Hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives and evaluation of their anticancer and antimycobacterial activity

Article abstract of DOI:10.1080/14756366.2016.1190711

The design, synthesis, structure, and in vitro anticancer and antimycobacterial activity of new hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives are described. The strategy adopted for synthesis is straight and efficient, involving a three-step setup procedure: N-acylation, N-alkylation, and quaternization of nitrogen heterocycle. The solubility in microbiological medium and anticancer and antimycobacterial activity of a selection of new synthesized compounds were evaluated. The hybrid derivatives have an excellent solubility in microbiological medium, which make them promising from the pharmacological properties point of view. One of the hybrid compounds, 9 (with a benzimidazole and 8-aminoquinoline skeleton), exhibits a very good and selective antitumor activity against Renal Cancer A498 and Breast Cancer MDA-MB-468. Moreover, the anticancer assay suggests that the hybrid Imz (Bimz)/2-AP (8-AQ) compounds present a specific affinity to Renal Cancer A498. Concerning the antimycobacterial activity, only the hybrid compound, 9, has a significant activity. SAR correlations have been performed.

Full text of DOI:10.1080/14756366.2016.1190711

Journal of Enzyme Inhibition and Medicinal Chemistry
ISSN: 1475-6366 (Print) 1475-6374 (Online) Journal homepage: http://www.tandfonline.com/loi/ienz20
Hybrid imidazole (benzimidazole)/pyridine
(quinoline) derivatives and evaluation of their
anticancer and antimycobacterial activity
Dorina Mantu, Vasilichia Antoci, Costel Moldoveanu, Gheorghita Zbancioc &
Ionel I. Mangalagiu
To cite this article: Dorina Mantu, Vasilichia Antoci, Costel Moldoveanu, Gheorghita Zbancioc
& Ionel I. Mangalagiu (2016): Hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives
and evaluation of their anticancer and antimycobacterial activity, Journal of Enzyme Inhibition
and Medicinal Chemistry, DOI: 10.1080/14756366.2016.1190711
To link to this article: http://dx.doi.org/10.1080/14756366.2016.1190711
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Date: 03 June 2016, At: 17:53

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ISSN: 1475-6366 (print), 1475-6374 (electronic)
J Enzyme Inhib Med Chem, Early Online: 1–8
2016 Informa UK Limited, trading as Taylor & Francis Group. DOI: 10.1080/14756366.2016.1190711
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RESEARCH ARTICLE
Hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives and
evaluation of their anticancer and antimycobacterial activity
Dorina Mantu, Vasilichia Antoci, Costel Moldoveanu, Gheorghita Zbancioc, and Ionel I. Mangalagiu
Faculty of Chemistry, ‘‘Alexandru Ioan Cuza’’ University of Iasi, Iasi, Romania
Abstract
Keywords
The design, synthesis, structure, and in vitro anticancer and antimycobacterial activity of new
hybrid imidazole (benzimidazole)/pyridine (quinoline) derivatives are described. The strategy
adopted for synthesis is straight and efficient, involving a three-step setup procedure:
N-acylation, N-alkylation, and quaternization of nitrogen heterocycle. The solubility in
microbiological medium and anticancer and antimycobacterial activity of a selection of new
synthesized compounds were evaluated. The hybrid derivatives have an excellent solubility in
microbiological medium, which make them promising from the pharmacological properties
point of view. One of the hybrid compounds, 9 (with a benzimidazole and 8-aminoquinoline
skeleton), exhibits a very good and selective antitumor activity against Renal Cancer A498 and
Breast Cancer MDA-MB-468. Moreover, the anticancer assay suggests that the hybrid Imz
(Bimz)/2-AP (8-AQ) compounds present a specific affinity to Renal Cancer A498. Concerning the
antimycobacterial activity, only the hybrid compound, 9, has a significant activity. SAR
correlations have been performed.
Anticancer, antimycobacterial, hybrid
imidazole (benzimidazole)/pyridine
(quinoline), synthesis
History
Received 17 March 2016
Revised 5 May 2016
Accepted 8 May 2016
Published online 30 May 2016
Introduction
anti-TB11–15 also included). Encouraged by the above consider-
ations and in continuation of our research in the area of novel
anticancer9,10,16–19 and anti-TB15–17,20–23 derivatives with azahe-
terocyclic skeleton, we report here the design, synthesis, structure,
and in vitro anticancer and antimycobacterial activity of new
Over the past years five- and six-member ring azaheterocyclic
compounds have received considerable attention due to their
important applications from pharmacological, industrial, and
synthetic points of view1. Pharmaceutical industry and modern
medicinal science pay a lot of effort in their combat with two
aggressive life-threatening diseases: cancer and tuberculosis (TB).
Both diseases are leading cause of death worldwide, millions of
people dying every year; the incidence of both are continually
increasing and the treatment became more and more complicated
and sophisticated2–4. The cancer chemotherapy is complex,
expensive and often rather inefficient, because of the large
variety of neoplasm types, high toxicity levels and non-specificity
of drugs and the emergence of drug resistance and multi-
drug-resistant (MDR)2,3. On the other hand, because of the
Mycobacterium tuberculosis (Mtb) versatility, the treatment
against TB became a challenging and difficult task, and the
situation begin to become even worse because of the phenomena
of drug resistance, MDR, extensively-drug-resistant (XDR),
association of TB with AIDS, etc.3,4
hybrid imidazole
derivatives.
(benzimidazole)/pyridine
(quinoline)
Methods
General
All the reagents and solvents employed were of the best grade
available and were used without further purification. Melting
points were determined using an electrothermal apparatus
(MELTEMP II, Dubuque, IA) and are uncorrected. The IR
spectra were recorded on an FTIR Shimadzu Prestige 8400s
spectrophotometer (Kyoto, Japan). Proton and carbon nuclear
magnetic resonance (ꢀH, ꢀC) spectra were recorded on a Bruker
1
Avance III 500 spectrometer operating at 500 MHz for H and
125 MHz for 13C. The following abbreviations were used to
designate chemical shift multiplicities: s ¼ singlet, d ¼ doublet,
t ¼ triplet, q ¼ quartet, brs ¼ broad singlet, as ¼ apparent singlet,
ad ¼ apparent doublet, at ¼ apparent triplet, aq ¼ apparent quartet,
dd ¼ doublet of doublets, td ¼ triplet of doublets, and m ¼ multi-
plet. All chemical shifts are quoted on the ꢀ-scale in ppm.
Coupling constants are given in Hertz. Thin-layer chromatog-
raphy (TLC) was carried out on Merck silica gel 60F254 plates
(Darmstadt, Germany). Column chromatography was carried out
on silica gel (Roth 60, 0.04–0.063 mm; Darmstadt, Germany).
Visualization of the plates was achieved using a UV lamp
(lmax ¼ 254 or 365 nm). The microanalyses were in satisfactory
It is well known from the literature1–4 that imidazole (and its
benzo-derivative benzimidazole) and pyridine (and its benzo-
derivative quinoline) derivatives are core scaffolds widely present
in many classes of drugs (of natural or synthetic origin),
displaying a large variety of interesting biological activities
(antimicrobials, antifungus, anti-inflammatory, antihypertensive,
antineuropathic, antihistaminic, etc.; anticancer5–10 and
Address for correspondence: Ionel I. Mangalagiu, Faculty of Chemistry,
‘‘Alexandru Ioan Cuza’’ University of Iasi, Iasi, Romania. Tel: +40
232201343. E-mail: ionelm@uaic.ro

2
D. Mantu et al.
J Enzyme Inhib Med Chem, Early Online: 1–8
agreement with the calculated values: C, 0.15; H, 0.10; C-5, 119.68 C-3, 120.66 C-14, 127.97 C-13, 138.31 C-4, 138.34
N, 0.30.
