Novel tetra-acridine derivatives as dual inhibitors of topoisomerase II and the human proteasome.

Acridine derivatives, such as amsacrine, represent a well known class of multi-targeted anti-cancer agents that generally interfere with DNA synthesis and inhibit topoisomerase II. But in addition, these tricyclic molecules often display secondary effects on other biochemical pathways including protein metabolism. In order to identify novel anti-cancer drugs, we evaluated the mechanism of action of a novel series of bis- and tetra-acridines. As expected, these molecules were found to interact with DNA and inhibit the topoisomerase II-mediated DNA decatenation. Interestingly when tested on human tumour cells either sensitive (HL-60) or resistant (HL-60/MX2) to topoisomerase II inhibitors, these molecules proved equicytotoxic against the two cell lines, suggesting that they do not only rely on topoisomerase II inhibition to exert their cytotoxic effects. In order to identify alternative targets, we tested the capacity of acridines 1-9 to inhibit the proteasome machinery. Four tetra-acridines inhibited the proteasome in vitro, with IC(50) values up to 40 times lower than that of the reference proteasome inhibitor lactacystin. Moreover, unlike peptide aldehydes used as reference inhibitors for the proteasome, these new acridine compounds demonstrated a good selectivity towards the proteasome, when tested against four unrelated proteases. A cellular assay based on the degradation of a proteasome protein substrate indicated that at least two of the tetra-acridines maintained this proteasome inhibition activity in a cellular context. This is the first report of tetra-acridines that demonstrate dual topoisomerase II and proteasome inhibition properties. This new dual activity could represent a novel anti-cancer approach to circumvent certain forms of tumour resistance.

Antimicrobial activity of 9-oxo and 9-thio acridines: correlation with interacalation into DNA and effects on macromolecular biosynthesis.

The antimicrobial activity of several new 9-acridinones and 9-thioalkylacridines towards Escherichia coli, Staphylococcus aureus, Mycobacterium smegmatis and Candida albicans was investigated. Minimal inhibitory, bactericidal and fungicidal concentrations were determined using a microplate assay which enabled inhibitory, bactericidal and fungicidal indices to be calculated. These indices facilitated structure/activity relationship studies. DNA-intercalating capability and DNA supercoiling inhibitory effects as well as inhibitory effects on macromolecular synthesis were determined. Results showed that intercalation into DNA, which is the mechanism of action usually postulated for acridines, cannot be correlated with the properties examined. However, inhibition of RNA synthesis may be involved in the antimicrobial activity of the drugs.

Effects of amino and imino acridines on tumor necrosis factor production by human leukocytes.

Tumor necrosis factor (TNF) is a multifunctional cytokine with diverse effects on different cells and tissues. The biological activity of TNF is described on the basis of its cytotoxic action in vivo and in vitro. Different acridines were systematically synthesized and their effects were tested on endotoxin and Staphylococcus aureus-induced TNF production by human leukocytes. 9-aminobutylacridine and 9-ethylaminoacridine totally abrogated the TNF production of leucocytes at a concentration of 3.5 microM, whereas 9-imino -10-butylacridine and 9-imino-10-ethylacridine exerted only a 50% inhibition in the same concentration. Derivatives designated as 9-amino-(2-dimethylamino-ethyl)-acridine and 9-imino-10-(2-dimethylamino-ethyl)-acridine in a concentration of 7 microM exerted only a 30% and a 10% inhibition respectively. A significant modulation of TNF production was not observed when other alkylated derivatives in this series were applied. The TNF-mediated cytotoxic effect of monocytes against WEHI cells was also reduced by the most effective compounds. The acridines did not interfere with the expression of CD 14 molecules on monocytes. The exact mechanism of the suppression of TNF synthesis by acridines remains to be elucidated, but might be useful in the screening and evaluation of their anticancer properties and antimalarial effects.

Effect of acridine derivatives on the multiplication of herpes simplex virus.

The antiviral effect of 22 acridine derivatives was studied on the multiplication of herpes simplex virus type 2 (HSV-2) in Vero cells. The inhibitory effect of four acridine derivatives on the multiplication of HSV-2 is emphasised, six other compounds have moderate activity and three only slightly affect the virus multiplication, while nine compounds are inactive. Some of the effective derivatives inhibit the virus replication without any direct effect on the virus particles. However, the mechanism of the antiviral effect is still not known.

