base
structure for the solution of the problems mentioned above such as
breast and liver cancers.
It is an advantage and a good starting point that the
cytotoxicities of mono-Mannich bases namely 1-aryl-3-isopropy-
lamino-1-propanone hydrochlorides against Huh7 and T47D cell
lines were reported in our previous study13. It is possible to find
new chemical structures which can be drug candidates by the
synthesis and investigation of the cytotoxic activities of semi-
cyclic mono-Mannich bases having piperidine structure namely
3-aroyl-4-aryl-1-isopropylamino-4-piperidinols. Furthermore, it is
also possible to observe the alterations in cytotoxicity depending
on chemical structures by comparing the cytotoxicities of the
compounds reported here with mono-Mannich bases reported in
our previous study13. Semi-cyclic mono-Mannich bases (piperi-
dines) reported here are non-classic bioisosters of mono-Mannich
bases reported before13. In addition, there are not any research
about cytotoxic activity of 4-piperidinol derivatives on breast
cancer and HCC in the literature.
Mannich bases are compounds that attract the attention of
researchers. According to the studies carried out, the following
activities of Mannich bases have been identified: anticancer4,
cytotoxic5–13
, ,
anti-inflammatory14–16 anticonvulsant17,18 and
antifungal19,20. Their cytotoxic activities were attributed to the
a,b-unsaturated ketone, which is available in the chemical
structure of the compound or to the product produced by
deamination process in vivo or under simulated conditions
in vitro7,21,22
.
Address for correspondence: Prof. Dr Halise Inci Gul, PhD, Department
of Pharmaceutical Chemistry, Faculty of Pharmacy, Ataturk University,
Erzurum 25240, Turkey. Tel: +90-442-2315219. Fax: +90-442-2360962.
E-mail: incigul1967@yahoo.com
The aims of this study were to synthesize 3-aroyl-4-aryl-1-
isopropylamino-4-piperidinols and evaluate their cytotoxicity
against human hepatoma and breast cancer cell lines.

DOI: 10.3109/14756366.2014.951350
4-Piperidinol derivatives 565
Experimental
and air-dried. SRB dye, which was bound to cellular proteins,
solubilized adding 200 ml–10 mM Tris–Base solution and the
absorbance was acquired at 515 nm, then IC50 values were
Chemistry
Chemicals used in synthesis of the compounds in this study were calculated as described34. The figures given were the average of
as follows: acetophenone, 40-methylacetophenone, 40-nitroaceto- the two independent determinations, which differed by 510%.
phenone, 40-chloroacetophenone, 2-acetylthiophene (Fluka,
Steinheim, Switzerland), 40-methoxyacetophenone, 40-fluoroace- 3-Benzoyl-4-phenyl-1-isopropyl-4-piperidinol 2a
tophenone, 40-bromoacetophenone, paraformaldehyde (Merck,
M.p. 123–124 ꢀC. Yield: 26%. 1H NMR [400 MHz, CDCl3,
Darmstadt, Germany), methanol (J.T. Baker, Deventer, Holland)
parts per million (ppm)] d ¼ 7.87 (br d, 2H, H-20/60, J ¼ 7.3 Hz),
and diethyl ether (Fluka, Steinheim, Switzerland). The 1H and
7.54 (t, 1H, H-40, J ¼ 7.3 Hz), 7.51 (d, 2H, H-200/600, J ¼ 7.7 Hz),
13C-NMR spectra were recorded at 400 (100) MHz on a Varian
7.41 (t, 2H, H-30/50, J ¼ 7.7 Hz), 7.23 (t, 2H, H-300/500, J ¼ 7.7 Hz),
Mercury Plus spectrometer (Varian, Palo Alto, CA). Electron
7.11 (t, 1H, H-400, J ¼ 7.3 Hz), 5.15 (d, 1H, OH, J ¼ 2.6 Hz), 4.35
ionization mass spectrometry (EI-MS) spectra were recorded on a
(dd, 1H, H-3, J ¼ 11.0, 2.9 Hz), 2.96–2.77 [m, 5H, CH(CH3)2,
Thermo-Finnigan’s mass analyzer (Thermo-Finnigan LLC, San
2XH-2, 2XH-6], 2.06–2.00 [m, 1H, H-5(a)], 1.84 [br d, 1H,
Jose, CA). Infrared spectra were obtained for KBr disks on a
H-5(b), J ¼ 13.9 Hz], 1.10 [d, 6H, CH(CH3)2, J ¼ 6.6 Hz]; 13C
Mattson 1000 FT-IR (Fourier transform infrared spectroscopy)
NMR (100 MHz, CDCl3, ppm) d ¼ 204.9, 147.6, 136.2, 134.1,
spectrophotometer (Mattson Instruments, Cambridge, UK).
