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The proof of concept for two-photon activated photodynamic therapy has already been achieved for cancer treatment but the efficiency of this approach still heavily relies on the availability of photosensitizers combining high two-photon absorption and biocompatibility. In this line we recently reported on a series of porphyrin-triphenylamine hybrids which exhibit high singlet oxygen production quantum yield as well as high two-photon absorption cross-sections but with a very poor cellular internalization. We present herein new photosensitizers of the same porphyrin-triphenylamine hybrid series but bearing cationic charges which led to strongly enhanced water solubility and thus cellular penetration. In addition the new compounds have been found localized in mitochondria that are preferential target organelles for photodynamic therapy. Altogether the strongly improved properties of the new series combined with their specific mitochondrial localization lead to a significantly enhanced two-photon activated photodynamic therapy efficiency.

Porphyrin- or phthalocyanine-bridged silsesquioxane nanoparticles (BSPOR and BSPHT) were prepared. Their endocytosis in MCF-7 cancer cells was shown with two-photon excited fluorescence (TPEF) imaging. With two-photon excited photodynamic therapy (TPE-PDT), BSPOR was more phototoxic than BSPHT, which in contrast displayed a very high signal for photoacoustic imaging in mice.

Fourier Transform Infrared (FTIR) microspectroscopy was used to highlight the interactions between two photosensitisers (PS) of different geometries, TPPmOH4 and a glycoconjugated analogous, TPPDegMan, and lipid bilayers modelling retinoblastoma cell membranes. Retinoblastoma is a rare disease occurring in young infants, for whom conservative treatments may present harmful side-effects. Photodynamic therapy (PDT) is expected to induce less side-effects, as the photosensitiser is only activated when the tumour is illuminated. Since efficiency of the treatment relies on photosensitiser penetration in cancer cells, bilayers with three lipid compositions - pure SOPC, SOPC/SOPE/SOPS/Chol (56:23:11:10) and SOPC/SOPE/SOPS/Chol/CL (42:32:9:8:6) – were used as plasma and mitochondria model membranes. FTIR spectra showed that the interaction of the PSs with the lipid bilayers impacted the lipid organization of the latter, causing significant spectral variations. Both studied photosensitisers inserted at the level of lipid hydrophobic chains, increasing chain fluidity and disorder. This was confirmed by surface pressure measurements. Photosensitisers - TPPmOH4 more than TPPDegMan - also interacted with the polar region of the bilayer, forming hydrogen bonds with phosphate groups that induced major shifts of phosphate absorption bands. This difference in PS interaction with moieties in the polar region was more pronounced with the models with complex lipid composition.

International audience; A new family of amphiphilic glycoconjugated porphyrin dimers usable in two-photon photodynamic therapy was designed, prepared and characterized. The physicochemical and biological data were presented and discussed. Their two-photon absorption cross section was determined, revealing quite good performances of the compounds (d % 300 GM at 880 nm for 2 and 3 and d % 1000 GM at 840 nm for 5 and 6). Despite their promising photophysical properties, porphyrin dimers are penalized by their low solubility and an insufficient penetration into tumour cells. Incorporation into nanocarriers such as lipid vesicles could be profitable, provided that the positioning and degree of freedom of the saccharide moieties are optimal to target the receptors of the cells of interest.

In this paper, we report the synthesis of a series of porphyrins, designed as photodynamic therapy (PDT) agents, substituted by three glycosyl units linked by a triazole group to chromophore in the aim to target tumor cells overexpressing lectin-type membrane receptors, by ‘click-chemistry’ under microwave heating.

We report the synthesis of a series of zinc porphyrins conjugated with pyrimidine derivatives. V shaped porphyrin dimer with a pyrimidine central core exhibits a planar geometry according to DFT computational studies, presents an internal charge transfer upon excitation proved by typical solvatochromic behavior and moderate two-photon absorption properties. Such porphyrin conjugates can afford valuable advantages in applications of TPA materials such as in photodynamic therapy and imaging of biological entities.

