SYNTHESIS AND EVALUATION OF NOVEL THIOSEMICARBAZONE DERIVATIVES AS ANTICANCER AGENTS

SYNTHESIS AND EVALUATION OF NOVEL THIOSEMICARBAZONE DERIVATIVES AS ANTICANCER AGENTS

Niharika Gokhale ¹* and Sanjay Jain ²

Department of Pharmaceutical Sciences, Gyan vihar University ¹, Jaipur Rajasthan, India

Smriti College of Pharmaceutical Education ², Indore Madhya Pradesh, India

ABSTRACT:  Thiosemicarbazobes are the compounds that possess wide range of biological activities. Presently the areas in which thiosemicarbazones receiving more attention is its use against cancer. Reports from the SAR studies confirms that the thiosemicarbazones with heterocyclic moiety shows carcinogenic potency. These are potent ribonucleotide reductase inhibitor. Adamantyl derivatives is also having interesting biological properties and most promising towards anticancer activity. The value of adamantyl group in drug design is multidimensional. A novel series of compounds of thiosemicarbazones were prepared by conjugating adamantyl group and using aromatic substitution. The various substitutions on thiosemicarbazones were reported as anti cancer activity and adamantyl group also show antiproliferative activity against some cell lines, so in present work 20 compounds were prepared on the basis of best results of QSAR studies and they were screened for anticancer activity using cell line studies. The results were compared with standard drug doxorubicin, 3 compounds show more inhibitory action than standard drug.

Adamantyl, Thiosemicarbazones

Antiproliferative, Ribonucleotide Reductase.

INTRODUCTION: The cancer is one of the leading cause of deaths worldwide, in developing countries it is second leading cause of death while in developed countries it is leading cause of death. Till 2030 one among eight peoples of world will suffer from this disease¹. The cancerous cells have property to proliferate uncontrollably and defensive apoptosis due to inactivation of tumor suppressive genes. The cells of cancer also invade easily and ability to metastasize in normal tissues ^2-3. Cancer is a complex disease with various genetic and epigenetic alterations. The all alteration also having much difference which is a challenge for synthesizing new analogues as anticancer agent ⁴.  Thiosemicarbazones is rapidly investigated compounds with different pharmacological actions ⁵. The fused thiosemicarbazones show potential anticancer effects.

The groups like benzopyridine, acetyl pyridine, metals like palladium, platinum and nickel when fused with thiosemicarbazone then they show cytotoxic activity against various solid cell tumors ^6-9.

The substitution of adamantane and its derivative have been known for antiviral effect ^10-14, anti microbial effect ^15-18 and as anti inflammatory agent ^17-21. Substitution on thiopyrimidine, caboxamide and acetamide ^22-24 shows potential cytotoxic effects.

So in the present work a novel series of compounds of thiosemicarbazones were prepared by conjugating Adamantyl Group and using aromatic Substitution.

 Experimental work:

Synthesis of Compounds:

For synthesis of aromatic/heterocyclic substituted thiosemicarbazone derivatives two step reaction was performed. Amantadine (0.01 mol), ethanolic solution of potassium hydroxide (1.68 gm 0.03 mol) were mixed together. The mixture was cooled below 10^oC and Carbon disulphide (1.8mL, 0.03mol) was added gradually with constant stirring d till CS₂ had completely dissolved. After standing for overnight, thioglycolic acid was obtained. It was shaked with a solution of sodium chloroacetate (1.0 mol) followed by hydrazine hydrate (5 ml, 100%) and was refluxed for two hours with continuous strirring. The filtrate was concentrated to half its initial volume and allowed to stand overnight, at 0^oC.  Dry ether (20mL) was added and the yellow ppt. was filtered, washed with ether and dried and recrystallized from ethanol. (Compound 1)

Scheme:

A mixture of carboxaldehyde (0.5mmol), thiosemicarbazide (0.55mmol) andconc. sulfuric acid (0.4mL) in 5mL of ethanol was heated under reflux for 4 h. The mixture was then cooled to room temperature, filtered and rinsed with cold solution of 50 % aqueous ethanol and diethyl ether respectively. By this scheme Compounds 2 Tsc-1 to Tsc-20 were prepared. (Table 1)

AR-AROMATIC/HETEROCYCLIC SUBSTITUTIONS

Characterization of Synthesized Compounds:

General:

After synthesizing the different compounds, they were lyophilized and their % yields were calculated. The Melting points of all Compounds were determined by the capillary method using Melting Point Apparatus (Lab-Hosp, Mumbai). Triplicate observations were recorded for melting range determination.

