Les dérivés macrocycliques tétrapyrroliques utilisés dans le traitement de certaines tumeurs solides regroupent les porphyrines proprement dites et leurs dérivés chlorines et bactériochlorines. Il s’agit de molécules fortement conjuguées, rigides, caractérisées par une forte absorbance dans le domaine spectral du proche ultraviolet au rouge lointain (350–750nm). La combinaison : dérivés tétrapyrroliques plus illumination est appelée photothérapie dynamique (PDT). Cette association fait passer la molécule à l’état triplet, qui, par désactivation, génère, à partir de l’oxygène moléculaire, radicaux libres et oxygène singulet, à l’origine de la destruction tumorale. Les tétrapyrroles sont donc, avec les psoralènes utilisés dans le traitement du psoriasis, les seuls médicaments dont le mécanisme d’action procède totalement de leurs caractéristiques spectroscopiques électroniques et photophysiques. Cette classe d’agents anticancéreux est généralement dépourvue de cytotoxicité propre. Il sera décrit les éléments actuels qui lient structure et spectroscopie et les observations qui conduisent à concevoir des composés de forte sélectivité tumorale tout en garantissant des propriétés cytotoxiques optimales.

The macrocyclic tetrapyrrole derivatives used for the treatment of certain solid tumors include porphyrins and their chlorine and bacteriochlorin derivatives. These are highly conjugated, rigid molecules characterized by a strong absorbance in the spectral domain from near ultra-violet to far red (350-750 nm). The combination of tetrapyrroles plus light is called dynamic phototherapy (DPT). This combination transforms the molecule to its triplet form which by deactivation generates free radicals and a singlet oxygen from molecular oxygen, causing tumor destruction. Tetrapyrroles are thus, with psoralens, used for the treatment of psoriasis. They are the only drugs whose mechanism of action results exclusively from their electronic and photophysical spectroscopic characteristics. This class of anticancer agents is usually free of any specific cytotoxic effect. We describe here the current elements linking structure and spectroscopy and observations leading to the design of compounds with strong tumor selectivity and optimal cytotoxic properties.

New optically active polyamides were synthesized according to two ways: using a microwave-assisted polycondensation of an optically active isosorbide-derived diacylchloride with different aromatic diamines in NMP and using interfacial polymerization from an isosorbide-derived diamine with different diacylchlorides. The polymers are obtained with inherent viscosities in the range from 0.11 to 1.05dL/g. The DSC and TGA measurements clearly demonstrate the high thermal stability of these polymers when considering the range of the melting points from 200°C to 300°C and the absence of decomposition till 350°C.

Background: Retinoblastoma is the most common malignant intraocular tumor in children. The current treatment gives a good vital prognostic but there are several drawbacks to the arsenal of "classical antitumoral" therapies. Photodynamic therapy (PDT) could be an exciting non-toxic and non-mutagenic alternative protocol.Method: In this paper, we report about the screening of the in vitro photocytotoxicity of hydrophenylporphyrins and chlorins and their glycoconjugated derivatives in a human retinoblastoma cell line (Y79) and for comparison in a colorectal adenocarcinoma cell line (HT29).Results: Despite lower photodynamic activity than that observed for hydroxylated photosensitizers, in particular Foscan (R) glycoconjugated derivatives display phototoxicity (IC50 2.4-0.05 mu M +/- 10%) against Y79 cells with examples of significant intrinsic cytotoxicity. Amongst them the triglucosyl porphyrin 10 is highly photocytotoxic (IC50 0.90 mu M +/- 10%) but is fully devoid of cytotoxicity (IC50 > 15 mu M). The photoactivity is highly modulated by the presence of a diethyleneglycol spacer between the chromophore and the glycoside (compounds 14-17, IC50 0.5, 0.6, 0.05 and 0.35 mu M +/- 10%) and by the anomeric configuration of the sugar (compound 15 and 17, IC50 0.6 and 0.05 mu M +/- 10% respectively). One of the main problems for the use of Foscan is its poor solubility which might be improved by glycoconjugation. Moreover Foscan has been shown to induce necrosis after PDT leading to a possible ulceration of surrounding tissues unsuitable for a conservative treatment. A preferential mitochondrial subcellular localization which has been previously reported for some glycoconjugated photosensitizers could enhance the contribution of apoptosis process.Conclusion: Tri-alpha-O-galactosyl porphyrin 16 is a better candidate than Foscan (R) for a clinical application of PDT for a conservative therapy of retinoblastoma. (C) 2007 Elsevier B.V. All rights reserved.

