Water-solubility croconic acid-bisindole dye with morpholine ring for tumor NIRF/PA imaging and photothermal therapy activated by lysosome pH-response.

A novel croconic acid-bisindole dye CR-630 with a morpholine ring showed good water-solubility and obvious lysosome-targeting. The protonation of the nitrogen atom in the indole and lysosome-targeting of morpholine ring let it exhibit stronger pH-responsive NIR/PA imaging and photothermal effect in the lysosome acidic microenvironment (pH 4.0-5.5) than in the tumor acidic microenvironment. In the animal study, compound CR-630 could NIRF/PA image in the tumor tissues in 1.5-2.0 h, effectively inhibit the growth of the tumor, and even ablate the tumor at the drug dose of 1 mg/kg. It also demonstrated good biosafety. This study gives a new idea to develop water-solubility organic dyes with lysosome targeting, stronger pH-responsive NIRF/PA imaging and PTT for breast cancer.

NIR C-Myc Pu22 G-quadruplex probe as a photosensitizer for bioimaging and antitumor study.

Despite the fact that C-Myc G-quadruplex in the oncogene promoter regions is one of the crucial targets of antitumor drugs, the selectivities and proliferation inhibitions of its probes towards tumor cells remain a big challenge. Until now, no effective C-Myc G-quadruplex probes have been reported as a photosensitizer to increase their antitumor activities. Here, the first NIR C-Myc G-quadruplex probe PDS-SQ has been designed, comprising a G-quadruplex binder PDS and a squaraine dye SQ as a photosensitizer. Conjugate PDS-SQ could selectively NIR image C-Myc Pu22 G-quadruplex in tumor cells, and show stronger antitumor activity in the irradiation by a chemo-photodynamic method than in the dark. The study provides a new way to develop the novel NIR C-Myc G-quadruplex probes with more potent antitumor activities.

Single aromatics sulfonamide substituted dibenzothiazole squaraines for tumor NIR imaging and efficient photodynamic therapy at low drug dose.

On the base of the zwiterionic dibenzothiazole squaraine SQ, five cationic aromatics sulfonamide substituted dibenzothiazole squaraines SQ-D1 âˆ¼ 5 have been designed and synthesized. Through the formation of the cationic compound, a higher rigid structure and the addition of the strong electron-withdrawing group (-CN), an ideal photosensitizer SQ-D2 has been gotten. In all the sulfonaminosquaraines, compound SQ-D2 exhibited the highest ROS generation efficacy and photostability. It also showed the highest photo-cytotoxicity (IC50 = 0.25 ± 0.08 µM), very low dark-cytotoxicity and the excellent cell uptake. In animal study, it not only showed the effective tumor retention and the easy removal from the body, but also exhibited the effective PDT efficacy at low drug dose (0.15 mg/kg) and the good biocompatibility. Furthermore, photosensitizer SQ-D2 as a single component exhibited greater potential than clinically approved photosensitizer m-THPC and some nanomaterials with photosensitizers in PDT therapy towards human breast cancer. This work provides a new perspective to develop the ideal photosensitizer of the squaraine dyes.

Human telomere double G-quadruplex recognition by berberine-bisquinolinium imaging conjugates in vitro and cells.

Molecular tools of double or multimeric G-quadruplexes have been given higher requirements on detection sensitivity, thermal stabilization and cell imaging to establish functions of these G-quadruplex aggregates and biological mechanisms as anticancer reagents. Here, two smart berberine-bisquinolinium conjugates (Ber-360A and Ber-PDS) by linking the berberine fluorophore ligand and an established G-quadruplex binder (i.e. bisquinolinium scaffold), have been designed and evaluated their activities and mechanisms for G-quadruplex aggregation. Two conjugates, especially Ber-PDS, are two highly selective, sensitive and fluorescent sensors which can distinguish human telomere double G-quadruplexes from other type G-quadruplexes and ds DNA. These two ligands could be the first example to stack two adjacent G-quadruplex units and fluorescently recognize human telomere double G-quadruplexes. Furthermore, conjugate Ber-PDS could enter the nucleoli and target G-quadruplex DNA through microscopy experiments, and also display strong telomerase inhibition and antitumor activities.

A Comparative Study on High Selectivities of Human Telomeric Dimeric G-Quadruplexes by Dimeric G-Quadruplex Binders.

