Novel heterocyclic family of phenyl naphthothiazole carboxamides derived from naphthalimides: synthesis, antitumor evaluation, and DNA photocleavage

A new heterocyclic family of (2-(dimethylamino)ethyl)-2-substituted phenylnaphtho[2,1-d]thiazole-5-carboxamides modified from naphthalimides was designed, synthesized, and quantitatively evaluated as antitumor agents and photonucleases. All these compounds were found to be more cytotoxic against P388 than against A549. B(3) (m-NO(2)) was found to be the strongest inhibitor for P388 with IC(50) of 1.49 microM, while B(2) was the most cytotoxic compound against A549 with IC(50) of 12 microM. B(4) (p-CH(3)), the most efficient DNA photocleaver, showed detectable DNA cleavage at 0.5 microM and total cleavage from form I to 100% form II at 50 microM. The photocleaving mechanism was changed with the modification to be via superoxide anion and radical.     

Novel 2-aminothiazonaphthalimides as visible light activatable photonucleases: effects of intercalation, heterocyclic-fused area and side chains

A new family of 2-aminothiazonaphthalimides with different side chains as novel intercalative and visible light activatable photonucleases, was designed, synthesized and quantitatively evaluated. The order of their photocleaving abilities was parallel to that of their intercalative properties. The compound with linear heterocyclic-fused chromophore could intercalate into and photocleave DNA more efficiently than the one with angular heterocyclic-fused chromophore. B(2), the most efficient compound, caused obvious DNA damage at 1 microM. Mechanism experiment showed that superoxide anion was involved.     

Antiproliferative effects on human tumor cells and rat aortic smooth muscular cells of 2,3-heteroarylmaleimides and heterofused imides

A series of 2,3-heteroarylmaleimides 9 and polyheterocondensed imides 12 were prepared in good yields and short reaction time using a very efficient procedure consisting in the condensation of the corresponding anhydrides and N,N-diethylethylenediamine and microwave heating. The antiproliferative activity of the novel molecules was tested against human tumor cells (NCI-H460 lung carcinoma) and rat aortic smooth muscle cells (SMCs). The IC50 values for the novel molecules ranged from 0.08 to 13.9 microM in SMCs, and from 0.84 to 9 microM in the tumor cell line. The activity profile for compounds 9 and 12 is comparable to that obtained for amonafide in NCI-H460, except for fused imides 12b,i which proved to be about 10-fold more potent. Whereas, in rat SMCs, only the compound 12b was shown to be 10-fold more potent than amonafide. Instead 12c is equipotent to amonafide. These results suggest that the extended pi-system and the kind of heteroatom are essential in the binding with the molecular target.     

Synthesis and cytotoxic activity of N-[(alkylamino)alkyl]carboxamide derivatives of 7-oxo-7H-benz[de]anthracene, 7-oxo-7H-naphtho[1,2,3-de]quinoline, and 7-oxo-7H-benzo[e]perimidine

7-Oxo-7H-naphtho[1,2,3-de]quinoline-11-carboxamides and analogues were prepared and evaluated for in vitro and in vivo antitumor activity. Chromophore variations included 'deaza' (7-oxo-7H-benz[de]anthracene) and 'diaza' (7-oxo-7H-benzo[e]perimidine) analogues, and side chain variations included chiral alpha-methyl compounds. The naphthoquinolines were the most cytotoxic, with IC(50) values of 5-20 nM, and showed the strongest DNA binding, with high selectivity for G-C rich DNA. The chiral alpha-methyl analogues were 10-20-fold more cytotoxic than the parent des-methyl compound. Both enantiomers provided substantial growth delays against s.c. colon 38 tumors in mice, with the R-enantiomer more active than the S (tumor growth delays of >35 and 12 days, respectively).     

Synthesis, antitumor evaluation and DNA photocleaving activity of novel methylthiazonaphthalimides with aminoalkyl side chains

A series of methylthiazonaphthalimides was synthesized and quantitatively evaluated as efficient DNA intercalators, antitumor agents and DNA photocleavers. A(1) showed both efficient antitumor activities against cell lines of A549 and P388 with IC50 of 82.8 and 31 nM, respectively. A(3) was the strongest antitumor agent against A549 with the IC50 of 20.8 nM. A(2), the most efficient DNA intercalator, was found to be the strongest DNA photocleaver via superoxide anion. An explanation was given for the disaccord between antitumor and DNA photocleaving activities.     

Design, synthesis, and evaluation of N-aroyloxy-2-thiopyridones as DNA photocleaving reagents.