C-11, 148.08 C-2, 151.58 C-6, 166.64 C-8.
General procedure for N-acylation of 2-AP and 8-AQ
2-(1H-benzo[d]imidazol-1-yl)-N-(pyridin-2-yl)acetamide (3)
Compounds 1 and 7 were obtained using some modified White powder (72% yield), mp ¼ 224–226 ꢀC. IR (KBr, ꢁ
1
procedures from the literature where they were first obtained24,25
.
(cmꢂ1)): 3417, 3032, 2984, 2962, 1703, 1540, 1435, 1301. H
Our experimental setup for N-acylation of 2-aminopyridine (2- NMR (500 MHz, DMSO-d6, 25 ꢀC): ꢀ 5.28 (s, 2H, 9-H), 7.12 (t,
AP) and 8-aminoquinoline (8-AQ) are the following:
J ¼ 6.5 Hz, 1H, 3-H), 7.19–7.26 (overlapped signals, 2H, 14-H,
15-H), 7.54 (d, J ¼ 7.5 Hz, 1H, 16-H), 7.68 (d, J ¼ 7.5 Hz, 1H, 13-
H), 7.76 (t, J ¼ 7.5 Hz, 1H, 4-H), 7.99 (d, J ¼ 7.0 Hz, 1H, 5-H),
8.26 (s, 1H, 11-H), 8.36 (ad, J ¼ 4.0 Hz, 1H, 2-H), 11.05 (s, 1-H,
7-H). 13C NMR (125 MHz, DMSO-d6): ꢀ 47.27 C-9, 110.29 C-16,
113.47 C-5, 119.38 C-13, 119.78 C-3, 121.54 C-14, 122.44 C-15,
134.42 C-16a, 138.37 C-4, 143.19 C-12a, 145.06 C-11, 148.13 C-
2, 151.57 C-6, 166.43 C-8.
2-Chloro-N-(pyridin-2-yl)acetamide (1)
2-Chloroacetyl chloride (1.24 g, 11 mmol) was slowly added
dropwise (30 min.) to a mixture of 2-aminopyridine (0.94 g,
10 mmol) and triethylamine (1.11 g, 11 mmol) in anhydrous
CH2Cl2 (150 mL) at 0 ꢀC. The reaction mixture was warmed to
room temperature and stirred for an additional 2 h. The solution
was washed with NaHCO3 (3 ꢁ 100 mL), then with water
(2 ꢁ 100 mL), and the organic layer dried over anhydrous
2-(1H-imidazol-1-yl)-N-(quinolin-8-yl)acetamide (8)
sodium sulfate. The obtained reddish precipitate was separated White powder (70% yield), mp ¼ 136–138 ꢀC. IR (KBr, ꢁ
by filtration, and was washed with anhydrous CH2Cl2. No other (cmꢂ1)): 3360, 3143, 3054, 2951, 1693, 1562, 1425, 1324. H
1
purification required.
NMR (500 MHz, CDCl3, 25 ꢀC): ꢀ 4.95 (s, 2H, 11-H), 7.14 (s, 1H,
1
White reddish solid (93% yield). H NMR (500 MHz, CDCl3, 15-H), 7.26 (ad, J ¼ 2.5 Hz, 1H, 16-H), 7.44 (aq, J ¼ 8.0 Hz, 1H,
25 ꢀC): ꢀ 4.21 (s,2H), 7.13–7.10 (m, 1H), 7.78–7.73 (m, 1H), 8.21 3-H), 7.54 (ad, J ¼ 6.5 Hz, 2H, 6-H, 7-H), 7.70 (s, 1H, 13-H), 8.15
(d, 1H, J ¼ 4.4 Hz), 8.34–8.32 (m, 2H), 8.94 (s, 1H).
2-Chloro-N-(quinolin-8-yl) acetamide (7)
(dd, J ¼ 8.0 Hz, 1H, 4-H), 8.71 (at, J ¼ 5.5 Hz, 2H, 2-H, 5-H), 9.97
(s, 1-H, 9-H). 13C NMR (125 MHz, CDCl3): d 51.10 C-11, 116.86
C-5, 120.07 C-15, 121.99 C-3, 122.73 C-6, 127.29 C-7, 127.97 C-
8, 130.76 C-16, 133.38 C-4a, 136.44 C-4, 138.29 C-13, 138.42 C-
8a, 148.73 C-2, 164.96 C-10.
2-Chloroacetyl chloride (4.07 g, 36 mmol) was slowly added
dropwise (2 h) to a mixture of 8-aminoquinoline (4.32 g, 30 mmol)
and pyridine (3.4 mL, 42 mmol) in anhydrous CHCl3 (75 mL) at
0 ꢀC. The reaction mixture was warmed to room temperature and
2-(1H-benzo[d]imidazol-1-yl)-N-(quinolin-8-yl)acetamide (9)
stirred for an additional 2 h. After the solvent was removed under Beige powder (63% yield), mp ¼ 161–163 ꢀC. IR (KBr, ꢁ (cmꢂ1)):
reduced pressure, the residue was washed with ice water 3348, 3116, 3021, 2895, 1699, 1544, 1483, 1325. 1H NMR
(3 ꢁ 75 mL), the organic layer dried over anhydrous sodium sulfate. (500 MHz, CDCl3, 25 ꢀC): ꢀ 5.14 (s, 2H, 11-H), 7.30–7.36 (m, 3H,
Theobtainedreddishprecipitatewasseparatedbyfiltration,andwas 3-H, 16-H, 17-H), 7.45–7.51 (overlapped signals, 3H, 5-H, 6-H,
washed with dry chloroform. No other purification required.
18-H), 7.90 (ad, J ¼ 7.0 Hz, 1H, 15-H), 8.08 (dd, J ¼ 7.0 Hz, 1H, 4-
Reddish powder (97% yield). 1H NMR (500 MHz, CDCl3, H), 8.11 (s, 1H, 13-H), 8.51 (dd, J ¼ 4.5 Hz, J ¼ 1.5 Hz, 1H, 2-H),
25 ꢀC): ꢀ 4.45–4.25 (m, 2H), 7.52–7.42 (m, 1H), 7.55 (dd, J ¼ 6.9, 8.67 (aq, J ¼ 4.5 Hz, 1H, 7-H), 10.02 (s, 1-H, 9-H). 13C NMR
3.7 Hz, 2H), 8.17 (d, J ¼ 8.3 Hz, 1H), 8.79–8.67 (m, 1H), (125 MHz, CDCl3): ꢀ 49.13 C-11, 109.70 C-18, 116.79 C-7, 120.79
8.96–8.81 (m, 1H), 9.98 (s, 1H).
C-15, 121.88 C-3, 122.61 C-5, 122.97 C-16, 123.91 C-17, 127.22
C-6, 127.87 C-8, 133.30 C-14a, 133.98 C-18a, 136.30 C-4, 138.29
C-4a, 143.59 C-13, 143.91 C-8a, 148.54 C-2, 164.56 C-10.
