Title of Invention	NOVEL BIS-PYRROLO[2,1-C][1,4] BENZODIAZEPINE-ANTHRAQUINONE CONJUGATES AND A PROCESS FOR THE PREPARATION THEREOF
Abstract	The present invention provides novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates of general formula V, useful as potential antitumour agents against human cancer cell lines. The present invention further provides a process for the preparation of novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates of general formula V. wherein n = 3, 4, or 5.

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FIELD OF THE INVENTION The present invention relates to a novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates and a process for the preparation thereof. More particularly, it relates to a process for the preparation of novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone hybrids as potential antitumour agents. The present invention particularly relates to the synthesis of pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone hybrids linked through alkanediyldioxy bridge with linkers of varying lengths as possible anticancer agents. The structural formula of novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone hybrids (Va-c) is as follows, (Formula Removed) wherein n = 3, 4, 5. BACKGROUND OF THE INVENTION The pyrrolo[2,1-c][1,4]benzodiazepines are a family of DNA interactive antitumour antibiotics derived from Streptomyces species. Examples of naturally occurring pyrrolo[2,1-c][1,4]benzodiazepines include anthramycin, tomaymycin, sibiromycin and DC-81. These compounds show their biological activity through covalent binding via their N10-C11 imine/carbinol amine moiety to the C2-amine position of a guanine residue within the minor groove of DNA giving rise to the preference for Pu-G-Pu sequences. (Kunimoto, S.; Masuda, T.; Kanbayashi, N.; Hamada, M.; Naganawa, H.; Miyamoto, M.; Takeuchi, T and Unezawa, H. J. Antibiot, 1980, 33, 665.; Kohn, K. W. and Speous, C. L J. Mol. Biol., 1970, 91, 551.; Hurley, L. H.; Gairpla, C. and Zmijewski, M. Biochem. Biophy. Acta., 1977, 475, 521.; Kaplan, D. J. and Hurley, L H. Biochemistry, 1981, 20, 7572.) The molecules have a right-handed twist, when viewed from the C-ring towards the A-ring. This enables the PBD to mirror the curvature of B-form DNA and maintain isohelical contact with the walls and floor of the minor groove. In the last few years a growing interest has been shown in the development of new pyrrolo[2,1-c][1,,4]benzodiazepine hybrids. Many PBD conjugates have been synthesized and investigated for their anticancer activity (Thurston, D. E.; Morris, S. J.; Hartley, J. A. Chem. Commun. 1996, 563.; Damayanthi, Y.; Reddy, B. S. P.; Lown, J. W. J. Org. Chem. 1999, 64, 290.; Kamal, A.; Reddy, B. S. N.; Reddy, G. S. K.; Ramesh, G Bioorg. Med. Chem. Lett. 2002, 12, 1933, Kamal, A.; Reddy, B. S. N.; Reddy Indian patent application No.209/DEL/2000). Recently C-8 linked PBD dimers with C2/C2 exo-unsaturation have been designed and synthesized (Gregson, S. J.; Howard, P. W.; Hartley, J. A.; Brooks, N. A.; Adam, L. J.; Jenkins, T. C; Kelland, L. R. and Thurston, D. E., J. Med. Chem. 2001, 44, 737). Also, non cross-linking mixed imine-amide PBD dimers have been synthesized that have significant DNA binding ability and potent antitumor activity (Kamal, A.; Ramesh, G.; Laxman, N.; Ramulu, P.; Srinivas, O.; Neelima, K.; Kondapi, A. K.; Srinu, V. B.; Nagarajaram, H. M. J. Med. Chem. 2002, 45, 4679). During earlier studies in this laboratory anthraquinone has been linked through its amino functionality to the C8 position of the A-ring of PBDs which have shown promising anticancer activity (Kamal, A.; Ramu, R.; Khanna, G. B. R.; Bioorg. Med. Chem. Lett. 2004, 14, 4907, Kamal, A.; Ramu, R.; Khanna, G. B. R. PCT Patent Appl. No. PCT/IN04/00212, US Patent Appl. No. 11/024,240). However, in the present invention the two pbd units have been joined to the 1, 4-positions of the anthraquinone through their a-c8 positions via alkanediyldioxy bridge with linkers