NMR Analysis:

¹H NMR and C¹³ NMR spectra of all synthesized were recorded on Bruker (400 MHz) spectrometer. The samples were dissolved and measured in DMSO. Chemical shifts are reported as δ (ppm) relative to Tetramethylsilane [TMS] as a standard. Various shifts in the peaks were interpreted for different groups present in conjugated system.

ESI MASS Spectoroscopy:

The electrospray mass spectra were recorded on a MICROMASS QUATTRO II triple mass spectrometer. The samples (dissolved in suitable solvents such as methanol/acetonitrile/DMSO) were introduced into ESI source through a syringe pump at the rate of 5μl/min. The ESI capillary was set at 3.5 KV and the cone voltage was 40 V. The spectra were collected in 6S scans and print outs are averaged spectra of 6-8 scans. Spectra recorded at high mass units are computerized decovoluted.

 Elemental Analysis:

The elemental analysis of Carbon, Hydrogen and other elements were performed by CHNS/O Elemental Analyzer (Perkin Elmer PE 2400). This analyzer was used for knowing concentration of C, H, N, S and O in newly synthesized compounds.

 Cytotoxic Assay:

Cytotoxicity was evaluated by the 3-(4,5-dimethyl-2-thiazolyl)- 2,5-diphenyl-2H-tetrazolium bromide (MTT) assay which measures the cellular metabolic viability²⁴. The cells were cultured in 96-well plates and, 12 h after incubation, they were treated with different concentrations of test compounds.

Another group of cells was treated with the same concentrations of Doxorubicin as a standard drug. Compounds were previously dissolved in DMSO and the final concentrations were adjusted, through an 8-fold serial dilution, in DMEM in such manner that the final DMSO concentration was lower than 0.5%. After 48 h-treatment the cells were incubated with MTT (0.5 mg ml^-1), and formazan crystals were solubilised in DMSO Absorbance was measured in a microplate reader at 570 nm.

Tests using DMSO (0.5% in DMEM) as negative control were carried out in parallel. IC50 values were calculated as the concentration of compound that induced 50% of cytotoxicity. Data were presented as average ± standard deviation. All experiments were carried out in quadruplicates and repeated in at least three independent experiments with full agreement between the results. The statistical significance was assessed using Student’s t-test (p <0.05).

 RESULTS AND DISCUSSION:

The prepared compounds were characterized for Melting point, different spectral analysis, and elemental analysis and In- Vitro Cell line studies.

 General:

The melting point of different compounds with their molecular weight, Molecular formula and % yield was given in Table 2.

 NMR, ESI Mass Spectroscopy and elemental analysis:

The data for ¹ H NMR, ¹³ C NMR, ESI mass and elemental analysis were represented for different compounds as follows.

1. (Tsc-1) 1-(adamantan-1-yl)-3-[(E)-(1H-indol-3-ylmethylidene) amino] thiourea ¹H NMR (DMSO- d₆ , 400MHz): δ66-1.74(t, 6H, Adamantane-H), 2.13(s, 3H, Adamantane-H), 2.35 (s, 6H, Adamantane-H), 8.05(s, 1H, CH=N), 8.13(s,1H, NH),11.32 (s,1H, CS-NH), 9.84 (s,1H,NH-Indole),7.18 (s,1H,CH,Indole), 7.41(s,2H, Ar-CH), 7.47 (s,2H,Ar-CH) ¹³C NMR: δ 147.19 (C=N), 177.52(C=S), 28.5, 36.4, 39.8, 43.2 (Adamantane-C), 111.5 (Indole-C), 102.5, 119.3, 120.8, 124.7, 127.5, 135.5 (Ar-C). ESI-MS m/z: 353 (M⁺ +1) Anal. Calcd for C₂₀H₂₄N₄S: C, 68.14; H, 6.86; N, 15.89. S, 9.08 Found: C, 68.12; H, 6.56; N, 15.34; S, 9.24