General procedure for synthesis of hybrid compounds 2,
3, 8, and 9
General procedure for synthesis of hybrid compounds 5,
6, 10, and 11
Sodium hydride (10 mmol, 0.24 g) in 20 mL of dry acetonitrile
was slowly added dropwise to a stirred mixture of imidazole
derivatives [5.5 mmol (0.37 g) for imidazole or 5.5 mmol (0.65 g) To a stirred solution of hybrid compounds 2, 3, 8, or 9 (1 mmol) in
for benzimidazole] dissolved in 50 mL of dry acetonitrile. To the 10 mL dry acetone, ethyl 2-bromoacetate (2 mmol, 0.33 g) or 2-
resulted mixture, 2-chloro-N-(pyridin-2-yl)acetamide 1 (5 mmol, iodocetamide (2 mmol, 0.37 g) or allyl bromide (2 mmol, 0.24 g)
0.852 g) or 2-chloro-N-(quinolin-8-yl)acetamide
7 (5 mmol, was slowly added. The mixture was stirred at room temperature
1.182 g) in 100 mL of dry acetonitrile (previously sonicated in a for 24 h in the case of compounds 2 and 8 or refluxed for 48 h in
ultrasonic bath) was added dropwise over 1 h (stirring, 0 ꢀC). The the case of compounds 3 and 9. The obtained precipitate was
reaction mixture was warmed to room temperature and stirred for separated by filtration, and was washed with few milliliters of dry
an additional 48 h. After the reaction was completed (TLC), the acetone. No other purification required.
solution was evaporated to dryness under reduced pressure on a
rotary evaporator, and the crude product was purified by flash 3-(2-ethoxy-2-oxoethyl)-1-(2-oxo-2-(pyridin-2-ylamino)ethyl)-
chromatography on silica gel (CH2Cl2/CH3OH ¼ 98/2).
1H-imidazol-3-ium bromide (5a)
White powder (54% yield), mp ¼ 170–172 ꢀC. IR (KBr, ꢁ
2-(1H-imidazol-1-yl)-N-(pyridin-2-yl)acetamide (2)
(cmꢂ1)): 3489, 3153, 3074, 2972, 1755, 1697, 1564, 1438,
1
White powder (61% yield), mp ¼ 183–185 ꢀC. IR (KBr, ꢁ 1303, 1176. H NMR (500 MHz, DMSO-d6, 25 ꢀC): d 1.25 (t,
(cmꢂ1)): 3480, 3149, 3043, 2954, 1695, 1564, 1436, 1303. H J ¼ 7.0 Hz, 3H (CH3), 50-H), 4.22 (q, J ¼ 7.0 Hz, 2H (CH2), 40-H),
1
NMR (500 MHz, DMSO-d6, 25 ꢀC): ꢀ 4.96 (s, 2H, 9-H), 6.89 (s, 5.35 (ad, 4H (2xCH2), 10-H, 9-H), 7.16 (at, J ¼ 5.5 Hz, 1H, 3-H),
1-H, 13-H), 7.13 (aq, J ¼ 5.0 Hz, 1H, 3-H), 7.16 (s, 1H, 14-H), 7.81 (ad, 3H, 4-H, 13-H, 14-H), 7.99 (brs, 1H, 5-H), 8.36 (ad,
7.63 (s, 1H, 11-H), 7.80 (td, J ¼ 5.0 Hz, J ¼ 7.0, 1H, 4-H), 8.01 (d, J ¼ 3.5 Hz, 1H, 2-H), 9.20 (as, 1H, 11-H), 11.09 (s, 1H, 7-H). 13C
J ¼ 7.5 Hz, 1H, 5-H), 8.34 (ad, J ¼ 5.0 Hz, 1H, 2-H), 10.81 (s, NMR (125 MHz, DMSO-d6): ꢀ 13.97 C-50, 49.69 C-9, 51.54 C-10,
1-H, 7-H). 13C NMR (125 MHz, DMSO-d6): ꢀ 49.15 C-9, 113.39 61.87 C-40, 113.44 C-5, 119.97 C-3, 123.25 C-14, 123.81 C-13,

DOI: 10.1080/14756366.2016.1190711
Anticancer and antimycobacterial activity of hybrid imidazole
3
138.51 C-4, 138.67 C-11, 148.22 C-2, 151.31 C-6, 164.60 C-8, NMR (500 MHz, DMSO-d6, 25 ꢀC): d 5.29 (d, J ¼ 4.5 Hz, 2H
166.79 C-20.
(CH2), 10-H), 5.41 (at, 2H (CH2¼), 30-H), 5.65 (brs, 2H (CH2), 9-
H), 6.12–6.17 (m, 1H, 20-H), 7.16 (at, J ¼ 5.5 Hz, 1H, 3-H), 7.70
3-(2-amino-2-oxoethyl)-1-(2-oxo-2-(pyridin-2-ylamino)ethyl)-1H- (brs, 2H, 14-H, 15-H), 7.80 (t, J ¼ 7.0 Hz, 1H, 4-H), 7.96 (brs, 1H,
imidazol-3-ium iodide (5b)
5-H), 8.05 (ad, J ¼ 5.5, 4.5 Hz, 2H, 13-H, 16-H), 8.39 (ad,
J ¼ 2.5 Hz, 1H, 2-H), 9.89 (s, 1H, 11-H), 11.21 (s, 1H, 7-H). 13C
NMR (125 MHz, DMSO-d6): ꢀ 48.87 C-10, 49.28 C-9, 113.52 C-5,
113.87 C-16, 113.92 C-13, 120.06 C-3, 120.44 C-30, 126.61 C-15,
126.88 C-14, 130.57 C-16a, 130.97 C-20, 131.95 C-12a, 138.50 C-
4, 143.67 C-11, 148.23 C-2, 151.27 C-6, 164.45 C-8.
Beige powder (75% yield), mp 192–193 ꢀC. IR (KBr, ꢁ (cmꢂ1)):
3383, 3238, 3171, 2995, 1687, 1591, 1564, 1444, 1296. H NMR
1
(500 MHz, DMSO-d6, 25 ꢀC): d 5.03 (s, 2H (CH2), 10-H), 5.31 (s,
2H (CH2), 9-H), 7.16 (at, J ¼ 5.5 Hz, 1H, 3-H), 7.54 (s, 1H (NH),
30-H), 7.72 (as, 1H, 14-H), 7.75 (as, 1H, 13-H), 7.80–7.84
(overlapped signals, 2H, 4-H, 30-H), 7.99 (brs, 1H, 5-H), 8.37 (ad,
J ¼ 3.5 Hz, 1H, 2-H), 9.11 (as, 1H, 11-H), 11.07 (s, 1H, 7-H). 13C
NMR (125 MHz, DMSO-d6): ꢀ 50.57 C-10, 51.36 C-9, 113.43
3-(2-ethoxy-2-oxoethyl)-1-(2-oxo-2-(quinolin-8-ylamino)ethyl)-
1H-imidazol-3-ium bromide (10a)
C-5, 119.98 C-3, 123.35 C-14, 123.39 C-13, 138.51 C-4, 138.61 Yellow powder (76% yield), mp ¼ 193–195 ꢀC. IR (KBr): ꢁmax
/
C-11, 148.23 C-2, 151.29 C-6, 164.59 C-8, 166.59 C-20.
