RESEARCH ARTICLE

Department of Pharmaceutical Chemistry

SYNTHESIS & ANTIFUNGAL ACTIVITY OF BIOACTIVE MOLECULE FLURO SUBSTITUTED BENZOTHIAZOLE

COMPRISING QUINAZOLINE DERIVATIVES

quinazoline have been of great interest because, of its various biological activities, so that the biological and pharmacological activity of quinazoline with fluorobenzothiazoles may be taken into account for synergism. It is well known that the introduction of fluorine atom into an organic molecule causes dramatic changes in its biological profile, mainly due to high electro negativity of fluorine, the strong carbon-fluorine bond and increased solubility in lipids. Therefore it was thought worthwhile to synthesize better kinds of drugs by incorporating quinazoline and fluorine atom in benzothiazole moiety. The rapid progress of organic Fluorine chemistry since 1950 has been translated as a pathfinder to invent useful biodynamic agents in Medicinal and Biochemistry. The new generation antibiotics like Norfloxacin,

The chemistry and pharmacology of

INTRODUCTION [1,2]

Ciproflaxacin, Flufloxacin, which were incorporated with fluorobenzene moiety proved their efficacy as potent bio active molecules. Nowadays vast number of compounds with Fluorobenzene moiety features in diverse areas like antibacterial, antifungal, anti-inflammatory, psychoactive agents, pesticides, herbicides etc.

The reasons forever increasing importance of Fluorine incorporated bio active molecules may be listed below.

a) Fluorine being the second smallest substituent next to Hydrogen, closely mimics Hydrogen in Enzyme-receptor interactions.

b) The substitution of fluorine by hydrogen increases lipid solubility which in turn increases the transport and absorption of drug in-vivo.

1 1 2Niladry Sekhar Ghosh, Isan Verma, Ekta Pandey*1School of Pharmaceutical Sciences, Bahra University, Shimla Hills-173234 .HP, INDIA

2Bundelkhand Institute of Eng. & Tech.Jhansi-(UP)-284128, INDIA

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ARTICLE INFO:Article history: Received:20 October 2015Received in revised form:23 October 2015Accepted: 1 November 2015Available online: 10 November 2015

Abstract

In present work, fluorochloro aniline was treated with KSCN in presence of bromine in glacial acetic acid and ammonia to get 2-amino-6-fluro-7-chloro (1,3)- benzothiazole, which was condensed with anthranilic acid in presence of dry pyridine to get 2-amino-N-(2'-benzothiazolyl 6'-fluoro-7'-chloro) benzamides. To the above condensed product treated with carbondisulphide in presence of alcoholic potassium hydroxide to get 2-thione-3-(2'-benzothiazolyl-6'-fluoro-7'-chloro)4-(3H) quinazolines (Cyclo addition reaction). To the above product different aromatic aniline, PABA, piperzino, diphenylamine, N-Methyl piperzino, O-toludine in presence of DMF were treated to get newly

thsynthesised compound through replacing at 7 position chlorine.The identity of compounds were confirmed on the basis of their spectral (UV, IR, 1 H NMR and MASS) data. Further, they have been screened for their antimicrobial activities.

Fluorine, Benzothiazole, quinazoline. Antifungal.Key words

Corresponding Author:

Ekta PandeyBundelkhand Institute of Eng. & Tech.Jhansi-(UP)-284128, INDIAE-mail: ektakush@rediffmail.comPhone: +91 7607869687

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can be accommodating for control of TB in Pakistan

c) The strong electron withdrawing, inductive

effect (-I effect) of Fluorine influences stability and

reactivity of functional groups which may in turn

influence the reactivity of neighbouring reaction

centers.

d) The replacement of 'Hydrogen' by 'Fluorine' at or near reactive sites causes inhibition of metabolism due to high C-F bond energy.

Based on the above observations we have synthesized some Fluoro-Benzothiazolequina-zolinone derivatives starting with fluorochloro-aniline, in hope of getting pharmacological agents with broad spectrum of clinical activity. In search for new bioactive potent molecule, it was thought worthwhile to incorporate some additional heterocyclic moieties in the quinazoline nucleus and study their biological and pharmacological activity, the review of literature reveal prompted us to synthesis substituted Fluoro-benzothiazolyl quinazoline compounds and those will be screened for antifungal activity to get potent bioactive molecule.