N-Benzoyloxy-2-thiopyridone (12) was shown to induce single-strand nicks in duplex DNA upon irradiation with visible light (lambda&350 nm). This finding led to the design of a series of compounds, in which an acridinyl nucleus was covalently linked to the N-benzoyloxy-2-thiopyridone unit. These conjugates (15, 16, 17 and 18) were synthesized and evaluated as novel DNA photocleaving reagents. Optimal photocleaving activity was observed for conjugate 16, in which a flexible polymethylene spacer of 4 carbons was used to connect the aminoacridine entity to the thiopyridone. This compound was shown to cleave DNA at low microM concentrations and was approximately two-orders of magnitude more efficient than the parent N-benzoyloxy-2-thiopyridone (12). Furthermore, the DNA cleavage ladders induced by 16 and 12 were found to be identical and of no significant sequence selectivity. These data suggest that the N-aroyloxy-2-thiopyridones can be used for the design of new DNA photocleaving reagents with potential use as 'photofootprinting agents' or as 'site-directed photonucleases'.     

Design, synthesis and cytotoxic activities of novel hybrid compounds between 2-phenylbenzofuran and imidazole

A series of novel hybrid compounds between 2-phenylbenzofuran and imidazole have been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that substitution of the imidazolyl-3-position with a naphthylacyl or bromophenacyl group, were vital for modulating cytotoxic activity. In particular, hybrid compound 15 was found to be the most potent compound against 4 strains human tumor cell lines and more active than cisplatin (DDP), and exhibited cytotoxic activity selectively against liver carcinoma (SMMC-7721).     

Design,synthesis, and molecular docking studies of novel pomalidomide-based PROTACs as potential anti-cancer agents targeting EGFRWT and EGFRT790M

A new class of EGFR PROTACs based on pomalidomide was developed, synthesised, and tested for their cytotoxic activity against a panel of human cancer cells. Compounds 15–21 were showed to be more effective against the four tested cell lines than erlotinib. In particular, compound 16 was found to be the most potent counterpart as it was 5.55, 4.34, 5.04, and 7.18 times more active than erlotinib against MCF-7, HepG-2, HCT-116, and A549 cells, respectively. Compound 15 was revealed to be more active than doxorubicin against the four tested cell lines. Furthermore, the most potent cytotoxic compounds were studied further for their kinase inhibitory effects against EGFR^WT and EGFR^T790M using HTRF test. Compound 16 showed to be the most effective against both kinds of EGFR, with IC₅₀ values of 0.10 and 4.02 µM, respectively. Compound 16 could effectively degrade EGFR protein through ubiquitination (D_max = 96%) at 72 h in the tested cells.     

Synthesis and antimicrobial activity of 3-arylamino-1-chloropropan-2-ols

A series of nine 3-arylamino-1-chloropropan-2-ols 2a-2i were synthesized and their anti-fungal activity against pathogenic strains of Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger and Candida albicans, and antibacterial activity against four pathogenic bacterial strains of Salmonella typhi, Pseudomonas aeruginosa, Streptococcus pneumonae and Staphylococcus aureus were evaluated using different assay systems. 1-Chloro-3-(4'-chlorophenylamino)-propan-2-ol was found to be the most active anti-fungal compound against three pathogenic strains under study, i.e., A. fumigatus, A. flavus and A. niger; the compound showed more than 90% inhibition of growth of A. fumigatus at a concentration of 5.85 microg/ml in disc diffusion assay. Interestingly, 1-chloro-3-(4'-chlorophenylamino)-propan-2-ol did not show any toxicity up to a concentration of 4000 microg/ml. Although 1-chloro-3-(4'-chlorophenylamino)-propan-2-ol was about 8 times less active than the standard compound amphotericin B, its toxicity was many more fold less than the toxicity of amphotericin B. Further, 1-chloro-3-(2',6'-dichlorophenylamino)-propan-2-ol and 1-chloro-3-(3',5'-dichlorophenylamino)-propan-2-ol were found to be the most active compounds against C. albicans. In the anti-microbial assay, 1-chloro-3-(2',4'-dichlorophenylamino)-propan-2-ol and 1-chloro-3-(3',5'-dichlorophenylamino)-propan-2-ol were found to be the most active compounds against Salmonella typhi and 1-chloro-3-(3',4'-dichlorophenylamino)-propan-2-ol was found to be the most active compound against P. aeruginosa. Although, the activities of 1-chloro-3-(2',4'-dichlorophenylamino)-propan-2-ol and 1-chloro-3-(3',5'-dichlorophenylamino)-propan-2-ol are about half the activity of the standard anti-bacterial compound tetracycline, these compounds also were many fold less toxic than the standard drug.     