Synthesis of two novel thioacridinic derivatives and comparison of their in vitro biological activities.

Two novel compounds, 3-amino-9-(diethylaminoethylthio) acridine and 9-diethylaminoethylthioacridine, were synthesized and characterized. They were shown to be cytotoxic against K562 and Raji cell lines. A concentration of 10(-5) M killed around 40% of the cells after 3 h time of incubation. Intercalation into DNA was more efficient when a protonated nitrogen was present in a side chain of the ring system. At the cytotoxic concentrations (10(-5) M, 10(-6) M), inhibition of nucleic acid synthesis in K562, Raji cell lines and human leukocytes has been shown. The results presented suggest that the cytotoxicity and the inhibition of nucleic acid synthesis of the two compounds studied are inversely related to their intercalating capability into the DNA helix.

Effects of acridines on bacterial plasmid replication and endotoxin.

Different amino- and imino-acridines were systematically synthesized. The antibacterial, antiplasmid, antimotility and endotoxin complexing effect of acridines were studied, when antibacterial effect of the compounds was compared on E. coli. Aminoderivatives were more active than imino-acridines. The N-heptyl-9-imino-acridine was able to select lon minus mutants in the E. coli culture, however, the other acridines tested were ineffective in this respect. The iminoacridines inhibited the motility of Proteus vulgaris more effectively than aminoderivatives. The antimotility action of the acridines was also dependent on the ionic content of the media. The antiplasmid effect was measured on an F-prime plasmid of E. coli LE140 strain. Iminoacridines had a more powerful antiplasmid effect than the amino-substituted derivatives. The majority of the compounds inhibited the intercellular plasmid transfer from E. coli. Kmr donor to a Na-azide resistant recipient. In this test the aminosubstituted derivatives were shown to be more effective inhibitors of conjugation than the imino-substituted compounds. Endotoxin formed complexes with N-butylamino. N-propy-lamino and imidoderivatives. However, complex formation of N-ethyl-, N-heptyl-, N-diethylaminoethyl- and N-diethylamino-propyl-acridines were different. Correlations between molecular orbitals and the antibacterial effects are also discussed.

[Trypanocidal structure- activity relationship in 9-thioalkylacridines]. / Relations structure-activité trypanocide chez les 9-thioalkylacridines.

A set of 9-thioalkylacridinones, has been prepared and investigated "in vitro" against T. cruzi. Structure-antiparasitic activity relationships are detailed with a view to identify the major structural parameters for the activity under consideration.

(1)H and (13)C chemical shifts for 2-aryl and 2-N-arylamino benzothiazole derivatives.

The (1)H and (13)C NMR resonances for forty-three 2-aryl and 2-N-arylamino benzothiazole derivatives were completely assigned using a concerted application of one- and two-dimensional experiments (DEPT, gs-COSY, gs-HMQC and gs-HMBC).

1H and 13C chemical shifts for acridines: Part XIX. N,N'-diacylproflavine derivatives.

The 1H and 13C NMR resonances of 15 N,N'-diacylproflavines were assigned completely and unequivocally using a concerted application of one- and two-dimensional experiments (DEPT, gs-COSY, gs-HMQC and gs-HMBC).

New antiamebic acridines. II. Synthesis and DNA binding of a series of 9-acridanones and 9-iminoacridines.

A series of novel 9-acridanones and 9-iminoacridines has been prepared and investigated by a number of spectroscopic techniques in order to determine the nature and extent of the binding of these compounds to DNA. Results are discussed with reference to antiamebic activity in vitro.

Activity and structure relationship of acridine derivatives against African trypanosomes.