129.0, 128.6, 128.5, 126.9, 124.8, 73.6, 55.0, 51.3, 48.8, 44.6,
Elemental analyses were carried out with a LECO’s CHNS-932
40.4, 18.8, 18.6; MS (EI, 70 eV): m/z 324 (M + 1, 63), 280 (18),
instrument (LECO Corporation, St. Joseph, MI). Melting points
235 (3), 203 (90), 186 (41), 160 (18), 105 (100), 77 (70%); IR
were determined on a BUCHI 530 (Bu¨chi Labortechnik AG,
(KBr, cmꢁ1): 3453, 3059, 2964, 2831, 1660, 1596, 1578, 1492,
Flawil, Switzerland).
1469, 1447, 1384, 1361, 1335, 1273, 1206, 1172, 1132, 1103,
1068, 1052, 1014, 1001, 958, 899, 759, 709. Calculated for
C21H25NO2 (323.43): C, 77.98; H, 7.79; N, 4.33. Found: C, 77.81;
Synthesis
The mixture of suitable ketone, paraformaldehyde and isopropy- H, 8.14; N, 4.38.
lamine hydrochloride in 2:2:1 mole ratios was stirred and heated
without solvent in an oil bath. Mono-Mannich bases type, namely 3-(p-Methylbenzoyl)-4-(p-methylphenyl)-1-isopropyl-4-piperidi-
1-aryl-3-isopropylamino-1-propanone hydrochloride, and piper- nol 2b
idinol type compounds, which are a semi-cyclic mono-Mannich
1
M.p. 141–142 ꢀC. Yield: 20%. H NMR (400 MHz, CDCl3, ppm)
base
namely
3-aroyl-4-aryl-1-isopropylamino-4-piperidinol
d ¼ 7.80 (d, 2H, H-20/60, J ¼ 8.1 Hz), 7.38 (d, 2H, H-200/600,
J ¼ 8.1 Hz), 7.22 (d, 2H, H-30/50, J ¼ 8.1 Hz), 7.03 (d, 2H, H-300/
500, J ¼ 8.1 Hz), 5.21 (d, 1H, OH, J ¼ 2.9 Hz), 4.30 (dd, 1H, H-3,
J ¼ 11.2, 3.9 Hz), 2.93–2.75 (m, 5H, CH(CH3)2, 2XH-2, 2XH-6),
2.38 (s, 3H, CH3), 2.22 (s, 3H, CH3), 2.03–1.94 [m, 1H, H-5(a)],
1.81 [br d, 1H, H-5(b), J ¼ 13.6 Hz], 1.09 [d, 6H, CH(CH3)2,
J ¼ 6.6 Hz]; 13C NMR (100 MHz, CDCl3, ppm) d ¼ 204.5, 145.1,
144.8, 136.4, 133.8, 129.7, 129.2, 128.8, 124.7, 73.5, 54.9, 50.9,
48.9, 44.7, 40.7, 21.9, 21.1, 18.8, 18.6; MS (EI, 70 eV): m/z 351
(M+, 1), 308 (7), 217 (6), 200 (8), 190 (6), 163 (8), 146 (11), 131
(5), 119 (100), 105 (8), 91 (56), 89 (7), 82 (5), 71 (10), 64 (17), 56
(19%); IR (KBr, cmꢁ1): 3449, 3025, 2964, 2921, 2831, 1658,
1605, 1570, 1512, 1458, 1407, 1384, 1361, 1333, 1302, 1273,
1258, 1203, 1178, 1071, 1014, 1002, 957, 902, 811, 738.
Calculated for C23H29NO2 (351.48): C, 78.59; H, 8.32; N, 3.99.
