Induction of apoptosis by aryl-substituted diamines: role of aromatic group substituents and distance between nitrogens

Deeper Insight into Photopolymerization: The Synergy of Time-Resolved Nonuniform Sampling and Diffusion NMR

The comprehensive real-time in situ monitoring of chemical processes is a crucial requirement for the in-depth understanding of these processes. This monitoring facilitates an efficient design of chemicals and materials with the precise properties that are desired. This work presents the simultaneous utilization and synergy of two novel time-resolved NMR methods, i.e., time-resolved diffusion NMR and time-resolved nonuniform sampling. The first method allows the average diffusion coefficient of the products to be followed, while the second method enables the particular products to be monitored. Additionally, the average mass of the system is calculated with excellent resolution using both techniques. Employing both methods at the same time and comparing their results leads to the unequivocal validation of the assignment in the second method. Importantly, such validation is possible only via the simultaneous combination of both approaches. While the presented methodology was utilized for photopolymerization, it can also be employed for any other polymerization process, complexation, or, in general, chemical reactions in which the evolution of mass in time is of importance.

Design and Development of Fluorescent Sensors with Mixed Aromatic Bicyclic Fused Rings and Pyridyl Groups: Solid Mediated Selective Detection of 2,4,6-Trinitrophenol in Water

For a strategic incorporation of both π-electron-rich moieties and Lewis basic moieties acting as hydrogen bonding recognition sites in the same molecule, two new fluorescent sensors, N,N'-bis(anthracen-9-ylmethyl)-N,N'-bis(pyridin-2-ylmethyl)butane-1,4-diamine (banthbpbn, 1) and N,N'-bis(naphthalen-1-ylmethyl)-N,N'-bis(pyridin-2-ylmethyl)butane-1,4-diamine (bnaphbpbn, 2), have been developed for the selective detection of highly explosive 2,4,6-trinitrophenol (TNP) in water. Each of the two identical ends of these sensors that are linked with a flexible tetra-methylene spacer contains a mixed aromatic bicyclic fused ring (anthracene or naphthalene) and a pyridyl group. These are synthesized via the simple reduced Schiff base chemistry, followed by the nucleophilic substitution reaction under basic conditions in high yields. Both 1 and 2 were characterized by Fourier transform infrared, UV-vis, and NMR (¹H and ¹³C) spectroscopy, and high-resolution mass spectrometry. The bulk phase purity of 1 and 2 and their stability in water were confirmed by powder X-ray diffraction (PXRD). Utilizing the effect of solvents on their emission spectra as determined by fluorescence spectroscopy, spectral responses for 1 and 2 toward various nitro explosives were recorded to determine a detection limit of 0.6 and 1.6 ppm, respectively, for TNP in water via the "turn-off" quenching response. Also, the detailed mechanistic investigation for their mode of action through spectral overlap, lifetime measurements, Stern-Volmer plots, and density functional theory calculations reveals that resonance energy transfer and photoinduced electron transfer processes, and electrostatic interactions are the key aspects for the turn-off response toward TNP by 1 and 2. In addition, the selectivity for TNP has been found to be more in 1 compared to 2. Both exhibit good recyclability and stability after sensing experiments, which is confirmed by PXRD and field-emission scanning electron microscopy.

Synthesis, Biological Activity and Preliminary in Silico ADMET Screening of Polyamine Conjugates with Bicyclic Systems

Polyamine conjugates with bicyclic terminal groups including quinazoline, naphthalene, quinoline, coumarine and indole have been obtained and their cytotoxic activity against PC-3, DU-145 and MCF-7 cell lines was evaluated in vitro. Their antiproliferative potential differed markedly and depended on both their chemical structure and the type of cancer cell line. Noncovalent DNA-binding properties of the most active compounds have been examined using ds-DNA thermal melting studies and topo I activity assay. The promising biological activity, DNA intercalative binding mode and favorable drug-like properties of bis(naphthalene-2-carboxamides) make them a good lead for further development of potential anticancer drugs.