cmꢂ1: 3334, 3110, 3011, 2895, 1735, 1697, 1561, 1518, 1489,
1
1229, 1182. H NMR (500 MHz, CDCl3, 25 ꢀC): ꢀ 1.25 (t,
3-allyl-1-(2-oxo-2-(pyridin-2-ylamino)ethyl)-1H-imidazol-3-ium
bromide (5c)
J ¼ 7.0 Hz, 3H (CH3), 50-H), 4.24 (q, J ¼ 7.0 Hz, 2H (CH2), 40-H),
5.36 (s, 2H (CH2), 11-H), 5.58 (s, 2H (CH2), 10-H), 7.60 (at,
J ¼ 8.5 Hz, 1H, 6-H), 7.69 (aq, J ¼ 8.5 Hz, J ¼ 4.0 Hz, 1H, 3-H),
7.74 (d, J ¼ 8.5 Hz, 1H, 5-H), 7.82 (as, 1H, 16-H), 7.87 (as, 1H,
15-H), 8.46 (d, J ¼ 8.5 Hz, 1H, 4-H), 8.57 (d, J ¼ 7.5 Hz, 1H, 7-
H), 9.00 (d, J ¼ 4.0 Hz, 1H, 2-H), 9.25 (s, 1H, 13-H), 10.88 (s, 1-
H, 9-H). 13C NMR (125 MHz, CDCl3): ꢀ 13.97 C-50, 49.71 C-11,
52.02 C-10, 61.87 C-40, 117.48 C-7, 122.30 C-3, 122.84 C-5,
123.38 C-16, 123.75 C-15, 126.87 C-6, 127.97 C-4a, 134.04 C-8,
136.68 C-4, 138.36 C-8a, 138.67 C-13, 149.07 C-2, 164.45 C-10,
166.80 C-20.
White powder (51% yield), mp 154–156 ꢀC. IR (KBr, ꢁ (cmꢂ1)):
1
3419, 3107, 3036, 2910, 1703, 1579, 1460, 1435, 1300. H NMR
(500 MHz, DMSO-d6, 25 ꢀC): d 4.95 (d, J ¼ 5.5 Hz, 2H (CH2), 10-
H), 5.27–5.39 (overlapped signals, 4H (CH2¼, CH2), 30-H, 9-H),
6.04–6.12 (m, 1H, 20-H), 7.15 (t, J ¼ 5.5 Hz, 1H, 3-H), 7.79–7.83
(overlapped signals, 3H, 4-H, 13-H, 14-H), 7.99 (brs, 1H, 5-H), 8.36
(d, J ¼ 4.0 Hz, 1H, 2-H), 9.24 (s, 1H, 11-H), 11.09 (s, 1H, 7-H). 13C
NMR (125 MHz, DMSO-d6): ꢀ 50.88 C-10, 51.43 C-9, 113.46 C-5,
119.99 C-3, 120.06 C-30, 121.99 C-14, 124.27 C-13, 131.81 C-20,
137.61 C-11, 138.51 C-4, 148.23 C-2, 151.30 C-6, 164.72 C-8.
3-(2-amino-2-oxoethyl)-1-(2-oxo-2-(quinolin-8-ylamino)ethyl)-
1H-imidazol-3-ium iodide (10b)
3-(2-ethoxy-2-oxoethyl)-1-(2-oxo-2-(pyridin-2-ylamino)ethyl)-
1H-benzo[d]imidazol-3-ium bromide (6a)
Yellow powder (83% yield), mp ¼ 201–203 ꢀC. IR (KBr, ꢁ
(cmꢂ1)): 3431, 3338, 3159, 3088, 3022, 2976, 2092, 1689, 1614,
Pink powder (55% yield), mp ¼ 205–207 ꢀC. IR (KBr, ꢁ (cmꢂ1)):
1
1537, 1491, 1321. H NMR (500 MHz, CDCl3, 25 ꢀC): ꢀ 5.04 (s,
2H (CH2), 11-H), 5.54 (s, 2H (CH2), 10-H), 7.54 (s, 1H (NH), 30-H),
7.60 (t, J ¼ 8.0 Hz, 1H, 6-H), 7.68 (q, J ¼ 8.5 Hz, 1H, 3-H), 7.73–
7.74 (m, 2H, 5-H, 16-H), 7.80 (s, 1H, 15-H), 7.85 (s, 1H (NH), 30-
H), 8.45 (dd, J ¼ 8.5 Hz, J ¼ 1.0 Hz, 1H, 4-H), 8.56 (d, J ¼ 7.5 Hz,
1H, 5-H), 9.00 (dd, J ¼ 4.0 Hz, J ¼ 1.5 Hz, 1H, 2-H), 9.18 (s, 1H,
13-H), 10.87 (s, 1-H, 9-H). 13C NMR (125 MHz, CDCl3): ꢀ 50.61
C-11, 51.88 C-10, 117.48 C-7, 122.32 C-3, 122.85 C-5, 123.31 C-
15, 123.54 C-16, 126.89 C-6, 127.98 C-4a, 134.05 C-8, 136.69 C-4,
138.37 C-8a, 138.63 C-13, 164.50 C-20, 166.64 C-10.
3419, 3140, 3045, 3032, 2987, 2962, 1753, 1705, 1570, 1435,
1
1222, 1184. H NMR (500 MHz, DMSO-d6, 25 ꢀC): ꢀ 1.26 (t,
J ¼ 7.0 Hz, 3H (CH3), 50-H), 4.25 (q, J ¼ 7.0 Hz, 2H (CH2), 40-H),
5.71 (ad, 4H (2xCH2), 10-H, 9-H), 7.17 (t, J ¼ 6.0 Hz, 1H, 3-H),
7.71 (at, 2H, 14-H, 15-H), 7.80 (t, J ¼ 7.5 Hz, 1H, 4-H), 7.97 (brs,
1H, 5-H), 8.08 (at, 2H, 13-H, 16-H), 8.40 (d, J ¼ 4.0 Hz, 1H, 2-H),
9.85 (s, 1H, 11-H), 11.23 (s, 1H, 7-H). 13C NMR (125 MHz,
DMSO-d6): ꢀ 13.98 C-50, 47.60 C-9, 49.43 C-10, 62.03 C-40,
113.50 C-5, 113.90 C-16, 113.95 C-13, 120.07 C-3, 126.82 C-15,
126.93 C-14, 131.09 C-16a, 131.42 C-12a, 138.52 C-4, 144.60 C-
11, 148.24 C-2, 151.27 C-6, 166.53 C-20, 167.03 C-8.
3-allyl-1-(2-oxo-2-(quinolin-8-ylamino)ethyl)-1H-imidazol-3-ium
bromide (10c)
3-(2-amino-2-oxoethyl)-1-(2-oxo-2-(pyridin-2-ylamino)ethyl)-1H-
benzo[d]imidazol-3-ium iodide (6b)