of varying lengths, provide novel pyrrolo[2,1-c][1,4]benzodiazepines useful as anticancer agents. It also provides a process for the preparation of novel pyrrolo[2,1-c][1,4]benzodiazepines useful as antitumor agents. (Formula Removed) OBJECTIVES OF THE INVENTION The main object of the present invention is to provide novel pyrrolo[2,1-c][1 ,4]benzodiazepines anthraquinone conjugates. Yet another object is to provide novel pyrrolo[2,1-c][1 4]benzodiazepines anthraquinone conjugates, which are useful as anti tumour agents against human cancer cell lines. Yet another object of the invention is to provide a process for the preparation of novel pyrrolo[2,1-c][1,4]benzodiazepines anthraquinone conjugates. SUMMARY OF THE INVENTION Accordingly the present invention provides a novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugate of general formula V, (Formula Removed) wherein n = 3; (va) or 4; (vb), or 5; (vc). In an embodiment of the present invention the Novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugate of formula V is representative by the group of the following compounds: 1,4-Bis-{3-[7-methoxy-8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo [2,1-c][1,4]-benzodiazepin-5-one]propyloxy}anthracene-9,10-dione (Va); 1,4-Bis-{4-[7-methoxy-8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo [2,1-c] [1,4] benzodiazepin-5-one]butyloxy}anthracene-9,10-dione (Vb) and 1,4-Bis-{5-[7-methoxy-8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo [2,1-c] [1,4] benzodiazepin-5-one]pentyloxy}anthracene-9,10-dione (Vc) In yet another embodiment wherein the structural formula of the representative compounds are: (Formula Removed) formula Vc In yet another embodiment the Novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone exhibits invitro anticancer/antitumour activity against human cancer cell lines selected from lung, cervix, breast, colon, prostate and ovary cell lines. In yet another embodiment the concentration of the compound bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone (Va-c) used for invitro activity against HoP62 for IC50 is in the range of 0.1 to 14µM, for an exposure period of atleast 48 hrs. In yet another embodiment the concentration of the compound bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone (Va-c) used for invitro anti tumour activity activity against SiHa for IC50 is in the range of 0.8 to 9.0µM, for an exposure period of atleast 48 hrs. In yet another embodiment the concentration of the compound bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone (Va-c) used for invitro anti tumour activity activity against MCF7 for IC50 is in the range of 0.6 to 9.0 µM, for an exposure period of atleast 48 hrs. In yet another embodiment the concentration of the compound bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone (Va-c) used for invitro anti tumour activity activity against Colo205 for IC50 is in the range of 1.0 to 10 .0 nM, for an exposure period of atleast 48 hrs. In yet another embodiment the concentration of the compound bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone (Va-c) used for invitro anti tumour activity activity against PC3 for IC50 is in the range of 1.0 to 1.4µM for an exposure period of at least 48 hrs. In yet another embodiment the concentration of the compound bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone (Va-c) used for invitro anti tumour activity activity against ZR-75-1 for IC50 is in the range of 0.5 to 1.5 µM for an exposure period of at least 48 hrs. In yet another embodiment the concentration of the compound bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone (Va-c)used for invitro anti tumour activity activity against A2780 is in the range of 0.6to 10.0 µM for an exposure period of at least 48 hrs. The present invention further provides a pharmaceutical composition comprising novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone, conjugates, its derivatives, analogues salts or mixture thereof optionally with pharmaceutically