Antineoplastic cyclolignan derivatives

Abstract: Antineoplastic cyclolignan derivatives are of formula (I): in which Ar is a 3,4,5-trialkoxyphenyl or 4-hydroxy-3,5-dialkoxyphenyl; X is an oxygen, sulphur or nitrogen atom, a methine group =CH- or an alkylmethine group =C(alkyl)-; Y is a hydrogen atom or an alkyl, alkenyl, (poly)haloalkyl, aryl, hydroxy, alkoxy, amino, monoalkylamino, dialkylamino, (poly)haloalkylamino, arylamino, acyl or acetamido group, or the group Y is absent; Z is an alkyl, hydroxyalkyl, acyl, carboxy, alkoxycarbonyl or aryloxycarbonyl group; and the dotted lines indicate one double bond located at position Δ⁷⁻⁸ or Δ 8-8' .

Description: This invention is concerned with antineoplastic cyclolignan derivatives, the preparation of such derivatives, and pharmaceutical compositions containing them. The biological assay and antimitotic activity of synthetic derivatives of podophyllotoxin is reported in Current Science, August 5, 1986, Vol. 55, No, 15, pp 701 - 706. Data is given for β-apopicropodophyllyl dialdehyde. Methyl 9-deoxy-9-oxo-α-apopicropodophyllate is a compound known from Chem. Soc. Perkin Trans. 1, 1993, 2541-2548, though no utility is indicated. US 3,524,844 describes epipodophyllotoxin glucoside derivatives with cytostatic activity. It has now been found, in accordance with the present invention, that certain new cyclolignan derivatives as hereinafter defined, possess good selectivity as cytotoxic agents against in vitro cultured solid tumour cell lines as compared with other lignans. Accordingly, the present invention provides a compound of formula (I): in which Ar is a 3,4,5-trialkoxyphenyl or a 4-hydroxy-3,5-dialkoxyphenyl; and X is a nitrogen atom; Y is a hydrogen atom or an alkyl, alkenyl, aryl, hydroxy, alkoxy, amino, monoalkylamino, dialkylamino, (poly)haloalkyl, arylamino, acyl or acetamido group; Z is an alkyl, hydroxyalkyl, acyl, carboxy, alkoxycarbonyl or aryloxycarbonyl group; and the dotted lines indicate one double bond located at position Δ 7-8 or Δ 8-8' . The present invention also provides a pharmaceutical composition which comprises a compound of formula (I): in which Ar is a 3,4,5-trialkoxyphenyl or a 4-hydroxy-3,5-dialkoxyphenyl; and X is a nitrogen atom; Y is a hydrogen atom or an alkyl, alkenyl, aryl, hydroxy, alkoxy, amino, monoalkylamino, dialkylamino, (poly)haloalkyl, arylamino, acyl or acetamido group; Z is an alkyl, hydroxyalkyl, acyl, carboxy, alkoxycarbonyl or aryloxycarbonyl group; and the dotted lines indicate one double bond located at position Δ 7-8 or Δ 8-8' , together with a pharmaceutically acceptable carrier. The alkyl groups preferably have from 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms. Examples include methyl, ethyl, propyl, isopropyl, butyl, t-butyl and other alkyl groups The aryl group is preferably a phenyl or substituted phenyl group. Suitable substituents include the groups given for Y. The alkoxycarbonyl groups preferably have from 1 to 6 carbon atoms in the alkoxy part, more preferably 1 to 4 carbon atoms. Examples include methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, t-butoxycarbonyl and other alkoxycarbonyl groups. The alkenyl groups preferably have from 3 to 6 carbon atoms, more preferably 3 to 4 carbon atoms. Examples include allyl or crotonyl groups. The (poly)haloalkyl groups preferably have from 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and preferably have one or more fluoro, chloro or bromo atoms. The (poly)haloalkyl groups are suitably monohalo or perhalo groups. Examples include chloroethyl or trifluoroethyl groups. The alkoxy groups preferably have from 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms. Examples include methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy and other alkoxy groups. The substituent groups in the substituted amino groups are suitably as described above. The acyl groups preferably have from 1 to 20 carbon atoms, and more preferably are either short-chain acyl groups with 1 to 3 carbon atoms or long-chain acyl groups with 12 to 18 carbon atoms. The long chain acyl groups may be saturated or unsaturated, preferably of the kind occurring in natural fatty acids. Examples of acyl groups include formyl, acetyl or stearyl. The aryl group of the arylamino group is suitably as described above. The hydroxyalkyl groups are preferably 1- hydroxyalkyl groups, have from 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms. Examples include hydroxymethyl, 1-hydroxyethyl, 1-hydroxypropyl and other hydroxyalkyl groups. The aryloxycarbonyl groups preferably have a phenyl or substituted phenyl group. The present compounds can exist as optical isomers, and the invention embraces the individual isomers and mixtures thereof, including the diastereomeric or racemic mix. The stereochemistry of the substituents may be selected as desired, and for example the group Z can be α or β. More generally, the preferred compounds of this invention include compounds of formula (I), wherein one double bond is located at position 7-8 and the function at position 9 is a hydrazone Individual preferred compounds of this invention include LL-16, which is the phenylhydrazone of methyl 9-deoxy-9-oxo-α-apopicropodophyllate. The compounds of formula I, as noted above, have cytotoxic activity and, accordingly, the invention also provides cytotoxic pharmaceutical compositions comprising a compound of formula I in association with a pharmaceutical carrier or diluent. Such compositions may, for example, be intended for oral, parenteral or rectal administration in association with suitable appropriate adjuvants. The invention also provides a method for the preparation of a cytotoxic composition which comprises using, as cytotoxic ingredient, a compound of formula I. The antineoplastic activity of compounds in accordance with this invention is illustrated by the following table, which shows the IC 50 (µ g/ml) values for several cyclolignan derivatives against different tumour cell lines. P-388 A-549 HT-29 *LL-16 1 0.5 0.02 podophyllotoxin 0.005 0.005 0.01 epipodophyllotoxin 0.5 0.1 0.1 Compounds of the invention may be prepared from podophyllotoxin and related compounds of the Formula (A): For example, see Hartwell and Schrecker, Fortschrite Chem. Org. Naturstoff 15 83 (1953), which describes podophyllotoxin where R is hydroxy and 8'-H is β; deoxypodophyllotoxin where R is hydrogen and 8'-H is β; and deoxypicropodophyllin where R is hydrogen and 8'-H is α. See also J. Med. Chem. 29 1547-1550 (1986) and Chem. Pharm. Bull. 40 2720-2727 (1992). The following reaction scheme illustrates the preparation of representative compounds: a)KOH/MeOH; b)CH 2 N 2 ; c)BCl 3 /C 6 H 6 , heating; d) Swern oxidation; e) Y-NH 2 ; Other equivalent reaction conditions can be employed, and as appropriate other known starting compounds can be used. EXAMPLES OF THE INVENTION In order that the invention may be further understood, the following Reference Examples and Examples are given by way of illustration only. Example 1 (Reference) Preparation of LL-15 400 mg of podophyllotoxin were dissolved in 30 ml of KOH/MeOH 10% and stirred at room temperature for 30 minutes. After removing the methanol, water was added and the solution was neutralized by 2N HCI until the pH was 7, and then extracted with EtOAc. The reaction product was treated with an ethereal solution of CH 2 N 2 to afford 430 mg of methyl picropodophyllate. To a precooled (-60°C) and stirred solution