2. (Tsc-2)1-(adamantan-1-yl)-3-[(E)-(1H-1,3-benzoimidazol-2 yl methylidene) amino] thiourea ¹H NMR (DMSO- d₆ , 400MHz): δ66 (s, 6H, Adamantane-H), 2.08-2.21 (m, 9H, Adamantane-H), 8.02 (s, 1H, CH=N), 8.23(s,1H, NH),11.30 (s,1H, CS-NH), 9.84 (s,1H,NH-Indole),7.8 (s,1H,Imidazole), 7.5-7.98 (m,8H, Ar-CH). ¹³C NMR: δ 148.21 (C=N), 176.82 (C=S), 29.53, 37.41, 38.51, 40.53 (Adamantane-C), 121.12, 122.43, 123.90, 126.85, 130.56 (Ar-C). ESI-MS m/z: 355 (M⁺ +2). Anal. Calcd for C₁₉H₂₃N₅S: C, 64.56; H, 6.56; N, 19.81. S, 9.07 Found: C, 65.12; H, 6.48; N, 18.34; S, 9.04

3. (Tsc-3) 3-(adamantan - 1-yl) – 1 - [(E)-{[3-(naphthalen-2-yl) phenyl] methylidene} amino] thiourea: ¹H NMR (DMSO- d_6, 400MHz): δ62-1.84 (m, 6H, Adamantane-H), 1.91 -2.06 (m, 9H, Adamantane-H), 8.04 (s, 1H, CH=N), 8.34 (s, 1H, NH), 11.53 (s, 1H, CS-NH), 6.98-8.63 (m, 11H, Ar-CH). ¹³C NMR: δ 150.63 (C=N), 178.65 (C=S), 27.42, 33.62, 34.91, 38.02 (Adamantane-C), 126.26, 128.13, 130.31, 131.34, 134.35, 135.32 (Ar-C). ESI-MS m/z: 440 (M⁺ +1) Anal. Calcd for C₂₈H₂₉N₃S: C, 76.42; H, 6.66; N, 9.55. S, 7.30 Found: C, 76.35; H, 6.74; N, 8.68. S, 8.98.

4. (Tsc-4)1-(adamantan-1-yl) – 3 - [(E) - ({5-[3-(hydroxynitroso) phenyl] furan - 2 yl} methylidene) amino] thiourea: ¹H NMR (DMSO- d₆ , 400MHz): δ68-1.86 (m, 6H, Adamantane-H), 2.06-2.23 (m, 9H, Adamantane-H), 8.23 (s, 1H, CH=N), 7.93 (s,1H, NH),11.63 (s,1H, CS-NH), 6.68 (s,1H, Furan-CH),7.04-7.15(m,4H, Ar-CH) ¹³C NMR: δ 146.53 (C=N), 174.32 (C=S), 28.58, 37.36, 38.54, 32.33 (Adamantane-C), 126.26, 128.13, 130.31, 131.14, 134.25, 135.82, 144.34 (Ar-C). ESI-MS m/z: 426 (M⁺ +2) Anal. Calcd for C₂₂H₂₄N₄O₃S: C, 62.34; H, 5.60; N, 13.10. S, 7.55 Found: C, 63.15; H, 6.04; N, 12.46. S, 7.72

5. (Tsc-5)1-(adamantan-1-yl)-3-[ (E) - {[2- (3-nitrophenyl)imidazo[1,2-a] pyridin-3-yl] methylidene} amino] thiourea^{: 1}H NMR (DMSO- d_6, 400MHz): δ84-1.99 (m, 6H, Adamantane-H), 2.13-2.27 (m, 9H, Adamantane-H), 8.34 (s, 1H, CH=N), 7.52 (s, 1H, NH), 11.82 (s, 1H, CS-NH), 6.90-8.30 (m, 8H, Ar-CH) ¹³C NMR: δ 148.21 (C=N), 178.22 (C=S), 29.24, 36.42, 40.52, 42.34 (Adamantane-C), 112.35, 122.29, 126.64, 128.43, 141.28, 145.32, 148.28 (Ar-C). ESI-MS m/z: 475 (M⁺ +1) Anal. Calcd for C₂₅H₂₆N₆O₂S: C, 63.24; H, 5.32; N, 17.62. S, 6.73 Found: C, 62.35; H, 6.18; N, 16.32. S, 6.72