acceptable carriers, adjuvants and additives. In yet another embodiment the novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates used in pharmaceutical composition has a general formula V, (Formula Removed) Va-c wherein n = 3; (Va) or 4; (Vb), or 5; (Vc). In yet another embodiment pharmaceutical composition exhibits invitro anticancer/anti tumour activity against human cancer cell lines selected from lung, cervix, breast, colon, prostate and ovary cell lines. The present invention further provides a process for the preparation of novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates of formula V, the said process comprising the steps of: a. reacting 1,4-dihydroxy anthraquinone of formula I with dibromoalkanes, in an aprotic water miscible organic solvent, in the presence of a mild inorganic base, at refluxing temperature, for a period of about 24 hours, followed by the removal of inorganic base by filtration and removing the organic solvent by evaporation, under reduced pressure, to obtain the 1,4-bis-(3-bromo alkoxy)-anthracene-9,10-dione of formula lla-c, (Formula Removed) Wherein n = 3; (lla) or 4; (lib), or 5; (lie) b. reacting 1,4-bis-(3-bromo alkoxy)anthracene-9,10-dione of formula lla-c with (2S)-A7-[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carbox aldehyde diethyl thioacetal in a dry organic solvent, in the presence of mild inorganic base, at refluxing temperature, for a period of about 24 hours, followed by the removal of inorganic base by filtration and removing the organic solvent by evaporation, under reduced pressure, to obtain the desired product 1,4-bis-{n-[(2S)-N-(4-oxy-5-methoxy-2- nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]alkyloxy}- anthracene-9,10-dione of formula llla-c. (Formula Removed) wherein n= 3; (Ilia) or 4; (1Mb), or 5; (lllc) c. reducing the compound 1,4-bis-{n-[(2S)-N-(4-oxy-5-methoxy-2- nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]alkyloxy}- anthracene-9,10-dione of formula III with tin chloride, in an alcoholic solvent, under reflux, for a period of about 4 hours, cooling the resultant reaction reaction mixture to a temperature of 20-25°C, and removing the excess alcohol by evaporation and adjusting the residue to a pH of about 8 with an inorganic base, followed by extraction with ethyl acetate and washing the combined organic phase with brine solution and evaporating the solvent to obtain the desired compound 1,4-bis-{n-[(2S)-A/-(4-oxy-5-methoxy-2-aminobenzoyl)pyrrolidine-2-carboxaldehy-de diethyl thioacetal]alkyloxy}anthracene-9,10-dione of formula IVa-c. (Formula Removed) formula IV wherein n = 3; (IVa) or 4; (IVb), or 5; (IVc) d. reacting amino thioacetal 1,4-bis-{n-[(2S)-N-(4-oxy-5-methoxy-2-aminobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetaljalkyloxy}-anthracene-9,10-dione of formula IVa-c with mercuric chloride in a mixture of water and acetonitrile, in the presence of and calcium carbonate, under stirring, for a period of about 8-10 hours, at a temperature in the range of 25-30°C and diluting it with ethyl acetate, followed by filtration and extraction of the organic supernatant with ethyl acetate, washing the resultant organic phase with sodium bi carbonate and brine, and evaporating the organic layer, followed by purification by known method to obtain the desired product of formula Va-c. In an embodiment of the present invention the mild inorganic base used in steps (a) & (b) is potassium bicarbonate. In yet another embodiment the novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone of formula V obtained is represented by the group of the following compounds: 1,4-Bis-{3-[7-methoxy-8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo[2,1-c][1,4] -benzodiazepin-5-one]propyloxy}anthracene-9,10-dione(Va), 1,4-Bis-{4-[7-me thoxy- 8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo[2,1-c][1,4]benzo diazepin-5- one]butyloxy}anthracene-9,10-dione (Vb) and 1,4-Bis-{5-[7-methoxy-8-oxy-(11aS)- 1,2,3,11a tetrahydro-5H-pyrrolo[2,1-c][1,4]benzodiazepin-5-one]pentyl