of oxalyl chloride (0.24 ml) in dry CH 2 CI 2 (5 ml) was added dropwise 0.4 ml of DMSO in CH2CI 2 (2 ml). After 5 minutes at -60°C, a solution of 430 mg of methyl picropodophyllate in 3 ml of CH 2 CI 2 was slowly added. The reaction mixture was kept at the same temperature for 30 min, then triethylamine (1.27 ml) was added. The mixture was warmed to 0°C over 1 hour, quenched with water and extracted with CH 2 CI 2 . The reaction product gave 220 mg of LL-15 after flash chromatography. mp: 72 - 74°C [α] D (CHCI 3 ): -160.9° UVλ max (EtOH) (ε): 215(34500), 250 (30000), 358 (26300). IR (CHCI 3 ) cm- 1 : 3020, 2840, 1740, 1680, 1510, 1240, 1140, 1050 Example 2 Preparation of LL-16 0.1 ml of phenylhydrazine was added to a solution of 180 mg of LL-15 (obtained in Example 1) in 5 ml of glacial acetic acid. The reaction mixture was stirred at room temperature for 7 days. Then water was added and 150 mg of LL-16 were collected. [M + ]: 515 mp: 172-174°C [α] D (CHCl 3 ): - 309.1° UVλ max (EtOH) (ε): 209(28600), 377(24100) IR (CHCl 3 ) cm -1 : 3020, 2950, 1740, 1610, 1510, 1260, 1140, 1050 Example 3 (Reference) Preparation of LL-34, LL-35 and LL-36 0.15 ml of 1,2-ethanedithiol and 3 ml of SiMe 3 Cl were added to 100 mg of LL-15 in 3 ml of CH 2 Cl 2 . After 20 hours at room temperature with stirring under N 2 and washing with diluted aq. NaOH, 112 mg of LL-34 were obtained. To 40 mg of LL-34 in 3 ml of dry ether a suspension of 50 mg of LiAlH 4 in dry ether was added. After 3 hours at room temperature and usual working, 37 mg of LL-35 were obtained. To a solution of 40 mg of HgO and 0.25 ml of BF 3 Et 2 O in 5 ml of THF/H 2 O (85-15) were added 40 mg of LL-35. The mixture was stirred under N 2 for 3 hours. Then diluted with CH 2 Cl 2 and the precipitate discarded. The solution after evaporation yielded 30 mg of LL-36. [α] D (CHCl 3 ): -85.1° UVλ max (EtOH) (ε): 215 (16500), 245(14300), 356 (8200) IR (CHCl 3 ) cm -1 : 3600-3100, 2940, 2860, 1670, 1600, 1510, 1240, 1135, 1045

Claims: A compound of formula (I): in which Ar is a 3,4,5-trialkoxyphenyl or a 4-hydroxy-3,5-dialkoxyphenyl; and X is a nitrogen atom; Y is a hydrogen atom or an alkyl, alkenyl, aryl, hydroxy, alkoxy, amino, monoalkylamino, dialkylamino, (poly)haloalkyl, arylamino, acyl or acetamido group; Z is an alkyl, hydroxyalkyl, acyl, carboxy, alkoxycarbonyl or aryloxycarbonyl group; and the dotted lines indicate one double bond located at position Δ 7-8 or Δ 8-8' The compound LL-16, which is the phenylhydrazone of methyl 9-deoxy-9-oxo-α-apopicropodophyllate. A pharmaceutical composition which comprises a compound of formula (I): in which Ar is a 3,4,5-trialkoxyphenyl or a 4-hydroxy-3,5-dialkoxyphenyl; and X is a nitrogen atom; Y is a hydrogen atom or an alkyl, alkenyl, aryl hydroxy, alkoxy, amino, monoalkylamino, dialkylamino, (poly)haloalkyl, arylamino, acyl or acetamido group; Z is an alkyl, hydroxyalkyl, acyl, carboxy, alkoxycarbonyl or aryloxycarbonyl group; and the dotted lines indicate one double bond located at position Δ 7-8 or Δ 8-8' together with a pharmaceutically acceptable carrier. A pharmaceutical composition according to claim 3, wherein the compound of formula (I) is the compound LL-16, which is the phenylhydrazone of methyl 9-deoxy-9-oxo-α-apopicropodophyllate.

Inventors: CASTRO MARIA ANGELES, DEL CORRAL JOSE MARIA MIGUEL, GORDALIZA MARINA, GRAVALOS DOLORES G, LOPEZ MARIA LUISA, SAN FELICIANO ARTURO, CASTRO, MARIA ANGELES, DEL CORRAL, JOSE MARIA MIGUEL, GORDALIZA, MARINA, GRAVALOS, DOLORES G., LOPEZ, MARIA LUISA, SAN FELICIANO, ARTURO, GRAVALOS, DOLORES G. C/O PHARMA MAR S.A.
Applicants: UNIV SALAMANCA, UNIVERSIDAD DE SALAMANCA
Application year: 1995
Main classification: C07D317
IPC codes: A61K31, C07D317, A61P35