Background: Porphyrins are a group of heterocyclic macrocycle organic compounds. They have shown good efficiency in the photodynamic treatment of tumors in the last twenty years. The photodynamic therapy could be an alternative treatment for retinoblastoma using a photosensitizer with low dark toxicity and low mutagenic properties unlike the conventional chemotherapies. The objectives of this study were to develop a photosensitizer in our lab which is a diethylene glycol mannoconjugated tetraphenyl porphyrin (TPP, MW: 1413.6) and to determine the optimal interval time for photodynamic therapy using the concentration of TPP in eye and blood samples of mice. Materials and method: Transgenic mice developed bilateral retinoblastoma from the retina since 4 weeks of age to 16 weeks of age (tumors fill the ocular globe and the mice will be sacrificed for ethic purpose). The evaluation of the biodistribution of our TPP was realized to know the best drug-light interval to perform the photodynamic therapy. For this purpose, an intraperitoneal injection of 200 µl at 5.25 mg/ml in PEG 400/physiological serum (1:1, v/v) was performed on the LHbetaTag transgenic mice. At different time intervals (8h, 24h, 40h, 48h, and 72h) following injection, the mice were sacrificed and the eyes and blood were collected. TPP in eye samples were extracted in methanol and the level of TPP was measured by ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS) analysis (0.5-100 ng/mL). The level of TTP in blood samples was quantified after protein precipitation by UPLC-MS/MS method (5.00-1000 ng/mL). Results: We observed a time dependency accumulation of TPP in eyes with observed Tmax=48 hours. TPP serum concentrations decreased by the same manner up to 48 h. The determination of drug-light interval allowed us to perform the light delivery when the TPP level is highest (48 h) in the ocular tumor tissue (retinoblastoma). Conclusions: Our TPP had a good in vitro photocytotoxicity at very low doses and showed a good efficacy in vivo with subcutaneous patient derived retinoblastoma xenografts in immunodeficient mice. The knowledge of Tmax and this interval is essential to realize the photodynamic therapy with the better efficiency, the final goal being to eradicate the retinoblastoma from the retina. Citation Format: Florent Poyer, Samuel Hugeut, Stéphanie Lemaitre, Olivier Madar, Carole D Thomas, Philippe Maillard, Marie-Paule Teulade-Fichou, Nathalie Cassoux, François Doz, Keyvan Rezai. Evaluation of porphyrin biodistribution for use in photodynamic therapy of retinoblastoma in transgenic mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3213.

7 pages; International audience; Photodynamic therapy involves administration of a photosensitizing drug and its subsequent activation by visible light of the appropriate wavelength. Several approaches to increasing the specificity of photosensitizers for cancerous tissues and, in particular, through their conjugation to ligands that are directed against tumor-associated antigens have been investigated. Here, we have studied the delivery of the photocytotoxic porphyrin compound TPP(p-O-beta-D-GluOH)3 into tumor cells that overexpress the glycosphingolipid Gb3, using the Gb3-binding nontoxic B-subunit of Shiga toxin (STxB) as a vector. To allow for site-directed chemical coupling, an STxB variant carrying a free sulfhydryl moiety at its C-terminal end has been used. Binding affinity, cellular uptake, singlet oxygen quantum yield, and phototoxicity of the conjugate have been examined. Despite some effect of coupling on both the photophysical properties of TPP(p-O-beta-D-GluOH)3 and the affinity of STxB for its receptor, the conjugate exhibited a higher photocytotoxic activity than the photosensitizer alone and was exquisitely selective for Gb3-expressing tumor cells. Furthermore, our data strongly suggest that STxB-mediated retrograde delivery of the photosensitizer to the biosynthetic/secretory pathway is critical for optimal cytotoxic activity. In conclusion, a strong rationale for using retrograde delivery tools such as STxB in combination with photosensitizing agents for the photodynamic therapy of tumors is presented.

International audience; A porphyrin monosubstituted by three triethyleneglycol chains grafted on a pentaerythritol skeleton was designed to display an optimized amphiphilicity for an enhanced cellular uptake and thus to exert enhanced photocytotoxicity. This porphyrin proved to be an excellent photosensitiser with submicromolar IC50.