oxy} anthracene-9,10-dione (Vc). In yet another embodiment the bromoalkane used in step (a) is selected from the group conssiting of 1,3 dibromopropane, 1,3 dibromobutane, and 1,3 dibromopentane. In yet another embodiment the organic solvent used in step (a) is selected from acetone, and acetonitrile. In yet another embodiment the compound of formula lla-c used in step (b) is selected from the group consisting of 1,4-bis-(3-bromo propyloxy)-anthracene-9,10-dione, 1,4-bis-(3-bromobutyloxy)-anthracene-9,10-dione and 1,4-bis-(3-bromo pentyloxy)-anthracene-9,10-dione. In yet another embodiment the organic solvent used in step (b) is selected from acetonitrile, acetone and DMF. In yet another embodiment the compound of formula llla-c used in step (c) is selected from the group consisting of 1,4-bis-{3-[(2S)-N-(4-oxy-5-methoxy-2-nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]propyloxy}anthracene-9,10-dione (IIIa), 1,4-bis-{4-[(2S)-A/-(4-oxy-5-methoxy-2-nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]butyloxy}anthracene-9,10-dione (lllb) and 1,4-bis-{5-[(2S)-N-(4-oxy-5-methoxy-2-nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]pentyloxy}-anthracene-9,10-dione (lllc). In yet another embodiment the alcohol used in step (c) is selected from methanol and ethanol. In yet another embodiment the compound of formula IVa-c used in step (d) is selected from 1,4-bis-{3-[(2S)-N-(4-oxy-5-methoxy-2-aminobenzoyl)pyrrolidine-2- carboxaldehyde diethyl thioacetal]propyloxy}anthracene-9,10-dione (IVa), 1,4-bis-{4- [(2S)-A/-(4-oxy-5-methoxy-2-aminobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]butyloxy}-anthracene-9,10-dione (IV b), and 1,4-bis-{5-[(2S)-N-(4-oxy-5-methoxy-2-aminobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetaljpentyloxy}-anthracene-9,10-dione (IVc). In still another embodiment the novel bis-pyrrolo[2,1-c][1,4] benzodiazepine-anthraquinone conjugates of formula V exhibits an anti tumour activity against human cancer lines selected from the group consisting of lung, cervix, breast, colon, prostate and ovary cell lines. DETAILED DESCRIPTION OF THE INVENTION The present invention provides a process for the preparation of pyrrolo[2,1c][1,4]benzodiazepines anthraquinone- anthraquinone of formula V of the drawing accompanying the specification , (Formula Removed) wherein n = 3, 4 or 5. The invention involves the reaction of 1,4-dihydroxy anthraquinone of formula I with dibromoalkanes in an aprotic water miscible organic solvent, in the presence of a mild inorganic base, at refluxing temperature, for a period of 24h, isolating 1,4-bis-(n-bromo alkyloxy)-anthracene-9,10-dione of formula II and reacting the compound of formula lla-c with (2S)-N-[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carboxaldehyde diethylthioacetal in presence of mild inorganic bases isolating compound of formula III, reducing it with SnCl2H2O in presence of organic solvent at a reflux temperature, reacting the above amino compound of formula IV with known deprotecting agents in a conventional manner to get the novel pyrrol[2,1-c][1,4]benzodiazepine of formula V wherein 'n' are as stated above. The precursor, (2S)-N-[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carboxaldehyde diethylthioacetal has been prepared by literature methods (Thurston, D. E.; Murthy, V. S.; Langley, D. R.; Jones, G. B. Synthesis, 1990, 81). The representative compounds of formula V of present invention are given below: 1] 1,4-Bis-{3-[7-methoxy-8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo [2,1-c][1,4]-benzodiazepin-5-one]propyloxy}anthacene-9,10-dione (Va) 2] 1,4-Bis-{4-[7-methoxy-8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo [2,1-c] [1,4] benzodiazepin-5-one]butyloxy}anthacene-9,10-dione (Vb) 3] 1,4-Bis-{5-[7-methoxy-8-oxy-(11aS)-1,2,3,11a tetrahydro-5H-pyrrolo [2,1-c] [1,4] benzodiazepin-5-one]pentyloxy}anthacene-9,10-dione(Vb) These new analogues of pyrrolo[2,1-c][1,4]benzodiazepine hybrids have shown promising anticancer activity in selected human cancer cell lines. The molecules synthesized are of immense biological significance with potential sequence selective DNA-binding property. This resulted in the design and synthesis of new congeners as illustrated in Scheme which comprises of 1. The ether linkage at C-8 position of DC-81 intermediates with anthraquinone moiety. 