Home A preliminary investigation of anticancer activity of novel benzothiazole derivatives against A549 lung carcinoma cell line
Article Publicly Available

A preliminary investigation of anticancer activity of novel benzothiazole derivatives against A549 lung carcinoma cell line

  • Leyla Yurttaş EMAIL logo , Betül Kaya Çavuşoğlu , Arda Sever and Gülşen Akalin Çiftçi
Published/Copyright: July 5, 2017
Download Article (PDF)
Turkish Journal of Biochemistry
From the journal Turkish Journal of Biochemistry Volume 42 Issue 5

Abstract

Objective(s)

In this study, it was aimed to synthesize new chemotherapeutic agents based on known antiproliferative properties of benzothiazol-2-amine moiety. The antitumor activity of the newly synthesized compounds was determined against A549 lung cancer cell lines.

Methods

Eighteen compounds were obtained by two steps synthetic route. The anticancer potency of the compounds were detected using MTT assay and flow cytometric analysis on A549 cell line. Some physicochemical properties of the compounds were calculated, virtually.

Results

Compounds 15 and 18 showed the highest cytotoxic activity even than cisplatin. Also, it was determined that compound 18 caused 19.1% (early and late) apoptosis whereas cisplatin caused 21.6% (early and late).

Conclusion

Considering the calculated virtual data, eighteen new compounds were found within the boundaries of Lipinski rule of five to be an oral drug. Besides, the most potent compounds 15 and 18 were detected that both have 1-methylbenzimidazole structure, and also methoxy and ethoxy substituents on benzothiazole ring.

Özet

Amaç

Bu çalışmada, benzotiyazol-2-amin kalıntısının bilinen antiproliferatif özelliklerinden yola çıkılarak yeni kemoterapötik ajanların sentezlenmesi amaçlanmıştır. Yeni sentezlenen bileşiklerin antitümör etkinliği, A549 akciğer kanseri hücre dizisine karşı belirlenmiştir.

Yöntemler

On sekiz bileşik iki aşamalı sentetik yolla elde edilmiştir. Bileşiklerin antikanser potansiyeli A549 hücre dizisinde MTT yöntemi ve akış sitometrisi analizi kullanılarak tespit edilmiştir. Bileşiklerin bazı fizikokimyasal özellikleri sanal olarak hesaplanmıştır.

Bulgular

Bileşiklerden 15 ve 18, sisplatinden daha yüksek sitotoksik aktivite göstermiştir. Ayrıca sisplatinin %21.6’lık (erken ve geç) apoptoza sebep olurken, bileşik 18’in %19.1 (erken ve geç) apoptoza neden olduğu belirlenmiştir.

Sonuç

Sanal olarak hesaplanan veriler göz önüne aldığında, on sekiz yeni bileşiğin Lipinsiki’nin oral ilaç olabilmek için gerekli beş kuralının sınırları içerisinde olduğu belirlenmiştir. Ayrıca en aktif bileşikler olan 15 ve 18’in, her ikisinin de 1-metilbenzimidazol yapısına sahip oldukları ve benzotiyazol halkasında metoksi ve etoksi sübstitüentleri taşıdıkları belirlenmiştir.

Keywords: Benzothiazole; Synthesis; Lung cancer; Cytotoxicity; Apoptosis
Anahtar kelimeler: Benzotiyazol; Sentez; Akciğer kanseri; Sitotoksisite; Apoptoz

Introduction

Lung cancer is the most common cause of cancer-related death which represents 29% of all cancer deaths worldwide. Among its types, non-small cell lung cancer (NSCLC) is higher than eighty percent of all lung cancer diseases [1], [2]. Chemotherapy provides symptomatic treatment and modest improvement in survival in advanced non-small cell lung cancer [3], [4]. However, recent literature indicate that newer chemotherapeutic agents extend life span and relieve symptoms in all stages of lung cancer, such as NSCLC [5].

Benzothiazoles have been known to have a large scale of biological activities including antimalarial, antitubercular, antihelmintic, anticonvulsant, analgesic, anti-inflammatory, antidiabetic and antitumor activities [6], [7], [8]. The diversity of biological activity varies according to the alkyl, aryl group or any other functional groups at the second position of benzothiazole ring. It has been reported that the benzothiazole structure modified with an aryl group and imidazole ring can affect inhibition of the growth of certain cancer cell lines [9], [10], [11]. In various studies, new benzothiazole compounds were focused on substituting 2-aminobenzothiazoles, 2-arylbenzothiazoles and benzothiazole-2-thiol as functional groups [12], [13], [14], [15], [16], [17]. Among them, a large number of 2-aminobenzothiazoles are generated one of the privileged part of medicinal chemistry which are also extensively studied [18], [19]. Related compounds were reported to possess cytotoxic properties on different cancer cells which were comparable to cisplatin [20]. Besides, combination of 2-aminobenzothiazoles with other heterocycles is a well-known approach to design new drug like molecules, which allows achieving new pharmacological profile, action, toxicity lowering [21].

Considering these literature, we have designed novel benzothiazole derivatives including different heterocyclic rings, imidazole, triazole and benzimidazole. Compounds have been studied to determine their anticancer potency against A549 tumor cell line (human lung carcinoma cell) compared with cisplatin.

Materials and methods

Chemistry

All chemicals were purchased from Sigma-Aldrich Chemical Co (Sigma-Aldrich Corp., St. Louis, MO, USA) and Merck Chemicals (Merck KGaA, Darmstadt, Germany). Melting points were determined by MP90 digital melting point apparatus (Mettler Toledo, OH) and were uncorrected. Spectroscopic data were recorded on the following instruments: Bruker Tensor 27 IR spectrophotometer; 1H NMR (nuclear magnetic resonance) Bruker DPX- 300 FT-NMR spectrometer, 13C NMR, Bruker DPX 75 MHz spectrometer (Bruker Bioscience, Billerica, MA, USA); M+1 peaks were determined by Shimadzu LC/MS ITTOF system (Shimadzu, Tokyo, Japan). Elemental analyses were performed in a Perkin Elmer EAL 240 elemental analyser for C, H, N, O and S.

Synthesis of the compounds

General method for the synthesis of 2-chloro-N-(6-substituted benzothiazol-2-yl)acetamides (1–6)

A solution of 2-amino-6-substituted benzothiazol (1g, 6 mmol) in 250 mL of tetrahydrofuran was prepared and triethylamine (1.1 mL, 7.2 mmol) was added. Chloroacetyl chloride (0.64 mL, 7.2 mmol) in 5 mL of tetrahydrofuran was added dropwise in ice bath. After completion of dropping, the resulting mixture was stirred for 1 h at room temperature and evaporated to dryness. The residue was washed with water, dried and recrystallized from ethanol to afford the pure compounds 1–6.