Found: C, 78.10; H, 8.59; N, 3.99.
hydrochlorides were produced in the reaction medium at the
same time. Corresponding mono-Mannich bases were removed
from the reaction medium to obtain piperidinol type compounds
2a–2g and 3 synthesized in this study. To obtain piperidinols, 5%
sodium hydroxide solution was added to the residue. The reaction
content was stirred in water bath at 40 ꢀC. The reaction content,
which had fat emulsion view initially, was stirred until a
solidification observed (24–96 h), except compound 2c. In the
synthesis of compound 2c, any solidification was not observed at
the end of period of time. The residue of 2c was filtered on the
column containing basic Al2O3 using ethanol as the solvent. The
crude compounds of 2a, 2b and 2d were crystallized from
methanol; 2e, 2f and 2g were crystallized from chloroform and
hexane; 2c and 3 were crystallized from methanol and diethyl
ether. The elemental analysis results of the compounds 2c, 2f and
2g were consistent with the hydrochloride salts of the compounds
and were within the acceptable limits according to elemental
analysis results although 5% sodium hydroxide had been used
during the reaction process.
3-(p-Methoxybenzoyl)-4-(p-methoxyphenyl)-1-isopropyl-4-piperi-
dinol hydrochloride 2c
Yellow oil. Yield: 40%. 1H NMR (400 MHz, CDCl3, ppm)
d ¼ 7.87 (br d, 2H, H-20/60, J ¼ 9.0 Hz), 7.39 (br d, 2H, H-200/600,
J ¼ 9.0 Hz), 6.88 (br d, 2H, H-30/50, J ¼ 9.0 Hz), 6.75 (br d, 2H, H-
300/500, J ¼ 9.0 Hz), 5.30 (d, 1H, OH, J ¼ 2.6 Hz), 4.24 (dd, 1H, H-
3, J ¼ 10.8, 3.9 Hz), 3.84 (s, 3H, OCH3), 3.70 (s, 3H, OCH3),
2.91–2.78 [m, 5H, CH(CH3)2, 2XH-2, 2XH-6], 2.09–1.90 [m, 1H,
H-5(a)], 1.80 [br d, 1H, H-5(b), J ¼ 13.9 Hz], 1.09 [d, 6H,
CH(CH3)2, J ¼ 6.6 Hz]; 13C NMR (100 MHz, CDCl3, ppm)
d ¼ 203.3, 164.4, 158.4, 140.0, 131.0, 129.3, 126.0, 114.2,
113.7, 73.3, 55.7, 55.3, 54.9, 50.7, 49.0, 44.7, 40.6, 18.8, 18.6;
MS (EI, 70 eV): m/z 383 (M+, 1), 162 (34), 135 (100), 119 (2),
107 (11), 92 (8), 77 (16), 64 (6%); IR (KBr, cmꢁ1): 3434, 2962,
2839, 2670, 2578, 2462, 2049, 1981, 1909, 1780, 1667, 1660,
1651, 1600, 1574, 1514, 1463, 1456, 1423, 1384, 1306, 1259,
1232, 1174, 1119, 1071, 1031, 999, 972, 842, 759. Calculated for
C23H30ClNO4 (419.94): C, 65.78; H, 7.20; N, 3.34. Found: C,
65.46; H, 7.29; N, 3.36.
Determination of the cytotoxic activity of the compounds
synthesized against human hepatoma cell line34 and
human breast cancer cell line (T47D)
Chemicals were tested with (National Cancer Institute, NCI)
anticancer drug screening method34. Human hepatoma cells
(Huh7 cells) (5000 or 10 000 cells) were inoculated into 96-well
microtiter plates in 100 ml of standard medium 24 h prior to
treatment with inhibitors (compounds). Compounds with various
(40–2.5 mM) concentrations were applied in additional 100 ml of
cell culture medium. After 72 h of treatment with compounds,
cells were fixed by gentle addition of 50 ml of cold 50% (w/v)
TCA for 60 min at 4 ꢀC. After fixation, cell culture medium is
discarded and washed with distilled water and dried in air. Then,
100 ml of 0.4% sulforhodamine B (SRB) solution were applied to
each well and incubated for 10 min at room temperature. Extra
unbound dye were washed five times with 200 ml 1% acetic acid