2. Refluxing the reaction mixture for 24-48h. 3. Synthesis of C-8 linked PBD hybrids. 4. Purification by column chromatography using different solvents like ethyl acetate, hexane, dichloromethane and methanol. The following examples are given by way of illustration and therefore should not be construed to limit the scope of the invention. Example 1 To a solution of 1,4-dihydroxy anthraquinone (480 mg, 2 mmol) in acetone (30 mL) were added anhydrous potassium carbonate (1.1 g, 8 mmol) and 1,3 dibromopropane (1.21 g, 6 mmol) and the mixture was refluxed for 24 h. The progress of the reaction was monitored by TLC. After completion of the reaction, potassium carbonate was removed by filtration and the solvent was evaporated under reduced pressure to get the crude product. This was further purified by column chromatography (30% EtOAc-hexane) to afford the compound IIa as a yellow solid (791 mg, 82%). 1H NMR (CDCI3): δ 2.40-2.52 (m, 4H), 3.85-3.91 (t, 4H, J = 6.51 Hz), 4.22-4.28 (t, 4H, J = 5.53 Hz), 7.34 (s, 2H), 7.71-7.77 (m, 2H), 8.15-8.18 (m, 2H). FABMS: 482 (M+). To a solution of 1,4-bis-(3-bromo propyloxy)-anthracene-9,10-dione (Ha) (482 mg, 1mmol) in dry acetonitrile (30 mL) were added anhydrous K2C03 (829 mg, 6 mmol)and (2S)-N-[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carboxaldehyde diethyl thioacetal (801 mg, 2mmol). The reaction mixture was refluxed for 24 h. After completion of reaction K2CO3 was removed by filtration and the solvent was evaporated under reduced pressure, the crude product was purified by column chromatography (80% EtOAc-hexane) to afford compound Ilia (807 mg, 72%). 1H NMR (CDCI3): δ 1.24-1.40 (m, 12H), 1.92-2.15 (m, 8H), 2.62-2.82 (m, 8H), 3.12-3.25 (m, 4H), 3.92 (s, 6H), 4.05-4.32 (m, 8H), 4.60-4.72 (m, 2H), 4.82 (d, 2H, J = 3.66 Hz), 6.75 (s, 2H), 7.24 (s, 2H), 7.61-7.74 (m, 4H), 8.02-8.18 (m, 2H). FABMS: 1121 (M+). The compound Ilia (1.121 g, 1 mmol) dissolved in methanol (40 mL) and added SnCl2.2H20 (2.256 g, 10 mmol) was refluxed for 4 h. The reaction mixture was cooled and the methanol was evaporated under vacuum. The residue was carefully adjusted to pH 8 with saturated NaHC03 solution and then extracted with ethyl acetate (2x30 mL). The combined organic phase was washed with brine (15 mL), dried over anhydrous Na2S04 and evaporated under vacuum to afford the amino diethyl thioacetal IVa as a yellow oil (895 mg, 82%) and directly used in the next step. A solution of amino thioacetal 33a (1.19 g, 1 mmol), HgCb (1.19 mg, 4.4 mmol) and CaC03 (480 mg, 4.8 mmol) in acetonitrile-water (4:1) was stirred slowly at rt for overnight, until TLC indicate the complete disappearance of starting material. The reaction mixture was diluted with ethyl acetate (30 mL) and filtered through a celite. The clear yellow organic supernatant was extracted with ethyl acetate (2x20 mL). The organic layer was washed with saturated NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried over anhydrous Na2S04. The organic layer was evaporated under vacuum and the crude product was purified by column chromatography (15% MeOH-EtOAc) to afford the compound Va as a yellow solid (493 mg, 51%). 1H NMR (CDCI3): 5 1.96-2.05 (m, 4H), 2.20-2.50 (m, 8H), 3.55-3.85 (m, 6H), 3.92 (s, 6H), 4.20-4.32 (m, 4H), 4.42-4.52 (m, 4H), 6.85 (s, 2H), 7.22 (s, 2H), 7.40 (s, 2H), 7.52 (d, 2H, J = 4.39 Hz), 7.65-7.71 (m, 2H), 8.02-8.15 (m, 2H). FABMS: 968 (M++1). Example 2 To a solution of 1,4-dihydroxy anthraquinone (480 mg, 2 mmol) in acetone (30 mL) were added anhydrous potassium carbonate (1.1 g, 8 mmol) and 1,3 dibromobutane (1.29 g, 6 mmol) and the mixture was refluxed for 24 h. The progress of the reaction was monitored by TLC. After completion of the reaction, potassium carbonate was removed by filtration and the solvent was evaporated under reduced pressure to get the crude product. This was further purified by column chromatography (30% EtOAc-hexane) to afford the compound lib as a yellow solid (826mg, 81%). 