General method for the synthesis of 2-[(1H- benzimidazol-2-yl)thio]-N-(6-substituted benzo[d]thiazol-2-yl)acetamides (7–12) and 2-[(1-methyl-1H-benzimidazol-2-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamides (13–18)

For the preparation of compounds 13–18, 2-[(1H-benzimidazol-2-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamides (7–12) were employed as key intermediates. Compounds 7–12 were synthesized using appropriate 2-chloro-N-(6-substituted benzothiazol-2-yl)acetamide (1–6) as starting materials. Compounds (1–6) (0.5 g, 2 mmol) and 1H-benzimidazole-2-thiol (A) (2 mmol) were stirred at room temperature for 5 h in acetone (40 mL) with the presence of potassium carbonate (2.4 mmol). Acetone was evaporated and the product was washed with water, dried and recrystallized from ethanol to give 7–12. After this procedure, compounds 7–12 (2 mmol) and methyl iodide (2 mmol) were dissolved in acetone (40 mL) and stirred at room temperature for 12 h with potassium hydroxide (10 mmol). After evaporation of acetone, the residue was washed, dried and recrystallized from ethanol to synthesize compounds 13–18.

General method for the synthesis of 2-[(1-methyl-1H-imidazol-2-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamides (19–24) and 2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamides (25–30)

A mixture of appropriate 2-chloro-N-(6-substituted benzothiazol-2-yl)acetamide (1–6) (0.5 g, 2 mmol), 2-mercaptobenzimidazole (A)/1-methyl-1H-imidazole-2-thiol (B)/4-methyl-3-mercapto-1,2,4-triazole (C) (2 mmol) and potassium carbonate (2.4 mmol) were stirred at room temperature for 6 h in 40 mL of acetone. The solvent was evaporated under reduced pressure, the product was washed, dried and recrystallized from ethanol to give compounds 7–12 and 19–30. Compounds derived from benzimidazole was then methylated with methyl iodide/KOH reagent to gain 13–18.

N-(Benzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio]acetamide (13) Yield 69%, m.p. 222–226°C. IR (cm−1): ʋmax 3396 (N–H), 3061 (aromatic C–H), 2974 (aliphatic C–H), 1699 (C=O), 1598–1440 (C=N and C=C), 1255 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 4.33 (3H, s, NCH3), 5.08 (2H, s, COCH2), 7.75–7.81 (2H, m, Ar-H), 7.87–7.93 (1H, m, Ar-H), 8.01–8.12 (3H, m, Ar-H), 8.35 and 8.38 (1H, dd, J1=2.3 Hz, J2=8.0 Hz, Ar-H), 8.55 and 8.58 (1H, dd, J1=2.3 Hz, J2=7.8 Hz, Ar-H), 13.36 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 31.06 (NCH3), 36.55 (COCH2), 110.65, 118.59, 121.72, 122.64, 122.78, 122.82, 124.72, 127.25, 132.53, 137.91, 143.64, 168.39 (C=O). For C17H14N4OS2 calculated: 57.61% C, 3.98% H, 15.81% N, 4.51% O, 18.09% S; found: 57.69% C, 3.99% H, 15.77% N, 4.50% O, 18.15% S. HRMS (m/z): [M+H]+ calculated for C17H14N4OS2: 355.0682; found 355.0683.

N-(6-Methylbenzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio]acetamide (14) Yield 71%, m.p. 212–216°C. IR (cm−1): ʋmax 3392 (N–H), 3055 (aromatic C–H), 2974 (aliphatic C–H), 1689 (C=O), 1606–1444 (C=N and C=C), 1172 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 2.39 (3H, s, CH3), 3.73 (3H, s, NCH3), 4.47 (2H, s, COCH2), 7.12–7.26 (3H, m, Ar-H), 7.49 and 7.51 (2H, dt, J1=1.8 Hz, J2=8.4 Hz, Ar-H), 7.65 (1H, d, J=8.3 Hz, Ar-H), 7.74 (1H, s, Ar-H), 12.70 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 21.44 (CH3), 30.47 (NCH3), 35.94 (COCH2), 110.03, 117.99, 120.75, 121.79, 122.03, 122.17, 127.96, 132.07, 133.59, 137.30, 143.04, 146.95, 151.21, 157.34, 167.64 (C=O). For C18H16N4OS2 calculated: 58.67% C, 4.38% H, 15.21% N, 4.34% O, 17.40% S; found: 58.60% C, 4.36% H, 15.17% N, 4.33% O, 17.37% S. HRMS (m/z): [M+H]+ calculated for C18H16N4OS2: 369.0838; found 369.0831.

N-(6-Methoxybenzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio] acetamide (15) Yield 70%, m.p. 213–216°C. IR (cm−1): ʋmax 3356 (N–H), 3062 (aromatic C–H), 2972 (aliphatic C–H), 1683 (C=O), 1598–1465 (C=N and C=C), 1261–1056 (C–N and C–O). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.74 (3H, s, NCH3), 3.79 (3H, s, OCH3), 4.46 (2H, s, COCH2), 7.02 and 7.05 (1H, dd, J1=2.6 Hz, J2=8.8 Hz, Ar-H), 7.11–7.23 (2H, m, Ar-H), 7.50 (2H, d, J=7.9 Hz, Ar-H), 7.56 (1H, d, J=2.6 Hz, Ar-H), 7.66 (1H, d, J=8.9 Hz, Ar-H), 12.64 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 30.47 (NCH3), 35.87 (COCH2), 56.07 (OCH3), 105.19, 110.03, 115.47, 117.99, 121.74, 122.03, 122.17, 133.25, 137.31, 143.04, 151.22, 156.13, 156.67, 167.46 (C=O). For C18H16N4O2S2 calculated: 56.23% C, 4.19% H, 14.57% N, 8.32% O, 16.68% S; found: 56.32% C, 4.20% H, 14.60% N, 8.30% O, 16.72% S. HRMS (m/z): [M+H]+ calculated for C18H16N4O2S2: 385.0787; found 385.0780.

N-(6-Chlorobenzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio]acetamide (16) Yield 68%, m.p. 257–261°C. IR (cm−1): ʋmax 3358 (N–H), 3064 (aromatic C–H), 2976 (aliphatic C–H), 1687 (C=O), 1589–1440 (C=N and C=C), 1230 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.73 (3H, s, NCH3), 4.33 (2H, s, COCH2), 7.11–7.21 (2H, m, Ar-H), 7.30 and 7.33 (1H, dd, J1=2.2 Hz, J2=8.6 Hz, Ar-H), 7.46–7.52 (2H, m, Ar-H), 7.58 (1H, d, J=8.6 Hz, Ar-H), 7.91 (1H, d, J=2.2 Hz, Ar-H), 12.84 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 30.38 (NCH3), 38.27 (COCH2), 109.84, 117.90, 121.13, 121.24, 121.84, 121.92, 125.90, 126.36, 134.37, 137.23, 143.22, 148.91, 152.25, 170.33 (C=O). For C17H13ClN4OS2 calculated: 52.50% C, 3.37% H, 9.12% Cl, 14.41% N, 4.11% O, 16.49% S; found: 52.63% C, 3.38% H, 9.10% Cl, 14.36% N, 4.12% O, 16.53% S. HRMS (m/z): [M+H]+ calculated for C17H13ClN4OS2: 389.0292; found 389.0288.