566 K. Kucukoglu et al.
J Enzyme Inhib Med Chem, 2015; 30(4): 564–568
3-(p-Chlorobenzoyl)-4-(p-chlorophenyl)-1-isopropyl-4-piperidi-
nol 2d
J ¼ 9.0 Hz), 8.03 (br d, 2H, H-20/60, J ¼ 9.0 Hz), 7.67 (br d, 2H, H-
200/600, J ¼ 9.0 Hz), 4.92 (br s, 1H, OH), 4.39 (dd, 1H, H-3,
J ¼ 10.8, 3.5 Hz), 2.98–2.80 [m, 5H, CH(CH3)2, 2XH-2, 2XH-6],
2.05–1.97 [m, 1H, H-5(a)], 1.84 [br d, 1H, H-5(b), J ¼ 13.9 Hz],
1.10 (d, 3H, CH3, J ¼ 6.2 Hz), 1.09 (d, 3H, CH3, J ¼ 6.6 Hz); 13C
NMR (100 MHz, CDCl3, ppm) d ¼ 202.8, 154.6, 151.2, 147.2,
140.0, 129.6, 125.9, 124.4, 123.9, 73.8, 55.1, 52.1, 48.6, 44.0,
40.0, 18.8, 18.3; MS (EI, 70 eV): m/z 413 (M+, 1), 177 (29), 160
(8), 150 (100), 131 (21), 120 (23), 104 (48), 92 (25), 76 (40), 65
(6), 55 (59%); IR (KBr, cmꢁ1): 3470, 2966, 2834, 1672, 1603,
1521, 1470, 1347, 1273, 1257, 1201, 1172, 1109, 1069, 1011,
903, 853, 805, 753. Calculated for C21H24ClN3O6 (449.88): C,
56.06; H, 5.38; N, 9.34. Found: C, 56.03; H, 5.49; N, 9.20.
1
M.p. 135–137 ꢀC. Yield: 16%. H NMR (400 MHz, CDCl3, ppm)
d ¼ 7.80 (d, 2H, H-20/60, J ¼ 8.4 Hz), 7.40 (d, 4H, H-30/50, H-200/
600, J ¼ 7.7 Hz), 7.19 (d, 2H, H-300/500, J ¼ 8.4 Hz), 5.06 (d, 1H,
OH, J ¼ 2.2 Hz), 4.24 (dd, 1H, H-3, J ¼ 10.6, 3.3 Hz), 2.90–2.75
[m, 5H, CH(CH3)2, 2XH-2, 2XH-6], 1.99–1.92 [m, 1H, H-5(a)],
1.79 [br d, 1H, H-5(b), J ¼ 13.9 Hz], 1.09 (d, 3H, CH3,
J ¼ 6.2 Hz], 1.08 (d, 3H, CH3, J ¼ 6.6 Hz); 13C NMR (100 MHz,
CDCl3, ppm) d ¼ 203.4, 146.0, 141.0, 134.3, 132.9, 129.9, 129.5,
128.7, 126.3, 73.4, 55.0, 51.2, 48.8, 44.3, 40.3, 18.8, 18.4; MS
(EI, 70 eV): m/z 392 (M + 1, 8), 348 (4), 303 (2), 252 (2), 238
(21), 226 (87), 210 (40), 194 (8), 182 (14), 167 (20), 149 (4), 139
(37), 111 (100), 98 (12), 85 (7), 72 (69), 56 (93%); IR (KBr,
cmꢁ1): 3455, 2965, 2831, 1662, 1588, 1569, 1489, 1469, 1401,
1384, 1362, 1308, 1272, 1204, 1172, 1093, 1011, 979, 900, 841,
3-(Thiophen-2-yl-carbonyl)-4-(thiophen-2-yl)-1-isopropyl-4-
piperidinol 3
1
827. Calculated for C21H23Cl2NO2 (392.32): C, 64.29; H, 5.91; N, M.p. 143–144 ꢀC. Yield: 11%. H NMR (400 MHz, CDCl3, ppm)
