Synthesis, antitumor cytotoxicity, and DNA-binding of novel N-5,2-di(omega-aminoalkyl)-2,6-dihydropyrazolo[3,4,5-kl]acridine-5-carboxamides.

A series of DNA-binding potential antitumor agents bearing a cationic carboxamide side chain attached in position peri to an electron-withdrawing atom, N-5,2-di(omega-aminoalkyl)-2,6-dihydropyrazolo[3,4,5-kl]acridine-5-carboxamides, has been prepared by reaction of the appropriate 1-chloro-9-oxo-9,10-dihydro-4-acridinecarboxamides with the suitable (omega-aminoalkyl)hydrazine. The noncovalent DNA-binding properties of these compounds have been examined using a fluorometric technique. In vitro cytotoxic potency of these derivatives toward the human colon adenocarcinoma cell line (HT29) is described and compared to that of reference drugs. Structure-activity relationships are discussed. Two highly DNA-affinic and potent cytotoxic compounds, 4m,o, have been identified as new leads in the antitumor strategies.

N4-(omega-Aminoalkyl)-1-[(omega-aminoalkyl)amino]-4- acridinecarboxamides: novel, potent, cytotoxic, and DNA-binding agents.

A series of DNA-binding potential antitumor agents, (omega-aminoalkyl)-4-acridinecarboxamides, has been prepared either by reduction of the corresponding (omega-aminoalkyl)-9-oxo-9, 10-dihydro-4-acridinecarboxamides with aluminum amalgam or by aminolysis of the corresponding (omega-aminoalkyl)-1-chloro-4-acridinecarboxamides with the suitable amine. The noncovalent DNA-binding properties of these compounds have been examined using a fluorometric technique. In vitro cytotoxic potencies of these derivatives toward six tumor cell lines, including human colon adenocarcinoma (HT29) and human ovarian carcinoma (A2780-sensitive, A2780cisR cisplatin-resistant, CH1-sensitive, CH1cisR cisplatin-resistant, and SKOV-3) cells, are described and compared to that of reference drugs. One highly DNA affinic analogue (3a) has been identified with a useful broad spectrum of cytotoxic activity in the 4-7 nM range (mean IC(50) of 6 nM).

2,3-Dihydro-1H,7H-pyrimido[5,6,1-de]acridine-1,3,7-trione derivatives, a class of cytotoxic agents active on multidrug-resistant cell lines: synthesis, biological evaluation, and structure-activity relationships.

A series of DNA-intercalating potential antitumor agents, (amino)alkyl-substituted 2,3-dihydro-1H,7H-pyrimido[5,6, 1-de]acridine-1,3,7-triones, has been prepared by aminolysis of the corresponding 6-chloro derivative with a suitable omega-aminoalkylamine. The noncovalent DNA-binding properties of these compounds have been examined using a fluorometric technique. In vitro cytotoxic potencies of these derivatives toward eight tumor cell lines, including human colon adenocarcinoma (HT29, LoVo sensitive and LoVo/Dx (doxorubicin-resistant)) and human ovarian carcinoma (A2780 sensitive, A2780cisR (cisplatin-resistant), CH1, CH1cisR (cisplatin-resistant), and SKOV-3) cells, are described and compared to that of reference drugs. The cytotoxic activity often parallels the observed DNA affinities, for almost all the target compounds. Interesting structure-activity relationships have been found. The octanol/water partition coefficients have also been calculated, but there was no correlation either with cytotoxicity values or with resistance index. Three highly DNA-affinic analogues, 9 and 15f,15h, have been identified with a useful broad spectrum of cytotoxic activity.

Pyrimido[4,5,6-kl]acridines. Synthesis, in vitro cytotoxicity and structure-activity relationships.