N-(6-Fluorobenzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio]acetamide (17) Yield 70%, m.p. 233–238°C. IR (cm−1): ʋmax 3325 (N–H), 3070 (aromatic C–H), 2970 (aliphatic C–H), 1697 (C=O), 1604–1448 (C=N and C=C), 1149 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.74 (3H, s, NCH3), 4.48 (2H, s, COCH2), 7.10–7.23 (2H, m, Ar-H), 7.29 (1H, t, J=9.1 Hz, Ar-H), 7.50 (2H, d, J=8.1 Hz, Ar-H), 7.76–7.80 (1H, m, Ar-H), 7.87 and 7.90 (1H, dd, J1=2.7 Hz, J2=8.7 Hz, Ar-H), 12.79 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 30.48 (NCH3), 35.87 (COCH2), 108.51, 108.87, 110.04, 114.61, 114.93, 117.99, 122.04, 122.18, 122.32, 133.10, 133.25, 137.31, 143.03, 145.72, 149.80, 151.17, 157.56, 158.21, 160.74, 167.90 (C=O). For C17H13FN4OS2 calculated: 54.82% C, 3.52% H, 5.10% F, 15.04% N, 4.30% O, 17.22% S; found: 54.72% C, 3.51% H, 5.11% F, 15.03% N, 4.29% O, 17.25% S. HRMS (m/z): [M+H]+ calculated for C17H13FN4OS2: 373.0588; found 373.0576.

N-(6-Ethoxybenzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio]acetamide (18) Yield 75%, m.p. 220–225°C. IR (cm−1): ʋmax 3318 (N–H), 3087 (aromatic C–H), 2942 (aliphatic C–H), 1682 (C=O), 1608–1467 (C=N and C=C), 1183 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 1.34 (3H, t, J=6.9 Hz, OCH2CH3), 3.74 (3H, s, NCH3), 4.05 (2H, q, J=6.9, OCH2CH3), 4.46 (2H, s, COCH2), 7.00 and 7.03 (1H, dd, J1=2.6 Hz, J2=8.8 Hz, Ar-H), 7.12–7.23 (2H, m, Ar-H), 7.48–7.54 (3H, m, Ar-H), 7.65 (1H, d, J=8.8 Hz, Ar-H), 12.63 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 15.15 (OCH2CH3), 30.47 (NCH3), 35.88 (COCH2), 64.05 (OCH2) 105.83, 110.03, 115.81, 117.99, 121.73, 122.03, 122.17, 133.24, 137.31, 143.04, 151.21, 155.89, 156.10, 167.45 (C=O). For C19H18N4O2S2calculated: 57.27% C, 4.55% H, 14.06% N, 8.03% O, 16.09% S; found: 57.38% C, 4.53% H, 14.04% N, 8.05% O, 16.10% S. HRMS (m/z): [M+H]+ calculated for C19H18N4O2S2: 399.0944; found 399.0931.

N-(Benzothiazol-2-yl)-2-[(1-methyl-1H-imidazol-2-yl)thio]acetamide (19) Yield 70%, m.p. 164–167°C. IR (cm−1): ʋmax 3361 (N–H), 3053 (aromatic C–H), 2970 (aliphatic C–H), 1687 (C=O), 1600–1446 (C=N and C=C), 1280 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.61 (3H, s, NCH3), 4.03 (2H, s, COCH2), 6.97 (1H, d, J=1.1 Hz, Ar-H), 7.28 (1H, d, J=1.1 Hz, Ar-H), 7.31 (1H, t, J=7.6 Hz, Ar-H), 7.44 (1H, t, J=7.6 Hz, Ar-H), 7.76 (1H, d, J=8 Hz, Ar-H), 7.98 (1H, d, J=7.9 Hz, Ar-H), 12.73 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 33.46 (NCH3), 37.57 (COCH2), 121.09, 122.21, 124.10, 124.18, 124.55, 126.63, 129.10, 131.93, 139.62, 148.96, 158.19, 168.43 (C=O). For C13H12N4OS2 calculated: 51.30% C, 3.97% H, 18.41% N, 5.26% O, 21.07% S; found: 51.25% C, 3.96% H, 18.46% N, 5.24% O, 21.02% S. HRMS (m/z): [M+H]+ calculated for C13H12N4OS2: 305.0525; found 305.0509.

N-(6-Methylbenzothiazol-2-yl)-2-[(1-methyl-1H-imidazol-2-yl)thio]acetamide (20) Yield 72%, m.p. 180–182°C. IR (cm−1): ʋmax 3338 (N–H), 3053 (aromatic C–H), 2922 (aliphatic C–H), 1697 (C=O), 1608–1456 (C=N and C=C), 1261 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 2.41 (3H, s, CH3), 3.61 (3H, s, NCH3), 4.02 (2H, s, COCH2), 6.97 (1H, d, J=1.2 Hz, Ar-H), 7.23–7.28 (2H, m, Ar-H), 7.64 (1H, d, J=8.3 Hz, Ar-H), 7.76 (1H, s, Ar-H), 12.65 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 21.43 (CH3), 33.45 (NCH3), 37.55 (COCH2), 120.72, 121.78, 122.63, 123.78, 124.17, 124.53, 127.55, 127.95, 129.08, 132.08, 133.57, 139.65, 146.93, 157.30, 168.27 (C=O). For C14H14N4OS2 calculated: 52.81% C, 4.43% H, 17.60% N, 5.02% O, 20.14% S; found: 52.93% C, 4.41% H, 17.54% N, 5.03% O, 20.17% S. HRMS (m/z): [M+H]+ calculated for C14H14N4OS2: 319.0682; found 319.0659.

