Design, Synthesis and Anticancer Evaluation of Novel Quinazoline-Sulfonamide Hybrids

By combining the structural features of quinazoline and sulfonamides, novel hybrid compounds 2–21 were synthesized using a simple and convenient method. Evaluation of these compounds against different cell lines identified compounds 7 and 17 as most active anticancer agents as they showed effectiveness on the four tested cell lines. The anticancer screening results of the tested compounds provides an encouraging framework that could lead to the development of potent new anticancer agents.


Introduction
Cancer continues to be a leading health problem in developed as well as developing countries.It has become the number one killer due to various worldwide factors [1][2][3][4][5].This enormous incidence of cancer has increased the urgency of the search for the latest, safer and efficacious anticancer agents, aiming at the prevention or the cure of this illness [6][7][8].In the efforts to identify various chemical substances which may serve as leads for designing novel anticancer agents, nitrogen-and sulfur-containing heterocycles are of particular interest [9][10][11].Quinazoline and sulfonamide moieties have been identified as classes of cancer chemotherapeutic agents with significant therapeutic efficacy against solid tumors.In recent years, quinazolines, as an important pharmacophore, have emerged as a versatile template for inhibition of a diverse range of receptor tyrosine kinases [12][13][14][15][16].The most widely studied of these is the epidermal growth factor receptor (EGFR), with the small-molecule inhibitor gefitinib being the first quinazoline derivative to be approved for the treatment of Non-Small Cell Lung Cancer [17][18][19][20][21]. Subsequent research aimed at further exploration of the SAR of this novel template has led to discovery of highly selective compounds that target EGFR such as erlotinib, lapatinib, canertinib and vandetanib [22][23][24] (Figure 1).These compounds act via competing with ATP for binding at the catalytic domain of tyrosine kinase.Later on, a great structural variety of compounds of structurally diverse classes have proved to be highly potent and selective ATP-competitive inhibitors [25][26][27][28].Based on the good performances of quinazoline derivatives in anticancer applications, the development of novel quinazoline derivatives as anticancer drugs is a promising field.
Varied biological activities have been attributed to sulfonamide compounds, including carbonic anhydrase inhibition, antitumoral, antimalarial and antimicrobial activities [29][30][31].In the design of new drugs, the development of hybrid molecules through the combination of different pharmacophores Molecules 2016, 21, 189; doi:10.3390/molecules21020189www.mdpi.com/journal/moleculesmay lead to compounds with interesting biological profiles [32].In view of the abovementioned knowledge about different pharmacophores and in continuation of our research programme [33][34][35][36][37][38][39][40][41][42][43][44][45], we have now synthesized quinazoline-sulfonamide hybrids to obtain a single molecular framework incorporating both moieties.These hybrid molecules consist of a planar heterocyclic ring (quinazoline) with a hydrophobic phenyl ring at position-2 as a central core that can act as a scaffold to carry a functionalized branch at position-4, in such a way to accommodate a sulfonamide moiety (Figure 2).Introduction of the benzensulfonamide amino group at position-4 will add a new hydrogen bond donor, a very much needed characteristic for the desired activity [46].These compounds were then screened for their in vitro anticancer activity against various cell lines.
about different pharmacophores and in continuation of our research programme [33][34][35][36][37][38][39][40][41][42][43][44][45], we have now synthesized quinazoline-sulfonamide hybrids to obtain a single molecular framework incorporating both moieties.These hybrid molecules consist of a planar heterocyclic ring (quinazoline) with a hydrophobic phenyl ring at position-2 as a central core that can act as a scaffold to carry a functionalized branch at position-4, in such a way to accommodate a sulfonamide moiety (Figure 2).Introduction of the benzensulfonamide amino group at position-4 will add a new hydrogen bond donor, a very much needed characteristic for the desired activity [46].These compounds were then screened for their in vitro anticancer activity against various cell lines.

