Controllable Direction of Porphyrin Derivatives in Two Cyclodextrin Cavities

"On-Off" Switching of Functional Guest Molecules via Exchange of Natural Product Solubilizing Agents

For the development of delivery systems, the solubilization of hydrophobic guest molecules in water is an important yet challenging task. This can be achieved by preparing stable aqueous solutions with a high concentration of guest molecules using a natural product as a solubilizing agent and a mechanochemical high-speed vibration milling apparatus as a solubilizing method. Various solubilizing agent-guest molecule complexes can be obtained via the exchange between solubilizing agents, which enables the "on-off" switching of the properties of functional guest molecules, such as fluorescence intensity, and photodynamic activity. In the exchange method, guest molecules can transfer into cell membranes such as lysosomes and exosomes. Therefore, the exchange method of the solubilizing agents not only creates novel solubilizing agent-guest molecule complexes but also is applied to drug delivery systems.

Selective Photodynamic Activity of Tetrakis(4-aminophenyl)porphyrins with and without Acetyl Protecting Groups on Cancer and Normal Cells

Tetrakis(4-aminophenyl)porphyrin (1) and tetrakis(4-acetamidophenyl)porphyrin (2) were dissolved in water with the incorporation of a polysaccharide (λ-carrageenan (CGN)) as a water-solubilizing agent. Although the photodynamic activity of the CGN-2 complex was considerably lower than that of the CGN-1 complex, the selectivity index (SI; IC50 in a normal cell/IC50 in a cancer cell) of the CGN-2 complex was considerably higher than that of the CGN-1 complex. This is because the photodynamic activity of the CGN-2 complex was significantly affected by the intracellular uptakes by the normal and cancer cells. During in vivo experiments, the CGN-2 complex inhibited tumor growth under light irradiation with high blood retention compared with the CGN-1 complex and Photofrin, which exhibited lower blood retention. This study showed that the photodynamic activity and SI are influenced by substituent groups of arene in the meso-positions of porphyrin analogs.

Fluorescence Turn-on of Tetraphenylethylene Derivative by Transfer from Cyclodextrin to Liposomes, HeLa Cells, and E. coli

Herein, trimethyl-β-cyclodextrin (TMe-β-CDx) and γ-cyclodextrin (γ-CDx) could dissolve a tetraphenylethylene derivative (TPE-OH₄ ) in water through high-speed vibration milling. The fluorescence intensity of the TMe-β-CDx-TPE-OH₄ complex was much higher than that of the γ-CDx-TPE-OH₄ complex, as the rotation of the central C=C double bond of TPE-OH₄ after photoactivation was inhibited in a smaller TMe-β-CDx cavity in comparison with the γ-CDx cavity. In contrast, the fluorescence intensity of the γ-CDx-TPE-OH₄ complex was very weak; nevertheless, it increased after the addition of liposomes due to the transfer of TPE-OH₄ from the γ-CDx cavity to the lipid membrane as a "turn-on" phenomenon. Furthermore, to apply temperature sensor, it was demonstrated that the fluorescence intensity in the liposomes depended on the phase-transition temperature. By using the fluorescence turn-on phenomenon, TPE-OH₄ could detect the presence of HeLa cells and E. coli by fluorescence.

Effect of meso Positioned Substituents on the Stability and Photodynamic Activity of Lipid-Membrane-Incorporated Porphyrin Derivatives

Here, we prepared aqueous solutions of lipid-membrane incorporated tetraarylporphyrins and tetrapyridylporphyrin (LMIPors) by the injection method using dimethyl sulfoxide. The porphyrins with proton-donor groups at the meso position afforded stable aqueous solutions of LMIPors. However, although tetrakis(carboxyphenyl)porphyrin was scarcely incorporated in lipid membranes, it was soluble in water. Among these LMIPors, the photodynamic activity of tetrakis(hydroxyphenyl)porphyrin was higher than that of tetrakis(aminophenyl)porphyrin. This was attributed to the self-aggregation of a part of tetrakis(aminophenyl)porphyrin in the liposomes, which induced self-quenching and the consequent decrease of its photodynamic activity.