In a previous report we described the synthesis and biological properties of a group of pyrimido[4,5,6-kl]acridines 2, related to the pyrazolo[4,5,6-kl]acridines 1, promising antitumor agents possessing a broad spectrum of activity. Since the substitution of the pyrazole ring of the pyrazoloacridine chromophore with a pyrimidinone leads to derivatives that retain in vitro cytotoxic activity, we decided to further investigate the pyrimido[4,5 6-kl]acridines. Modifications at the ring system level, leading to chromophores with different characteristics, changes of substituent groups in position 6, simultaneous alteration of the chromophore and the introduction of a second cationic side chain in position 1 afforded 29 new pyrimido[4,5,6-kl]acridines, which were tested in vitro against the human colon adenocarcinoma HT29 cell line. Interesting structure-activity relationships could be drawn. Some selected derivatives were screened for their cytotoxic activity on the National Cancer Institute cell panel (60 human tumor lines).

1,4- and 2,6-disubstituted amidoanthracene-9,10-dione derivatives as inhibitors of human telomerase.

A number of 1,4- and 2,6-difunctionalized amidoanthracene-9, 10-diones have been prepared. We have examined their in vitro cytotoxicity in several tumor cell lines and their ability to inhibit the telomere-addition function of the human telomerase enzyme together with their inhibition of the Taq polymerase enzyme. Compounds with -(CH2)2- side chains terminating in basic groups such as piperidine show inhibition of telomerase at telIC50 levels of 4-11 microM. These are thus among the most potent nonnucleoside telomerase inhibitors reported to date. Cytotoxicity levels in human tumor cell lines were at comparable levels for several compounds. Implications for amidoanthracene-9,10-dione telomerase inhibitors as potential anticancer agents are discussed.

1-[(omega-aminoalkyl)amino]-4-[N-(omega-aminoalkyl)carbamoyl]-9-oxo-9, 10-dihydroacridines as intercalating cytotoxic agents: synthesis, DNA binding, and biological evaluation.

A series of DNA-intercalating potential antitumor agents, 1-[(omega-aminoalkyl)amino]-4-[N-(omega-aminoalkyl)carbamoyl]-9-oxo-9, 10-dihydroacridines, has been prepared by aminolysis of the corresponding 4-[N-(omega-aminoalkyl)carbamoyl]-1-chloro derivative with a suitable omega-aminoalkylamine. The noncovalent DNA-binding properties of these bis-functionalized compounds have been examined using a combination of fluorometric and thermal denaturation techniques and are compared with the behaviors for established DNA intercalants and cationic minor groove ligands. The results indicate that (i) the agents are considerably more DNA-affinic than less functionalized acridinones, with 'apparent' binding constants of (0.1-2.1) x 10(7) and (0.3-7.5) x 10(7) M-1 at pH 5 and 7, respectively, (ii) overall affinity is sensitive to both the length of the flexible side chain and the complexity of the attached amine substituents, and (iii) the pendant side chains effect a switch to moderate AT-preferential binding. In vitro cytotoxic potencies toward six tumor cell lines broadly parallel the observed DNA affinities, although poor correlation is evident for certain compounds. The octanol/water partition coefficients have been also calculated, but there is no correlation with cytotoxicity values. Two highly DNA-affinic analogs, 10 and 13, have been identified with a useful broad spectrum of cytotoxic activity.

Pyrimido [4,5,6-kl] acridines, a new class of potential anticancer agents. Synthesis and biological evaluation.

A series of 3-(aminoalkyl)-2,7-dihydro-6-nitropyrimido [4,5,6-kl] acridin-2-ones 3, strictly related to the pyrazoloacridines 1, have been synthesized. Thus, the reaction of the suitable 1-(aminoalkyl)amino-9, 10-dihydro-9-imino-4-nitroacridine 2 with ethyl chloroformate afforded the pyrimidoacridines 3a-f. By hydrolysis in hydrobromic acid of the 10-methoxy derivatives 3d-f, the 10-hydroxy derivatives 3g-i were obtained. The pyrimidoacridines 3a-i were tested in vitro for their cytotoxic activity against L1210 murine leukemia and HT29 human colon adenocarcinoma cell lines, showing significant potency of growth inhibition. Different DNA-binding assays as well as attempts to correlate cytotoxicity and DNA affinity have been carried out.