Chemistry
The aim of this work was to design and synthesize novel quinazoline-sulfonamide hybrids to evaluate their anticancer activity.Thus, interaction of 4-chloro-2-phenylquinazoline (1) with several sulfonamides in dry N,N-dimethylformamide afforded the corresponding quinazoline-sulfonamide derivatives 2-18 (Scheme 1).The structures of the formed compounds were confirmed on the basis of elemental analyses and spectral data.Thus, the IR spectra of compounds 2-18 showed absorption bands for (NH), (CH aromatic), (CH aliphatic), (C=N) and (SO2) functional groups.The 1 H-NMR spectra exhibited singlets assigned to the NH group which were exchanged upon deuteration.Also, interaction of compound 1 with sulfanilamide in dimethylformamide in the presence of anhydrous K2CO3 furnished 4-amino-N-(2-phenylquinazoline-4-yl)-benzenesulfonamide (19, Scheme 2), this reaction proceeded through salt formation of the acidic amino group of sulfonamide (SO2NH2) which further reacted with the chloro group of the quinazoline to yield compound 19.about different pharmacophores and in continuation of our research programme [33][34][35][36][37][38][39][40][41][42][43][44][45], we have now synthesized quinazoline-sulfonamide hybrids to obtain a single molecular framework incorporating both moieties.These hybrid molecules consist of a planar heterocyclic ring (quinazoline) with a hydrophobic phenyl ring at position-2 as a central core that can act as a scaffold to carry a functionalized branch at position-4, in such a way to accommodate a sulfonamide moiety (Figure 2).Introduction of the benzensulfonamide amino group at position-4 will add a new hydrogen bond donor, a very much needed characteristic for the desired activity [46].These compounds were then screened for their in vitro anticancer activity against various cell lines.

Chemistry
The aim of this work was to design and synthesize novel quinazoline-sulfonamide hybrids to evaluate their anticancer activity.Thus, interaction of 4-chloro-2-phenylquinazoline (1) with several sulfonamides in dry N,N-dimethylformamide afforded the corresponding quinazoline-sulfonamide derivatives 2-18 (Scheme 1).The structures of the formed compounds were confirmed on the basis of elemental analyses and spectral data.Thus, the IR spectra of compounds 2-18 showed absorption bands for (NH), (CH aromatic), (CH aliphatic), (C=N) and (SO2) functional groups.The 1 H-NMR spectra exhibited singlets assigned to the NH group which were exchanged upon deuteration.Also, interaction of compound 1 with sulfanilamide in dimethylformamide in the presence of anhydrous K2CO3 furnished 4-amino-N-(2-phenylquinazoline-4-yl)-benzenesulfonamide (19, Scheme 2), this reaction proceeded through salt formation of the acidic amino group of sulfonamide (SO2NH2) which further reacted with the chloro group of the quinazoline to yield compound 19.

Chemistry
The aim of this work was to design and synthesize novel quinazoline-sulfonamide hybrids to evaluate their anticancer activity.Thus, interaction of 4-chloro-2-phenylquinazoline (1) with several sulfonamides in dry N,N-dimethylformamide afforded the corresponding quinazoline-sulfonamide derivatives 2-18 (Scheme 1).The structures of the formed compounds were confirmed on the basis of elemental analyses and spectral data.Thus, the IR spectra of compounds 2-18 showed absorption bands for (NH), (CH aromatic), (CH aliphatic), (C=N) and (SO 2 ) functional groups.The 1 H-NMR spectra exhibited singlets assigned to the NH group which were exchanged upon deuteration.Also, interaction of compound 1 with sulfanilamide in dimethylformamide in the presence of anhydrous K 2 CO 3 furnished 4-amino-N-(2-phenylquinazoline-4-yl)-benzenesulfonamide (19, Scheme 2), this The IR spectrum of compound 19 showed characteristic bands at 3412, 3209 cm ´1 (NH, NH 2 ), 3084 cm ´1 (CH aromatic) 1635 cm ´1 (C=N), 1375, 1134 cm ´1 (SO 2 ).The 1 H-NMR spectrum of compound 19 exhibited signals at 7.0 ppm due to the NH 2 group, which exchangeable with D 2 O, and a singlet at 11.9 ppm assigned to the NH group which was exchangeable with D 2 O.The mass spectrum of compound 19 revealed a molecular ion peak m/z at of 376[M + ] (11.64).