1H NMR (CDCI3, 200 MHz) 1.25-1.40 (m, 6H), 1.72-2.42 (m, 6H), 2.70-2.8 (m, 4H), 3.15-3.30 (m, 2H), 3.60 (t, 2H, J = 6.20 Hz), 3.95 (s, 3H), 4.20 (t, 2H, J = 4.96 Hz), 4.60-4.75 (m, 1H), 4.82 (d, 1H, J=4.33 Hz), 6.78 (s, 1H), 7.68 (s, 1H). To a solution of 1,4-bis-(3-bromo butyloxy)-anthracene-9,10-dione (llb) (510 mg, 1mmol) in dry acetonitrile (30 mL) were added anhydrous K2CO3 (829 mg, 6 mmol) and (2S)-N-[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carboxaldehyde diethyl thioacetal (810 mg, 2mmol). The reaction mixture was refluxed for 24 h. After completion of reaction K2CO3 was removed by filtration and the solvent was evaporated under reduced pressure, the crude product was purified by column chromatography (80% EtOAc-hexane) to afford compound lllb (805 mg, 70%). 1H NMR (CDCI3): δ 1.25-1.40 (m, 12H), 2.0-2.32 (m, 16H), 2.62-2.80 (m, 8H), 3.12-3.25 (m, 4H), 3.92 (s, 6H), 4.08-4.40 (m, 8H), 4.60-4.71 (m, 2H), 4.82 (d, 2H, J= 3.62 Hz), 6.77 (s, 2H), 7.23 (s, 2H), 7.62-7.78 (m, 4H), 8.02-8.18 (m, 2H). FABMS: 1150[M+1]+ The compound lllb (1.15 g, 1 mmol) dissolved in methanol (40 mL) and added SnCI2.2H20 (2.256 g, 10 mmol) was refluxed for 4 h. The reaction mixture was cooled and the methanol was evaporated under vacuum. The residue was carefully adjusted to pH 8 with saturated NaHC03 solution and then extracted with ethyl acetate (2x30 mL). The combined organic phase was washed with brine (15 mL), dried over anhydrous Na2S04 and evaporated under vacuum to afford the amino diethyl thioacetal IVb as a yellow oil (895 mg, 80%) and directly used in the next step. A solution of amino thioacetal IVb (1.12 mg, 1 mmol), HgCI2 (1.19 mg, 4.4 mmol) and CaCO3 (480 mg, 4.8 mmol) in acetonitrile-water (4:1) was stirred slowly at rt for overnight, until TLC indicate the complete disappearance of starting material. The reaction mixture was diluted with ethyl acetate (30 mL) and filtered through a celite. The clear yellow organic supernatant was extracted with ethyl acetate (2x20 mL). The organic layer was washed with saturated NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried over anhydrous Na2S04. The organic layer was evaporated under vacuum and the crude product was purified by column chromatography (15% MeOH-EtOAc) to afford the compound Vb as a yellow solid (517 mg, 52%). 1H NMR (CDCI3): δ 1.96-2.35 (m, 16H), 3.50-3.84 (m, 6H), 3.92 (s, 6H), 4.12-4.38 (m, 8H), 6.82 (s, 2H), 7.23 (s, 2H), 7.42 (s, 2H), 7.56 (d, 2H, J = 4.39 Hz), 7.62-7.72 (m, 2H), 8.02-8.18 (m,2H). FABMS: 996 [M+1]+ Example 3 To a solution of 1,4-dihydroxy anthraquinone (480 mg, 2 mmol) in acetone (30 mL) were added anhydrous potassium carbonate (1.1 g, 8 mmol) and 1,3 dibromopentane (1.38 mg, 6 mmol) and the mixture was refluxed for 24 h. The progress of the reaction was monitored by TLC. After completion of the reaction, potassium carbonate was removed by filtration and the solvent was evaporated under reduced pressure to get the crude product. This was further purified by column chromatography (30% EtOAc-hexane) to afford the compound lie as a yellow solid (904 mg, 84%). 1H NMR (CDCI3): 81.75-2.07 (m, 12H), 3.49 (t, 4H, J = 6.59 Hz), 4.08 (t, 4H, J = 6.13 Hz), 7.25 (s, 2H), 7.69-7.75 (m, 2H), 8.13-8.20 (m, 2H). FABMS: 538 [M]+ To a solution of 1,4-bis-(3-bromo pentyloxy)-anthracene-9,10-dione (lie) (538 mg, 1 mmol) in dry acetonitrile (30 mL) were added anhydrous K2C03 (829 mg, 6 mmol) and (2S)-/V-[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carboxaldehyde diethyl thioacetal (801 mg, 2 mmol). The reaction mixture was refluxed for 24 h. After completion of reaction K2CO3 was removed by filtration and the solvent was evaporated under reduced pressure, the crude product was purified by column chromatography (80% EtOAc-hexane) to afford compound lllc (824 mg, 70%). 