Cu(I)-catalyzed N,N'-diarylation of natural diamines and polyamines with aryl iodides

The Cu(I)-catalyzed N,N’-diarylation of natural diamines and polyamines such as putrescine, cadaverine, spermine, spermidine and their homologues is described. Aryl iodides bearing electron-donating and electron-withdrawing groups have been employed in the study. The CuI/2-(isobutyryl)cyclohexanone/DMF catalytic system has found to be more efficient in the diarylation of diamines and spermine while the CuI/L-proline/EtCN system proved to be preferable for the diarylation of other tri- and tetraamines like spermidine, norspermidine and norspermine.

In vitro antileishmanial, trypanocidal, and Mammalian cell activities of diverse n,n' -dihetaryl substituted diamines and related compounds

The leishmaniasis and Chagas diseases constitute a serious public health problem worldwide with few and ineffective treatment options. The search for new antiparasitic candidates at the initial steps of drug discovery and development is still necessary. The synthesis of 22 de novo synthetized N,N′-dihetaryl-alkyldiamine derivatives and in vitro antiparasitic activity were evaluated for the first time against intracellular and extracellular forms of Leishmania (Leishmania) infantum, L. (Viannia) panamensis, L. (Leishmania) amazonensis, and Trypanosoma cruzi. Additionally, the toxicity on mammalian cells was determined. Some of these substituted N,N′-diamines (25–35 % of the tested compounds) showed interesting results against free-living forms of parasites with activities at the inhibitory concentration (IC₅₀) level of 1.96 to 28.83 μM for L. (L.) infantum promastigotes and IC₅₀ of 0.02 to 5.31 μM for T. cruzi epimastigotes. No activity at the IC₅₀ level on intracellular amastigotes of T. cruzi was observed. However, N¹,N²-dibenzylethane-1,2-diamine 5a revealed an important activity against the intracellular amastigotes of L. infantum (IC₅₀ 25.42 μM ±0.33) and L. panamensis (IC₅₀ 58.20 μM ±3.23), while their analogue N¹,N⁴-dibenzylbutane-1,4-diamine 5c resulted in activity only against L. panamensis (IC₅₀ 11.19 μM ±0.20) without toxicity on Vero and THP-1 mammalian cells. The active compounds against intracellular parasites with low toxicity in mammalian cells may be considered for future studies in experimental models.

Mechanistic studies of para-substituted N,N'-dibenzyl-1,4-diaminobutanes as substrates for a mammalian polyamine oxidase

The kinetics of oxidation of a series of para-substituted N,N'-dibenzyl-1,4-diaminobutanes by the flavoprotein polyamine oxidase from mouse have been determined to gain insight into the mechanism of amine oxidation by this member of the monoamine oxidase structural family. The k(cat)/K(m) values are maximal at pH 9, consistent with the singly charged substrate being the active form. The rate constant for flavin reduction, k(red), by N,N'-dibenzyl-1,4-diaminobutane decreases about 5-fold below a pK(a) of approximately 8; this is attributed to the need for a neutral nitrogen at the site of oxidation. The k(red) and k(cat) values are comparable for each of the N,N'-dibenzyl-1,4-diaminobutanes, consistent with rate-limiting reduction. The deuterium kinetic isotope effects on k(red) and k(cat) are identical for each of the N,N'-dibenzyl-1,4-diaminobutanes, consistent with rate-limiting cleavage of the substrate CH bond. The k(red) values for seven different para-substituted N,N'-dibenzyl-1,4-diaminobutanes correlate with a combination of the van der Waals volume and sigma value of the substrates, with rho values of -0.59 at pH 8.6 and -0.09 at pH 6.6. These results are consistent with direct transfer of a hydride from the neutral CN bond of the substrate to the flavin as the mechanism of polyamine oxidase.