White powder (61% yield), mp ¼ 169–171 ꢀC. IR (KBr, ꢁ
(cmꢂ1)): 3317, 3138, 3101, 3063, 2943, 2902, 1693, 1562,
1
Yellowish white powder (78% yield), mp ¼ 210–212 ꢀC. IR (KBr,
1537, 1485, 1425, 1329. H NMR (500 MHz, CDCl3, 25 ꢀC): ꢀ
1
ꢁ (cmꢂ1)): 3368, 3216, 3153, 2995, 1697, 1564, 1448, 1306. H
4.96 (d, J ¼ 5.5 Hz, 2H (CH2), 10-H), 5.30 (d, J ¼ 17.0 Hz, 1H
from CH2¼, 30-H), 5.39 (d, J ¼ 10.0 Hz, 1H from CH2¼, 30-H),
5.52 (brs, 2H (CH2), 11-H), 6.07–6.12 (m, 1H, 20-H), 7.60 (t,
J ¼ 8.0 Hz, 1H, 6-H), 7.68 (q, J ¼ 8.5 Hz, 1H, 3-H), 7.74 (d,
J ¼ 8.0 Hz, 1H, 7-H), 7.80 (s, 1H, 16-H), 7.87 (s, 1H, 15-H), 8.45
(d, J ¼ 8.5 Hz, 1H, 4-H), 8.56 (d, J ¼ 7.5 Hz, 1H, 5-H), 9.00 (d,
J ¼ 3.0 Hz, 1H, 2-H), 9.28 (s, 1H, 13-H), 10.89 (s, 1-H, 9-H). 13C
NMR (125 MHz, CDCl3): ꢀ 50.92 C-10, 51.94 C-11, 117.54 C-5,
120.06 C-30, 122.10 C-16, 122.31 C-3, 122.86 C-7, 124.22 C-15,
126.88 C-6, 127.89 C-4a, 131.83 C-20, 134.05 C-8a, 136.69 C-4,
137.62 C-13, 138.38 C-8, 149.08 C-2, 164.60 C-10.
NMR (500 MHz, DMSO-d6, 25 ꢀC): ꢀ 5.06 (s, 2H (CH2), 10-H),
5.28 (s, 2H (CH2), 9-H), 7.15 (t, J ¼ 6.5 Hz, 1H, 3-H), 7.21–7.28
(overlapped signals, 2H, 14-H, 15-H), 7.51 (s, 1H (NH), 30H), 7.56
(d, J ¼ 7.5 Hz, 1H, 16-H), 7.68 (d, J ¼ 7.5 Hz, 1H, 13-H), 7.80 (t,
J ¼ 7.5 Hz, 1H, 4-H), 7.83 (s, 1H (NH), 30H), 8.00 (d, J ¼ 7.0 Hz,
1H, 5-H), 8.30 (s, 1H, 11-H), 8.38 (ad, J ¼ 6.0 Hz, 1H, 2-H), 11.10
(s, 1-H, 7-H). 13C NMR (125 MHz, DMSO-d6): ꢀ 50.59 C-10, 49.28
C-9, 110.67 C-16, 114.21 C-5, 119.56 C-13, 119.87 (C-3), 121.58
C-14, 122.86 C-15, 134.43 C-16a, 138.64 C-4, 143.26 C-12a,
145.16 C-11, 148.13 C-2, 152.03 C-6, 165.89 C-8, 166.61 C-20.
3-allyl-1-(2-oxo-2-(pyridin-2-ylamino)ethyl)-1H-benzo[d]
imidazol-3-ium bromide (6c)
3-(2-ethoxy-2-oxoethyl)-1-(2-oxo-2-(quinolin-8-ylamino)ethyl)-
1H-benzo[d]imidazol-3-ium bromide (11a)
White powder (54% yield), mp ¼ 195–197 ꢀC. IR (KBr, ꢁ (cmꢂ1)):
Yellow powder (77% yield), mp ¼ 215–217 ꢀC. IR (KBr, ꢁ
3443, 3153, 3036, 3020, 2972, 2928, 1693, 1687, 1575, 1305. 1H
(cmꢂ1)): 3336, 3113, 3012, 2895, 2823, 1737, 1699, 1558,

4
D. Mantu et al.
J Enzyme Inhib Med Chem, Early Online: 1–8
1529, 1523, 1487, 1325, 1226, 1184. 1H NMR (500 MHz, CDCl3,
The screening is beginning with the evaluation of all
25 ꢀC): ꢀ 1.27 (t, J ¼ 7.0 Hz, 3H (CH3), 50-H), 4.26 (q, J ¼ 7.0 Hz, compounds against the 60 cell lines at a single dose of 10ꢂ5 M.
2H (CH2), 40-H), 5.72 (s, 2H (CH2), 11-H), 5.96 (s, 2H (CH2), 10- The output from the single-dose screen is reported as a mean
H), 7.59 (t, J ¼ 8.0 Hz, 1H, 6-H), 7.70–7.76 (m, 4H, 3-H, 5-H, 15- graph and is available for analysis by the COMPARE program.
H, 18-H), 8.10–8.13 (m, 2H, 16-H, 17-H), 8.47 (dd, J ¼ 8.0 Hz, All details concerning the in vitro anticancer assay could be found
J ¼ 1.5 Hz, 1H, 4-H), 8.55 (d, J ¼ 7.5 Hz, 1H, 7-H), 9.04 (dd, in the Supplementary Information of this article.
J ¼ 4.0 Hz, J ¼ 1.5 Hz, 1H, 2-H), 9.89 (s, 1H, 13-H), 11.02 (s, 1-
H, 9-H). 13C NMR (125 MHz, CDCl3): ꢀ 13.98 C-50, 47.65 C-11, Antimycobacterial activity
49.70 C-10, 62.04 C-40, 113.78 C-17, 114.00 C-16, 117.42 C-7,
Compounds were evaluated for antimycobacterial activity against
122.36 C-3, 122.95 C-5, 126.87 C-18, 126.89 C-15, 127.00 C-
Mycobacterium tuberculosis, as a part of the TAACF (Center of
6, 127.98 C-4a, 131.16 C-18a, 131.35 C-14a, 134.00 C-8, 136.71
Tuberculosis Antimicrobial Acquisition and Coordinating
C-4, 138.36 C-8a, 144.63 C-13, 149.14 C-2, 164.13 C-20,
Facility) TB screening program under direction of the US
166.55 C-10.
National Institute of Health, the NIAID division, at Southern
Research Institute.
3-(2-amino-2-oxoethyl)-1-(2-oxo-2-(quinolin-8-ylamino)ethyl)-
1H-benzo[d]imidazol-3-ium iodide (11b)
Compound solubility in microbiological medium
Yellow powder (89% yield), mp ¼ 208–210 ꢀC. IR (KBr, ꢁ
Compounds were prepared as 10-point 2-fold serial dilutions in
(cmꢂ1)): 3348, 3309, 3149, 3022, 2918, 1681, 1672, 1597,
DMSO and diluted into 7H9-Tw-OADC medium in 96-well
1
1552, 1489, 1325. H NMR (500 MHz, CDCl3, 25 ꢀC): ꢀ 5.38 (s,
plates. The highest concentration of compound was 200 mM
2H (CH2), 11-H), 5.92 (s, 2H (CH2), 10-H), 7.59 (t, J ¼ 8.0 Hz,
where compounds were soluble in DMSO at 10 mM. For
1H, 6-H), 7.68 (s, 1H (NH), 30-H), 7.70–7.73 (m, 3H, 3-H, 16-H,
compounds with limited solubility, the highest concentration
17-H), 7.75 (d, J ¼ 8.0 Hz, 1H, 5-H), 7.97 (at, J ¼ 7.0, J ¼ 4.0, 1H,
was 50 times less than the stock concentration e.g. 100 mM for
18-H), 8.00 (s, 1H (NH), 30-H), 8.01 (at, J ¼ 7.0, J ¼ 4.0, 1H, 15-
5 mM DMSO stock, 20 mM for 1 mM DMSO stock. Turbidity was
H), 8.45 (dd, J ¼ 8.5 Hz, J ¼ 1.0 Hz, 1H, 4-H), 8.56 (d, J ¼ 7.5 Hz,
measured using a Nepheloskan Ascent microplate reader. A
1H, 7-H), 9.01 (dd, J ¼ 4.0 Hz, J ¼ 1.5 Hz, 1H, 2-H), 9.85 (s, 1H,
compound was considered insoluble if the turbidity was 300%
13-H), 11.02 (s, 1-H, 9-H). 13C NMR (125 MHz, CDCl3): ꢀ 48.49
greater than that of the negative control. The lowest insoluble
C-11, 49.58 C-10, 113.70 C-18, 113.73 C-15, 117.40 C-7, 122.37
concentration is reported. Each plate of test compounds included
C-3, 122.94 C-5, 126.76 C-17, 126.81 C-16, 126.90 C-6, 127.99
a positive control (1 mM haloperidol) and a DMSO negative
C-4a, 131.38 C-18a, 131.40 C-14a, 134.03 C-8, 136.72 C-4,
control (2% DMSO in 7H9-Tw-OADC). Each experiment run
138.36 C-8a, 144.62 C-13, 149.14 C-2, 164.20 C-20, 166.36 C-10.
included control compounds: metoprolol tartrate, rifampicin,
phenytoin, haloperidol, simvastatin, diethylstilbestrol, and
3-allyl-1-(2-oxo-2-(quinolin-8-ylamino)ethyl)-1H-benzo[d]
tamoxifen.
imidazol-3-ium bromide (11c)
White powder (64% yield), mp ¼ 191–193 ꢀC. IR (KBr, ꢁ The Primary Cycle High-Throughput Screening (HTS).