Synthesis and biological evaluation of mono- and bis-[(alkylamino)alkylamino] substituted thienopyridopyridazines, a new class of potential antitumor agents.

A new class of potential antitumor agents, provided with thieno[2',3':5,6]pyrido[2,3-d]pyridazin-9(4H)-one nucleus as chromophore, was synthesized. Thus, the suitable amines were reacted, in different conditions, with 5,8-dichlorothieno[2',3':5,6]pyrido[2,3- d]pyridazin-9(4H)-one (5) to afford the 8-alkylamino derivatives 6a-f, the 5-alkylamino derivatives 7a-f, and the 5,8-bis-alkylamino derivatives 8a,b. Selected compounds were evaluated for cytotoxic potency in vitro against the human colon adenocarcinoma HT 29 cell line and studied in DNA binding assays. The cytotoxic potency versus HT29 was also correlated with binding affinity for calf thymus DNA.

A molecular anchor for stabilizing triple-helical DNA.

Molecular modeling has been used to predict that 2,6-disubstituted amidoanthraquinones, and not the 1,4 series, should preferentially interact with and stabilize triple-stranded DNA structures over duplex DNA. This is due to marked differences in the nature of chromophore-base stacking and groove accessibility for the two series. A DNA foot-printing method that monitors the extent of protection from DNase I cleavage on triplex formation has been used to examine the effects of a number of synthetic isomer compounds in the 1,4 and 2,6 series. The experimental results are in accord with the predicted behavior and confirm that the 1,4 series bind preferentially to double- rather than triple-stranded DNA, whereas the isomeric 2,6 derivatives markedly favor binding to triplex DNA.

Synthesis of (dialkylamino)alkyl-disubstituted pyrimido[5,6,1- de]acridines, a novel group of anticancer agents active on a multidrug resistant cell line.

A series of pyrimidoacridine derivatives with two basic side chains, 7a-e, was synthesized, as potential antitumor drugs, starting from 2-[2-(dimethylamino)ethyl]-6-chloropyrimido[5,6,1-de]acridine-1,3, 7- trione (6) and a suitable (alkylamino)alkylamine. The products 6 and 7a-e showed significant cytotoxic activity in vitro against L1210 leukemia. Compounds 7a,d were 2 orders of magnitude more cytotoxic than ametantrone. All compounds were also examined for their activity on LoVo and resistant LoVo/Dx cell lines. Unlike ametantrone, the compounds have shown to be able to overcome the multidrug resistance. Compounds 7a,d, the two most active in vitro, were tested in vivo against murine P388 leukemia showing good activity.

Synthesis of 9,10-anthraquinone monoalkylaminoalkylhydrazones as potential antitumor drugs.

In the constant search for new compounds endowed with antitumor activity we have synthesized a series of anthraquinone hydrazones, which can bee seen either as opened-cycle modified anthrapyrazoles or as chromophore-modified anthracenediones. Seven 9,10-anthraquinone monoalkylaminoalkylhydrazones (3c-i) were synthesized from 10,10-dibromoanthrone (4) and a suitable N-alkylhydrazine. The hydrazones were converted into hydrochlorides and tested for their cytotoxic activity against L1210 murine leukemia cells. Two of them possess marginal activity in vitro.

Synthesis of 7-oxo-7H-benzo[e]perimidine-4-carboxamides as potential antitumor drugs.

A series of 7-oxo-7H-benzo[e]perimidine-4-carboxamides (4a-f) was synthetized from the corresponding acid (3) and the suitable amines by the "mixed anhydride" method. The amide derivatives were tested for antitumor activity against P 388 leukemia "in vivo". Only the N-[2-(diethylamino)ethyl]-7-oxo-7H-benzo[e]perimidine-4-carboxa mid e (4b) shows borderline antineoplastic activity.