Photodynamic therapy (PDT) is emerging as a new strategy for the conservative treatment of hereditary retinoblastoma. The glycoconjugated porphyrins TPP(p-Deg-O-alpha-GalOH)(3), TPP(p-Deg-O-beta-GalOH)(3), TPP(p-Deg-O-alpha-ManOH)(3), and their S-analogues were synthesized to obtain efficient photosensitizers with some retinoblastoma cell affinity. In these systems, a sugar motif and porphyrin core were linked by a diethylene glycol spacer (Deg). Cellular uptake, localization, and photoactivity have been examined in human retinoblastoma cells (Y79). After preincubation with corresponding glycosylated albumin, the uptake of TPP(p-Deg-O-beta-GalOH)(3) and TPP(p-Deg-O-alpha-ManOH)(3) was 40-45% inhibited, indicating a possible cell-sugar-receptor saturation. High photoactivity was observed for the two alpha-galacto/manno porphyrins 8 and 10 (LD(50) = 0.05 and 0.35 muM, respectively) at 514 nm and low fluence (1 J/cm(2)). Analysis by MALDI-TOF mass spectrometry only indicated a small metabolic cleavage of the O-glycoconjugates and a good stability of the S-glycoside porphyrins. On the basis of these in vitro data, TPP(p-Deg-O-alpha-GalOH)(3) and TPP(p-Deg-O-alpha-ManOH)(3) were selected for in vivo studies.

Microwave irradiation was applied to synthesize to the bulk synthesis of novel poly(ether–ester)s based on diol-ether of isosorbide (1) and adipoyl chloride (2) or terephthaloyl chloride (3). Thus, the poly(ether–ester)s (4 and 5) consist partially of isosorbide. In order to check the influence of microwaves and possible specific non-thermal microwave effects, the reactions were comparatively performed inside a thermostated oil bath under similar conditions. The reaction conditions were varied to optimize both yields and molecular weights of poly(ether–ester)s. The reaction proceeded roughly five times faster under microwave irradiation, the polycondensation being almost completed (yields upto approximately 95%) within 5min to afford a series of novel poly(ether–ester)s based with relatively high average molecular weights (Mw upto approximately 8000). The resulting poly(ether–ester)s were characterized by NMR (1H and 13C), FT-IR spectrometry, SEC measurements and MALDI-TOF mass spectrometry. Thermal properties of the poly(ether–ester)s (4 and 5) were investigated by means of differential scanning calorimetry (DSC).

An efficient five-step synthesis method was developed to obtain tritolylporphyrin and protoporphyrin IX polyamine conjugates. These compounds were composed of either one polyamine unit (spermidine or spermine) covalently tethered to monocarboxyphenyl tritolylporphyrin or two molecules of polyamines borne by protoporphyrin IX In each compound, an aliphatic spacer arm is linked to the N-4 polyamine position. Photocytotoxicity of these new compounds was evaluated against K562 human chronic myelogenous leukemia cells and compared to Photofrin II (R); protoporphyrin IX polyamine conjugates exhibited much stronger photocytocicity than Photofrin II (R) and were shown to readily induce necrosis in treated cells. (c) 2005 Elsevier Ltd. All rights reserved.

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 (ΦT) were ranging from 0.42 to 0.55 and triplet life times (τT) from 1 to 5 μs. High reaction rate constants (kq) with molecular oxygen (kq: 1.2–1.6 × 109 s−1) have been found. The triplet lifetimes of chlorin derivatives were about four times higher than those of porphyrins whereas the ΦT and kq values remained quite similar. Singlet oxygen yields of glucosylated and non-glucosylated porphyrins and chlorins were not significantly different within experimental errors (ΦΔ(1O2): 0.41–0.58). Furthermore, it has been shown that glucoconjugated photosensitizers could undergo associations with the methyl-β-cyclodextrin (Me-β-CD) which exhibit high triplet lifetimes and singlet oxygen yields ranging from 0.27 to 0.48.

New aromatic polyamides were synthesized by the microwave-assisted poly-condensation of an optically active isosorbide-derived diamine with different diacyl chlorides in the presence of a small amount of N-methylpyrrolidinone. Polymers with inherent viscosities between 0.22 and 0.73 dL/g were obtained corresponding to molecular weights up to 140,000 g/mol. With interfacial polymerization or the Higashi method, lower molecular weight polymers were obtained with inherent viscosities in the range of 0.04-0.36 dL/g. Differential scanning calorimetry measurements clearly demonstrated the high thermal stability of these polymers (mp = 180-300 degrees C) and the absence of decomposition. (c) 2005 Wiley Periodicals, Inc.

