Synthesis, structural studies, and biological evaluation of some purine substituted 1-aminocyclopropane-1-carboxylic acids and 1-amino-1-hydroxymethylcyclopropanes

The novel purine derivatives of 1-aminocyclopropane-1-carboxylic acid (8 and 9) and 1-amino-1-hydroxymethylcyclopropane (12 and 13) with methylene spacer between the base and the cyclopropane ring were prepared by multistep synthetic route involving alkylation of adenine and 6-(N-pyrrolyl)purine with 2-hydroxy-methyl-1-aminocyclopropane-1-carboxylic acid derivative 3 as a key reaction. All novel compounds were racemic. The N-9 substitution of the purine ring and the Z-configuration of the cyclopropane ring in 4-13 were deduced from their 1H and 13C NMR spectra by analyses of chemical shifts, H-H coupling constants and connectivities in two-dimensional homo- and heteronuclear correlation spectra. An unequivocal proof of the stereostructure of 1, 4 and 5 was obtained by their X-ray structure analysis. The novel compounds were evaluated on cytostatic and antiviral activities in several cell lines. The 6-(N-pyrrolyl)purine derivative of 1,2-aminocyclopropane alcohol 12 exhibited a more pronounced inhibitory activity against the proliferation of cervical carcinoma (HeLa) and human fibroblast (WI-38) cells than other types of tumor cell lines. None of the compounds showed inhibitory activities against cytomegalovirus, varicella-zoster virus or other viruses.

Homoarcyriaflavin: Synthesis of Ring-Expanded Arcyriaflavin Analogues

The construction of the ring-expanded carbazole system, forming arcyriaflavin homologues, is efficiently accomplished by the reaction of 2,2'-bridged bis-indoles with 3,4-dibromo-2,5-dihydro-1H-2,5-pyrroledione derivatives under Grignard conditions. A ring size of up to nine members in the central ring is achievable. Substitutions either at the indole system or at the imide-N are also possible. The conformation of homoarcyriaflavins as a cross-link between the rigid arcyriaflavins and the flexible arcyriarubins was investigated by NMR, X-ray, and semiempiric quantum chemical calculation methods.

Syntheses of Anthracenones. 2. Preparation of 1,8-Dimethoxy- (Dimethylanthralin) and 4,5-Dihydroxy-9(10H)-anthracenone (Isoanthralin): A Revision

The reduction of 1,8-dimethoxyanthracenedione with zinc dust and aqueous ammonia gives a mixture of 1,8-dimethoxyanthracene and 4,5-dimethoxy-9(10H)-anthracenone, rather than the isomeric 1,8-dimethoxy-9(10H)-anthracenone (dimethylanthralin). This isomer was obtained exclusively using SnCl(2) in HCl and acetic acid as reducing agent at room temperature. The structure was confirmed to exist as the tautomeric 1,8-dimethoxy-9-hydroxyanthracene. Furthermore, the reduction of 1,8-diacetoxyanthracenedione with SnCl(2) in HCl and acetic acid leads to 1,8-dihydroxy-9(10H)-anthracenone (anthralin) rather than 4,5-dihydroxy-9(10H)-anthracenone (isoanthralin), which was prepared by ether cleavage of 4,5-dimethoxy-9(10H)-anthracenone. In light of these findings some biological studies on antipsoriatic anthracenones have to be reconsidered.

[Synthesis of carbazole derivatives. 1. The reaction of 3-(2-nitroethenyl)-indole-2-malonic acid esters with Michael acceptors]

Michael-type reaction of compounds of type 9 were studied. Addition reactions with acrolein and methyl vinyl ketone, respectively, lead--depending on the conditions--to pyridoindoles of type 16 and 14 and/or to tetrahydrocarbazoles of type 17 and 15. With Triton B compounds 15 undergo retro-Michael-type elimination of the nitromethyl group, followed by hydrolysis/decarboxylation and dehydrogenation, leading to the disubstituted carbazoles 20. In the case of 17a, the primary elimination product 18 could be isolated. The synthetic potential of these reaction types is discussed. Some of the described compounds and derivatives of them show antimycobacterial activity.

[1,2-Bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer. II. Synthesis and preliminary testing of the enantiomeric complexes

The enantiomeric [1,2-bis(2-hydroxyphenyl)-ethylenediamine]dichloroplatinum(II) complexes were synthesized and their configuration assessed. A preliminary test in the cisplatin-resistant human NIH:OVCAR-3 ovarian cancer cell line, which was previously characterized by its sensitivity against several therapeutically used drugs, showed that both enantiomers produce cytocidal effects in a concentration of 2.5 microM. A difference between the enantiomers became evident from the faster onset of cytocidal activity of the S,S-configurated compound.

[1,2-Bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II), a new compound for the therapy of ovarian cancer. III. Detailed evaluation of the antitumor activity of the enantiomeric complexes on the human NIH:OVCAR-3 ovarian cancer cell line

The stereoisomeric [1,2-bis(2-hydroxyphenyl)ethylenediamine]dichloroplatinum(II) complexes were thoroughly tested on the cisplatin-resistant human NIH:OVCAR-3 ovarian cancer cell line. The racemate and its enantiomers produced cytocidal effects at a concentration of 2.5 microM (incubation time 256 h). The meso form, however, was merely cytostatically active. Differences between the enantiomers became evident after a short drug incubation time (1 h) followed by an incubation in drug-free medium (243 h). The S,S-configurated enantiomer (-)-3-PtCl2 proved to be the most active compound. To achieve cytocidal effects concentrations of 2.5-5.0 microM and incubation times of about 3 h were necessary for (-)-3-PtCl2. This compound is also sufficiently stable under test conditions as shown by the preincubation in cell-free medium for 3 h. These results and the augmentation of its antitumor activity by buthionine sulfoximine recommend the further preclinical development of (-)-3-PtCl2 for clinical use.

Tumor-inhibiting [1,2-bis(fluorophenyl)ethylenediamine]platinum(II) complexes. V. Synthesis and evaluation of enantiomeric [1,2-bis-(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) complexes

The enantiomeric [1,2-bis(4-fluorophenyl)ethylenediamine]dichloroplatinum(II) complexes were synthesized and tested on the hormone-sensitive human MCF7 breast cancer cell line and on the P388 leukemia of the mouse. They showed a strong and comparable activity on both tumor models.

Aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2- phenylethylenediamine](sulfato)platinum-(II) complexes with variable substituents in the 2-phenyl ring. 1. Synthesis and antitumor and estrogenic properties

Erythro- and threo-configurated aqua[1-(2,6-dichloro-4-hydroxyphenyl)-2- phenylethylenediamine](sulfato)platinum(II) complexes with variable substituents in the 2-phenyl ring (2-PtSO4 to 9-PtSO4: H, 4-F, 3-OH, 4-OH, 2,6-F2, 2,6-Cl2, 2-F/4-OH, 2-Cl/4-OH) were synthesized and tested for estrogenic and antitumor activities. The ligands were obtained by a three-step reaction. The stilbenes were reacted with a mixture of IN3 and NaN3 to yield the respective 1,2-diazido-1,2-diphenylethanes. The subsequent reduction with LiAlH4 led to the corresponding 1,2-diphenyl-ethylenediamines. The (sulfato)platinum(II) complexes were synthesized by reaction of Ag2SO4 with the diiodo complexes, which had been obtained by coordination of the diamines with K2PtI4. Two complexes, erythro-8-PtSO4 and erythro-9-PtSO4, possess antitumor and estrogenic effects and are therefore of interest for the therapy of breast cancer.