Reversal of multidrug resistance in human colon carcinoma cells

The present invention describes the use of fumitremorgin A, B and C and a series of diketopiperazines of Formula (I) to resensitize multidrug resistant (MDR) cancer cells to the cytotoxic effects of chemotherapeutic drugs.

EXAMPLE 1 
 (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester To the suspension of L-tryptophan methyl ester hydrochloride (1 mmol) in dry toluene(150 ml), was added isovaleraldehyde (1 mmol). The resulting mixture was refluxed for about 15 hours with stirring and cooled to room temperature before methanol (100 ml) was added to dissolve the products. The organic solution, upon filtration, was concentrated in vacuo to afford the hydrochloride salts of a pair of diastereoisomers at C-1 of the desired product with quantitative yield and a 2:1 cis/trans ratio. 
 EXAMPLE 2 
 (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methyl-1-propenyl)-methyl ester The compound was prepared by procedures described for example 1, except that isovaleraldehyde was replaced with 3-methyl-2-butenal. 
 EXAMPLE 3 
 (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-nonyl-methyl ester The compound was prepared by procedures described for example 1, except that isovaleraldehyde was replaced with decyl aldehyde. 
 EXAMPLE 4 
 (3S)-1H-Pyrido &lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(5-phenylpentyl)-methyl ester The compound was prepared by procedures described for example 1, except that isovaleraldehyde was replaced with 6-phenyldecanal. 
 EXAMPLE 5 
 (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(3-benzyloxycarbamate-propyl)-methyl ester A mixture of L-tryptophan methyl ester hydrochloride (2.0 mmol), p-toluenesulfonic acid (0.5 mmol), and 4-benzyloxycarbamate-butyraldehyde diethyl acetal (2.0 mmol), in N,N-dimethylformamide (2 mL) was stirred at 110° C. for 45 min. The yellowish solution was cooled to room temperature, before sodium bicarbonate solution (sat., 100 mL) was added. The products were extracted with ethyl acetate (200 mL), washed with water, dried, and evaporated in vacuo to afford the hydrochloride salts of a pair of diastereoisomers at C-1 with quantitative yield. The 4-benzyloxycarbamate-butyraldehyde diethyl acetal was synthesized by reacting 4-animo-butyraldehyde diethyl acetal with benzyloxycarbonyl chloride in sodium carbonate solution (sat.) at room temperature. 
 EXAMPLE 6 
 (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-methyl ester A solution of L-tryptophan methyl ester hydrochloride (2.1 mmol), p-toluenesulfonic acid (0.5 mmol) in 1:1 N,N-dimethylformamide/diethoxymethane (4 ml total) was refluxed for 30 minutes. The reaction mixture was partitioned between ethyl acetate (200 ml) and 10% sodium bicarbonate (200 ml). The organic layer was separated, washed with water and evaporated in vacuo to afford the desired product with quantitative yield. 
 EXAMPLE 7 
 (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-methyl-methyl ester The compound was prepared by procedures described for example 6, except that the diethoxymethane was replaced with acetaldehyde diethyl acetal. 
 EXAMPLE 8 
 (3R)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester The compound was prepared by procedures described for example 1, except that the L-tryptophan methyl ester hydrochloride was replaced with its D enantiomer. 
 EXAMPLE 9 
 2,2,2-Trichloroethoxy-carbonyl(Troc)-L-prolyl Chloride Solutions of 2,2,2-trichloroethyl chloroformate (2.0 mmol) in ether (1 ml), and 2N sodium hydroxide (1 ml) were carefully added simultaneously to a vigorously stirred emulsion of L-proline (1.6 mmol) in 2N NaOH (1 ml) and ether (0.5 ml) with ice-cooling. The bath was removed and the reaction mixture was stirred for one hour. The aqueous layer, washed with ether, was acidified with concentrate hydrochloric acid to pH 1. The product was extracted with ether, washed with water, dried over sodium sulfate, and evaporated under reduced pressure to afford 2,2,2-trichloroethoxy-carbonyl(Troc)-proline as a colorless oil with quantitative yield. The 2,2,2-trichloroethoxy-carbonyl(Troc)-proline (1 mmol) was dissolved in thionyl chloride (1.5 mmol) and the solution stirred for 15 hours at ambient temperature. The volatiles were removed by evaporation under reduced pressure to obtain a colorless oil, identified as the desired product by NMR analysis. 