3.57. Found: C, 63.05; H, 5.85; N, 3.58.
d ¼ 7.80 (d, 1H, H-30, J ¼ 3.7 Hz), 7.67 (d, 1H, H-50, J ¼ 4.8 Hz),
7.12 (dd, 1H, H-40, J ¼ 4.8, 3.7 Hz), 7.07 (d, 1H, H-500,
3-(p-Fluorobenzoyl)-4-(p-fluorophenyl)-1-isopropyl-4-piperidinol J ¼ 4.6 Hz), 6.91 (br d, 1H, H-300, J ¼ 3.3 Hz), 6.82 (dd, 1H, H-
2e
400, J ¼ 4.6, 3.3 Hz), 5.44 (s, 1H, OH), 4.04 (br d, 1H, H-3,
J ¼ 8.8 Hz), 2.98–2.75 [m, 5H, CH(CH3)2, 2XH-2, 2XH-6], 2.05–
2.00 [m, 2H, H-5(a), H-5(b)], 1.09 [d, 6H, CH(CH3)2, J ¼ 6.2 Hz];
13C NMR (100 MHz, CDCl3, ppm) d ¼ 196.9, 153.4, 143.8,
135.8, 133.5, 128.8, 127.0, 123.9, 122.2, 72.9, 54.9, 54.4, 49.1,
44.4, 41.6, 18.8, 18.6; MS (EI, 70 eV): m/z 335 (M+, 1), 292 (3),
170 (17), 155 (11), 138 (19), 110 (100), 82 (8), 58 (4%); IR (KBr,
cmꢁ1): 3425, 3095, 2963, 2827, 1635, 1516, 1468, 1412, 1384,
1361, 1305, 1275, 1261, 1235, 1206, 1166, 1065, 1040, 1004,
954, 852, 793, 725, 699. Calculated For C17H21NO2S2 (335.48):
C, 60.86; H, 6.31; N, 4.18; S, 19.12. Found: C, 60.55; H, 6.55; N,
4.18; S, 19.47.
1
M.p. 113–115 ꢀC. Yield: 24%. H NMR (400 MHz, CDCl3, ppm)
3
4
d ¼ 7.89 (dd, H-20/60, 2H, JH,H ¼ 8.6 Hz, JH,F ¼ 5.3 Hz), 7.43
3
4
(dd, 2H, H-200/600, JH,H ¼ 8.6 Hz, JH,F ¼ 5.3 Hz), 7.09 (t, 2H, H-
30/50, 3JH,H ¼ 3JH,F ¼ 8.6 Hz), 6.90 (t, 2H, H-300/500,
3JH,H ¼ 3JH,F ¼ 8.6 Hz), 5.10 (d, 1H, OH, J ¼ 2.6 Hz), 4.23 (dd,
1H, H-3, J ¼ 10.2, 3.3 Hz), 2.91–2.76 [m, 5H, CH(CH3)2, 2XH-2,
2XH-6], 2.01–1.95 [m, 1H, H-5(a)], 1.80 [br d, 1H, H-5(b),
J ¼ 13.9 Hz], 1.09 [d, 6H, CH(CH3)2, J ¼ 6.6 Hz]; 13C NMR
1
(100 MHz, CDCl3, ppm) d ¼ 203.2, 166.5 (d, JC–F ¼ 257 Hz),
1
3
161.8 (d, JC–F ¼ 245 Hz), 143.3, 132.6, 131.3 (d, JC–F ¼ 9 Hz),
3
2
126.5 (d, JC–F ¼ 8 Hz), 116.3 (d, JC–F ¼ 22 Hz), 115.2 (d,
2JC–F ¼ 21 Hz), 73.4, 55.0, 51.4, 48.8, 44.4, 40.4, 18.8, 18.5;
MS (EI, 70 eV): m/z 360 (M + 1, 41), 342 (5), 316 (51), 281 (3),
271 (8), 221 (36), 204 (49), 194 (62), 178 (20), 151 (28), 123
(100), 109 (14), 95 (40), 75 (8), 56 (24%); IR (KBr, cmꢁ1): 3453,
2966, 2832, 1663, 1598, 1508, 1470, 1409, 1385, 1362, 1299,
1273, 1222, 1204, 1173, 1158, 1096, 1070, 1013, 979, 958, 902,
847, 833, 773. Calculated for C21H23F2NO2 (359.41): C, 70.18;
H, 6.45; N, 3.90. Found: C, 69.75; H, 6.43; N, 3.88.