Cross-resistance of an amsacrine-resistant human leukemia line to topoisomerase II reactive DNA intercalating agents. Evidence for two topoisomerase II directed drug actions.

HL-60/AMSA is a human leukemia cell line that is 50-100-fold more resistant than its drug-sensitive HL-60 parent line to the cytotoxic actions of the DNA intercalator amsacrine (m-AMSA). HL-60/AMSA topoisomerase II is also resistant to the inhibitory actions of m-AMSA. HL-60/AMSA cells and topoisomerase II are cross-resistant to anthracycline and ellipticine intercalators but relatively sensitive to the nonintercalating topoisomerase II reactive epipodophyllotoxin etoposide. We now demonstrate that HL-60/AMSA and its topoisomerase II are cross-resistant to the DNA intercalators mitoxantrone and amonafide, thus strongly indicating that HL-60/AMSA and its topoisomerase II are resistant to topoisomerase II reactive intercalators but not to nonintercalators. At high concentrations, mitoxantrone and amonafide were also found to inhibit their own, m-AMSA's, and etoposide's abilities to stabilize topoisomerase II-DNA complexes. This appears to be due to the ability of these concentrations of mitoxantrone and amonafide to inhibit topoisomerase II mediated DNA strand passage at a point in the topoisomerization cycle prior to the acquisition of the enzyme-DNA configuration that yields DNA cleavage and topoisomerase II-DNA cross-links. In addition, amonafide can inhibit the cytotoxic actions of m-AMSA and etoposide. Taken together, these results suggest that the cytotoxicity of m-AMSA and etoposide is initiated primarily by the stabilization of the topoisomerase II-DNA complex. Other topoisomerase II reactive drugs may inhibit the enzyme at other steps in the topoisomerization cycle, particularly at elevated concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)     

Design, synthesis and in vitro antiprotozoal activity of benzimidazole-pentamidine hybrids

A series of ten novel hybrids from benzimidazole and pentamidine were prepared using a short synthetic route. Each compound was tested in vitro against the protozoa Trichomonas vaginalis, Giardia lamblia, Entamoeba histolytica, Leishmania mexicana, and Plasmodium berghei, in comparison with pentamidine and metronidazole. Some analogues showed high bioactivity in the low micromolar range (IC(50)<1 microM) against the first four protozoa, which make them significantly more potent than either standard. 1,5-bis[4-(5-methoxy-1H-benzimidazole-2-yl)phenoxy]pentane (2) was 3- and 9-fold more potent againstG. lamblia than metronidazole and pentamidine, respectively. This compound was 23-, 108-, and 13-fold more active than pentamidine against T. vaginalis, E. histolytica and L. mexicana, respectively. Studying further structure-activity relationships through the use of bioisosteric substitution in these hybrids should provide new leads against protozoal diseases.     

Novel cytotoxic chalcones from Litsea rubescens and Litsea pedunculata

Two novel flavonoids with chalcone skeleton, together with seven known flavonoids, were isolated from the stem barks of Litsea rubescens and Litsea pedunculata. The structures of the new compounds were elucidated on the basis of spectral methods including IR, UV, 1D and 2D NMR. The new chalcones were found to contain the rare epoxy or ethylidenedioxy group. This is the first report on the presence of chalcone in the plant genus Litsea. The cytotoxic potential of two new chalcones was evaluated in vitro against three human tumor cell lines. Both new chalcones displayed potent cytotoxic activities against myeloid leukaemia (HL-60) and epidermoid carcinoma (A431) cell lines and more active than cisplatin (DDP). Interestingly, compound 1 exhibited cytotoxic activity against HL-60 with IC₅₀ value 2.1-fold more sensitive to DDP.     

Synthesis and biology of 3'-N-acyl-N-debenzoylpaclitaxel analogues.

The, 3'-N-acyl-N-debenzoylpaclitaxel analogues 1a-d were synthesized and evaluated on biological systems. Some of the analogues 1a-d exhibited higher cytotoxicities (up to 20-fold) and stronger abilities to induce apoptosis than paclitaxel. In an in vivo experiment against i.p. implanted B16 melanoma, the most cytotoxic compound 1b in vitro caused tumor growth inhibition more than paclitaxel.     