International audience; We report the synthesis of 20-nm-sized mesoporous silica nanoparticles encapsulating three different porphyrin photosensitizers (PS). Synthesized by the sol–gel method, in the presence of cetyltrimethylammonium bromide surfactant and tetraorthosilicate as silica source, we developed those nanoparticles with the aim of treating cancer cells using photodynamic therapy. The colloidal stability, due to the PEG-silane chain grafted on the surface,was demonstrated at 37 C in cell culture medium. Then, nanoparticles were functionalized by silylated squarate mannose and used in MCF-7 breast cancer cells for one-photon therapy. Promising results were obtained after 5 h of incubation.

Porphyrins are a class of photosensitizers used in photodynamic therapy (PDT). Understanding the interaction of porphyrins with membrane cells components is important in order to improve this therapy. Many analytical methods can be used for this aim. High performance liquid chromatography (HPLC) was used for the separation of porphyrins on RP and HILIC stationary phases as well as on a biomimetic membrane IAM phase. Twenty-six tetraphenyl porphyrins (TPP) were successfully separated on an IAM column, a C18 Gravity RP column, a C8 Gravity RP column, a PolarTec RP column and a HILIC column. Stationary phases were chosen as the most appropriate to cover the study of different types of interactions. Elution was performed with a 45 min linear gradient. Obtained gradient retention times were converted to gradient chromatography hydrophobicity index (CHI) and to an apparent retention factor (kapp). The partition coefficients (log P) of the 26 compounds were measured in a 2-octanol/PBS system and estimated in silico. Correlation between kapp values was studied. Moreover, a multivariate analysis was performed to explain columns relationships. Obtained results show that porphyrins are separated mainly according to hydrophobic interactions that are relative to their structure (sugar number and the disposition around the porphyrin macrocycle).

The nonaqueous capillary electrophoresis mode which includes a preconcentration step based on a transient pseudo-isotachophoresis to the simultaneous separation of seven glucoconjugated and hydroxylated porphyrins and chlorins, exhibiting very close structures, is reported. A high methanol content, of the buffer solution, was necessary in order to prevent self-assembly of the compounds and to enhance their solubility during separation. With the addition of 66% (v/v) methanol and 1% (w/v) NaCl in the aqueous sample solution, large volumes could be injected (44% capillary volume) without a loss in resolution. Sensitivity of detection was therefore improved by a 100-fold factor with regard to the method employing normal injection (2% capillary volume). Optimum electrophoretic conditions, in terms of sensitivity and performance, were obtained by using 20 mM phosphoric acid buffer, pH 2.2 and 50% methanol. The method was validated and applied to qualitative analysis of glucoconjugates in serum samples.

The use of porphyrin derivatives in photodynamic therapy is of excellent prospect for the treatment of superficial or easily reachable tumors. The selection of porphyrin derivatives by tumor cells depends to a large extent of their ability to interact with the biological membrane. The evaluation of porphyrin interaction with phospholipids can thus be used as a screening method. In this work we report on the assessment of the interaction of three new porphyrin derivatives with various phospholipids forming Langmuir films by surface tension and surface pressure measurements, grazing incidence X-ray diffraction, and liquid chromatography on an IAM stationary phase. The results show that the hydroxylated phenylporphyrin (m-THPP) is able to interact with all studied phospholipids and to significantly disorganize the structure of their monolayers. Obviously, the interaction occurs at the level of the hydrophobic chains of a phospholipid. A triglucoconjugated phenylporphyrin (m-TPP(Glu)3) also interacts with the phospholipids though to a lesser extent. Conversely, the tetraglucoconjugated derivative (m-TPP(Glu)4) exhibits both a weak surface activity and a poor affinity for the studied phospholipids. Thus, whereas m-THPP and m-TPP(Glu)3 are expected to penetrate into a biological membrane, m-TPP(Glu)4 seems unlikely to do so.