N-(6-Methoxybenzothiazol-2-yl)-2-[(1-methyl-1H-imidazol-2-yl)thio]acetamide (21) Yield 64%, m.p. 168–170°C. IR (cm−1): ʋmax 3350 (N–H), 3062 (aromatic C–H), 2966 (aliphatic C–H), 1685 (C=O), 1598–1462 (C=N and C=C), 1276–1056 (C–N and C–O). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.61 (3H, s, NCH3), 3.81 (3H, s, OCH3), 4.01 (2H, s, COCH2), 6.97 (1H, d, J=1.2 Hz, Ar-H), 7.02 and 7.05 (1H, dd, J1=2.6 Hz, J2=8.8 Hz, Ar-H), 7.27 (1H, s, Ar-H), 7.57 (1H, d, J=2.4 Hz, Ar-H), 7.65 (1H, d, J=8.8 Hz, Ar-H), 12.59 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 33.45 (NCH3), 37.50 (COCH2), 56.07 (OCH3), 105.19, 115.44, 121.70, 124.17, 129.09, 133.26, 139.65, 143.05, 156.12, 156.65, 168.11 (C=O). For C14H14N4O2S2 calculated: 50.28% C, 4.22% H, 16.75% N, 9.57% O, 19.18% S; found: 50.37% C, 4.23% H, 16.70% N, 9.59% O, 19.22% S. HRMS (m/z): [M+H]+ calculated for C14H14N4O2S2: 335.0631; found 335.0625.

N-(6-Chlorobenzothiazol-2-yl)-2-[(1-methyl-1H-imidazol-2-yl)thio]acetamide (22) Yield 69%, m.p. 201–203°C. IR (cm−1): ʋmax 3354 (N–H), 3051 (aromatic C–H), 2972 (aliphatic C–H), 1687 (C=O), 1593–1451 (C=N and C=C), 1269 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.60 (3H, s, NCH3), 4.03 (2H, s, COCH2), 6.96 (1H, d, J=1.2 Hz, Ar-H), 7.27 (1H, d, J=1.1 Hz, Ar-H), 7.44 and 7.46 (1H, dd, J1=2.4 Hz, J2=8.6 Hz, Ar-H), 7.74 (1H, d, J=8.6 Hz, Ar-H), 8.12 (1H, d, J=2.1 Hz, Ar-H), 12.82 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 33.46 (NCH3), 37.51 (COCH2), 121.93, 122.30, 124.19, 126.98, 128.15, 133.64, 139.58, 147.87, 159.06, 168.65 (C=O). For C13H11ClN4OS2 calculated: 46.08% C, 3.27% H, 10.46% Cl, 16.54% N, 4.72% O, 18.93% S; found: 45.97% C, 3.26% H, 10.49% Cl, 16.50% N, 4.73% O, 18.90% S. HRMS (m/z): [M+H]+ calculated for C13H11ClN4OS2: 339.0136; found 339.0124.

N-(6-Fluorobenzothiazol-2-yl)-2-[(1-methyl-1H-imidazol-2-yl)thio]acetamide (23) Yield 75%, m.p. 189–193°C. IR (cm−1): ʋmax 3323 (N–H), 3059 (aromatic C–H), 2964 (aliphatic C–H), 1689 (C=O), 1608–1452 (C=N and C=C), 1257 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.60 (3H, s, NCH3), 4.03 (2H, s, COCH2), 6.96 (1H, d, J=1.2 Hz, Ar-H), 7.24–7.31 (2H, m, Ar-H), 7.73–7.78 (1H, m, Ar-H), 7.86 and 7.89 (1H, dd, J1=2.7 Hz, J2=8.7 Hz, Ar-H), 12.76 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 33.45 (NCH3), 37.49 (COCH2), 108.47, 108.83, 114.57, 114.90, 122.14, 122.26, 124.18, 129.10, 133.11, 133.26, 139.61, 145.69, 157.55, 158.18, 158.21, 160.73, 168.52 (C=O). For C13H11FN4OS2 calculated: 48.43% C, 3.44% H, 5.89% F, 17.38% N, 4.96% O, 19.89% S; found: 48.51% C, 3.44% H, 5.88% F, 17.33% N, 4.95% O, 19.95% S. HRMS (m/z): [M+H]+ calculated for C13H11FN4OS2: 323.0431; found 323.0414.

N-(6-Ethoxybenzothiazol-2-yl)-2-[(1-methyl-1H-imidazol-2-yl)thio]acetamide (24) Yield 70%, m.p. 123–126°C. IR (cm−1): ʋmax 3354 (N–H), 3068 (aromatic C–H), 2980 (aliphatic C–H), 1668 (C=O), 1604–1458 (C=N and C=C), 1251–1058 (C–N and C–O). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 1.34 (3H, t, J=6.9 Hz, OCH2CH3), 3.60 (3H, s, NCH3), 4.00 (2H, s, COCH2), 4.06 (2H, q, J=6.96, OCH2CH3), 6.96 (1H, d, J=1.2 Hz, Ar-H), 7.00 and 7.02 (1H, dd, J1=2.6 Hz, J2=8.8 Hz, Ar-H), 7.27 (1H, d, J=1.2 Hz, Ar-H), 7.54 (1H, d, J=2.5 Hz, Ar-H), 7.63 (1H, d, J=8.9 Hz, Ar-H), 12.57 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 15.15 (OCH2CH3), 33.45 (NCH3), 37.51 (COCH2), 64.04 (OCH2) 105.83, 115.78, 121.69, 124.17, 129.09, 133.24, 139.64, 142.97, 155.88, 156.08, 168.10 (C=O). For C15H16N4O2S2 calculated: 51.70% C, 4.63% H, 16.08% N, 9.18% O, 18.40% S; found: 51.84% C, 4.62% H, 16.11% N, 9.15% O, 18.46% S. HRMS (m/z): [M+H]+ calculated for C15H16N4O2S2: 349.0787; found 349.0788.

N-(Benzothiazol-2-yl)-2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]acetamide (25) Yield 68%, m.p. 227–232°C. IR (cm−1): ʋmax 3336 (N–H), 3049 (aromatic C–H), 2926 (aliphatic C–H), 1683 (C=O), 1597–1440 (C=N and C=C), 1253 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.61 (3H, s, NCH3), 4.21 (2H, s, COCH2), 7.31 (1H, t, J=7.6 Hz, Ar-H), 7.44 (1H, t, J=7.7 Hz, Ar-H), 7.76 (1H, d, J=7.9 Hz, Ar-H), 7.98 (1H, d, J=7.3 Hz, Ar-H), 8.57 (1H, s, Ar-H), 12.64 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 31.30 (NCH3), 36.86 (COCH2), 121.14, 122.23, 124.15, 126.66, 131.91, 146.84, 148.81, 148.97, 158.12, 167.72 (C=O). For C12H11N5OS2 calculated: 47.20% C, 3.63% H, 22.93% N, 5.24% O, 21.00% S; found: 47.30% C, 3.62% H, 22.88% N, 5.25% O, 20.95% S. HRMS (m/z): [M+H]+ calculated for C12H11N5OS2: 306.0478; found 306.0469.