6. (Tsc-6) 3 - (adamantan-1-yl) - 1 -[(E)-[(2,4,5 trimethoxyphenyl) methylidene ]amino] thiourea: ¹H NMR (DMSO- d₆ , 400MHz): δ68-1.88 (m, 6H, Adamantane-H), 1.98-2.10 (m, 9H, Adamantane-H), 8.18 (s, 1H, CH=N), 7.53 (s,1H, NH),11.38 (s,1H, CS-NH), 6.98 (s,2H, Ar-CH), 3.62 (s,3H,OCH₃), 3.72 (s,6H,OCH₃) ¹³C NMR: δ 146.09 (C=N), 178.60 (C=S), 27.61, 34.23, 35.24, 38, 98 (Adamantane-C), 98.47, 110.39, 112.46, 120.21, 122.26 (Ar-C), 55.32, 54.43, 56.18 (Methoxy-C) ESI-MS m/z: 404 (M⁺ +1) Anal. Calcd for C₂₁H₂₉N₃O₃S: C, 62.51; H, 7.24; N, 10.41. S, 7.95 Found: C, 62.48; H, 6.39; N, 9.38. S, 7.98

7. (Tsc-7) 3 - [(E)-{[(4S)-4- (acetylsulfanyl)-2-formylpyrazolidin-1-yl] methylidene} amino]-1-(adamantan-1-yl) thiourea: ¹H NMR (DMSO- d₆ , 400MHz): δ78 (s, 6H, Adamantane-H), 2.08 (s, 9H, Adamantane-H), 8.29 (s, 1H, CH=N), 7.50 (s,1H, NH),10.82 (s,1H, CS-NH), 4.26-4.52 (m,4H, pyrazolidine-CH), 3.08 (s,3H,OCH₃), 8.82 (s,1H,CHO) ¹³C NMR: δ 143.60 (C=N), 179.50 (C=S), 28.60, 33.24, 35.24, 39, 98 (Adamantane-C), 60.82, 62.36, 57.43 (Pyrazolidine-C), 45.34 (Alkyl-C), 168.41 (N-C=0), 184.32(S-C=O) ESI-MS m/z: 410 (M⁺ +1) Anal. Calcd for C₁₈H₂₇N₅O₂S₂: C, 52.79; H, 6.64; N, 17.10. S, 15.66 Found: C, 52.68; H, 6.75; N, 17.48. S, 14.64.

8. (Tsc-8) 3-(adamantan-1-yl)-1-[(E)-{[3,4-bis(benzyloxy)phenyl]methylidene}amino]thiourea: ¹H NMR (DMSO- d₆ , 400MHz): δ62-2.13 (m, 15H, Adamantane-H), 8.42 (s, 1H, CH=N), 7.52 (s,1H, NH),11.32 (s,1H, CS-NH), 4.23-4.26 (m,4H,O-CH₂),7.23-7.48 (m,6H, Ar-CH), 7.54-7.62 (m,7H, Ar-CH) ¹³C NMR: δ 144.25 (C=N), 175.69 (C=S), 28.63, 32.98, 36.18, 42.29 (Adamantane-C), 62.32 (CH₂), 111.82, 120.97,1 27.65, 128.86, 132.43, 136.57, 143.64, 146.32, 148.53 (Ar-CH) ESI-MS m/z: 527 (M⁺ +2) Anal. Calcd for C₃₂H₃₅N₃O₂S: C, 73.10; H, 6.72; N, 7.96. S, 6.16 Found: C, 75.10; H, 6.85; N, 6.98. S, 6.58.

9. (Tsc-9)3-(adamantan-1-yl)-1-[(E)-{[3-(3-hydroxyphenyl) phenyl]methylidene}amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ72 (s, 6H, Adamantane-H), 2.16 (s, 9H, Adamantane-H), 8.34 (s, 1H, CH=N), 7.35 (s, 1H, NH), 11.33 (s, 1H, CS-NH), 7.40-7.58 (m, 8H, Ar-CH), 4.78 (s, 1H, OH) ¹³C NMR: δ 141.25 (C=N), 177.62 (C=S), 26.23, 31.82, 34.24, 40.30 (Adamantane-C), 126.35, 128.23, 130.37, 132.43, 148.74, 151.94 (Ar-CH) ESI-MS m/z: 405 (M⁺), Anal. Calcd for C₂₄H₂₇N₃OS: C, 71.05; H, 6.71; N, 10.32. S, 7.92. Found: C, 70.14; H, 6.92; N, 10.58. S, 6.98.