In this work, we study the physicochemical properties of some newly developed glycoconjugated photosensitizers that can be used in photodynamic therapy (PDT) of cancers: meso-tri-and tetra-( meta-O-β-d-glucosyloxyphenyl)porphyrins and meso-, tri-, and tetra-( meta-O-β-d-glucosyloxyphenyl)chlorins. Their properties are compared to the non-glycosylated hydroxylated parent compounds meso-tetra-( meta-hydroxyphenyl) porphyrin and meso-tetra-( meta-hydroxyphenyl)chlorin. It was found that at the ground state, all porphyrins present, independent of the substitution, have the same mean ionization constant (pKa = 2.7), corresponding to two indistiguishable steps of protonation of tetrapyrrolic nitrogens. On the other hand, in the case of chlorins, one proton process can be observed and the corresponding nitrogen exhibits a slightly superior basicity (pKa = 3.0) with respect to porphyrins. Hydroxylated compounds present a second transition at high pH corresponding to the ionization of phenol groups (pKa = 10.5). Consequently, all photosensitizers are not charged at physiological pH (≈7.4), and so the ionization process does not influence their activity in biological media. Ionization induces very important variations in photosensitizer absorption and emission spectra. For example, absorption in the red region (band V), one of the most important characteristics of a good photosensitizer, is only important for diprotonated porphyrins and neutral chlorins. As far as fluorescence emission is concerned, neutral chlorins are almost six times more fluorescent than the corresponding neutral porphyrins (Φchlorin/Φporphyrin ≈ 6). It should be emphasized that the spectra modifications induced by pH variations can find interesting applications in the optimization of visible and fluorescence detection in high-performance liquid chromatography (HPLC) as well as in the development of direct, rapid fluorimetric analytical methods.

International audience; We report the properties of glycoconjugated porphyrin dimers behaving as highly sensitive ratiometric temperature sensors in water. This effect results from interactions between carbohydrate and water altering molecular relaxation kinetics leading to temperature sensitive dual emission. These dimers are robust ratiometric fluorescent probes over a large temperature window (20-90 °C)

Two glycodendrimeric phenylporphyrins were synthesized and their interaction with phospholipids was studied at the air-water interface and in liposome bilayers; such liposomes bearing glycodendrimeric porphyrin could constitute an efficient carrier for drug targeting in photodynamic therapy.

Porphyrin derivatives are one of the major groups of compounds applied in photodynamic therapy. Their effect and interaction with different cell organelles and macromolecules is dependent on their chemical structure.We have examined the effect of the molecular structure of porphyrin derivatives on binding to liposomes without net charge and with negative charge. In this study a series of substituted tetraphenyl porphyrins (TPPs) has been used. Two of them, TP(4-OGluOH)4P and TP(4-OXylOH)4P, are symmetrically substituted derivatives having four carbohydrate — glucose or xylose — moieties linked to the macrocycle. The other two derivatives, TP(4-OGluOH)3P and TPF5(4-OGalOH)3P, were selected as asymmetrically substituted amphiphilic molecules with slightly different hydrophobic character due to the different ligand moieties. Association constants (KL) of derivatives to liposomes and rate constants of liposome binding have been determined and also the gel-to-liquid-crystalline phase-transition parameters have been monitored in order to determine the type and strength of interaction. According to our measurements, the KL values follow the order TP(4-OGluOH)3P>TPF5(4-OGalOH)3P>TP(4-OXylOH)4P for both types of liposomes. TP(4-OGluOH)4P is able to bind only to vesicles holding negative charges on their surface. At 18°C, the measured data are best fitted by two exponentials for three TPP derivatives. The binding of TP(4-OGluOH)4P follows single-exponential kinetics. At 37°C, TP(4-OGluOH)3P binds to DMPC liposomes according to biexponential kinetics, but all the other binding processes follow monoexponential kinetics under similar conditions. The strongest effect on phase-transition parameters is caused by TP(4-OGluOH)3P. From the results it can be concluded, that the binding process of TPPs, especially that of the symmetrically substituted derivatives, is drastically influenced by the surface charges of the model membranes. According to present data, the negative surface charges of DMPC/DMPG liposomes can facilitate the association of the symmetrically substituted hydrophilic porphyrins to the liposomes. However, the asymmetrically substituted derivative TP(4-OGluOH)3P, which is the most lipophilic compound in the present investigation, still has the largest association constant to both neutral and negatively charged liposomes. In general, in both types of liposomes the order of the association constant follows the order of the lipophilicity of the porphyrin derivatives.

International audience; In order to avoid side effects at the time of cancer eradication to the patients, the selectivity of treatments has become of strategic importance. In the case of photodynamic therapy (PDT), two-photon absorption combined with active targeting of tumors could allow both spatial and chemical selectivity. In this context, we present the synthesis, spectroscopic, and biological properties of a series of porphyrin-triphenylamine hybrids with excellent singlet oxygen production capacities and good two-photon absorption.