 EXAMPLE 10 
 Troc-S-(−)-2-Azetidinecarboxyl Chloride The product of the example was prepared using the procedure of Example 9 with the exception that L-proline was replaced by S-(−)-2-Azetidinecarboxylic acid. 
 EXAMPLE 11 
 Troc-L-pipecolinyl Chloride The product of the example was prepared using the procedure of Example 9 with the exception that L-proline was replaced with L-pipecolinic acid. 
 EXAMPLE 12 
 Troc-D-prolinyl Chloride The product of the example was prepared using the procedure of Example 9 with the exception that L-proline was replaced with D-proline. 
 EXAMPLE 13 
 Troc-D-pipecolinyl Chloride The product of the example was prepared using the procedure of Example 9 with the exception that L-proline was replaced with D-pipecolinic acid. 
 EXAMPLES 14a and 14b 
 (5aS,12R,14aS)-12-isobutyl-1,2,3,5a6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione(14a) and 
 (5aS,12S,14aS)-12-isobutyl-1,2,3,5a6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione(14b) To the stirred solution of (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester (1.0 mmol) in dry dichloromethane (5.0 ml) and triethylamine (0.3 g), was slowly added Troc-L-prolyl chloride at 1:1 molar ratio in dichloromethane (2.0 ml) with ice-cooling. The bath was removed and the reaction mixture was stirred at ambient temperature for 1 hour before diluted with dichloromethane (50 ml). The organic solution was then washed sequentially with water, sodium bicarbonate (sat.) and water, dried over sodium sulfate, and evaporated to afford a yellowish powder. The powder was then dissolved in 2:1 methanol/dichloromethane (2.0 ml) and refluxed in the presence of zinc dust (0.3 g) for 2 hours. The metal was removed by filtration through diatomaceous earth and the organic solution evaporated to afford a yellowish solid, which was suspended in 5% hydrochloric acid (100 ml) and extracted by dichloromethane (2×50 ml). The combined organic layer was washed with water, dried and evaporated in vacuo to yield a mixture of diastereoisomer pair with 2:3 12R/12S ratio. The mixture was further separated by HPLC on a C18 column using mobile phase that consisted of gradient solvent system of acetonitrile in water to afford desired products in pure form with a 54% overall combined yield. ESIMS (MH &plus; ): 14a, 352.1; 14b, 352.2. 
 EXAMPLES 15a and 15b 
 (5aR,12R,14aS)-12-isobutyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione(15a) and 
 (5aR,12S 14aS)-12-isobutyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione(15b) The compounds were prepared by procedures described for Examples 14a and 14b, except that the (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester was replaced by (3R)-1-H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester. ESIMS(MH &plus; ): 15a, 352.2; 15b, 352.2. 
 EXAMPLES 16a and 16b 
 (5aS,12R,14aR-12-isobutyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione(16a) and 
 (5aS,12S,14aR)-12-isobutyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione(16b) The compounds were prepared by procedures described for Examples 14a and 14b, except that the Troc-L-prolyl chloride was replaced with Troc-D-prolyl chloride. ESIMS(MH &plus; ): 16a, 352.2; 16b, 352.2. 
 EXAMPLES 17a and 17b 
 (5aR,12R,14aR)-12-isobutyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione(17a) and 
 (5aR,12S,14aR)-12isobuty-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione(17b) The compounds were prepared by procedures described for Examples 14a and 14b, except that the (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester and Troc-L-prolyl chloride were respectively replaced with (3R)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester and Troc-D-prolyl chloride. ESIMS(MH &plus; ): 17a, 352.3; 17b, 352.2. 
 EXAMPLES 18a and 18b 
 (6aS,13R,15aS)-13-isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro-6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-6H,15H-dione(18a) and 
 (6aS,13S,15aS)-13-isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro-6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-6H,15H-dione(18b) The compounds were prepared by procedures described for Examples 14a and 14b, except that the Troc-L-prolyl chloride was replaced with Troc-L-pipecolinyl chloride. ESIMS (MH &plus; ): 18a, 366.2; 18b, 366.2. 
 EXAMPLES 19a and 19b 
 (6aR,13R,15aS)-13-isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro-6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-6H,15H-dione(19a) and 
 (6aR,13S,15aS)-13-isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro-6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-6H,15H-dione(19b) The compounds were prepared by procedures described for Examples 15a and 15b, except that the Troc-L-prolyl chloride was replaced with Troc-L-pipecolinyl chloride. ESIMS (MH &plus; ): 19a, 366.1; 19b, 366.3. 