MATERIAL & METHODS

Melting point was determined by open capillary tube method and are uncorrected T. L. C was run on silica gel G plates using butanol, ethyl acetate and chloroform (1 : 2 : 1) as developing solvent for testing the purity of the compounds. I. R. Spectra w e r e r e c o r d e d o n S h i m a d z u F T I R Spectrophotometer by using nujol mull technique

All the compounds synthesized was screened for antifungal activities at two different concentrations (50ìg/ml, 100ìg/ml) against Candida albicans, Aspergillus niger by diffusion method using Griseoflavin as standards. Activity calculated which are shown in the table-3.

First Step

General synthesis of 2-amino-6-fluoro-7-chloro-benzothiazole [3, 4, 5]

To glacial acetic acid (20ml) cooled below room temperature were added 8gm (0.08mol) of potassium thiocyanate and 1.45g (0.01 mol) of fluorochloro aniline. The mixture was placed in freezing mixture of ice and salt and mechanically stirred while 1.6ml of bromine in 6ml of glacial

acetic acid was added from a dropping funnel at such a rate that the temperature never rose beyond room temperature. After all the bromine was added (105min), the solution was stirred for 2 hours below room temperature and at room temperature for 10 hours, it was then allowed to stand overnight, during which period an orange precipitate settle at the bottom, water (6ml) was added quickly and

0slurry was heated at 85 c on a steam bath and filtered hot. The orange residue was placed in a reaction flask and treated with 10ml of glacial

0acetic acid heated again to 85 c and filtered hot. The combined filtrate was cooled and neutralized with concentrated ammonia solution to pH 6 A dark yellow precipitate was collected. Recrystallized from benzene, ethanol of (1:1) after treatment with animal charcoal gave yellow plates of 2-amino-6-fluoro-7-chloro-(1,3)-benzothiazole. After drying

0in a oven at 80 C, the dry material (1gm 51.02%) 0melted at 210-212 c.

Second Step

General synthesis of 2-amino-N-(2'-benzothiazolyl 6'-fluoro-7'-chloro) benzamides [6, 7]

Anthranilic acid (4.0 g, 0.029 mol) and 2-amino-benzothiazole (5.22 g, 0.026 mol), were dissolved in dry pyridine (20 ml, 0.25 mol). The solution was refluxed for 8 hr. The solution was cooled and pured in water. The separated mass was filtered, washed with water and dried. The product was recrystallized using ethanol.

Third Step

General synthesis of 2-thione-3-(2'-benzothiazolyl 6'-fluoro-7'-chloro)-4-(3H)-quinazolinones [4, 5]

To an ice cold solution of potassium hydroxide (0.1 g, 0.02 mol) in dry ethanol (50 ml), 2-amino-N-(2'-benzothiazolyl 6'-fluoro-7'-chloro) benzamide (2.6 g, 0.008 mol) and carbon disulphide (6.0 ml, 0.078 mol) was added with stirring. The solution was refluxed for 10 hr and cooled. The quantity of solvents was reduced by distillation. The separated solid was filtered, washed with dry ether and dried. The product was recrystallized using ethanol.

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RESEARCH ARTICLE

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Fourth Step

General synthesis of 2-(2'-thione-4'(3H) qu inazo l inony l ) -6 - f luoro 7 subs t i tu ted benzothiazole [1,3]

The 0.0075 mol (2.7 gm) of 2-thione-3-(2'-benzohiazolyl 6'-fluoro-7'-chloro)-4-(3H) quinazolinone was treated with 0.008 mol of various substituted aromatic aniline, PABA, morpholine, piperazine, diphenylamine O-toluidine, N-Methyl piperazine and refluxed for 2 hrs in presence of DMF (dimethyl formamide) then the mixture was cooled and poured into crushed ice.

The solid separated was filter off, dried and recrystallize with super dry alcohol.

RESULT AND DISCUSSION

The synthesized compounds are screened against two selected fungal strains Candida albicans and Aspergillus niger by using diffusion method. Sythesised compounds of 2(2'-thione-4'(3'H)-quinazolinonyl) -6-fluoro-7-substituted (1,3) benzothiazole was tested for antifungal activity [8, 9,10] against Candida albicans and Aspergillus niger. Among the compounds tested; VA5, VA9, showed good activity against Candida albicans at both concentration compare to standard Griseoflavin. VA4, VA5, VA10 & VA12 showed significant activity against Aspergillus niger compared to standard Griseoflavin.