(cmꢂ1)): 3477, 3421, 3144, 3088, 3041, 2964, 2928, 1695, Determination of 50% inhibitory concentration (IC50),
1597, 1566, 1539, 1489, 1325. 1H NMR (500 MHz, CDCl3, 90% inhibitory concentration (IC90) and minimum
25 ꢀC): ꢀ 5.31 (d, J ¼ 5.5 Hz, 2H (CH2), 10-H), 5.41 (at, 2H inhibitory concentration (MIC)
(CH2¼), 30-H), 5.91 (brs, 2H (CH2), 11-H), 6.13–6.19 (m, 1H, 20-
The antimicrobial activity of compounds against Mycobacterium
H), 7.58 (t, J ¼ 8.0 Hz, 1H, 6-H), 7.70–7.76 (m, 4H: 3-H, 5-H, 16-
tuberculosis H37Rv grown under aerobic conditions was assessed
H, 17-H), 8.06 (at, J ¼ 5.5 Hz, J ¼ 2.5 Hz, 1H, 18-H), 8.11 (at,
by determining the minimum inhibitory concentration (MIC) of
J ¼ 5.5 Hz, J ¼ 2.5 Hz, 1H, 15-H), 8.47 (d, J ¼ 8.0 Hz, 1H, 4-H),
compound. The MIC of compound was determined by measuring
8.55 (d, J ¼ 7.5 Hz, 1H, 7-H), 9.04 (d, J ¼ 3.0 Hz, 1H, 2-H), 9.94
bacterial growth after five days in the presence of test compounds.
(s, 1H, 13-H), 11.02 (s, 1-H, 9-H). 13C NMR (125 MHz, CDCl3):
For potent compounds, assays were repeated at lower starting
ꢀ 48.89 C-10, 49.57 C-11, 113.82 C-18, 113.92 C-15, 117.44 C-7,
concentrations. Each run experiment included as control rifam-
120.38 C-30, 122.35 C-3, 122.93 C-5, 126.66 C-17, 126.87 C-6,
picin. The assay was based on measurement of growth in liquid
126.93 C-16, 127.98 C-4a, 130.63 C-18a, 131.02 C-20, 131.88
medium of a fluorescent reporter strain of H37Rv where the
C-14a, 134.02 C-8, 136.71 C-4, 138.35 C-8a, 143.74 C-13, 149.12
readout is either optical density (OD) or fluorescence. The use of
C-2, 164.32 C-10.
two readouts minimizes problems caused by compound precipi-
tation or autofluorescence. A linear relationship between OD and
fluorescence readout has been established justifying the use of
Microbiology
Cell proliferation assay
fluorescence as a measure of bacterial growth. MICs, IC50, and
IC90 generated from the OD are reported in Supplementary
Information. All details concerning the Primary Cycle High-
Throughput Screening (HTS) assay could be found in
Supplementary Information of this article.
The in vitro biological tests were performed at the National
Cancer Institute (NCI, USA), under the Developmental
Therapeutics Program (DTP). The DTP screens include the NCI
60 cell line screen and, as appropriate, the hollow fiber assay and
relevant human tumor xenograft and rodent tumor models. The
operation of this screen utilizes 60 different human tumor cell
lines, representing leukemia, melanoma, and cancers of the lung,
colon, brain, ovary, breast, prostate, and kidney. This screen is
unique in that the complexity of a 60 cell line dose response
produced by a given compound results in a biological response
pattern which can be utilized in pattern recognition algorithms via
COMPARE program (See: http://dtp.nci.nih.gov/docs/compare/
compare.html).
Results and discussion
Chemistry
In order to synthesize our hybrid compounds, we chose as starting
azaheterocycles two six-member ring derivatives, 2-aminopyr-
idine (2-AP) and 8-aminoquinoline (8-AQ), and two five-member
ring derivatives, imidazole (Imz) and benzimidazole (Bimz). The
strategy we used for synthesis was straight and efficient, involving

DOI: 10.1080/14756366.2016.1190711
Anticancer and antimycobacterial activity of hybrid imidazole
5
N
N
N
1
N
H
NH
9
NH
7
10
X
N
N
Y
ClCH2COCl
N
O
2
N
X
O
N
N
1'
14
Y
a
5
. X=-Br; Y= -COOEt
NH
NH2
N
b
. X=-I; Y= -CONH2
Cl
O
N
a
4
. X=-Br; Y= -COOEt
c
. X=-Br; Y= -CH=CH2
N
N
b
c
. X=-I; Y= -CONH2
. X=-Br; Y= -CH=CH2
1
H
1
NH
NH
10
X
N
7
N
3
Y
O
N
O
N
1'
13
6 a
b
. X=-Br; Y= -COOEt
. X=-I; Y= -CONH2
c
. X=-Br; Y= -CH=CH2
Scheme 1. Synthesis of hybrid imidazole (benzimidazole)/pyridine derivatives 2–6.
a three-step setup procedure: N-acylation, N-alkylation, and atoms. The signals for C10 appear at 164.56 ppm (typical for a
quaternization of N-heterocycle. Thus, the N-acylation of 2-AP C¼O from amide carbonyl group) while the methylene C11
with 2-chloroacetyl chloride is leading to the corresponding appears at 49.13 ppm, due to the strong unshielded effect of the
pyridine acylamine 1 (Scheme 1). Subsequent treatment of adjacent carbonyl group and imidazole moiety. The C13 carbon
acylamine 1 with Imz or Bimz is leading to a first class of appears at 143.59 ppm, in accordance with the powerful
hybrid Imz (Bimz)/pyridine derivatives 2 and 3, via an N- unshielded effect of the two adjacent nitrogen atoms from
alkylation reaction of the NH-imidazolic moiety. In the last step, a imidazole ring.
quaternization reaction of N-imidazole atom with variously
In the case of compound 11c, the most important signals
1
activated halogenated derivatives 4 (2-bromo/iodo-alkyl esters/ furnished by H NMR spectra are those one of the protons H9,
amide 4a,b or allyl bromide 4c) is leading to a second class of H11, H13, H7,and H2 as well as those one from N-allyl-moiety
hybrid N-(1-alkylcarboxy)- and N-allyl-imidazole/pyridine from the quaternizated benzimidazole (H10, H20, H30). The
derivatives 5a–c and benzimidazole/pyridine derivatives 6a–c most unshielded proton remains H9 (11.02 ppm, singlet, NH-
(Scheme 1). A similar strategy was used in the case of 8-AQ; proton from amide carbonyl group), because of the proximity
the hybrid Imz (Bimz)/quinoline derivatives 8–11 being obtained with the positive nitrogen from imidazole moiety. The next
(Scheme 2). The structures of the new compounds were proven unshielded proton is H13 (9.94 ppm, singlet) due to the
1
by elemental (C, H, N) and spectroscopic analysis: IR, H NMR, powerful electron-withdrawing effect of the two adjacent
13C NMR, and two-dimensional experiments 2D COSY, 2D nitrogen atoms from imidazole ring, one of them positive.