Unsymmetrical, monocarboxyalkyl meso-arylporphyrins in the photokilling of breast cancer cells using permethyl-β-cyclodextrin as sequestrant and cell uptake modulator

In the search for photosensitizers with chemical handles to facilitate their integration into complex drug delivery nanosystems, new, unsymmetrically substituted, water insoluble meso-tetraphenylporphyrin and meso-tetra(m-hydroxyphenyl)porphyrin derivatives bearing one carboxyalkyl side chain were synthesized. Permethyl-β-cyclodextrin (pMβCD) was their ideal monomerizing host and highly efficient shuttle to transfer them into water. New assembly modes of the extremely stable (K_binding > 10¹² M^-2) 2:1 complexes were identified. The complexes are photostable and do not disassemble in FBS-containing cell culture media for 24 h. Incubation of breast cancer MCF-7 cells with the complexes results in intense intracellular fluorescence, strongly enhanced in the endoplasmic reticulum (ER), high photokilling efficiency (~90%) and low dark toxicity. pMβCD stands out as a very capable molecular isolator of mono-carboxyalkyl-arylporphyrins that increases uptake and modulates their localization in the cells. The most efficient porphyrins are envisaged as suitable photosensitizers that can be linked to biocompatible drug carriers for photo- and chemo-therapy applications.

Water Solubilization and Thermal Stimuli-Triggered Release of Porphyrin Derivatives Using Thermoresponsive Polysaccharide Hydroxypropyl Cellulose for Mitochondria-Targeted Photodynamic Therapy

With minimal invasiveness and spatiotemporal therapeutic effects, photodynamic therapy is one of the most elegant strategies for achieving effective tumor therapy. Herein, a facile preparation and thermal process-triggered release of water-soluble photosensitizer 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (THPP) has been developed using a thermoresponsive polysaccharide, hydroxypropyl cellulose. Current systems using hydroxypropyl cellulose enable manipulation of the loading capacity of THPP into a polymer matrix and the size of the complex by varying the temperature of the solution in preparation. Furthermore, current systems have enabled the release of THPP using a heating process, mimicking the surrounding of mitochondria, and have resulted in THPP potency as a mitochondria-targeted photodynamic therapy.

Improved water solubility and photodynamic activity of hydroxy-modified porphyrins by complexation with cyclodextrin

Porphyrin derivatives with hydroxyphenyl or dihydroxyphenyl moieties in the meso-position were able to dissolve in water by complexation with two trimethyl-β-cyclodextrins (TMe-β-CDxs) without further chemical modification of porphyrins or addition of dimethyl sulfoxide as a co-solvent. TMe-β-CDx-complexed tetra(hydroxyphenyl)porphyrins (THPPs) with phenols in meso-positions have a much higher photodynamic activity than TMe-β-CDx-complexed tetrakis(dihydroxyphenyl)porphyrins (TDHPPs) with dihydroxyphenyl in the meso-position. The main reason for the different photoactivity is due to the intracellular uptakes of these complexes. Thus phenols in meso-positions of porphyrin derivatives in the complexes were recognized by HeLa cell receptors. Furthermore, the photodynamic activity of TMe-β-CDx-complexed THPP was much higher than that of THPP injected as a dimethyl sulfoxide solution.

Molecular structure study of a heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin complex of cholesterol

Heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (2) and cholesterol form a water-soluble complex 3. We performed several NMR studies, particularly ¹H, ¹³C, 2D NOESY and DOSY, at various temperatures on 500 and 950 MHz instruments. We discovered that the complex 3 is unstable above 57 °C in heavy water, while it is kinetically stable enough to be studied by NMR in detail at 1 °C. We demonstrated the formation of a face-to-face 2:1 complex with a binding constant of approximately 2.2 × 10⁶ M^-2.

High photodynamic activities of water-soluble inclusion complexes of 5,15-diazaporphyrins in cyclodextrin

Inclusion complexes of 5,15-diazaporphyrin derivatives in trimethyl-β-cyclodextrin exhibited high photodynamic activity under visible-light irradiation at wavelengths greater than 620 nm.

Stabilisation of lipid membrane-incorporated porphyrin derivative aqueous solutions and their photodynamic activities

A porphyrin derivative which exists on the hydrophilic surface of the liposomes showed high photodynamic activity.