Synthetic control of interchromophoric interaction in cationic bis-porphyrins toward efficient DNA photocleavage and singlet oxygen production in aqueous solution

Interactions of porphyrins with DNA: A review focusing recent advances in chemical modifications on porphyrins as artificial nucleases

The advance of porphyrins as artificial nucleases along the years have developed a class of compounds having potential therapeutic applications. Being an extrovert of chemistry, a variety of chemical modifications have been done on porphyrin macrocycle in order to improve the spectroscopic properties and to adapt as artificial receptors that can recognize molecules. The last twenty years has witnessed broad research in the arena of porphyrin- DNA interactions and their evolution from simple to more complex entities. In this review, we summarize the recent advances in the porphyrin-based structural modifications, with a specific emphasis on various effects of porphyrin on DNA cleavage potency. We particularly detailed the nuclease activity of cationic and anionic porphyrins, porphyrin dimers and conjugates as well as heme proteins till the third generation porphyrins as artificial nucleases.

N-Methylpyridylporphyrin tailed with folate conjugate as a potential lysosomal-targeted photosensitizer: Synthesis, DNA interaction, singlet oxygen and subcellular localization

In recent years, great interest has been focused on the use of photosensitizers (PS) for photodynamic therapy (PDT) as safe and effective anti-tumor drugs. As a good lysosomal-targeted drug, folic acid (FA) is highly interesting as well. [Formula: see text]-methylpyridylporphyrin tailed with folate conjugate (Me-Por-FA) was newly designed and synthesized and the structure was confirmed by UV-vis, IR, 1H NMR, MS and elemental analysis. The interaction of this porphyrin with calf thymus DNA was the intercalative binding mode, which was confirmed by ultraviolet and fluorescence spectra, and the binding constants [Formula: see text] was 6.24 × 104 L/mol. The singlet oxygen (1O[Formula: see text] generated by Me-Por-FA was determined by 1, 3-diphenylisobenzofuran (DPBF) method using tetrapyridylporphyrin (H[Formula: see text]TMPyP) as a comparison with the following order: H2TMPyP > Me-Por-FA. Stained with LysoTracker[Formula: see text] Green DND-26, Me-Por-FA was mainly distributed over the lysosomes during 4 h, but H[Formula: see text]TMPyP was not. This suggests that Me-Por-FA could be developed as a targeted photosensitizer for precise photodynamic therapy.

Synthesis, singlet oxygen generation and DNA photocleavage of β,β′-conjugated polycationic porphyrins

In this paper, three [Formula: see text],[Formula: see text]-conjugated cationic porphyrin compounds were designed and synthesized. The structure of the intermediates and desired porphyrins were confirmed by UV, IR, 1H NMR, MS and elemental analysis. The interaction modes between these porphyrins and ct-DNA were studied by UV-vis spectroscopy and fluorescence emission spectroscopy. The results showed that PCP 1 had an external binding mode with DNA at low DNA concentration and could intercalate DNA with the increase of concentration. PCP 2 interacted with DNA through an external binding mode, and PCP 3 could insert into DNA. The binding constants ([Formula: see text] between PCP1[Formula: see text]PCP3 and ct-DNA were calculated to be 8.41 × 104, 7.33 × 104 and 4.14 × 104 M[Formula: see text], respectively. The singlet oxygen (1O[Formula: see text] generation of PCP1[Formula: see text]PCP3 was determined by the 1,3-diphenylisobenzofuran (DPBF) method using tetrapyridylporphyrin (H2TMPyP) as a reference. The 1O2 generation rate of PCP1[Formula: see text]PCP3 followed the order of PCP2 >PCP1>H2TMPyP >PCP3. Subsequently, the photocleavage effect of porphyrins on pBR322 plasmid DNA was studied by gel electrophoresis. At 10.0 [Formula: see text]M, PCP1 and PCP2 could cleave DNA completely. At 2.0 [Formula: see text]M, the cleavage rate of DNA by PCP3 was 57.5%, which was significantly higher than that of H2TMPyP (38.8%). These results verified that the amount of cationic ions in the porphyrin structure could affect the binding modes of porphyrins with DNA and their cleavage ability of DNA.

Improved Optical and Morphological Properties of Vinyl-Substituted Hybrid Silica Materials Incorporating a Zn-Metalloporphyrin

This work is focused on a novel class of hybrid materials exhibiting enhanced optical properties and high surface areas that combine the morphology offered by the vinyl substituted silica host, and the excellent absorption and emission properties of 5,10,15,20-tetrakis(N-methyl-4-pyridyl)porphyrin-Zn(II) tetrachloride as a water soluble guest molecule. In order to optimize the synthesis procedure and the performance of the immobilized porphyrin, silica precursor mixtures of different compositions were used. To achieve the requirements regarding the hydrophobicity and the porous structure of the gels for the successful incorporation of porphyrin, the content of vinyltriacetoxysilane was systematically changed and thoroughly investigated. Substitution of the silica gels with organic groups is a viable way to provide new properties to the support. An exhaustive characterization of the synthesized silica samples was realised by complementary physicochemical methods, such as infrared spectroscopy (FT-IR), absorption spectroscopy (UV-Vis) and photoluminescence, nuclear magnetic resonance spectroscopy (²⁹Si-MAS-NMR) transmission and scanning electron microscopy (TEM and SEM), nitrogen absorption (BET), contact angle (CA), small angle X ray and neutron scattering (SAXS and SANS). All hybrids showed an increase in emission intensity in the wide region from 575 to 725 nm (Q bands) in comparison with bare porphyrin. By simply tuning the vinyltriacetoxysilane content, the hydrophilic/hydrophobic profile of the hybrid materials was changed, while maintaining a high surface area. Good control of hydrophobicity is important to enhance properties such as dispersion, stability behaviour, and resistance to water, in order to achieve highly dispersible systems in water for biomedical applications.