Porous silicon nanoparticles (pSiNPs) act as a sensitizer for the 2-photon excitation of a pendant porphyrin using NIR laser light, for imaging and photodynamic therapy. Mannose-functionalized pSiNPs can be vectorized to MCF-7 human breast cancer cells through a mannose receptor-mediated endocytosis mechanism to provide a 3-fold enhancement of the 2-photon PDT effect.

Hemoprotein mimics, cobalt picket fence porphyrins have been prepared in the gas phase as neutral molecules for the first time. Their ligation properties have been studied with 1-methylimidazole and compared with those of other cobalt porphyrins, tetraphenyl porphyrin, and cobalt protoporphyrin IX chloride, in view of studying the sterical properties of the ligation. It is shown that the cobalt picket fence porphyrin can only accept one 1-methylimidazole ligand in contrast to less sterically crowded porphyrins like cobalt tetraphenylporphyrin that present two accessible ligation sites. The femtosecond dynamics of these ligated systems have been studied after excitation at 400 nm, in comparison with the unligated ones. The observed transients are formed in much shorter times, 30 fs for the ligated species, as compared to free species (100 fs), supporting the porphyrin to metal charge transfer nature of these transients. The similar decays of the ligated transients

Amphiphilic glycoconjugated benzochlorin was prepared efficiently from meso monoaryl porphyrin and 3-(dimethylamino)acrolein by regiospecific Vilsmeier's reaction followed by cyclisation under acidic conditions and glycosylation. This compound displays a good in vitro photocytotoxicity on tumor cell lines after irradiation with light > 590 nm.

Non-toxic porous silicon nanoparticles carry porphyrin covalently attached to their surface inside breast cancer cells for a more efficient photodynamic effect.

International audience; An original fluorophore engineered for two-photon excitation or a porphyrin derivative were entrapped in the silica shell of magnetic porous silica nanoparticles during the synthesis of the silica moiety without damaging the structure of the organic part. The mild conditions involved allowed obtaining microporous or mesoporous silica magnetic nanoparticles, respectively. Mannose was grafted on the surface of the nanoparticles to target MCF-7 breast cancer cells. The studies of magnetic properties of these hybrid nanoparticles showthat they present a blocking temperature at 190 K. The nano-objects designed with the twophoton fluorophore were efficient for two-photon imaging of MCF-7 cancer cells, whereas the nanoobjects with the photosensitizer efficiently killed cancer cells. The presence of the mannose moiety was demonstrated to improve both imaging and therapy properties.

International audience; We propose a spectroscopic study of π-conjugated porphyrin dimers and a triphenylamine centered trimer bearing monoethyleneglycol-peracetylated α-mannose targeting moieties, which were synthesized for application to two-photon absorption photodynamic therapy (2PA-PDT). The collected spectroscopic data are explained through comparison with previous results obtained on similar nonvectorized analogues. It appears that the different shifts and variations in linear and nonlinear absorption and emission bands are mainly due to an increased twist between the tetrapyrrolic units. The 2PA properties of the triphenylamine-centered trimer have been studied, and two fluorescence emission bands are observed that seem to originate from two different 2PA excitation pathways. These results have important implication for the design of new vectorized photosensitizers for 2PA-PDT.

International audience; We report the synthesis of a series of conjugated zinc porphyrin oligomers designed as photodynamic therapy agents. These compounds exhibit exceptionally high two-photon absorption cross-sections, redshifted linear absorption spectra, and high singlet oxygen quantum yields, making them ideal for one-photon- and two-photon-excited photodynamic therapy. These products are substituted by three α-mannose units on each chromophore with the aim to target tumor cells with over-expressing lectin-type membrane receptors.