N-(6-Methylbenzothiazol-2-yl)-2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]acetamide (26) Yield 63%, m.p. 244–247°C. IR (cm−1): ʋmax 3361 (N–H), 3062 (aromatic C–H), 2912 (aliphatic C–H), 1670 (C=O), 1610–1456 (C=N and C=C), 1257 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 2.41 (3H, s, CH3), 3.61 (3H, s, NCH3), 4.20 (2H, s, COCH2), 7.24 and 7.27 (1H, dd, J1=1.3 Hz, J2=8.3 Hz, Ar-H), 7.64 (1H, d, J=8.2 Hz, Ar-H), 7.76 (1H, s, Ar-H), 8.57 (1H, s, Ar-H), 12.58 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 21.44 (CH3), 31.30 (NCH3), 36.85 (COCH2), 120.72, 121.80, 127.98, 132.05, 133.63, 146.83, 148.82, 157.24, 167.56 (C=O). For C13H13N5OS2 calculated: 48.88% C, 4.10% H, 21.93% N, 5.01% O, 20.08% S; found: 48.74% C, 4.09% H, 21.99% N, 5.00% O, 20.02% S. HRMS (m/z): [M+H]+ calculatedfor C13H13N5OS2: 320.0634; found 320.0622.

N-(6-Methoxybenzothiazol-2-yl)-2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]acetamide (27) Yield 67%, m.p. 227–232°C. IR (cm−1): ʋmax 3404 (N–H), 3018 (aromatic C–H), 2927 (aliphatic C–H), 1683 (C=O), 1614–1469 (C=N and C=C), 1261–1165 (C–N and C–O). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.61 (3H, s, NCH3), 3.81 (3H, s, OCH3), 4.19 (2H, s, COCH2), 7.02 and 7.05 (1H, dd, J1=2.6 Hz, J2=8.9 Hz, Ar-H), 7.57 (1H, d, J=2.6 Hz, Ar-H), 7.65 (1H, d, J=8.9 Hz, Ar-H), 8.57 (1H, s, Ar-H), 12.51 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 31.30 (NCH3), 36.79 (COCH2), 56.08 (OCH3), 105.20, 115.48, 121.75, 133.24, 143.05, 146.83, 148.83, 156.05, 156.68, 167.39 (C=O). For C13H13N5O2S2 calculated: 46.55% C, 3.91% H, 20.88% N, 9.54% O, 19.12% S; found: 46.67% C, 3.90% H, 20.85% N, 9.51% O, 19.17% S. HRMS (m/z): [M+H]+ calculated for C13H13N5O2S2: 336.0583; found 336.0575.

N-(6-Chlorobenzothiazol-2-yl)-2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]acetamide (28) Yield 76%, m.p. 263–266°C. IR (cm−1): ʋmax 3377 (N–H), 3078 (aromatic C–H), 2968 (aliphatic C–H), 1678 (C=O), 1600–1444 (C=N and C=C), 1257 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.62 (3H, s, NCH3), 4.23 (2H, s, COCH2), 7.47 (1H, d, J=6.8 Hz, Ar-H), 7.76 (1H, d, J=7.2 Hz, Ar-H), 8.13 (1H, s, Ar-H), 8.58 (1H, s, Ar-H), 12.76 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 31.30 (CH3), 36.81 (COCH2), 121.94, 122.33, 127.00, 128.20, 133.61, 146.84, 147.85, 148.80, 159.01, 167.97 (C=O). For C12H10ClN5OS2 calculated: 42.41% C, 2.97% H, 10.43% Cl, 20.61% N, 4.71% O, 18.87% S; found: 42.35% C, 2.97% H, 10.45% Cl, 20.57% N, 4.69% O, 18.92% S. HRMS (m/z): [M+H]+ calculated for C12H10ClN5OS2: 340.0088; found 340.0074.

N-(6-Fluorobenzothiazol-2-yl)-2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]acetamide (29) Yield 60%, m.p. 257–260°C. IR (cm−1): ʋmax 3307 (N–H), 3062 (aromatic C–H), 2922 (aliphatic C–H), 1676 (C=O), 1602–1454 (C=N and C=C), 1161 (C–N). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 3.60 (3H, s, NCH3), 4.21 (2H, s, COCH2), 7.29 (1H, t, J=9.1 Hz, Ar-H), 7.74–7.79 (1H, m, Ar-H), 7.87 and 7.90 (1H, dd, J1=2.7 Hz, J2=8.7 Hz, Ar-H), 8.57 (1H, m, Ar-H), 12.68 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 31.30 (NCH3), 36.78 (COCH2), 108.50, 108.86, 114.62, 114.95, 122.20, 122.32, 133.08, 133.23, 145.69, 146.84, 148.80, 157.57, 158.13, 160.76, 167.83 (C=O). For C12H10FN5OS2 calculated: 44.57% C, 3.12% H, 5.88% F, 21.66% N, 4.95% O, 19.83% S; found: 44.67% C, 3.11% H, 5.90% F, 21.60% N, 4.96% O, 19.79% S. HRMS (m/z): [M+H]+ calculated for C12H10FN5OS2: 324.0384; found 324.0362.

N-(6-Ethoxybenzothiazol-2-yl)-2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]acetamide (30) Yield 64%, m.p. 215–218°C. IR (cm−1): ʋmax 3385 (N–H), 3055 (aromatic C–H), 2970 (aliphatic C–H), 1676 (C=O), 1614–1462 (C=N and C=C), 1259–1041 (C–N and C–O). 1H-NMR (300 Mhz, DMSO-d6, ppm) δ 1.34 (3H, t, J=6.9 Hz, OCH2CH3), 3.60 (3H, s, NCH3), 4.06 (2H, q, J=7 Hz, OCH2CH3), 4.18 (2H, s, COCH2), 7.00 and 7.03 (1H, dd, J1=2.3 Hz, J2=8.9 Hz, Ar-H), 7.54 (1H, d, J=2.5 Hz, Ar-H), 7.64 (1H, d, J=8.8 Hz, Ar-H), 8.57 (1H, s, Ar-H), 12.50 (1H, s, NH). 13C-NMR (75 MHz, DMSO-d6, ppm) δ 15.16 (OCH2CH3), 31.30 (CH3), 36.81 (COCH2), 64.06 (OCH2) 105.85, 115.82, 121.75, 146.84, 155.91, 167.38 (C=O). For C14H15N5O2S2 calculated: 48.12% C, 4.33% H, 20.04% N, 9.16% O, 18.35% S; found: 48.00% C, 4.32% H, 19.98% N, 9.18% O, 18.31% S. HRMS (m/z): [M+H]+ calculated for C14H15N5O2S2: 350.0740; found 350.0730.

Biochemistry

MTT assay

MTT assay (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was carried out to determine cytotoxicity of the compounds against A549 (human lung adenocarcinoma cells) cell line according to the reported data [22], [23]. A549 cells were cultured in 96-well flat-bottom plates at 37oC for 24 h (2 x 104 cells per well). After 24 h drug incubation, 20 μL MTT solution (5 mg/mL MTT powder in PBS) was added to each well and incubated for 2 h in the same conditions. Formazan crystals were dissolved in 200 μL DMSO and the absorbance was read by ELISA reader (OD570 nm). The percentage of viable cells was calculated based on the medium control. All experiments were performed at least three times.