In-Vitro Anticancer Evaluation
The synthesized compounds were evaluated for their in vitro anticancer activity against human lung cancer cell line (A549), cervical (HeLa) cancer cell line, colorectal cell line (LoVo) and breast cancer cell line (MDA-MB-231) using doxorubicin as reference drug.The relationship between surviving fraction and drug concentration was plotted to obtain the survival curves of the cancer cell lines.The response parameter calculated was the IC 50 value, which corresponds to the concentration required for 50% inhibition of cell viability.The results are presented in Table 1, where all compounds exhibit moderate activity compared to doxorubicin as positive control.In the case of the human lung cancer cell line (A549) compounds 2, 3, 4, 7, 8, and 17 were the most potent, with IC 50 values ranging from 77.8-161.6 µM, lower than the reference.On the other hand, the tested compounds showed low activity on the HeLa cell line where he most potent were the sulfonamide derivatives 7 and 17 (IC 50 = 91.5 and 87.6 µM, respectively).In case of the colorectal cell line LoVo, all compounds showed excellent activity and were found to be more active than doxorubicin.Moderate activity was observed for the synthesized compounds on the MDA-MB-231 breast cancer cell line, where the most potent candidates were compounds 2-4, 7, 8, 10, 14 and 17, which all showed lower activity than the reference drug doxorubicin.Generally, the colorectal (LoVo) and breast (MDA-MB-231) cancer cell lines were the most sensitive to the synthesized compounds.With regard to broad spectrum anticancer activity, close examination of the data presented in Table 1, reveals that compounds 7 and 17 were the most active, showing effectiveness toward the four cell lines.

General Information
All analyses were done at the Research Center, King Saud University (Riyadh, Saudi Arabia).Melting points (uncorrected) were determined in open capillaries on a Gallenkamp melting point apparatus (Sanyo Gallenkamp, Southborough, UK).Precoated silica gel plates (Kieselgel 0.25 mm, 60 F254, Merck, Darmstadt, Germany) were used for thin layer chromatography.A developing solvent system of 4:1 chloroform/methanol was used and the spots were detected by ultraviolet light.IR spectra (KBr discs) were recorded using an FT-IR spectrometer (Perkin Elmer, Waltham, MA, USA). 1 H-NMR spectra were scanned on NMR spectrometer (Bruker AXS Inc., Flawil, Switzerland), operating at 500 MHz for 1 H-and 125.76 MHz for 13 C.Chemical shifts are expressed in δ-values (ppm) relative to TMS as an internal standard, using DMSO-d 6 as a solvent.Mass spectra were recorded on a 600 GC/MS (Clarus, Middletown, CT, USA) and TQ 320 GC/MS/MS mass spectrometers (Varian, West Sussex, UK).Elemental analyses were done on a model 2400 CHNSO analyser (Perkin Elmer, Waltham, MA, USA).All the values were within ˘0.4% of the theoretical values.All reagents used were of AR grade.The starting material 4-chloro-2-phenylquinazoline was purchased from Sigma (St. Louis, MO, USA) and was directly used for the preparation of target compounds.Spectroscopic data of the synthesized compounds can be accessed as supplementary materials.
C-NMR and mass spectral data.The IR spectrum of compound 20 revealed characteristic bands at 3375, 3257, (NH, NH 2 ), 1664 (C=O), 1618 (C=N), 1389, 1140 (SO 2 ).The 1 H-NMR spectrum of compound 20 exhibited signals at 5.9 ppm due to a NH 2 group, which was exchangeable with D 2 O, and a singlet at 10.1 ppm assigned to a NH group which was exchangeable with D 2 O.The mass spectrum of compound 20 revealed a molecular ion peak at m/z 453 [M + ] (13.72).The IR spectrum of 21 showed characteristic bands at 3367 (2NH), 1622 (2C=N), 1375, 1181 (SO 2 ).The 1 H-NMR spectrum of 21 revealed signals at 10.1 ppm corresponding to two NH groups which were exchangeable with D 2 O.The mass spectrum of compound 21 showed a molecular ion peak at m/z 657 [M + ] (32.18); this increase in the mass demonstrated the introduction of the second mole of dapsone.

Table 1 .
In vitro anticancer screening of the synthesized compounds against four cell lines.Data are expressed as IC 50 (µM) ˘SD (n = 3).