Tetrapyrrole rings possess four nitrogen atoms, two of which act as Brondsted bases in acidic media. The two protonation steps occur on a close pH range, particularly in the case of meso-tetraphenylporphyrin (TPP) derivatives. If the cause of this phenomenon is well known – a protonation-induced distortion of the porphyrin ring – data on stepwise protonation constants and on electronic absorption spectra of monoprotonated TPPs are sparse. A multivariate approach has been systematically applied to a series of glycoconjugated and hydroxylated TPPs, potential anticancer drugs usable in Photodynamic Therapy. The dual purpose was determination of protonation constants and linking substitution with basicity. Hard-modeling version of MCR-ALS (Multivariate Curve Resolution Alternating Least Squares) has given access to spectra and distribution profile of pure components. Spectra of monoprotonated species (H 3 TPP + ) in solution resemble those of diprotonated species (H 4 TPP 2+ ), mainly differing by a slight blue-shift of bands. Overlap of H 3 TPP + and H 4 TPP 2+ spectra reinforces the difficulty to evidence an intermediate form only present in low relative abundance. Depending on macrocycle substitution, p K values ranged from 3.5 ± 0.1 to 5.1 ± 0.1 for the first protonation and from 3.2 ± 0.2 to 4.9 ± 0.1 for the second one. Inner nitrogens’ basicity is affected by position, number and nature of peripheral substituents depending on their electrodonating character. p K values have been used to establish a predictive Multiple Linear Regression (MLR) model, relying on atom-type electrotopological indices. This model accurately describes our results and should be applied to new TPP derivatives in a drug-design perspective.

International audience; Three series of glycoconjugated and hydroxylated derivatives of 5,10,15,20-meso-tetraphenyl porphyrin (TPP) were studied in order to evaluate the effect of a porphyrin structure on its binding to dimyris- toylphosphatidylcholine (DMPC) liposomes and to human serum albumin (HSA). The studied derivatives have been developed as potent photosensitizers for photodynamic therapy (PDT) of cancers. Steady state and time resolved fluorescence emission spectroscopy, Stern–Volmer quenching and fluorescence anisotropy were used for this evaluation. The lipophilicity of the compounds has been deduced from their retention time in reverse phase liquid chromatography. The results demonstrated that the more polar glycoconjugated compounds presented limited aggregation in aqueous media and very rapid binding kinetics to DMPC liposomes and HSA. Derivatives having intermediate or high hydrophobicity showed extensive auto-association in aqueous media and as a consequence slow association kinetics. The strength of porphyrin binding to DMPC liposomes also depended on their lipophilicity and was lower for the polar glycoconjugated analogues. The highest affinity for liposomes was observed for hydroxylated derivatives with intermediate lipophilicity. In contrast, the highest binding constant for albumin was observed for a polar tetra-glycoconjugated analogue. The depth of penetration into the phospholipid bilayer did not appear to be directly related to the global hydrophobicity of the compounds, but depended more on the number of apolar, non-substituted phenyl groups grafted to a tetrapyrrolic macrocycle. Furthermore, liposome–albumin competition studies revealed that the porphyrins were always mainly partitioned into the phospholipid bilayer.

Double- and triple-decker-sandwich free base and copper porphyrins, where tetraphenylporphyrin rings are linked together by two urea bridges, have been studied by cyclicvoltammetry and UV-vis spectroelectrochemistry. Mixed-valent states appear in all cases, even with dimers and trimers containing twice or thrice the same porphyrin. The separations between the standard potentials in the H 2 -H 2 , Cu-Cu, H 2 -Cu dimers as well as in the H 2 -H 2 -H 2 , Cu-Cu-Cu, H 2 -Cu-H 2 trimers are interpreted in terms of Coulombic repulsion and interaction with the counter cations

A variety of glycoconjugated porphyrins has been synthesized by Lindsey's method from pyrrole and o-acetylglycosylated benzaldehyde precursors. Deprotection of glucose and maltose moieties allows the production of derivatives which had a good solubility in neutral aqueous solution and covered a range of amphiphilic character. The structure in solution of these new compounds was studied by 1 H NMR analysis. A study of the complexation characteristics of their zinc derivatives shows low values of affinity constants which are dependent on the steric hindrance of both faces of the porphyrin macrocycle. The present strategy should prove applicable to the synthesis of other glycoconjugated tetrapyrrolic compounds

Amphiphilic glycoconjugated benzochlorin was prepared efficiently from meso monoaryl porphyrin and 3-(dimethylamino)acrolein by regiospecific Vilsmeier's reaction followed by cyclisation under acidic conditions and glycosylation. This compound displays a good in vitro photocytotoxicity on tumor cell lines after irradiation with light > 590 nm.