1H NMR (CDCI3): δ 1.23-1.42 (m, 12H), 1.83-2.18 (m, 20H), 2.65-2.85 (m, 8H), 3.12-3.28 (m, 4H), 3.93 (s, 6H), 4.05-4.20 (m, 8H), 4.60-4.71 (m, 2H), 4.83 (d, 2H, J = 3.66 Hz), 6.77 (s, 2H), 7.24 (s, 2H), 7.60-7.73 (m, 4H), 8.02-8.18 (m, 2H). FABMS: 1178[M+1]+ The compound lllc (1.18 g, 1 mmol) dissolved in methanol (40 mL) and added SnCl2.2H2O (2.256 g, 10 mmol) was refluxed for 4 h. The reaction mixture was cooled and the methanol was evaporated under vacuum. The residue was carefully adjusted to pH 8 with saturated NaHC03 solution and then extracted with ethyl acetate (2x30 mL). The combined organic phase was washed with brine (15 mL), dried over anhydrous Na2S04 and evaporated under vacuum to afford the amino diethyl thioacetal IVc as a yellow oil (963 mg, 84%) and directly used in the next step. A solution of amino thioacetal IVc (1.15 mg, 1 mmol), HgCI2 (1.19 mg, 4.4 mmol) and CaC03 (480 mg, 4.8 mmol) in acetonitrile-water (4:1) was stirred slowly at rt for overnight, until TLC indicate the complete disappearance of starting material. The reaction mixture was diluted with ethyl acetate (30 mL) and filtered through a celite. The clear yellow organic supernatant was extracted with ethyl acetate (2x20 mL). The organic layer was washed with saturated NaHCO3 (20 mL), brine (20 mL) and the combined organic phase was dried over anhydrous Na2SO4. The organic layer was evaporated under vacuum and the crude product was purified by column chromatography (15% MeOH-EtOAc) to afford the compound Vc as a yellow solid (522 mg, 51%). 1H NMR (CDCl3): δ 1.95-2.32 (m, 20H), 3.53-3.82 (m, 6H), 3.92 (s, 6H), 4.07-4.13 (m, 8H), 6.76 (s, 2H), 7.23 (s, 2H), 7.44 (s, 2H), 7.58 (d, 2H, J = 4.40 Hz), 7.65-7.69 (m, 2H), 8.02-8.16 (m,2H). FABMS: 1024[M+1]+ Biological activity In vitro cytotoxicity against human cancer cell lines: Cytotoxicity: Compounds Va-c have been evaluated for the primary anticancer activity in selected human cancer cell lines. The cytotoxicity data for some representative compounds is shown in Table 1. For each compound, dose response curves against each cell line were measured at a minimum of five concentrations at 10 fold dilutions. A protocol of 48 h continuous drug exposure was used and a sulforhodamine B (SRB) protein assay was used to estimate cell viability or growth. The concentration causing 50 % cell growth inhibition compared with the control has been calculated. Table 1. In vitro cytotoxicity of compounds Va-c (Table Removed) aDose of compound required to inhibit cell growth by 50% compared to untreated cell controls The comparison of the data of Table 1 reveals the importance of the alkane spacer. The 3 carbon spacer of compound Va confers a suitable fit in the minor groove of double helix DNA and shows slightly higher activity in this series of compounds. We claim 1. Novel bis-pyrrolo[2,1-c][1,4]benzodiazepine-anthraquinone conjugates of general formula v, (Formula Removed) wherein n = 3; (va) or 4; (vb), or 5; (vc). 2. A process for the preparation of novel bis-pyrrolo[2,1-c][1,4]benzodiazepine- anthraquinone conjugates of formula V, the said process comprising the steps of: a. reacting 1,4-dihydroxy anthraquinone of formula I with dibromoalkanes, in an aprotic water miscible organic solvent, in the presence of a mild inorganic base, at refluxing temperature, for a period of about 24 hours, followed by the removal of inorganic base by filtration and removing the organic solvent by evaporation, under reduced pressure, to obtain the 1,4-bis-(3-bromo (Figure Removed) alkoxy)-anthracene-9,10-dione of formula lla-c, Wherein n = 3; (Ha) or 4; (llb), or 5; (lle) b. reacting 1,4-bis-(3-bromo alkoxy)anthracene-9,10-dione of formula lla-c with (2S)-N-[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carbox aldehyde diethyl thioacetal in a dry organic solvent, in the presence of mild inorganic base, at refluxing temperature, for a period of