Results
In this study, 4-piperidinol derivative compounds 2a–2g and 3
were synthesized as presented in Scheme 1 for the first time,
except compounds 2a and 2d (Figure 1). Experimental and
spectral data of the compounds synthesized are presented at the
experimental section. The compounds were obtained with the
yield of 11–40%. The chemical structures of synthesized
1
compounds were confirmed with IR, H NMR, 13C NMR, MS
3-(p-Bromobenzoyl)-4-(p-bromophenyl)-1-isopropyl-4-piperidi-
nol hydrochloride 2f
and elemental analyses data. Purity level of the compound were
within 0.4 %, except 2d (calculated C:64.29; found C:63.05).
All the synthesized compounds having the chemical structures
of 3-aroyl-4-aryl-1-isopropylamino-4-piperidinols were evaluated
against the Huh7 and breast cancer (T47D) cells. The cytotoxicity
of the compounds and reference compound 5-fluorouracil (5-FU)
are listed in Table 1 in terms of the inhibitory potencies
(IC50, mM).
1
M.p. 212–214 ꢀC. Yield: 14%. H NMR (400 MHz, CDCl3, ppm)
d ¼ 8.02 (d, 2H, H-20/60, J ¼ 8.4 Hz), 7.61 (d, 2H, H-200/600,
J ¼ 8.4 Hz), 7.43 (d, 2H, H-30/50, J ¼ 8.4 Hz), 7.36 (d, 2H, H-300/
500, J ¼ 8.4 Hz), 5.78 (dd, 1H, H-3, J ¼ 12.1, 3.7 Hz,), 5.01 (d, 1H,
OH, J ¼ 2.6 Hz), 3.51–3.31 [m, 5H, CH(CH3)2, 2XH-2, 2XH-6],
2.91–2.84 [m, 1H, H-5(a)], 1.94 [br d, 1H, H-5(b), J ¼ 14.3 Hz],
1.53 (d, 3H, CH3, J ¼ 6.6 Hz), 1.44 (d, 3H, CH3, J ¼ 6.6 Hz); 13C
NMR (100 MHz, CDCl3, ppm) d ¼ 201.2, 143.2, 133.0, 132.3,
132.0, 131.3, 130.9, 126.6, 122.0, 72.2, 58.5, 47.7, 46.1, 43.7, 36.4,
17.6, 16.3; MS (EI, 70 eV): m/z 484/482/480 (M + 1, 1,2,1), 440/
438/436 (3,6,3), 283/281 (21,23), 256/254 (27,29), 212/210
(28,30), 185/183 (94,100), 156/154 (31,33), 132 (18), 98 (10), 72
(28), 56 (39%); IR (KBr, cmꢁ1): 3279, 2977, 2507, 1675, 1584,
1485, 1398, 1285, 1254, 1228, 1210, 1179, 1155, 1071, 1001, 973,
897, 864, 824, 750. Calculated for C21H24Br2ClNO2 (517.68): C,
48.72; H, 4.67; N, 2.71. Found: C, 48.74; H, 4.70; N, 2.83.
Discussion
In the literature, compounds 2a and 2d were already synthe-
sized35,36. Plati et al.34 synthesized some 1,3,4-trisubstituted
piperidine derivatives from mono-Mannich bases. In that study, a
suspension of 128 g of b-benzoylethylisopropylamine hydrochlor-
ide, which is a corresponding mono-Mannich base, was stirred for
about an hour with 20 g of sodium hydroxide and 1200 cc of water
and allowed to stand until solidification was completed for
compound 2a. The solid was crystallized from methanol and
acetone in a yield of 85% and the melting point was determined as
123–124 ꢀC. The result of elemental analysis of 2a in literature
was found 77.88 for C and 7.65 for H35. The melting point value
was in accordance with ours. Although the compound 2d was
used in a literature for zinc electroplating process with acidic zinc
3-(p-Nitrobenzoyl)-4-(p-bromophenyl)-1-isopropyl-4-piperidinol
hydrochloride 2g
1
M.p. 118–120 ꢀC. Yield: 11%. H NMR (400 MHz, CDCl3, ppm)
d ¼ 8.27 (br d, 2H, H-30/50, J ¼ 9.0 Hz), 8.10 (br d, 2H, H-300/500,

DOI: 10.3109/14756366.2014.951350
4-Piperidinol derivatives 567
O
O
Scheme 1. The synthesis of 3-aroyl-4-aryl-1-
isopropylamino-4-piperidinols, 2a–2g and 3.
no solvent
heating
+
+
(CH ) CHNH . HCl
3 2
2
Ar
CH
H
H
3
2 eq.