48 newly synthesized acridine derivatives of different classes were screened for antitrypanosomal activity. They showed a dose dependent effect on Trypanosoma rhodesiense and T. brucei bloodstream forms measured by the inhibition of esterase activity in a fluorescence based in vitro assay. After analysis of the IC50 and MIC values of the investigated acridines it was obvious that no new compound reached the level of the trypanocidal drugs in use (50 ng/ml). Most of the derivatives had IC50 values in the range of 1 to 10 micrograms/ml. 9 derivatives from different classes of acridines were in vitro active below 1 microgram/ml. Correlations between structure and effect on trypanosomes have been elucidated by comparing the IC50 and MIC values of these compounds, in the course of which no significant differences in the drug susceptibility between T. brucei und T. rhodesiense was noticed. The dialkylaminoalkyl derivatives among the group of the 9-thioacridines were slightly more potent than the mono-alkylated ones. 1,2,3,4-tetrahydro-9-thioacridines showed the influence of higher substituted side chains on the trypanocidal activity in the same way as 9-thioacridines. The corresponding ketones of 9-thioacridines confirmed the tendency of increasing toxicity due to the derivatisation of the dialkylaminoalkyl side chain. Within the series of the 9-aminoacridines the elongation of the side chain did not markedly change the activity, however the IC50 values are generally low between 0.13 and 1.2 micrograms/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Preparation of a series of 9-alkylaminoacridines and 9-imino-10-alkylacridines and their binding to desoxyribonucleic acid.

The preparation, separation and identification of a series of 9-alkylaminoacridines and 9-imino-10-alkylacridines is described. Their binding to desoxyribonucleic acid which has been investigated by a number of spectroscopic techniques is reported.

[High resolution proton magnetic resonance study of a series of 9-substituted acridines: correlation with biological activities]. / Etude par résonance magnétique nucléaire protonique à haut champ d'une série d'acridines-9 substituées; essai de corrélation avec les activités biologiques.

250 MHz 1H N.M.R. spectra of a set of 9-substituted derivatives of acridine as solutes in DMSO-d6 were studied. Because of ABCD coupling figures, magnetic parameters were determined by means of simulated spectra. Semi-empirical correlations were proposed for chemical shifts. Moreover, pi distribution in the heterocycle was investigated. Results are discussed in relation to some weak biological properties of the acridine drugs.

Synthesis and antiparasitic activity of new 1-nitro, 1-amino and 1-acetamido 9-acridinones.

The synthesis of 1-amino-10-alkyl-9-acridinones 4 and 5 and of homologous 9-thio-acridinones 7 and 8 are described. Similarly, the synthesis of 1-nitro-4-(2'-aminoethylamino)-9-acridinones 13 and 15, is described. Compound 4 was used as starting material for the preparation of 10-alkyl-9-acridinone dimers 6, bridged with an alpha,omega-diamido chain. Compound 15 was selected for biological investigations on pathogenic parasite strains, and a promising antiamoebic activity could be shown.

Antiamebic activity of new acridinic derivatives against Naegleria and Acanthamoeba species in vitro.

In vitro antiamebic activity of selected acridine derivatives has been investigated against Naegleria and Acanthamoeba species. The most active compounds belong to the 9-thioacridanone and the 1,2,3,4-tetrahydro-9-thioacridanone series. In addition, some structure-activity relationships are proposed.

New antiparasitic agents. III. Comparison between trypanocidal activities of some acridine derivatives against Trypanosoma cruzi in vitro.

Some acridine compounds referred to as 9-imino, 9-oxo and 9-thio derivatives were screened for activity against Trypanosoma cruzi in vitro. The results are discussed here with reference to the structure of the compounds tested. Attempts to elucidate the mode of action of active acridines are also included. The most active compounds that were tested were 9-thioacridanones and 9-thio-1,2,3,4-tetrahydroacridanones Added to this, the dialkylaminoalkylthio group seems to be the most convenient molecular moiety for trypanocidal activity in the 9-substituted acridine series.

1,4-Dimethoxy-9(10H)-acridinone derivatives. Synthesis, DNA binding studies and trypanocidal activity.

New acridinonic derivatives, which are hydroxy- and methoxy-substituted in positions 1, 4, and 1,4 were prepared with a view to obtain antiparasitic drugs. These compounds were tested against Trypanosoma cruzi strains and their capability of interacalation into DNA was determined. Nucleus substitutions, DNA binding, and trypanocidal activities have been correlated.