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SCHEME

R = o, m, p- nitro aniline (A - A ) R' = morpholine, piperazine1 3

= o, m, p- chloro aniline (A – A ) = N-methyl piperazine4 6

= N- phenyl (A ) = ( A , A , A )9 7 8 1 2

= o-ethyl, p-carboxyl (A – A )10 11

RESEARCH ARTICLE

Department of Pharmaceutical ChemistryEkta Pandey et.al / UJPSR / 1 (2), 2015, 12-16

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ANALYTICAL DATA

TABLE-1

TABLE-2

Sl. NoComp. Code

M.P/ B.P C

% Yield

MOL. FORMM.Wt.

gm. C% H% N%

C H O S N F 21 12 3 2 5 15.05 2.58 4.19 4651 V A1 192-193 78

2

3

4

5

6

7

8

9

10

11

12

15.05

15.05

12.32

12.32

12.32

13.52

16.94

11.29

12.90

12.99

16.39

2.58

2.58

2.64

2.64

2.64

3.62

3.87

3.42

3.45

3.01

4.21

54.19

54.19

55.44

55.44

55.44

55.07

55.20

65.32

60.82

61.25

56.20

465

465

454.5

454.5

454.5

414

413

496

434

431

427

C H O S N F21 12 3 2 5

C H O S N F21 12 3 2 5

C H OS N ClF21 12 2 4

C H OS N ClF21 12 2 4

C H OS N ClF21 12 2 4

C H O S N lF19 15 2 2 4

C H OS N F19 16 2 5

C H OS N F27 17 2 4

C H OS N F27 15 2 4

C H O S N F22 13 3 2 4

C H OS N F20 18 2 5

81

76

76

78

80

82

75

82

85

77

86

142-144

160-162

206-208

216-218

216-218

192-194

218-220

120-122

136-138

166-168

145-146

V A2

V A3

V A4

V A5

V A6

V A7

V A8

V A9

V A10

V A11

V A12

NMR Spectral Data of Compounds VA , VA , VA , VA .3 6 8 9

Sl. No.

Spectra No.

Compound Code

Hydrogen (ppm) Multiplity Solventä

1 32 VA3

-Ar-H--1H-NH

7.0-7.65.5

MultipletSinglet CDCl3

2 33 VA6

-Ar-H--1H-NH

-1H-NH-Ar

7.0-7.65.53.4

MultipletSingletSinglet

CDCl3

3 34 VA8

-Ar-H--1H-NH

7.0-7.65.5

MultipletSinglet CDCl3

4 35 VA9

-Ar-H--1H-NH

6.8-7.45-7

MultipletSinglet CDCl3

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TABLE-3

Antifungal activity

Mean zone of inhibition (in mm)

Sl. No.

Name of the compounds Candida albicans Aspergillus niger

50µg 100µg 50µg 100µg

Griseoflavin01

02

03

04

05

06

07

08

09

10

11

12

13

V A1

V A2

V A3

V A4

V A5

V A6

V A7

V A8

V A9

V A10

V A11

V A12

22162216

15131210

15121210

15131311

18141311

19151413

14121412

14121311

12101413

18151714

18151311

19151413

16131312

The lead compounds of scheme I was characterized by melting point, TLC, calculated elemental analysis, UV, IR and 1HNMR spectral studies. The compounds were tested for antifungal studies.

1. FILLER RJ. Fluorine Chem 1986; 33: 361-375.

2. Greco Micheal N, Hangman William E.ChemAbstr 1992; 117; 131109.

3. Abdel-Hamide SG. Indian J Heterocyclic Chem 200; 10: 59-64.

4. VarshaJatav, Jain SK, Kashaw SK, Mishra P. Indian J Pharmaceutical Sci 2006; 360-363.

5. Amar R Desai, Kishor R Desai. ARKIVOC 2005, (AKRAT USA, Inc) 98-108.

6. Chakole RD, Amenkar ND, Khedekar PB, Bhusarik P. Indian J Heterocyclic Chem2005; 15: 27-30.

The antifungal studies of synthesized compounds VA , VA , VA , and VA showed significant activity 4 5 9 10

at low and high concentrations compared to standard; still further studies are requested.

7. Chakole RD, Amenkar ND, Khedekar PB, Bhusarik P. Indian J Heterocyclic Chem 2006; 1: 217-220.

8. Gangwal NA, Kothwade UR, Galande AD, Pharande DS, Dhake AS. Ind J Heterocyclic Chem 2001; 10: 291-294.

9. VarshaJatav, Jain SK, Kashaw SK, Mishra P. Indian J Pharmaceutical Sci 2006; 360-363.

10. Amar R Desai, Kishor R Desai. ARKIVOC 2005, (AKRAT USA, Inc) 98-108.

CONCLUSION

REFERENCES

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