10. (Tsc-10) 3 - (adamantan-1-yl) – 1 - [(E)-({4-[(4fluorophenyl) methoxy] phenyl} methylidene) amino] thiourea: ¹H NMR (DMSO- d_6, 400MHz): δ76 (s, 6H, Adamantane-H), 2.08 (s, 9H, Adamantane-H), 9.32 (s, 1H, CH=N), 7.46 (s, 1H, NH), 11.72 (s, 1H, CS-NH), 6.23 (d, 2H, CH₂), 7.58-7.70 (m, 8H, Ar-CH). ¹³C NMR: δ 136.82 (C=N), 178.54 (C=S), 27.44, 32.58, 34.34, 39.45 (Adamantane-C), 64.42(O-CH₂), 114.58, 115.76, 124.28, 131.52, 133.49, 136.57, 138.49, 162.54 (Ar-CH) ESI-MS m/z: 438 (M⁺ +1) Anal. Calcd for C₂₅H₂₈ FN₃OS: C, 68.64; H, 6.44; N, 9.62. S, 7.34. Found: C, 70.37; H, 6.52; N, 10.13. S, 7.18

11. Tsc-11) 3-(adamantan-1-yl)-1-[(E)-[(2-amino-6-bromo - 4 - oxo- 4H -chromen-3-yl) methylidene] amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ58-2.13 (m, 15H, Adamantane-H), 9.28 (s, 1H, CH=N), 7.28 (s, 1H, NH), 11.80 (s, 1H, CS-NH), 8.94 (s, 2H, NH₂), 7.64-7.82 (m, 3H, Ar-CH). ¹³C NMR: δ 134.92 (C=N), 177.98 (C=S), 24.68, 26.58, 29.82, 36.48 (Adamantane-C), 64.42(O-CH₂), 98.55, 117.28, 124.35, 126.13, 152.53, 154.65 (Chromyl-CH) ESI-MS m/z: 477 (M⁺ +2) Anal. Calcd for C₂₁H₂₃ BrN₄O₂S: C, 53.06; H, 4.86; N, 11.72. S, 6.76. Found: C, 55.06; H, 4.96; N, 11.76. S, 6.89.

12. Tsc-12) 1-(adamantan – 1 - yl) -3-[(E)-{8-oxatricyclo [7.4.0.0 {2, 7}] trideca-1(13), 2, 4, 6, 9, 11-hexaen-4-ylmethylidene} amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ68 (s, 6H, Adamantane-H), 2.14 (s, 9H, Adamantane-H), 9.32 (s, 1H, CH=N), 7.38 (s, 1H, NH), 11.52 (s, 1H, CS-NH), 8.94 (s, 2H, NH₂), 7.42-7.80 (m, 7H, Ar-CH). ¹³C NMR: δ 140.23 (C=N), 177.54 (C=S), 29.32, 32.45, 40.36, 41.42 (Adamantane-C), 98.75, 110.87, 121.57, 123.45, 132.61, 134.87, 136.93, 140.22, 143.28 (Aryl & Furan CH) ESI-MS m/z: 404 (M⁺ +1) Anal. Calcd for C₂₄H₂₅ N₃OS: C, 71.44; H, 6.28; N, 10.42. S, 7.92. Found: C, 70.89; H, 7.34; N, 10.58. S, 7.95.

13. (Tsc-13) 1-(adamantan-1-yl)-3-[(E)-{[5-(dimethylamino) furan-2-yl] methylidene} amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ63-2.02 (m, 15H, Adamantane-H), 8.92 (s, 1H, CH=N), 7.29 (s, 1H, NH), 11.32 (s, 1H, CS-NH), 6.82 (s, 1H, Furan-H), 7.23 (s, 1H, Furan-H), 2.54 (m, 6H, CH₃). ¹³C NMR: δ 138.56 (C=N), 178.24 (C=S), 30.23, 32.45, 34.36, 35.42 (Adamantane-C), 105.07, 111.31, 141.82, 145.68 (Furan CH), 38.4 (N-CH₃) ESI-MS m/z: 347 (M⁺ +1) Anal. Calcd for C₁₈H₂₆ N₄OS: C, 62.49; H, 7.56; N, 16.17. S, 9.25. Found: C, 61.87; H, 6.96; N, 16.87. S, 8.75.