Annexin V/ PI staining

FACS-Aria I (Becton Dickinson USA) instrument was used to detect apoptosis ratios using the Annexin V-FITC Apoptosis Detection Kit from BD, Pharmingen, according to the manufacturer’s instruction. A549 cells in normal life cycle, cells treated with IC50 concentrations of selected compounds (15, 18, 22, 23 and 26) and cells treated with cisplatin (24 h incubation) were applicated to the system. The results were analyzed by using FACS Express software and represented as percentage of normal and apoptotic cells at various stages [24]. The percentage of apoptotic cells was determined from the number of cells in sub-G1 phase, representing fragmented cell vesicles. The four areas in the diagrams represent for necrotic cells (Q1, positive for PI and negative for annexin/ FITC, left square on the top), live cells (Q3, negative for annexin and PI, left square at the bottom), late apoptotic or necrotic cells (Q2, positive for annexin and PI, right square on the top) and apoptotic cells (Q4, negative for PI and positive for annexin, right square at the bottom), respectively.

Results and discussion

Chemistry

The preparation of final compounds was performed according to the reactions outlined in Figure 1. The starting compounds 1–6 were synthesized via acetylation of 2-amino-6-substituted benzothiazole with chloroacetyl chloride. The bimolecular nucleophilic substitution (SN2) reaction between 2-chloro-N-(6-substituted benzothiazol-2-yl)acetamides (1–6) and appropriate thiol compound A, B and C gave 2-[(1H-benzimidazol-2-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamides (7–12), 2-[(1-methyl-1H-imidazol-2-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamides (19–24) and 2-[(4-methyl-4H-1,2,4-triazol-3-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamides (25–30), respectively. N-methylation of compounds 7–12 with methyl iodide in acetone provided 2-[(1-methyl-1H-benzimidazol-2-yl)thio]-N-(6-substituted benzothiazol-2-yl)acetamide (13–18).

Figure 1: The synthetic route for the preparation of compounds 1–30.
Figure 1:

The synthetic route for the preparation of compounds 1–30.

Structure clarifications of the final compounds (13–30) were carried out through FT-IR, 1H-NMR, 13C-NMR and HRMS spectroscopic data and elemental analysis. Characteristic stretching absorptions of C=O and N-H bonds were observed in the region of 1699–1668 cm−1 and 3404–3307 cm−1, respectively. The stretching bands for C=N and C=C were recorded at about 1614–1440 cm−1. In the 1H-NMR spectra, the signal due to methylene and NH protons of acetamide (-NHCOCH2) moiety appeared as singlet peaks at 4.00–5.08 ppm and 12.50–13.36 ppm, respectively. N-CH3 protons of 1H-imidazole, 1H-triazole and 1H-benzimidazole rings were observed as singlet peaks about 3.60–4.33 ppm. All the other aromatic and aliphatic protons were observed at the expected regions. In the 13C-NMR spectra, the signals belonging to N-CH3 and the methylene carbons of -COCH2 moiety were assigned at between 30.38–33.46 ppm and 35.87–38.27 ppm, respectively. The carbonyl carbons were recorded at between 167.39 and 170.33 ppm. HRMS spectra of all the compounds showed that M+1 peaks were in agreement with the calculated molecular weight of the final compounds (13–30). Elemental analysis results for C, H, and N elements were satisfactory within ±0.4% calculated values of the compounds.

Biochemistry

The synthesized compounds were screened for their in vitro antiproliferative activity against A549 non-small cell lung cancer cell line. The results were represented in Table 1 as in inhibition concentration (IC50). The compounds were displayed cytotoxic profile within ranges 9.0±1.0 μg/mL–500 μg/mL whereas standard drug showed cytotoxicity at 21.0±2.0 μg/mL concentration. Compounds 15 and 18 exhibited highest antiproliferative activity with IC50 values 10.67±2.02 and 9.0±1.0 μg/mL which were lower even than cisplatin. These two compounds both have 1-methylbenzimidazole moiety, and also methoxy and ethoxy substituents on benzothiazole ring. This extraordinary result was not seen in the other members of this group, that IC50 values were not calculated for compounds 13, 14 and 17 at the highest tested concentration. Among compounds containing 1-methylimidazole heterocyclic ring, compounds 22 and 23 exhibited remarkable cytotoxicity with IC50 of 46.67±2.87 and 31.33±7.57 μg/mL, respectively. Other compounds with the same ring showed poor activity with concentration higher than 256.67 μg/mL. Compounds bearing 1-methyltriazole showed moderate activity IC50 values between 64.33 and 153.33 μg/mL.

Table 1:

IC50 (μg/mL)a values of the compounds against A549 cell line.

CompoundsA549
3a>500
3b>500
3c10.67±2.02
3d236.67±73.34
3e>500
3f9.0±1.0
4a466.67±41.63
4b256.67±11.54
4c256.67±83.86
4d46.67±2.87
4e31.33±7.57
4fntb
5a>500
5b64.33±6.03
5c103.33±5.77
5d95.33±5.03
5e136.67±5.77
5f153.33±15.27
Cisplatin21.0±2.0

  1. aCytotoxicity of the compounds. Incubation for 24 h. The values represent mean±standard deviation of triplicate determinations.

  2. bnt, Not tested.

Five compounds (15, 18, 22, 23 and 26) showed higher cytotoxicity, were studied further in the flow cytometry to detect apoptotic cell death ratios that they caused. Compounds and cisplatin were performed to the system at IC50 concentrations. The results of the Annexin V/PI staining protocol were summarized in Table 2 and the diagrams were represented in Figure 2. The survival of A549 cell line was confirmed and viable cells were found 96.7% for control group. Early, late apoptotic and viable cell ratios were determined as 17.0, 4.6, 37.0% for cisplatin treated tumor cells survived with a ratio of 37.0%. None of the compounds did not reach cisplatin’s potency. Only compound 18 caused 19.1% (early and late) apoptosis totally whereas standard drug had 21.6% (early and late). Also, compound 26 exhibited half apoptotic potency of cisplatin.

Table 2:

Percentage of typical quadrant analysis of Annexin V FITC/Propidium Iodide flow cytometry of A549 cells treated with compounds 15, 18, 22, 23, 26 and Cisplatin.

GroupsEarly apoptotic cells (%) Late apoptotic cells (%)Viable cells (% )
Control (untreated)1.90.196.7
156.40.981.1
1818.11.071.7
222.00.084.2
230.30.195.4
268.23.282.7
Cisplatin17.04.637.0

  1. A549 cells were cultured for 24 hours in medium with compounds 15, 18, 22, 23, 26 and Cisplatin at IC50 values. At least 10.000 cells were analyzed per sample, and quadrant analysis was performed.