HMQC, and 2D HMBC. If we consider compound 9 as The protons from the quinoline heterocycle are the next one:
representative for the first series of hybrid Imz (Bimz)/2-AP H2 (9.04 ppm, apparent doublet, J ¼ 3.0 Hz) and H7 (8.55 ppm,
(8-AQ) derivatives2,3,8,9and 11c for the second series of hybrid N- doublet, J ¼ 7.5 Hz). The methylene protons H11 appear at
(1-alkylcarboxy)- and N-allyl-Imz (Bimz)/2-AP (8-AQ) deriva- 5.91 ppm (singlet) due to the strong electron-withdrawing effect
tives5,6,10,11, the spectral analysis reveals strong evidence for the of the adjacent carbonyl group and positive nitrogen from
proposed structures. Thus, in the case of compound 9, the most imidazole moiety. The allyl methylene protons H10 appear at
1
important signals furnished by H NMR spectra are those one of 5.31 ppm (doublet, J ¼ 5.5 Hz), while the vinyl protons appear
the protons H9, H11, H13, H7, and H2. The most unshielded at 6.13–6.16 ppm (multiplet, H20), respectively at 5.39–5.43 ppm
proton is H9 (10.02 ppm, singlet), being a NH-proton from amide (apparent triplet, H30). In the 13C NMR spectra, the most
carbonyl group. The next unshielded protons are from the important data are furnished by the signals corresponding to
quinoline heterocycle, H7 (8.67 ppm, triplet, J ¼ 4.5 Hz) and H2 the atoms C10 (carbonyl), C11 (methylene), C13 (a-endocyclic
(8.51 ppm, two doublets, J ¼ 4.5 Hz, and J ¼ 1.5 Hz), H7 being carbon from imidazole), and the carbons from N-allyl-moiety
unshielded by the electron withdrawing effect of the adjacent from the quaternizated benzimidazole (C10, C20, C30). The
carbonyl amide group while H2 is unshielded by the withdrawing signal for C10 appears at 164.32 ppm (typical for a C¼O from
effect of the adjacent nitrogen N1 (a-endocyclic proton). The H13 amide carbonyl group), C11 methylene carbon appears at
protons appear at 8.11 ppm (singlet) due to the powerful electron- 49.57 ppm (strong unshielded effect of the carbonyl group and
withdrawing effect of the two adjacent nitrogen atoms from imidazole moiety), and the C13 carbon appears at 143.74 ppm,
imidazole ring. The signals for methylene protons H11 appear at in accordance with the powerful unshielded effect of the two
low field (5.14 ppm, singlet), due to the strong electron-with- adjacent nitrogen atoms from imidazole ring, one of them
drawing effect of the adjacent carbonyl group and imidazole positive. The allyl methylene carbon C10 appears at 48.89 ppm,
moiety. In the 13C NMR spectra, the most important data are while the vinyl carbons appear at 131.04 ppm (C20), respect-
furnished by the signals corresponding to the C10 (carbonyl), C11 ively at 120.38 ppm (C30). All the remaining signals from NMR
(methylene), and C13 (a-endocyclic carbon from imidazole) spectra are in accordance with the proposed structures. See also

6
D. Mantu et al.
J Enzyme Inhib Med Chem, Early Online: 1–8
Supporting Information for the 1H- and 13C-NMR spectra for derivatives: a first series which contains main graph Imz (Bimz)/
compounds 9 and 11c.
2-AP (8-AQ) heterocycles, interconnected through an acetamide
linker, and a second seriesis the corresponding N-(1-alkylcar-
boxy)- and N-allyl-salts (Scheme 3).
Three hybrid Imz (Bimz)/
Design and biological activity
2-AP (8-AQ) derivatives, 2, 8, and 9, were selected and tested
in vitro for anticancer activity by the National Cancer Institute
(NCI, USA), under the DTP, at a single high dose (10ꢂ5 M) cell
assay. This assay was performed in a 60 human tumor cell line
panel, representing leukemia, melanoma, and cancers of lung,
colon, brain, breast, ovary, kidney, and prostate, in accordance
with the protocol of the NCI26–29. The results are expressed as
‘‘Percentage Growth Inhibition’’ (PGI) term, and represent
growth relative to the no-drug control, and relative to the time
zero number of cells (Table 1). This allows detection of both
growth inhibition (values between 0 and 100) and lethality (values
less than 0). For example, a value of 40 would mean 60% growth
inhibition while a value of ꢂ40 would mean 40% lethality
(Supplementary Information concerning full in vitro anticancer
assay could be found in the ESI of this article).
One of the strategies widely used in cancer and TB therapy is
targeting DNA with small molecules, imidazole/benzimidazole,
and pyridine/quinoline derivatives being leading structures in
this respect [anticancer5–10, anti-TB11–15]. In previously research
work, we successfully identify azaheterocycles derivatives
(imidazole/benzimidazole and pyridine/quinoline included)
with anticancer9,10,16–19 and anti-TB15–17,20–23 activity.
In the light of the above consideration, it appears rational to
combine the pharmacophoric potential of the two core scaffolds,
imidazole (and its benzo-derivative benzimidazole) and pyridine
(and its benzo-derivative quinoline), intending to obtain new
entities with better anticancer and antimycobacterial activity and,
also, with better pharmaceutical properties (i.e. increasing the
water solubility for salts). In this respect, we design two new
classes of hybrid imidazole (benzimidazole)/pyridine (quinoline)
5
N
N
N
N
1
H
NH
NH
5
11
9
X
N
N
Y
12
ClCH2COCl
Cl
O
N
X
O
N
1'
8
N
N
15
Y
10 a
. X=-Br; Y= -COOEt
NH
NH2
N
4 a-c
b
c
. X=-I; Y= -CONH2
. X=-Br; Y= -CH=CH2
7
O
N
N
H
N
1
NH
NH
11
12
9
X
Y
N
N
O
N
O
N
1'
11 a
. X=-Br; Y= -COOEt
b
15
. X=-I; Y= -CONH2
9
c
. X=-Br; Y= -CH=CH2
Scheme 2. Synthesis of hybrid Imz (Bimz)/quinoline derivatives 8–11.
Y
Y
Scheme 3. Design in the class of hybrid
imidazole (benzimidazole)/pyridine (quin-
oline) derivatives.
N
X
N
N
N
X
N
Pharmacophoric moieties
with anticancer and/or
anti-TB potential
N
Y
Y
N
NH
N
N
NH
X
N
N
NH
N
Y
NH
O
N
X
O
N
N
N
O
N
Y
O
N
O
X
X
R

DOI: 10.1080/14756366.2016.1190711
Anticancer and antimycobacterial activity of hybrid imidazole
7
The results from Table 1 indicate that one of the hybrid inhibition of 23.26% for 2 and 28.68% for 8). The above results
compounds, namely Bimz/8-AQ, 9, has a very good antitumor suggest that the presence of a benzimidazole and 8-aminoquino-
activity against Renal Cancer A498 (with a growth inhibition of line moieties in the same molecule is favorable for anticancer
46.08%) and Breast Cancer MDA-MB-468 (with a growth activity. Comparative with the literature data of other compounds
inhibition of 43.46%). We may also notice a significant antitumor containing only imidazole or pyridine in their molecule, the
growth inhibitory activity (around 35%) of 9 against Leukemia anticancer activity of our hybrid imidazole (benzimidazole)/
(RPMI-8226, CCRF-CEM, K-562, SR), Non-Small Cell Lung pyridine (quinoline) derivatives is more promising.