Two glycodendrimeric phenylporphyrins were synthesized and their interaction with phospholipids was studied at the air–water interface and in liposome bilayers; such liposomes bearing glycodendrimeric porphyrin could constitute an efficient carrier for drug targeting in photodynamic therapy.

Photodynamic therapy (PDT) involves a non invasive treatment of small and superficial cancers using a photosensitive drug and light to kill tumoral cells. 5,10,15-meso-tri-(meta-O-β- d -glucosyloxyphenyl)-20-phenylporphyrin [m-TPP(glu)3] is a new photosensitizer (PS) with more enhanced photocytotoxicity relative to 5,10,15,20-meso-tetra-(meta-hydroxyphenyl) chlorin [m-THPC] (Foscan®). It was injected intravenously once to healthy rats at three different doses (0.25, 0.5 and 1 mg kg−1) and compared to m-THPC (0.3 mg kg−1). Pharmacokinetic parameters for both photosensitizers were derived from plasma concentration-time data using a non-compartmental analysis and a two-compartment pharmacokinetic model. m-TPP(glu)3 is more rapidly eliminated throughout the organism than m-THPC. Its mean plasma clearance is 19 mL h−1 kg−1 (6 mL h−1 kg−1 for m-THPC), and its mean residence time is 5 h (20 h for m-THPC). The area under curve (AUC) and initial mean serum concentration (C0) were found to be proportional to the dose. As for Foscan®, no metabolite of m-TPP(glu)3 was detected in plasma. The biodistribution study demonstrates that the most significant amount of m-TPP(glu)3 was concentrated in organs such as lung, liver and spleen which are rich in reticulo-endothelial cells. Maximum concentrations were reached in organs 14 h after IV administration. At 48 h, the photosensitizer was essentially eliminated from all organs. Because of its shorter elimination time, m-TPP(glu)3 is more attractive than m-THPC as a PDT agent since secondary side effects of shorter duration could be expected.

Glucoconjugated analogues of the meta-hydroxyphenyl porphyrin (m-THPP) and meta-hydroxyphenyl chlorin (m-THPC) has been recently synthesized. The characteristics of their triplet states have been determined with regard to their involvement in the photodynamic (PDT) efficiency. In the case of porphyrin derivatives, triplet quantum yields (Phi(T)) were ranging from 0.42 to 0.55 and triplet life times (tau(T)) from 1 to 5 micros. High reaction rate constants (k(q)) with molecular oxygen (k(q): 1.2-1.6 x 10(9)s(-1)) have been found. The triplet lifetimes of chlorin derivatives were about four times higher than those of porphyrins whereas the Phi(T) and k(q) values remained quite similar. Singlet oxygen yields of glucosylated and non-glucosylated porphyrins and chlorins were not significantly different within experimental errors (Phi(Delta)((1)O(2)): 0.41-0.58). Furthermore, it has been shown that glucoconjugated photosensitizers could undergo associations with the methyl-beta-cyclodextrin (Me-beta-CD) which exhibit high triplet lifetimes and singlet oxygen yields ranging from 0.27 to 0.48.

Iron(II) hanging-imidazole basket-handle porphyrins in which one or two amino-acids [(L)phenylalanine or (L)-valine] are inserted into one of the two handles, have been prepared in order to increase the steric hindrance and polarity of the distal side cavity. These complexes resulting from reduction of their hematine forms in a heterogeneous two-phase system, organic solvent–aqueous sodium dithionite solution, have been characterized by spectroscopic and magnetic methods. In wet toluene solution, they are found to be a mixture of high (S= 2) and low (S= 0) spin states at a temperature of 295 K. At a lower temperature of 243 K they give complexes in a pure magnetic low spin state. On the contrary, in solution of a dry solvent, they exhibit a high spin state. This uncommon magnetic property is due to a water molecule present at the sixth co-ordination site of the iron(II) atom stabilized in the distal cavity by hydrogen bond(s). Rate and affinity constants for the unusual water ligation have been measured. Water binding is shown to be controlled by diffusion when toluene is used as solvent. The dissociation rate constants decrease at least 100-fold in the presence of amino acid residues, relative to those of a single hanging-imidazole basket-handle porphyrin. Carbon monoxide and oxygen binding kinetics have been determined and it is concluded that the polarity increase of the distal cavity has no additional stabilizing effects, but the steric effect due to the presence of amino-acid(s) interferes with O2 and CO ligation.