Figure 2: Flow cytometric diagrams of the A549 cell line as control group, cells treated with cisplatin and cell treated with compounds 15, 18, 22, 23 and 26.
Figure 2:

Flow cytometric diagrams of the A549 cell line as control group, cells treated with cisplatin and cell treated with compounds 15, 18, 22, 23 and 26.

Some physicochemical characteristics were calculated virtually and demonstrated in Table 3. For all compounds, log octanol/water partition coefficient, molecular weight, total polar surface area, number of hydrogen acceptors, number of hydrogen donors, number of rotatable bonds were calculated using Molinspiration Calculation of Molecular Properties toolkit. According to Lipinski rule of five [25] and its variations; an oral drug has log P lower than five, hydrogen bond donors lower than five, hydrogen bond acceptors lower than 10, molecular mass less than 500 daltons, polar surface area equal to or less than 140 Å2 and number of rotable bonds less than 10. Eighteen new compounds were found within the boundaries of this rule and they may be oral drugs considering the data.

Table 3:

In silico physicochemical parameters of the compounds 13–30.

Table 3: In silico physicochemical parameters of the compounds 13–30.
CompRHetetocyclic ringLog PTPSAMWnONnOHNHnrotbVolume
13H1-CH3 benzimidazole3.7859.82354.46514294.08
14CH31-CH3 benzimidazole4.2059.82368.49514310.64
15OCH31-CH3 benzimidazole3.8169.05384.49615319.62
16Cl1-CH3 benzimidazole4.4359.82388.90514307.62
17F1-CH3 benzimidazole3.9259.82372.45514299.01
18OC2H51-CH3 benzimidazole4.1869.05398.51616336.43
19H1-CH3 imidazole2.2759.82304.40514250.09
20CH31-CH3 imidazole2.7059.82318.43514266.65
21OCH31-CH3 imidazole2.3169.05334.43615275.63
22Cl1-CH3 imidazole2.9359.82338.85514263.62
23F1-CH3 imidazole2.4159.82322.39514255.02
24OC2H51-CH3 imidazole2.6869.05348.45616292.44
25H1-CH3 triazole1.7472.71305.39614245.93
26CH31-CH3 triazole2.1672.71319.42614262.49
27OCH31-CH3 triazole1.7781.94335.41715271.48
28Cl1-CH3 triazole2.3972.71339.83614259.47
29F1-CH3 triazole1.8872.71323.38614250.86
30OC2H51-CH3 triazole2.1581.94349.44716288.28

  1. Log P, log octanol/water partition coefficient; MW, Molecular weight; TPSA, total polar surface area; nON, no of hydrogen acceptors; nOHNH, no. of hydrogen donors; nrotb, no of rotatable bonds were calculated using molinspiration calculation of molecular properties toolkit.

Conclusion

Compounds (15), namely, N-(6-methoxybenzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio] acetamide and (18), namely, N-(6-ethoxybenzothiazol-2-yl)-2-[(1-methyl-1H-benzimidazol-2-yl)thio] acetamide were found as the most potent compounds with lowest IC50 values 10.67 and 9.0 μg/mL against A549 lung cancer cell line. Among these two compounds, 18 caused 19.1% (early and late) apoptosis which was very close to cisplatin caused. Compounds were all detected to be an oral drug and some of them were found to be a potential antitumor agent. In further studies, new and similar compounds are planned to be sythesized for developing this issue. Besides, promising results are expected to be obtained with increased number of cell lines.

Corresponding author: Dr. Leyla Yurttaş, Faculty of Pharmacy, Department of Pharmaceutical Chemistry, Anadolu University, 26470 Eskisehir, Turkey, Phone: +90 222 335 05 80 – ext. 3783, Fax: +90 222 335 07 50

  1. Conflict of interest: The authors confirm that this article content has no conflict of interest.

References

1. Namba Y, Kijima T, Yokota S, Niinaka M, Kawamura S, Iwasaki T, et al. Gefitinib in patients with brain metastases from non-small-cell lung cancer: review of 15 clinical cases. Clin Lung Cancer 2004;6:123–8.10.3816/CLC.2004.n.026Search in Google Scholar

2. Subramanian J, Govindan R. Lung cancer in never smokers: a review. J Clin Oncol 2007;25:561–70.10.1200/JCO.2006.06.8015Search in Google Scholar

3. Shepherd FA, Rodrigues Pereira J, Ciuleanu T, Tan EH, Hirsh V, Thongprasert S, et al. Erlotinib in previously treated non-small-cell lung cancer. N Engl J Med 2005;353:123–32.10.1056/NEJMoa050753Search in Google Scholar

4. Steels E, Paesmans M, Berghmans T, Branle F, Lemaitre F, Mascaux C, et al. Role of p53 as a prognostic factor for survival in lung cancer: a systematic review of the literature with a meta-analysis. Eur Respir J 2001;18:705–19.10.1183/09031936.01.00062201Search in Google Scholar

5. Bunn PA Jr, Kelly K. New chemotherapeutic agents prolong survival and improve quality of life in non-small cell lung cancer: a review of the literature and future directions. Clin Cancer Res 1998;4:1087–100.Search in Google Scholar

6. Hutchinson I, Chua MS. Antitumor benzothiazoles. 14. Synthesis and in vitro biological properties of fluorinated 2-(4-aminophenyl)benzothiazoles. J Med Chem 2001;44:1446–55.10.1021/jm001104nSearch in Google Scholar

7. Kok SH, Gambari R, Chui CH, Yuen MC, Lin E, Wong RS, et al. Synthesis and anti-cancer activity of benzothiazole containing phthalimide on human carcinoma cell lines. Bioorg Med Chem 2008;16:3626–31.10.1016/j.bmc.2008.02.005Search in Google Scholar

8. Noolvi MN, Patel HM, Kaur M. Benzothiazoles: search for anticancer agents. Eur J Med Chem 2012;54:447–62.10.1016/j.ejmech.2012.05.028Search in Google Scholar

9. Trapani G, Franco M, Latrofa A, Reho A, Liso G. Synthesis, in vitro and in vivo cytotoxicity, and prediction of the intestinal absorption of substituted 2-ethoxycarbonyl-imidazo[2,1-b] benzothiazoles. Eur J Pharm Sci 2001;14:209–16.10.1016/S0928-0987(01)00173-7Search in Google Scholar

10. Song EY, Kaur N, Park MY, Jin Y, Lee K, Kim G, et al. Synthesis of amide and urea derivatives of benzothiazole as Raf-1 inhibitor. Eur J Med Chem 2008;43:1519–24.10.1016/j.ejmech.2007.10.008Search in Google Scholar PubMed