2 eq.
1 eq.
i Pr
i Pr
N
N
O
.
basic Al O or
5%NaOH
2
3
.
HCl
Ar
Ar
Ar
NHPr
i
+
HO
Ar
HO
Ar
HCl
O
O
i Pr
N
Figure 1. 3-Aroyl-4-aryl-1-isopropylamino-4-
piperidinols type compounds synthesized,
2a–2g and 3.
.
X
Ar
HO
Ar
O
Ar: (C H ) for 2a, (4-CH C H ) for 2b, (4-CH OC H ) for 2c, (4-ClC H ) for 2d,(4-FC H )
6
5
3
6
4
3
6
4
6
4
6 4
for 2e, (4-BrC H ) for 2f, (4-NO C H ) for 2g, (C H S(2-yl)) for 3. X: HCl for 2c, 2f, 2g.
6
4
2
6
4
4 3
Table 1. Cytotoxic activities against Huh7 cells and T47D cells of the
compounds synthesized.
was filtered on Al2O3 using EtOH. Our experimental procedure
was different than the reported experimental procedure of Plati
et al.34. Our experimental procedure provides an advantage to
obtain mono-Mannich bases and semi-cyclic mono-Mannich
bases which have piperidine structure at the same time. The
reason of production of piperidine type semi-cyclic mono-
Mannich base instead of bis Mannich base can be attributed to
the relatively high temperature applied.
Compounds 2a (3.1 times), 2c (3.8 times), 2f (4.6 times), 2g
(1.3 times) and 3 (3.2 times) had higher cytotoxic potency than
the reference compound, 5-FU, against Huh7 cells while all the
compounds had less cytotoxicity than 5-FU against T47D cells.
The cytotoxicities of the compounds 2a–2g and 3 were 0.10–0.75
times of 5-FU. The cytotoxicities of the compounds were 0.50
times for 2a, 0.10 times for 2b, 0.60 times for 2c, 0.15 times for
2d, 0.24 times for 2e, 0.75 times for 2f, 0.25 times for 2g and 0.55
times for 3.
When the effect of the chemical modification on cytotoxic
activity was evaluated, it can be said that preparation of
piperidinol derivatives had increased the cytotoxicity 1.38–24.7
times comparing with corresponding mono-Mannich base13. The
increase in cytotocity in piperidinols was 1.38 times for 2a, 1.71
times for 2c, 5.85 times for 2d, 8.39 times for 2e, 24.7 times for 2f
and 1.5 times for 3 against Huh7 cell line comparing mono-
Mannich bases reported before. In our previous study, Huh7 was
the only cell line used. In the case of 2b and 2g, cytotoxicity
decreased 7.59 times and 1.7 times, respectively comparing the
mono-Mannich bases reported earlier.
The increase in cytotoxicity in piperidinols may possibly be
with resulted from the production of 1-aryl-2-propen-1-one which
was considered the responsible cytotoxic moiety in Mannich bases
in high ration in piperidinols. There was no correlation between the
cytotoxicities of the compounds and s, ꢀ, values of the substituents
and log p values of the compounds (data were not shown).
When the cytotoxicities of the compounds against Huh7 and
T47D cell lines were compared, the compounds 2b and 2e had
shown more potent cytotoxicity against T47D cell line 2.04 and
1.56 times, respectively. While the other compounds had similar
cytotoxicities.