about 24 hours, followed by the removal of inorganic base by filtration and removing the organic solvent by evaporation, under reduced pressure, to obtain the desired product 1,4-bis-{n-[(2S)-N-(4-oxy-5-methoxy-2- nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]alkyloxy}-anthracene-9,10-dione of formula llla-c, wherein n = 3; (Ilia) or 4; (1Mb), or 5; (lllc) c. reducing the compound 1,4-bis-{n-[(2S)-N-(4-oxy-5-methoxy-2- nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]alkyloxy}- anthracene-9,10-dione of formula III by using tin chloride, in an alcoholic solvent, under reflux, for a period of about 4 hours, cooling the resultant reaction reaction mixture to a temperature of 20-25°C, and removing the excess alcohol by evaporation and adjusting the residue to a pH of about 8 with an inorganic base, followed by extraction with ethyl acetate and washing the combined organic phase with brine solution and evaporating the solvent to obtain the desired compound amino thioacetal 1,4-bis-{n- [(2S)-/V-(4-oxy-5-methoxy-2-aminobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]alkyloxy}-anthracene-9,10-dione of formula IVa-c, (Formula Removed) wherein n = 3; (IVa) or 4; (IVb), or 5; (IVc) d. reacting amino thioacetal amino thioacetal 1,4-bis-{n-[(2S)-N-(4-oxy-5- methoxy-2-aminobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioace- tal]alkyloxy}anthracene-9,10-dione of formula IVa-c with mercuric chloride in a mixture of water and acetonitrile, in the presence of and calcium carbonate, under stirring, for a period of about 8-10 hours, at a temperature in the range of 25-30°C and diluting it with ethyl acetate, followed by filtration and extraction of the organic supernatant with ethyl acetate, washing the resultant organic phase with sodium bi carbonate and brine, and evaporating the organic layer, followed by purification by known method to obtain the desired product of formula Va-c. 3. A process as claimed in claim 2, wherein the mild inorganic base used in steps (a) & (b) is potassium bicarbonate. 4. A process as claimed in claim 2, wherein the bromoalkane used in step (a) is selected from the group conssiting of 1,3 dibromopropane, 1,3 dibromobutane, and 1,3 dibromopentane. 5. A process as claimed in claim 2, wherein the aprotic organic solvent used in step (a) is selected from acetone and acetonitrile. 6. A process as claimed in claim 2, wherein the compound of formula lla-c used in step (b) is selected from the group consisting of 1,4-bis-(3-bromo propyloxy)-anthracene-9,10-dione, 1,4-bis-(3-bromobutyloxy)-anthracene-9,10-dione and 1,4-bis-(3-bromo pentyloxy)-anthracene-9,10-dione. 7. A process as claimed in claim 2, wherein the organic solvent used in step (b) is selected from acetonitrile, acetone and DMF. 8. A process as claimed in claim 2, wherein the compound of formula llla-c used in step (c) is selected from the group consisting of 1,4-bis-{3-[(2S)-N-(4-oxy-5- methoxy-2-nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]- propyloxy}anthracene-9,10-dione (Illa), 1,4-bis-{4-[(2S)-N-(4-oxy-5-methoxy-2- nitrobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]butyloxy}- anthracene-9,10-dione (1Mb) and 1,4-bis-{5-[(2S)-N-(4-oxy-5-methoxy-2-nitro- benzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]pentyloxy}- anthracene-9,10-dione (Illc). 9. A process as claimed in claim 2, wherein the alcohol used in step (c) is selected from methanol and ethanol. 10. A process as claimed in claim 2, wherein the compound of formula IVa-c used in step (d) is selected from 1,4-bis-{3-[(2S)-N-(4-oxy-5-methoxy-2-aminobenzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]propyloxy}-anthracene-9,10-dione (Na), 1,4-bis-{4-[(2S)-N-(4-oxy-5-methoxy-2-amino- benzoyl)pyrrolidine-2-carboxaldehyde diethyl thioacetal]butyloxy}-anthracene-9,10-dione (IV b), and 1,4-bis-{5-[(2S)-N-(4-oxy-5-methoxy-2-aminobenzoyl)-pyrrolidine-2-carboxaldehyde diethyl thioacetal]pentyloxy}-anthracene-9,10-dione

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