11. Srimanth K, Rao VR, Krishna DR. Synthesis and evaluation of anticancer activity of some imidazothiazolyl, imidazobenzothiazolyl and dihydroimidazothiazolyl coumarins. Arzneimittelforschung 2002;52:388–92.10.1055/s-0031-1299903Search in Google Scholar PubMed

12. Peng X, Xie G, Wang Z, Lin H, Zhou T, Xiang P, et al. SKLB-163, a new benzothiazole-2-thiol derivative, exhibits potent anticancer activity by affecting RhoGDI/JNK-1 signaling pathway. Cell Death Dis 2014;5:e1143.10.1038/cddis.2014.107Search in Google Scholar

13. Shi DF, Bradshaw TD, Wrigley S, McCall CJ, Lelieveld P, Fichtner I, et al. Antitumor benzothiazoles. 3.1 synthesis of 2-(4-aminophenyl)benzothiazoles and evaluation of their activities against breast cancer cell lines in vitro and in vivo. J Med Chem 1996;39:3375–84.10.1021/jm9600959Search in Google Scholar

14. Hutchinson I, Jennings SA, Vishnuvajjala BR, Westwell AD, Stevens MF. Antitumor benzothiazoles. 16.1 synthesis and pharmaceutical properties of antitumor 2-(4-aminophenyl)benzothiazole amino acid prodrugs. J Med Chem 2002;45:744–7.10.1021/jm011025rSearch in Google Scholar

15. Mortimer CG, Wells G, Crochard JP, Stone EL, Bradshaw TD, Stevens MF, et al. Antitumor benzothiazoles. 26.1 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (GW 610, NSC 721648), a simple fluorinated 2-arylbenzothiazole, shows potent and selective inhibitory activity against lung, colon, and breast cancer cell lines. J Med Chem 2006;49:179–85.10.1021/jm050942kSearch in Google Scholar

16. Vicini P, Geronikaki A, Incerti M, Busonera B, Poni G, Cabras CA, et al. Synthesis and biological evaluation of benzo[d]isothiazole, benzothiazole and thiazole schiff bases. Bioorg Med Chem 2003;11:4785–9.10.1016/S0968-0896(03)00493-0Search in Google Scholar

17. Aiello S, Wells G, Stone EL, Kadri H, Bazzi R, Bell DR, et al. Synthesis and biological properties of benzothiazole, benzoxazole, and chromen-4-one analogues of the potent antitumor agent 2-(3,4-dimethoxyphenyl)-5-fluorobenzothiazole (PMX 610, NSC 721648). J Med Chem 2008;51:5135–9.10.1021/jm800418zSearch in Google Scholar

18. Reddy PV, Lin Y-W, Chang H-T. Synthesis of novel benzothiazole compounds with an extended conjugated system. Arkivoc 2007;16:113–22.10.3998/ark.5550190.0008.g12Search in Google Scholar

19. Piscitelli F, Ballatore C, Smith A. Solid Phase synthesis of 2-aminobenzothiazoles. Bioorg Med Chem Lett 2010;20:644–8.10.1016/j.bmcl.2009.11.055Search in Google Scholar

20. Singh M, Singh SK. Benzothiazoles: how relevant in cancer drug design strategy? Anticancer Agents Med Chem 2014;14:127–46.10.2174/18715206113139990312Search in Google Scholar

21. Yadav PS, Dahiya D, Senthilkumar GP. Benzothiazole: different methods of synthesis and diverse biological activities. Int J Pharm Sci Drug Res 2011;3:01–7.10.1002/chin.201140238Search in Google Scholar

22. Mossmann T. Rapid colorimetric assay for cellular growth and survival: application to proliferation and cytotoxicity assays. J Immunol Methods 1983;65:55–63.10.1016/0022-1759(83)90303-4Search in Google Scholar

23. Keiser K, Johnson CC, Tipton DA. Cytotoxicity of mineral trioxide aggregate using human periodontal ligament fibroblasts. J Endod 2000;26:288–91.10.1097/00004770-200005000-00010Search in Google Scholar

24. Lowe SW, Lin AW. Apoptosis in cancer. Carcinogenesis 2000;21:485–95.10.1093/carcin/21.3.485Search in Google Scholar

25. Lipinski CA, Lombardo F, Dominy BW, Feeney PJ. Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings. Adv Drug Deliv Rev 1997;46:3–26.10.1016/S0169-409X(00)00129-0Search in Google Scholar

Received: 2017-01-13
Accepted: 2017-05-09
Published Online: 2017-07-05
Published in Print: 2017-06-01

©2017 Walter de Gruyter GmbH, Berlin/Boston

Articles in the same Issue

  1. Frontmatter
  2. Research Articles
  3. MicroRNA-101 downregulation increases C-Fos expression and contributes to the pathogenesis of non-small cell lung cancer
  4. Evaluation of angiogenesis with serum and tissue vascular endothelial growth factor, angiopoietin-1 and angiopoietin-2 levels in relation to clinicopathological features in lung cancer patients
  5. A preliminary investigation of anticancer activity of novel benzothiazole derivatives against A549 lung carcinoma cell line
  6. Soluble IL-1 decoy receptor is associated with gastric adenocarcinoma
  7. The effect of CTLA-4 and CD28 gene variants and circulating protein levels in patients with gastric cancer
  8. The neutrophil-to-lymphocyte ratio as a diagnostic marker for malignant thyroid diseases
  9. Computer-aided design of aptamers for SMMC-7721 liver carcinoma cells
  10. Serum levels of growth factors in patients with urinary bladder cancer
  11. Dicholoroacetate exerts anti-cancer activity on human renal cell carcinoma cells
https://doi.org/10.1515/tjb-2017-0015
Keywords for this article
Benzothiazole; Synthesis; Lung cancer; Cytotoxicity; Apoptosis

Articles in the same Issue

  1. Frontmatter
  2. Research Articles
  3. MicroRNA-101 downregulation increases C-Fos expression and contributes to the pathogenesis of non-small cell lung cancer
  4. Evaluation of angiogenesis with serum and tissue vascular endothelial growth factor, angiopoietin-1 and angiopoietin-2 levels in relation to clinicopathological features in lung cancer patients
  5. A preliminary investigation of anticancer activity of novel benzothiazole derivatives against A549 lung carcinoma cell line
  6. Soluble IL-1 decoy receptor is associated with gastric adenocarcinoma
  7. The effect of CTLA-4 and CD28 gene variants and circulating protein levels in patients with gastric cancer
  8. The neutrophil-to-lymphocyte ratio as a diagnostic marker for malignant thyroid diseases
  9. Computer-aided design of aptamers for SMMC-7721 liver carcinoma cells
  10. Serum levels of growth factors in patients with urinary bladder cancer
  11. Dicholoroacetate exerts anti-cancer activity on human renal cell carcinoma cells
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 29.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/tjb-2017-0015/html
Scroll to top button