Three new polyether-tethered bisquinolinium dimers (3 a-c) were synthesized, and their binding affinities, selectivities, and thermal stabilization towards dimeric G-quadruplex DNA (G2T1) in human telomeric regions were studied. The bisquinolinium dimer with a medium-length polyether linker (3 b) showed 30-425-fold higher binding affinity and selectivity towards antiparallel G2T1 than towards monomeric quadruplexes, which included human telomeric monomeric G-quadruplexes (G1), c-kit 1, c-kit 2, and c-myc. In addition, compound 3 b induced the formation of quadruplexes and displayed the highest level of thermal stabilization (ΔTm >28.1 °C) among all reported multimeric G-quadruplex binders. Compound 3 b also displayed a higher selectivity towards antiparallel G2T1 than monomer 360 A and bisquinolinium dimers 3 a and c. In contrast with our recent research on the analogous berberine dimer 1 b and dinickel-salphen complex 2 c, polyether linkers and their monomeric G-quadruplex binders in these dimeric G-quadruplex binders play a crucial role in regulating the binding affinities, selectivities, and thermal stabilization towards G2T1. More interestingly, these dimeric G-quadruplex compounds bind through end-stacking with the two adjacent G-quadruplex units in G2T1, and they showed high selectivity towards antiparallel G2T1 rather than mixed-type G2T1. In addition, compound 3 b, which displayed high selectivity towards antiparallel G2T1, showed strong telomerase inhibition and potent anticancer activities against HeLa and MCF-7 cells.

Specifically targeting mixed-type dimeric G-quadruplexes using berberine dimers.

Three polyether-tethered berberine dimers (1a-c) were studied for their binding affinity, selectivity and thermal stabilization towards human telomeric dimeric quadruplex DNA (G2T1). Compound 1a with the shortest polyether linker showed the highest affinity (Ka > 108 M-1) and 76-508-fold higher selectivity for mixed-type G2T1 over antiparallel G2T1 and three monomeric G-quadruplexes, which are human telomeric monomeric quadruplex G1, c-kit 1 and c-kit 2. Compound 1a induced the formation of quadruplex structures and showed higher thermal stabilization for mixed-type G2T1 than for anti-parallel G2T1, G1 and ds DNA. Spectroscopic studies suggest that compound 1a could bind to mixed-type G2T1 via end-stacking and external binding modes. These results suggest that the polyether linkers in these compounds play an important role in regulating the binding affinity and selectivity towards mixed-type G2T1 and that compound 1a could target mixed-type G2T1 at other genome regions with antiparallel G2T1 and monomeric G-quadruplexes. These results may provide useful guidance for the rational design of selective multimeric G-quadruplex binders and potential anticancer agents.

Synthesis and anticancer activities of 3-arylflavone-8-acetic acid derivatives.

This paper describes the synthesis and the antiproliferative activities of compounds 9a-r, 3-aryl analogs of flavone-8-acetic acid that bear diverse substituents on the benzene rings at the 2- and 3-positions of the flavone nucleus. Their direct and indirect cytotoxicities were evaluated against HT-29 human colon adenocarcinoma cell lines, A549 lung adenocarcinoma cell lines and Human Peripheral Blood Mononuclear Cells (HPBMCs). The results indicate that most of the compounds bearing electron-withdrawing substituents (9b-m) exhibited moderate direct cytotoxicities. And compounds 9e and 9i showed comparable indirect cytotoxicities with 5, 6-dimethylxanthenone-4-acetic acid (DMXAA), and low direct cytotoxicities toward HPBMCs. Interestingly, the compounds 9n-r bearing methoxy groups at the 2- or 3-position of the flavone nucleus exhibited higher indirect cytotoxicities against A549 cell lines than DMXAA, and lower cytotoxicities against HPBMCs. In addition, compounds 9p-r were found to be able to induce tumor necrosis factor α (TNF-α) production in HPBMCs.

Synthesis, hydrolytic DNA-cleaving activities and cytotoxicities of EDTA analogue-tethered pyrrole-polyamide dimer-based Ce(IV) complexes.