Methylene violet 3RAX-conjugated porphyrin for photodynamic therapy: synthesis, DNA photocleavage, and cell study

A novel PDT photosensitizer which features great biomedical properties can be simply prepared.

Selective binding and reverse transcription inhibition of single-strand poly(A) RNA by metal TMPyP complexes

Ni-, Cu-, and Zn-TMPyP are capable of binding to single-strand poly(A) RNA with high preference and affinity and inhibiting the reverse transcription of RNA by both M-MuLV and HIV-1 reverse transcriptase. With 10 nM azidothymidine, the IC50 value of M-TMPyP could be lowered to 10(-1) μM order.

Synthesis, circular dichroism, DNA cleavage and singlet oxygen photogeneration of 4-amidinophenyl porphyrins

5,10,15,20-tetrakis(4-amidinophenyl)porphyrin (Por 1), its Zn complex (Por 2) and its conjugate with a tetraphenylporphyrin to form a bisporphyrin (Por 3) were prepared. The monomeric Por 1 and Por 2 showed both intercalative and external binding with DNA whereas only external DNA binding was seen in the bisporphyrin, Por 3 by circular dichroism and UV-vis. The DNA photocleavage activities of these porphyrins followed the order: Por 1 ~ Por 2 > Por 3, which did not correlate with their measured 1O2 production rates. It suggests 4-amidinophenylporphyrins are promising new photodynamic therapeutic agents.

Synthesis, singlet oxygen photogeneration and DNA photocleavage of porphyrins with nitrogen heterocycle tails

Eight novel compounds were prepared by reaction of 5-(bromo- propoxyphenyl)-10,15,20-triphenylporphyrin with oxazole thiols, 1,3,4-oxadiazole thiols and 1,3,4-thiadiazole thiols, and their structures confirmed by UV-vis, IR, ¹H-NMR, MS and elemental analysis. The assessment of indirectly measured ¹O₂ production rates against 5,10,15,20-tetraphenyl porphyrin (H₂TPP) were described and the relative singlet oxygen production yields were: porphyrin 5 > porphyrins 1, 3, 4, 6-8, H₂TPP > porphyrin 2. Porphyrin 4 and porphyrin 7 showed substantial photocleavage activities toward DNA, with over 75% cleavage observed at 40 µM. It suggested that these those porphyrins with nitrogen heterocycle tails are potential photosensitive agents.

Photoenhanced oxidative DNA cleavage with non-heme iron(II) complexes

The DNA cleavage activity of iron(II) complexes of a series of monotopic pentadentate N,N-bis(2-pyridylmethyl)-N-bis(2-pyridyl)methylamine (N4Py)-derived ligands (1-5) was investigated under laser irradiation at 473, 400.8, and 355 nm in the absence of a reducing agent and compared to that under ambient lighting. A significant increase in activity was observed under laser irradiation, which is dependent on the structural characteristics of the complexes and the wavelength and power of irradiation. Under photoirradiation at 355 nm, direct double-stand DNA cleavage activity was observed with Fe(II)-1 and Fe(II)-3-5, and a 56-fold increase in the single-strand cleavage activity was observed with Fe(II)-2. Mechanistic investigations revealed that O(2)(•-), (1)O(2), and OH(•) contribute to the photoenhanced DNA cleavage activity, and that their relative contribution is dependent on the wavelength. It is proposed that the origin of the increase in activity is the photoenhanced formation of an Fe(III)OOH intermediate as the active species or precursor.

Greatly enhanced binding of a cationic porphyrin towards bovine serum albumin by cucurbit[8]uril

Binding affinity towards serum albumin and intracellular proteins is of importance for a photodynamic therapy (PDT) sensitizer to selectively localize in tumours and efficiently induce cell death. In this paper, it was found that cucurbit[8]uril (CB8) can greatly improve the binding affinity of 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP), a promising PDT photosensitizer, towards bovine serum albumin (BSA). Absorption, fluorescence emission, (1)H NMR, dynamic light scattering, atomic force microscope, as well as protein photocleavage measurements suggest that the binding enhancement originates from the formation of a ternary complex of CB8·TMPyP·tryptophan residues. This finding opens up a new approach for the development of more efficient PDT agents.

Synthesis of novel diselenide-linked porphyrin dimers under phase-transfer catalysis condition and their interactions with DNA

Novel diselenide-linked porphyrin dimers were synthesized under phase-transfer catalysis conditions. The targeted compounds were characterized by (1)H-NMR, high-resolution mass spectrometry, UV/VIS and fluorescence spectroscopies, redox-potential measurements, and elemental analysis. The interaction of the title compounds with DNA was studied using UV/VIS, fluorescence, and circular dichroism (CD) spectroscopies. The relative rates of singlet-oxygen production from the diselenide-linked porphyrin dimers upon photoirradiation were also measured.

Binding of cationic bis-porphyrins linked with p- or m-xylylenediamine and their zinc(II) complexes to duplex DNA

Spectroscopic, viscometric, and molecular docking analysis of binding of cationic bis-porphyrins linked with p- or m-xylylenediamine (H₂pXy and H₂mXy) and their zinc(II) complexes (ZnpXy and ZnmXy) to duplex DNA are described. H₂pXy and H₂mXy bound to calf thymus DNA (CTDNA) stronger than unichromophoric H₂TMPyP, and showed exciton-type induced circular dichroism spectra of their Soret bands. The H₂TMPyP-like units of the metal-free bis-porphyrins did not intercalate into CTDNA, and thus the binding mode is outside binding with intramolecular stacking. ZnpXy showed favorable binding to A·T over G·C region, and should lie in the major groove of A·T region.