Cytotoxicity
(IC50) (mM)
Cytotoxicity
(IC50) (mM)
Compounds
Ar
Huh7
13.8
136.6
11.1
48.9
45.9
9.1
32.3
13.3
42.2
T47D
13.9
66.9
11.6
47.4
29.5
9.3
28.3
12.8
7.00
2a
2b
2c
2d
2e
2f
2g
3
C6H5
4-CH3C6H4
4-CH3OC6H4
4-ClC6H4
4-FC6H4
4-BrC6H4
4-NO2C6H4
C4H3S(2-yl)
5FU
fluoborate electrolyte, there wasn’t detailed experimental proced-
ure for the synthesis of 2d36. In our experimental procedures,
the syntheses of the compounds were carried out using a
suitable ketone compound, paraformaldehyde and isopropylamine
hydrochloride in 2:2:1 mole ratios, respectively. All
reagents were stirred and heated without solvent in an oil bath
at ꢂ130 ꢀC.
It was expected that bis-[b-(p-substituted)benzoyl ethyl]
isopropylamine hydrochloride or 1-isopropyl-3-(p-substituted)
benzoyl-4-hydroxy-4-(p-substituted)phenyl piperidine hydro-
chloride can be produced with the experimental procedure used
here. But in the experimental condition applied, it was obtained
mono-Mannich bases namely 1-(p-substituted)phenyl-3-isopropy-
lamine-1-propanone hydrochlorides and semi-cyclic mono-
Mannich bases having piperidine structure namely 1-isoproply-
3-(p-substituted)benzoyl-4-hydroxy-4-(p-substituted)phenyl
piperidine hydrochlorides before the treatment of alkaline NaOH
solution. After removing mono-Mannich base from the reaction
medium as described in the literature13, the residue was treated
with NaOH aqueous solution (5%) in a water bath at 40 ꢀC until
the solidification observed (24–96 h). It was 72 h for 2a, 24 h for
2b, 96 h for 2c, 24 h for 2d, 24 h for 2e, 48 h for 2f, 24 h for 2g and
48 h for 3. Since there was no solidification in the case of 2d, it

568 K. Kucukoglu et al.
J Enzyme Inhib Med Chem, 2015; 30(4): 564–568
nimesulide and rofecoxib on cyclooxygenase activities in
carrageenan-induced paw edema model. Turk J Med Sci 2010;40:
723–8.
Conclusions
As a result, synthesized compounds having the structure of
3-aroyl-4-aryl-1-isopropylamino-4-piperidinols seem to be 17. Gul HI, Calis U, Vepsalainen J. Synthesis of some mono-Mannich
bases and corresponding azine derivatives and evaluation of their
anticonvulsant activity. Arzneimittelforschung 2004;54:359–64.
18. Gul HI, Calls U, Ozturk Z, et al. Evaluation of anticonvulsant
potential anticancer candidate which deserve further structural
modification and pharmacological evaluations. We reported here
2a–2g and 3 compounds for the first time with their synthesis,
activities of bis(3-aryl-3-oxo-propyl) ethylamine hydrochlorides
spectral analysis and cytotoxicities against Huh7 and T47D cell
lines. The compound 2a, 2c, 2f, 2g and 3 seem to be candidate
and 4-aryl-3-arylcarbonyl-1-ethyl-4-piperidinol hydrochlorides.
Arzneimittelforschung 2007;57:133–6.
compounds for further synthetic designes and studies.
19. Gul HI, Sahin F, Gul M, et al. Evaluation of antimicrobial activities
of several Mannich bases and their derivatives. Arch Pharm 2005;
338:335–8.
Acknowledgements
20. Mete E, Ozelgul C, Kazaz C, et al. Synthesis and antifungal activity
of 1-aryl-3-phenethylamino-1-propanone hydrochlorides and
3-aroyl-4-aryl-1-phenethyl-4-piperidinols. Arch Pharm 2010;343:
291–300.
The authors thank to Ataturk University Research Fund (project number
2011/289).
21. Gul M, Gul HI, Hanninen O. Effects of Mannich bases on cellular
glutathione and related enzymes of Jurkat cells in culture conditions.
Toxicol In Vitro 2002;16:107–12.
22. Gul M, Gul HI, Vepsalainen J, et al. Effect of acetophenone derived
Mannich bases on cellular glutathione level in Jurkat cells.
A possible mechanism of action. Arzneimittelforschung 2001;51:
679–82.
Declaration of interest
The authors report no conflicts of interest. The authors are responsible for
the content and writing of this article.
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