Composite layers of behenic acid and tetraphenyl porphyrins made amphiphilic by aliphatic chain grafting were transferred onto solid substrates by the Langmuir method. The orientation of the macrocycles was studied by three independent methods: UV-visible linear dichroism, infrared linear dichroism, and electron spin resonance with paramagnetic markers. The first part of this paper is devoted to the theory relating to each of those methods, with the conditions of validity of formulas. The second part of the paper exposes the experimental results obtained not only by these three methods, but also by specific molecular area measurements and by observations on film crystallinity and stiffness. Results are discussed. All the observations converge to show that the macrocycles are excluded from the behenic film and that they organize aside this film according to order-generating ring-ring, and disorder-generating porphyrin chains-behenic chains, interactions.

Local solvation can be created by including dipolar groups in a molecular superstructure attached to a reacting center. Changes in reactivity of the latter ensue in a manner which is reminiscent of the modulation of the reactivity of the prosthetic groups by surrounding protein chains in enzymatic systems. Quite large effects can thus be obtained as shown by an electrochemical study of two redox reactions, Fe(II) + e/sup -/ in equilibrium Fe(I)/sup -/, Fe(I)/sup -/ + e/sup -/ in equilibrium Fe(0)/sup 2 -/, in a series of basket-handle iron prophyrins including an increasing number of secondary amide groups in the chains. The local solvation which results from the electrostatic interaction between the CONH dipoles and the negatively charged porphyrin centers is shown to build up as more and more CONH groups are included and to depend upon the distance between these groups and the reacting center.

The synthesis of basket handle porphyrins in a cross-trans configuration (27) and (28) derived from 5,10,15,20-tetrakis(o-aminophenyl)porphyrin, and their hydroxy-iron(III) complexes, in which one of the faces is hindered by a bridge substituted by one or two amino-acids (L-phenylalanine or L-valine) and with the other face protected by a hanging-imidazole chain is described. The synthetic methodology for these compounds allows the preparation of other superstructured porphyrins containing several amino acids in the handles; this gives an increasing number of secondary amide groups in the vicinity of the metallic centre. Structural assignments for the various compounds were made on the basis of the 1H n.m.r. spectra of the free bases. The optical purity of the compounds was established by g.i.c. on a chiral phase. Absorption spectra of hydroxy-iron(III) derivatives of hanging imidazole basket handle porphyrins display an unusual pattern consistent with the presence of water partially co-ordinated to the metallic ion and stabilized in the distal cavity by a hydrogen bond formed between water proton(s) and the carbonyl group of the ‘peptide’ bond.

The first synthesis of two covalently linked mixed phthalocyanine–porphyrin dimers especially designed for the study of photoelectron processes is presented along with the very efficient intramolecular energy transfer from the porphyrin toward the phthalocyanine moiety under light irradiation in one of these compounds.

The synthesis of basket handle porphyrins in a cross-trans configuration (27) and (28) derived from 5,10,15,20-tetrakis(o-aminophenyl)porphyrin, and their hydroxy-iron(III) complexes, in which one of the faces is hindered by a bridge substituted by one or two amino-acids (L-phenylalanine or L-valine) and with the other face protected by a hanging-imidazole chain is described. The synthetic methodology for these compounds allows the preparation of other superstructured porphyrins containing several amino acids in the handles; this gives an increasing number of secondary amide groups in the vicinity of the metallic centre. Structural assignments for the various compounds were made on the basis of the 1H n.m.r. spectra of the free bases. The optical purity of the compounds was established by g.i.c. on a chiral phase. Absorption spectra of hydroxy-iron(III) derivatives of hanging imidazole basket handle porphyrins display an unusual pattern consistent with the presence of water partially co-ordinated to the metallic ion and stabilized in the distal cavity by a hydrogen bond formed between water proton(s) and the carbonyl group of the ‘peptide’ bond.