Molecular design, chemical synthesis, and biological evaluation of '4-1' pentacyclic aryl/heteroaryl-imidazonaphthalimides

A novel series of '4-1' pentacyclic naphthalimides, where the chromophore consists of a naphthalimide moiety, fused to an imidazole ring containing an unfused aryl or heteroaryl ring, were synthesized and evaluated for in vitro antitumor activity. In general, the new derivatives showed an improved cytotoxic activity over amonafide. DNA binding experiments supported that this class of compounds behaves as effective DNA-intercalating agents.     

Heterocyclic rimantadine analogues with antiviral activity

2-(1-Adamantyl)-2-methyl-pyrrolidines 3 and 4, 2-(1-adamantyl)-2-methyl-azetidines 5 and 6, and 2-(1-adamantyl)-2-methyl-aziridines 7 and 8 were synthesized and tested for their antiviral activity against influenza A. Parent molecules 3, 5, and 7 contain the alpha-methyl-1-adamantan-methanamine 2 pharmacophoric moiety (rimantadine). The ring size effect on anti-influenza A activity was investigated. Pyrrolidine 3 was the most potent anti-influenza virus A compound, 9-fold more potent than rimantadine 2, 27-fold more potent than amantadine 1, and 22-fold more potent than ribavirin. Azetidines 5 and 6 were both markedly active against influenza A H2N2 virus, 10- to 20-fold more potent than amantadine. Aziridine 7 was almost devoid of any activity against H2N2 virus but exhibited borderline activity against H3N2 influenza A strain. Thus, it appears that changing the five-, to four- to a three-membered ring results in a drop of activity against influenza A virus.     

Synthesis,anticancer activity and DNA-binding properties of novel 4-pyrazolyl-1,8-naphthalimide derivatives

A novel series of 4-pyrazolyl-1,8-naphthalimide derivatives have been designed and facilely synthesized. For anticancer activity in vitro, most of the compounds were found to be more toxic against human mammary cancer cells (MCF-7) than human cervical carcinoma cells (Hela) and human lung cancer cells (A549). Compounds 4i, 4h, 4b and 4a showed improved cytotoxic activity against MCF-7 cells over amonafide, in particular compounds 4i and 4h, the IC₅₀ values of which against cell lines of MCF-7 were 0.51 μM and 0.79 μM, respectively. The DNA-binding properties of 4i were investigated by UV–vis, fluorescence, and Circular Dichroism (CD) spectroscopies and thermal denaturation. The results indicated that compound 4i as the DNA-intercalating agent exhibited middle binding affinity with CT-DNA.     

Synthesis and study of antiproliferative,antitopoisomerase II,DNA-intercalating and DNA-damaging activities of arylnaphthalimides

A series of arylnaphthalimides were designed and synthesized to overcome the dose-limiting cytotoxicity of N-acetylated metabolites arising from amonafide, the prototypical antitumour naphthalimide whose biomedical properties have been related to its ability to intercalate the DNA and poison the enzyme Topoisomerase II. Thus, these arylnaphthalimides were first evaluated for their antiproliferative activity against two tumour cell lines and for their antitopoisomerase II in vitro activities, together with their ability to intercalate the DNA in vitro and also through docking modelization. Then, the well-known DNA damage response in Saccharomyces cerevisiae was employed to critically evaluate whether these novel compounds can damage the DNA in vivo. By performing all these assays we conclude that the 5-arylsubstituted naphthalimides not only keep but also improve amonafide’s biological activities.     

Design and synthesis of bioactive adamantane spiro heterocycles

Spiro[aziridine-2,2'-adamantanes] 1 and 2, spiro[azetidine-2,2'-adamantanes] 3 and 5, spiro[azetidine-3,2'-adamantane] 13, spiro[piperidine-4,2'-adamantanes] 25 and 27, and spiro barbituric analog 18 were synthesized and tested for their anti-influenza A virus properties and for trypanocidal activity. The effect of ring size on potency was investigated. Piperidine 25 showed significant anti-influenza A virus activity, being 12-fold more active than amantadine, about 2-fold more active than rimantadine, and 54-fold more potent than ribavirin. It also proved to be the most active of the compounds tested against bloodstream forms of the African trypanosome, Trypanosoma brucei, being 1.5 times more potent than rimantadine and at least 25 times more active than amantadine.     

Synthesis and biological activity of dialkylphosphocholines

A series of dialkylphosphocholines were prepared and evaluated for their biological activity. The antiprotozoal activity was determined against Acanthamoeba lugdunensis. Compound 15 exhibited excellent trophocidal activity. None of the tested dialkylphosphocholines exhibited better fungicidal activity against Candida albicans than miltefosine. The antineoplastic activity was determined against HeLa. The most cytotoxic was compound 10, which was more active against tumor cells as against normal cells.