14. (Tsc-14) 3 - (adamantan-1-yl) – 1 - [(E)-{[3-cyano-4-(dimethylamino)-2-fluorophenyl] methylidene} amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ63-1.82 (m, 6H, Adamantane-H),1.95- 2.34 (m, 9H, Adamantane-H), 9.02 (s, 1H, CH=N), 7.28 (s, 1H, NH), 11.45 (s, 1H, CS-NH), 3.52- 4.02 (m, 6H, CH₃), 7.92 (s, 2H, Ar-CH). ¹³C NMR: δ 148.54 (C=N), 174.25 (C=S), 28.32, 31.46, 32.32, 34.42 (Adamantane-C), 40.80  (N-CH₃)  98.75, 115.87(CN)89.43,96.28,110.26,113.48 (Aryl CH ) ESI-MS m/z: 400 (M⁺ +1) Anal. Calcd for C₂₁H₂₆ FN₅S: C, 63.04; H, 6.56; N, 17.52. S, 8.03. Found: C, 63.18; H, 7.06; N, 17.98. S, 9.83.

15. (Tsc-15) 3 - (adamantan-1-yl) - 1-[(E)-[(2-chloro-6-methylquinolin-3-yl) methylidene] amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ56-1.78 (m, 6H, Adamantane-H),1.94- 2.32 (m, 9H, Adamantane-H), 8.43 (s, 1H, CH=N), 7.42 (s, 1H, NH), 11.23 (s, 1H, CS-NH), 2.42 (s, 3H, CH₃), 8.52-9.62 (m, 4H, Ar-CH). ¹³C NMR: δ 146.43 (C=N), 172.38 (C=S), 30.23, 36.59, 40.24, 41.32 (Adamantane-C), 20.48 (CH₃) 118.23, 122.12, 124.28, 126.31, 128.18, 132.57, 142.76, 151.63 (Aryl CH) ESI-MS m/z: 412 (M⁺⁾ Anal. Calcd for C₂₂H₂₅ ClN₄S: C, 63.94; H, 6.12; N, 13.72. S, 7.76. Found: C, 64.18; H, 7.01; N, 13.12. S, 7.08

16. (Tsc-16) 3-(adamantan-1-yl)-1-[(E)-[(2-chloro-6-methylquinolin-3-yl) methylidene] amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ71-2.01 (m, 6H, Adamantane-H), 2.12- 2.41 (m, 9H, Adamantane-H), 9.10 (s, 1H, CH=N), 7.49 (s, 1H, NH), 11.26 (s, 1H, CS-NH), 7.52-8.83 (m, 6H, Ar-CH). ¹³C NMR: δ 148.25 (C=N), 176.88 (C=S), 30.34, 32.36, 34.42, 41.08 (Adamantane-C), 119.56, 120.87, 121.52, 128.72, 130.65, 131.72, 144.81 (Aryl CH) ESI-MS m/z: 366 (M⁺ +2) Anal. Calcd for C₂₁H₂₄ N₄S: C, 69.25; H, 6.64; N, 15.37. S, 8.86. Found: C, 67.97; H, 6.85; N, 14.65. S, 8.64

17. (Tsc-17) 1 - (adamantan-1-yl) – 3 - [(E)-[(1-methyl-1H-imidazol – 2 - yl) methylidene] amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ72-2.03 (m, 15H, Adamantane-H), 8.83 (s, 1H, CH=N), 7.64 (s, 1H, NH), 11.53 (s, 1H, CS-NH), 3.48(s, 3H, CH₃) 6.84-7.16 (m, 2H, Ar-CH). ¹³C NMR: δ 143.36 (C=N), 174.25 (C=S), 30.07, 32.48, 34.36, 40.14 (Adamantane-C), 32.32(CH₃) 120.43, 130.26, 132.47 (Imidazole CH) ESI-MS m/z: 318 (M⁺ +1) Anal. Calcd for C₁₆H₂₃ N₅S: C, 60.53; H, 7.37; N, 22.05. S, 10.13. Found C, 60.38; H, 7.58; N, 22.87. S, 9.98

18. (Tsc-18) 3 - (adamantan -1-yl) – 1 - [(E)-{[(2R,4R)- 2 – bromopiperidin - 4 - yl] methylidene} amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ71 (s, 6H, Adamantane-H), 2.21 (s, 9H, Adamantane-H), 8.26 (s, 1H, CH=N), 7.42 (s, 1H, NH), 11.53 (s, 1H, CS-NH), 1.93(s, 1H, NH- Piperidine) 1.42-1.86 (m, 8H, Piperidine). ¹³C NMR: δ 144.35 (C=N), 175.23 (C=S), 28.46, 29.54, 30.88, 34.69 (Adamantane-C), 21.56, 23.56, 24.58, 26.76, 27.89 (Aryl CH) ESI-MS m/z: 400 (M⁺ +1) Anal. Calcd for C₁₇H₂₇ Br N₄S: C, 51.13; H, 6.83; N, 14.06. S, 8.04. Found: C, 51.26; H, 6.97; N, 15.86. S, 8.57