 EXAMPLES 20a and 20b 
 (6aS,13R,15aR)-13-isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-6H,15H-dione(20a) and 
 (6aS,13S,15aR)-13-isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro-6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-6H,15H-dione(20b) The compounds were prepared by procedures described for Examples 16a and 16b, except that the Troc-D-prolyl chloride was replaced with Troc-D-pipecolinyl chloride. ESIMS (MH &plus; ): 20a, 366.2; 20b, 366.2. 
 EXAMPLES 21a and 21b 
 (6aR,13R,15aR)-13-isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro-6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-6H,15H-dione(20a) and 
 (6aR,13S,15aR)-13isobutyl-1,2,3,4,6a,7,12,13,15a-nonahydro-6H,15H-pyrido&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-6H,15H-dione(21b) The compounds were prepared by procedures described for Examples 17a and 17b, except that the Troc-D-prolyl chloride was replaced with Troc-D-pipecolinyl chloride. ESIMS (MH &plus; ): 21a, 366.1; 21b, 366.2. 
 EXAMPLES 22a and 22b 
 (4aS,11R,13aS)-11-isobutyl-1,4a,5,10,11,13a-hexahydro-4H-azeto&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-4,13(2H)-dione(22a) and 
 (4aS,11S,13aS)-1-isobutyl-1,4a,5,10,11,13a-hexahydro-4H-azeto&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-4,13(2H)-dione(22b) The compounds were prepared by procedures described for Examples 14a and 14b, except that the Troc-L-prolyl chloride was replaced with S-(−)-2-Azetidinecarboxyl chloride. ESIMS(MH &plus; ): 22a, 338.2; 22b, 338.1. 
 EXAMPLES 23a and 23b 
 (5aS,12R,14aS)-12-(5-phenylpentyl)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione(23a) and 
 (5aS,12S,14aS)-12-(5-phenylpentyl)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione(23b) As described for examples 14a and 14b, but substituting (3S)-1-H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(5-phenylpentyl)-methyl ester for (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester), the desired compounds were prepared. ESIMS (MH &plus; ): 23a, 442.2; 23b, 442.2. 
 EXAMPLES 24a and 24b 
 benzyl 3-&lsqb;(5aS,12R,14aS)-5,14-dioxo-2,3,5a,6,11,12,14,14a-octahydro-1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-12-yl&rsqb;propylcarbamate(24a) 
 and benzyl 3-&lsqb;(5aS,12S,14aS)-5,14-dioxo-2,3,5a,6,11,12,14,14a-octahydro-1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-12yl&rsqb;propylcarbamate(24b) (ESIMS, MH &plus; ) (24a,487.1) (24b, 487.2). As described for examples 14a and 14b, but substituting (3S)-1-H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(3-benzyloxycarbamate-propyl)-methyl ester for (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester), the desired compounds were prepared. ESIMS (MH &plus; ): 24a, 487.1; 24b, 487.2. 
 EXAMPLE 25 
 (5aS,14aS)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione As described for examples 14a and 14b, but substituting (3S)-1-H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-methyl ester for (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester), the desired compound was prepared. ESIMS (MH &plus; ): 296.3. 
 EXAMPLE 26 
 (5aS,12S 14aS)-12-methyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione As described for examples 14a and 14b, but substituting (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-methyl-methyl ester for (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester), the desired compound was prepared. 12S isomer was the predominant product, and was the only one isolated. ESIMS (MH &plus; ): 310.3. 
 EXAMPLE 27 
 (5aS,12S 14aS)-12-(2-methylprop-1-enyl)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione As described for example 14, but substituting (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methyl-1-propenyl)-methyl ester for (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester), the desired compound was prepared. 12S isomer was the predominant product, and was the only one isolated. ESIMS (MH &plus; ): 350.2. 
 EXAMPLE 28 
 (5aS,12S,14aS)-12-nonyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione As described for examples 14a and 14b, but substituting (3S)-1H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-nonyl-methyl ester for (3S)-1-H-Pyrido&lsqb;3,4-b&rsqb;indole-3-carboxylic acid, 2,3,4,9-tetrahydro-1-(2-methylpropyl)-methyl ester), the desired compound was prepared. 12S isomer was the predominant product, and was the only one isolated. ESIMS (MH &plus; ): 422.2. 