Inhibition of plant amine oxidases by a novel series of diamine derivatives

A series of N,N'-bis(2-pyridinylmethyl)diamines was synthesized and characterized for their inhibition effects towards plant copper-containing amine oxidase (EC 1.4.3.6) and polyamine oxidase (EC 1.5.3.11), which mediate the catabolic regulation of cellular polyamines. Even though these enzymes catalyze related reactions and, among others, act upon two common substrates (spermidine and spermine), their molecular and kinetic properties are different. They also show a different spectrum of inhibitors. It is therefore of interest to look for compounds providing a dual inhibition (i.e. inhibiting both enzymes with the same inhibition potency), which would be useful in physiological studies involving modulations of polyamine catabolism. The synthesized diamine derivatives comprised from two to eight carbon atoms in the alkyl spacer chain. Kinetic measurements with pea (Pisum sativum) diamine oxidase and oat (Avena sativa) polyamine oxidase demonstrated reversible binding of the compounds at the active sites of the enzymes as they were almost exclusively competitive inhibitors with K(i) values ranging from 10(-5) to 10(-3)M. In case of oat polyamine oxidase, the K(i) values were significantly influenced by the number of methylene groups in the inhibitor molecule. The measured inhibition data are discussed with respect to enzyme structure. For that reason, the oat enzyme was analyzed by de novo peptide sequencing using mass spectrometry and shown to be homologous to polyamine oxidases from barley (isoform 1) and maize. We conclude that some of the studied N,N'-bis(2-pyridinylmethyl)diamines might have a potential to be starting structures in design of metabolic modulators targeted to both types of amine oxidases.

Synthesis and biological evaluation of new symmetrical derivatives as cytotoxic agents and apoptosis inducers

Based on the research of less toxic anticancer therapies, we have looked for novel compounds with anticancer activity based on a proapoptotic mechanism. The described compounds are derivatives of ether, carbamate, urea, amide, or amine. Some of the prepared compounds decreased cell viability of various tumor cell lines in a time- and dose-dependent manner, and also induced DNA fragmentation, which indicated cell apoptosis. The potential antitumoral activity of the compounds was evaluated in vitro by examining their cytotoxic effects against human mama, colon, and bladder cancer cell lines (MD-MBA-231, HT-29, and T-24). Compounds showing cytotoxic activity were subjected to an apoptosis assay. In addition, some of the synthesized compounds provoked a rapid and dose-dependent increase in the level of caspase-3, an enzyme, which is considered to be one of the principal executing caspases in which all of the biochemical routes involved in the apoptosis response converge. The most promising compounds, with respect to cytotoxicity and apoptosis induction capability, were the 4-nitrophenylcarbamate derivative of 2,2'-methylenebis(4-chlorophenyl) 3c, the naphthylurea derivative 4d, and the n-propylurea derivative 4c, from 4,4'-methylenebisphenyl, all of which displayed cytotoxic activity and showed very interesting levels of apoptosis. Furthermore, good levels of apoptosis induction were achieved for 3a and 4b in the T-24 cell line. Therefore, compounds such as 7b, a pyrido[2,3-d]pyrimidine derivative, show a significant in vitro cytotoxicity, with IC(50) values between 3 and 8 microm in the three cell lines tested. This compound also produced a rapid and dose-dependent increase of the caspase-3 level and induced apoptosis in HT-29 cells. Other profiles have been found, such as those presented by 5c and 7c, which are cytotoxic and apoptotic but do not provoke an increase in the level of caspase-3, or those presented by 1c, 1d, and 2a, which are cytotoxic, without showing any other activity. The different types of behavior of each compound are not necessarily parallel in the three cell lines tested. A great number of these compounds of interest show no cytotoxicity in nontumoral human cells such as CRL-8799, a nontumoral line of mama. Subsequent modulation of these lead structures permits advances in the design of potent cytotoxic and proapoptotic anticancer drugs.