19. (Tsc-19) 1-(adamantan-1-yl) – 3 - [(E)-[(4-bromothiophen-2-yl) methylidene] amino] thiourea ¹H NMR (DMSO- d_6, 400MHz): δ69-1.78 (m, 6H, Adamantane-H), 1.86- 2.02 (m, 9H, Adamantane-H), 8.43 (s, 1H, CH=N), 7.68 (s, 1H, NH), 11.62 (s, 1H, CS-NH), 6.88 (s, 2H, Thiophene). ¹³C NMR: δ 146.43 (C=N), 174.64 (C=S), 30.53, 32.34, 34.58, 41.08 (Adamantane-C), 113.43, 122.53, 124.63, 128.53 (Thiophene CH) ESI-MS m/z: 399 (M⁺ +1) Anal. Calcd for C₁₆H₂₀ Br N₃S₂: C, 48.24; H, 5.06; N, 10.57. S, 16.17. Found: C, 48.78; H, 5.76; N, 10.43; S, 15.23

20. (Tsc-20) 1-(adamantan-1-yl)-3-[(E)-[(3,5-dimethyl - 1,2-oxazol – 4 - yl) methylidene] amino] thiourea: ¹H NMR (DMSO- d_6, 400MHz): δ63-1.84 (m, 6H, Adamantane-H), 1.92 (s, 9H, Adamantane-H), 8.23 (s, 1H, CH=N), 7.32 (s, 1H, NH), 11.38 (s, 1H, CS-NH), 2.08 (s, 6H, CH₃) . ¹³C NMR: δ 146.25 (C=N), 172.98 (C=S), 29.43, 30.68, 31.42, 34.32 (Adamantane-C), 156.36 (CH₃), 100.46, 130.61, 146.34 (Oxazole C) ESI-MS m/z: 333 (M⁺ +1) Anal. Calcd for C₁₇H₂₄ N₄ OS: C, 64.41; H, 7.28; N, 16.83; S, 9.64. Found: C, 63.48; H, 7.43; N, 15.88; S, 9.43.

Cytotoxic Studies:

The % cell inhibitions of different compounds were estimated by MTT assay. The IC₅₀ values of different batches were represented in table no 3-4. (Tsc- 1 to Tsc-10 in table 3 and Tsc- 11 to Tsc 20 in Table 4). The values were compared with standard drug doxorubicin and R² values were calculated. It was found that Amongst all the tested compounds Tsc-1, Tsc-2, Tsc-5, Tsc-7, Tsc-11, Tsc-12, Tsc-15, Tsc-16 and Tsc-18 gives highest potential effect on MCF-7 cell lines. Same ways compounds Tsc-3, Tsc-4, Tsc-13, Tsc-17 and Tsc-19 has comparable activity with Std. drug Doxorubicin as IC₅₀ values were almost same. While IC₅₀ values of Tsc-6, Tsc-8, Tsc-9, Tsc-10, Tsc-14 and Tsc-20 has less effective as compare to std. drug.

 TABLE 1: HETEROCYCLIC SUBSTITUTION WITH THEIR CODE

TABLE 2: GENERAL PROPERTIES OF SYNTHESIZED COMPOUNDS

TABLE 3: % CELL GROWTH INHIBITION OF TEST COMPOUNDS ON MCF-7 CELL LINE.

 TABLE 4: % CELL GROWTH INHIBITION OF TEST COMPOUNDS ON MCF-7 CELL LINE

 CONCLUSION: In present work, 20 compounds of thiosemicarbazones were synthesized by conjugating Admantyl Group and using aromatic Substitution. The synthesized compounds were characterized on basis of Melting point, ¹H- NMR, ¹³C NMR, ESI- mass and elemental analysis. The results of cytotoxic assay prove that some compounds shows more effective than standard drug. So this fusion of thiosemicarbazones with adamantyl group may be used further for synthesizing new anticancer compounds.

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    How to cite this article:

    Gokhale N and Jain S: Synthesis and Evaluation of Novel Thiosemicarbazone Derivatives as Anticancer Agents. Int J Pharm Sci Res 2015; 6(4): 1792-04.doi: 10.13040/IJPSR.0975-8232.6(4).1792-04.

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