 EXAMPLES 29a and 29b 
 (5aS,12R.14aS)-12-(3-aminopropyl)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione(29a) and 
 (5aS,12S,14aS)-12-(3-aminopropyl)-1,2,3,5 a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione(29b) The solution of benzyl 3-&lsqb;(5aS,12R,14aS)-5,14-dioxo-2,3,5a,6,11,12,14,14a-octahydro-1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indol-12-yl&rsqb;propylcarbamate (0.1 mmol) in methanol (2.0 ml) was stirred under hydrogen (1.5 atm) in the presence of 5% Palladium on carbon for 1 hour. The solid was removed by filtration, and the solution was evaporated to afford (5aS,12R,14aS)-12-(3-aminopropyl)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione (95%). The (5aS,12S,14aS)-12-(3-aminopropyl)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione was prepared in a similar manner, but using 3-&lsqb;(5aS,12S,14aS)-5,14-dioxo-2,3,5a,6,11,12,14,14a-octahydro-1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino &lsqb;2′,1′:6,1&rsqb;pyrido &lsqb;3,4-b&rsqb;indol-12-yl&rsqb;propylcarbamate as starting material. ESIMS (MH &plus; ): 29a, 353.2; 29b, 353.2. 
 EXAMPLE 30 
 N-&lcub;3-&lsqb;(5aS,12S,14aS)-5,14-dioxo-2,3,5a6,11,12,14,14a-octahydro-1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-12-yl&rsqb;propyl&rcub;acetamide To a solution of (5aS,12S,14aS)-12-(3-aminopropyl)-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:′,4′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4-b&rsqb;indole-5,14-dione (25 mg) in pyridine (0.5 ml) was added 3 drops of acetic anhydride, and the reaction mixture was stirred for 15 hours. The solution was evaporated and the residue purified by HPLC using a C18 column and gradient solvent of acetonitrile in water to afford the desired product (26 mg). ESIMS (MH &plus; ): 395.1. 
 EXAMPLE 31 
 N-&lcub;3-&lsqb;(5aS,12S,14aS)-5,14-dioxo-2,3,5a,6,11,12,14,14a-octahydro-1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-12-yl&rsqb;propyl&rcub;butanamide As described for Example 30, but substituting butyric anhydride for acetic anhydride the product of the example was prepared. ESIMS (M &plus; ): 423.2. 
 EXAMPLE 32 
 4-(&lcub;3-&lsqb;(5aS,12S,14aS)-5,14-dioxo-2,3,5a,6,11,12,14,14a-octahydro-1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-12-yl&rsqb;propyl&rcub;amino)-4-oxobutanoic acid As described for Example 30, but substituting succinic anhydride for acetic anhydride the product of the example was prepared. ESIMS (MH &plus; ): 453.2. 
 EXAMPLE 33 
 (2S)-N-&lcub;3-&lsqb;(5aS,12S,14aS)-5,14-dioxo-2,3,5a,6,11,12,14,14a-octahydro1H,5H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-12-yl&rsqb;propyl&rcub;pyrrolidine-2-carboxamide The compound was prepared by using procedure described for Example 30, but replacing acetic anhydride with Troc-L-prolyl chloride. The Troc group was then removed by refluxing with zinc dust and the product was purified by HPLC. ESIMS (MH &plus; ) 450.3. 
 EXAMPLE 34 
 (5aS,12S,4aS)-9-methoxy-11-(3-methylbut-2-enyl)-12-(2-methylprop-1-enyl-1,2,3,5a,6,11,12,14a-octahydro-5H,14H-pyrrolo&lsqb;1″,2″:4′,5′&rsqb;pyrazino&lsqb;2′,1′:6,1&rsqb;pyrido&lsqb;3,4b&rsqb;indole-5,14-dione To a stirred suspension of sodium hydride (0.12 mol) in dry dichloromethane (0.1 ml) was added a solution of fumitremorgin C (0.05 mmol) in dichloromethane (0.5 ml) under an atmosphere of nitrogen at room temperature. Upon stirring for forty-five minutes, 3,3-dimethyl allyl bromide (0.11 mmol) was added and the reaction mixture stirred under nitrogen for two hours. Saturated aqueous solution of ammonium chloride was then added, and the alkylation product was extracted with ethyl acetate and purified by HPLC on a C18 column using methanol/water as mobile phase. MS and 1 H NMR spectra were consistent with the desired product.