Cancer (NCI-H23, A549/ATCC), CNS Cancer SF-293,
The hybrid Imz (Bimz)/2-AP (8-AQ) derivatives, 2, 3, 8, 9, and
Melanoma (SK-MEL-5, UACC-257), Renal Cancer UO-31, 11a–c, were evaluated for in vitro antimycobacterial activity
Breast Cancer T-47D, and Ovarian NCI/ADR-RES. Another against M. tuberculosis H37Rv (grown under aerobic conditions),
important aspect that has to be underlined is the specificity of the as a part of the TAACF TB screening program under direction of
hybrid Imz (Bimz)/2-AP (8-AQ) compounds to Renal Cancer the US National Institute of Health, the NIAID division (Table 2).
A498: the highest activity of 9 is against this type of cancer In the first step, the relative solubility of compounds in
(growth inhibition of 46.08%), and the other two hybrids have a microbiological medium was measured using turbidity as a
slightly activity only against this type of cancer (with a growth measure30. A serial dilution of compounds was prepared in
DMSO and then transferred to microbiological medium at pH 6.8.
Turbidity was measured and compared to a control; the lowest
concentration at which compounds are insoluble (defined as
turbidity4300% of control) was recorded.
Table 1. Percentage growth inhibition (PGI, mM)* data of compounds 2,
8, and 9 against an NCI 60 human tumor cell lines (selection)y.
The data from Table 2 illustrate that the tested hybrid Imz
(Bimz)/2-AP (8-AQ) derivatives have an excellent solubility in
microbiological medium (4200 mM), which is very promising
from the pharmacological properties point of view. Then, IC50,
IC90, and MIC were determined by measuring bacterial growth
after five days in the presence of test compounds31–34. As can be
seen, from the seven tested compounds, only one9 had activity
against M. tuberculosis H37Rv under aerobic conditions, with an
IC90 of 77 mg/mL and a MIC4100 mM. We may also notice that
quaternization of N-imidazolic atom in salts 11a–c has no
influence on the antimycobacterial activity.
Compound 2,
PGI
Compound 8,
PGI
Compound 9,
PGI
Panel/cell line
Renal cancer
A498
UO-31
Breast cancer
MDA-MD-468
T-47D
76.38
95.67
71.32
86.67
52.92
66.68
99.69
95.02
96.84
84.83
56.54
66.49
CNS cancer
SF-295
101.52
102.13
66.68
Melanoma
SK-MEL-5
UACC-257
Leukemia
RPMI-8226
CCRF-CEM
K-562
107.01
96.08
101.55
103.82
63.62
76.57
Conclusions
98.44
103.51
96.39
95.61
102.28
101.22
109.15
64.14
70.70
79.72
70.75
The design, synthesis, structure, and in vitro anticancer and
antimycobacterial activity of new hybrid Imz (Bimz)/2-AP
(8-AQ) derivatives are described. The strategy adopted for
synthesis is straight and efficient, involving a three-step setup
procedure: N-acylation, N-alkylation, and quaternization of
nitrogen heterocycle. Fourteen new hybrid compounds (namely
5a–c, 6a–c, 8, 9, 10a–c, and 11a–c) were obtained and fully
characterized by elemental and spectral analysis. The solubility in
microbiological medium and anticancer and antimycobacterial
activity of a selection of new synthesized compounds were
evaluated against a NCI 60 human tumor cell line panel and
Mycobacterium tuberculosis H37Rv under aerobic conditions,
respectively. The hybrid derivatives have an excellent solubility in
microbiological medium, which make them promising from the
pharmacological properties point of view. One of the hybrid
SR
Non-small cell lung cancer
90.22
NCI-H23
104.67
89.85
95.31
103.65
69.62
77.74
A549/ATCC
Ovarian cancer
OVCAR-4
84.49
105.73
77.98
105.83
81.08
75.91
NCI/ADR-RES
Bold values indicate significant activity.
*The number reported for the one-dose assay, percentage growth
inhibition (PGI), is growth relative to the no-drug control, and relative
to the time zero number of cells.
yFull results are presented in the Supplementary Information.
Table 2. Solubility in microbiological medium and antimycobacterial activity of compounds 2, 3, 8, 9, and 11a–c against Mycobacterium tuberculosis
H37Rv under aerobic conditions.
Compound solubility
Starting
concentration (mM)
Lowest insoluble
concentration (mM)
Compound
IC50 (mg/mL)
IC90 (mg/mL)
MIC (mM)
2
3
8
9
11a
4200
4200
4200
4200
4200
4200
4200
4200
4200
4200
77
4200
4200
4200
4200
4200
4200
4100
4200
4200
4200
200
200
200
200
200
200
200
N/A
N/A
N/A
N/A
N/A
N/A
N/A
11b
11c
Control*
Rifampicin
0.0036
0.0061
0.0055
0.04
N/A
N/A means the compound was soluble at the highest concentration.
*Each experiment run included and other control compounds: metoprolol tartrate, phenytoin, haloperidol, simvastatin, diethylstilbestrol, and tamoxifen.

8
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compounds, 9, exhibits a very good antitumor activity against
Renal Cancer A498 and Breast Cancer MDA-MB-468 (with a
growth inhibition around 45%) and also presents a significant
antitumor activity (with a growth inhibition around 35%) against
Leukemia (RPMI-8226, CCRF-CEM, K-562, SR), Non-Small
Cell Lung Cancer (NCI-H23, A549/ATCC), CNS Cancer SF-293,
Melanoma (SK-MEL-5, UACC-257), Renal Cancer UO-31,
Breast Cancer T-47D, and Ovarian NCI/ADR-RES. Overall, the
results suggest that the hybrid Imz (Bimz)/2-AP (8-AQ) com-
pounds present a specific affinity to Renal Cancer A498.
Concerning the antimycobacterial activity, only the hybrid
compound 9 has a significant activity. The SAR correlation
suggests that the presence of a benzimidazole and 8-aminoquino-
line moieties in the same molecule is favorable for both anticancer
and antimycobacterial activity, and could be taken into consid-
eration as leading motifs for further studies.
Acknowledgements
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and antimycobacterial activity of some new azaheterocycles:
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The authors gratefully acknowledge the National Cancer Institute
(Developmental Therapeutics Program, Division of Cancer Treatment
and Diagnosis, website: http://dtp.cancer.gov/) for the in vitro evaluation
of anticancer activity and National Institutes of Health and the National
Institute of Allergy and Infectious Diseases, Contract No.
HHSN272201100009I, for the in vitro evaluation of anti-TB activity.
We also thank the POSCCE-O 2.2.1, SMIS-CSNR 13984-901, No. 257/
28.09.2010 Project, CERNESIM, for the NMR spectra.
21. Mantu D, Antoci V, Mangalagiu II. Design, synthesis and
antimycobacterial activity of some new pyridazine derivatives:
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Declaration of interest
The authors report no declarations of interest.
The authors are thankful to CNCSIS Bucuresti, Romania, grant
PN-II-DE-PCE-2011-3-0038, no. 268/05.10.2011, for financial
support.
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Supplementary material available online