Two EDTA analogue-tethered C2-symmetrical dimeric monopyrrole-polyamide 5 and dipyrrole-polyamide 6, and their corresponding Ce(IV) complexes Ce-5 and Ce-6 were synthesized and fully characterized. Agarose gel electrophoresis studies on pBR322 DNA cleavage indicate that complexes Ce-5 and Ce-6 exhibited potent DNA-cleaving activities under physiological conditions. The maximal first-order rate constants (kmax's) were (0.42 ± 0.02) h(-1) for Ce-5 and (0.52 ± 0.02) h(-1) for Ce-6, respectively, suggesting that both complexes catalyzed the cleavage of supercoiled DNA by up to approximately 10(8)-fold. Complex Ce-6 exhibited ca 10-fold higher overall catalytic activity (kmax/KM) than Ce-5, which may be ascribed to its higher DNA-binding affinity. Inhibition experiments and a model study convincingly suggest that both complexes Ce-5 and Ce-6 functioned as hydrolytic DNA-cleavers. In addition, both complexes were found to display moderate inhibitory activity toward A549 and HepG-2 cells.

Synthesis, DNA-cleaving activities and cytotoxicities of C2-symmetrical dipyrrole-polyamide dimer-based Cu(II) complexes: a comparative study.

Two C2-symmetrical dipyrrole-polyamide dimers 2 and 3 that were tethered with triethylenetetramine and spermine, respectively, and their corresponding Cu(II) complexes 2@Cu(2+) and 3@Cu(2+), were synthesized and fully characterized. Agarose gel electrophoresis studies on pBR322 DNA cleavage indicated that both Cu(II) complexes exhibited potent DNA-cleaving activities under physiological conditions, most probably via an oxidative mechanism. Kinetic assay indicate that 2@Cu(2+) and 3@Cu(2+) exhibited comparable catalytic efficiency with the Cu(II) complex of their 2,2'-(ethane-1,2-diylbis(oxy))diethanamine-tethered analog 1. The finding that compounds 2 and 3 showed higher Cu(II) ion-complexing abilities than compound 1, suggests that strong metal complexation does not necessarily lead to an enhancement in the catalytic efficiency of a DNA-cleaving agent. In addition, three Cu(II) complexes displayed moderate inhibitory activities toward three tumor cell lines.

Facile synthesis of a dimeric dipyrrole-polyamide and synergetic DNA-cleaving activity of its Cu(II) complex.

Inspired by the potent DNA-cleaving activity of the Cu(II) complex of monopyrrole-polyamide dimer 1 (i.e., 1@Cu(2+)), we designed a new dimeric dipyrrole-polyamide analog 2 with the aim to optimize the catalytic activities of the metal complexes of this type of polypyrrole-polyamides. Compound 2 was prepared in 50% yield from the reaction of 1-methyl-4-[(1-methyl-4-nitro-1H-pyrrole-2-carbonyl)-amino]-1H-pyrrole-2-carboxylic acid with 2,2'-(ethane-1,2-diylbis(oxy))diethanamine, and fully characterized on the basis of NMR ((1)H and (13)C), MS (ESI and HR) and IR. Spectrophotometric titration, ESI-MS and conductivity measurements indicated that compound 2 formed a 1:1 complex with Cu(2+) ion (i.e., 2@Cu(2+)). Agarose gel electrophoresis studies indicated that 2@Cu(2+) was capable of efficiently converting pBR322 DNA into open circular and linear forms under physiological conditions, most probably via an oxidative mechanism. Its overall catalytic activity was estimated to be at least 30-fold higher than that of 1@Cu(2+). The fact that the cleaving activities of these Cu(II) complexes parallel, exactly, their binding affinities, raises the possibility that the cleaving activities of polypyrrole-polyamide derivatives of the type can be regulated by the binding affinities.

Synthesis, cytotoxicities and DNA-binding affinities of benzofuran-3-ols and their fused analogs.

A series of benzofuropyrazoles 2a-i were synthesized in 10-92% from the reaction of 2-aroylbenzofuran-3-ols 1a-i with hydrazine hydrate, and screened for their antitumor activities toward four human solid tumor cell lines, including gastric carcinoma cells MKN45, hepatocellular carcinoma cells HepG2, breast cancer cells MCF-7, and lung cancer cells A549. The results indicated that both compounds 1a-i and 2a-i displayed moderate antitumor activities. Among them, compound 2e exhibited potent inhibitory activity toward all the four tumor cell lines. In addition, compounds 1e and 2e showed strong DNA-binding affinities, and induced an increase in the viscosity of calf-thymus DNA, suggesting that they might act as an intercalator.