Numerous polycondensations of aliphatic diol of isosorbide and 1,8-dimesyloctane or other aliphatic dibromo and disulphonated alkylating agent was performed under phase-transfer catalytic conditions. In order to check the possible specific non-thermal microwave (MW) effects, reactions were comparatively performed inside a thermostated oil bath (Δ) under similar conditions. The reactions conditions were varied to optimize both, the fraction insoluble in methanol (FP MeOH) and the molecular weight of polyethers. In all cases, it was found that microwave-assisted polycondensations proceeded more efficiently compared with conventional heating (the reaction time was reduced from 24 h to 30 min: ratio 1/50). The polycondensation under microwave yields 63% of polyethers precipitating in methanol with relatively high average-weight molecular weights (Mw up to approximately 7000). The polyethers were characterized by NMR (1H, 13C) and FT-IR spectroscopy and SEC measurement and MALDI-TOF mass spectrometry.

Asymmetrical glycoconjugated tetrapyrrolic macrocycles are under study as efficient sensitizers for photodynamic therapy (PDT). In this context, tri(meta-O-β-glucopyranosyloxyphenyl)chlorin [TPC(m-O-Glu)3] 2a/3a was found to be four times more photoactive in vitro than Foscan®. In a further study of this interesting glycoconjugate, its metabolism by cellular glycosidases in HT29 cells has to be explored. Cellular extracts of HT29 cells incubated with TPC(m-O-Glu)3 (24 h, 6 μM) were analyzed by MALDI-TOF mass spectrometry and high performance liquid chromatography (HPLC). In MALDI-TOF mass spectra, the presence of compounds distinct from TPC(m-O-Glu)3 (m/z 1151) were observed at m/z 989, 827 and 665 corresponding to the loss of one, two or three glucose units (162 u) and were be ascribed to TPC(m-OH)(m-O-Glu)2 2/3b,b′,b″, TPC(m-OH)2(m-O-Glu) 2/3c,c′,c″ and TPC(m-OH)3 isomers 2d/3d, respectively. The porphyrins resulting from chlorin oxidation TPP(m-O-Glu)3 4a, TPP(m-OH)(m-O-Glu)2 4b,b″, TPP(m-OH)2(m-O-Glu) 4c,c″ and TPP(m-OH)3 4d were also observed. The HPLC profile (λanal.=420 nm) showed eight peaks consistent with mass spectra. The kinetics of deglucosylation was studied from HPLC profiles between 1 and 48 h incubation. The concentration of triglucoconjugated and diglucoconjugated molecules was maximum around 3 and 8 h incubation, respectively, whereas, totally deglucosylated species appeared only after incubation for more than 10 h. The fully deglycosylated porphyrin TPP(m-OH)3 is the final metabolite, being observed at a concentration 15 times higher than that of the remaining TPC(m-O-Glu)3 2a/3a. Compared to the photobiological activity of the parent molecule [TPC(m-O-Glu)3], a three times higher TPP(m-OH)3 concentration was necessary to observe a similar in vitro photoactivity.

Microwave irradiation was applied to the synthesis of polyethers from 1,8-dibromo- and 1,8-dimesyloctane under solid-liquid phase-transfer catalytic conditions. To evaluate the influence of microwaves on the reaction rates and polyether properties, we carried out the polymerization reactions under similar conventional conditions (oil bath) with the same temperature profiles. First, the microwave-assisted syntheses proceeded more rapidly in comparison with conventional heating, and the reaction time was reduced from 24 h to 30 min with higher yields of polyethers. Second, the structure of the polymers strictly depended on the activation mode. Under microwave conditions, the polyethers were characterized by higher molecular weights with better homogeneity. Third, the mechanism of chain termination was different under microwave and conventional conditions. The polyethers prepared with conventional heating possessed shorter chains with mainly hydroxylated ends, whereas under microwave irradiation, the polymer chains were longer with mainly ethylenic group ends. In fact, under microwave irradiation, ethylenic group ends were formed rather rapidly and set up a hindrance to further polymer growth. In contrast, under conventional conditions terminations were essentially constituted by hydroxyl functions; however, further polymerization was terminated as well. (C) 2003 Wiley Periodicals, Inc.

Glucoconjugated tri and tetra(meta-hydroxyphenyl)chlorins have been synthesized in order to explore how glucoconjugation of the macrocycle affects the photoactivity of the molecule. Internalization processes, photosensitizing efficacy of TPC(m-O-GluOH)3 and TPC(m-O-GluOH)4, in HT29 human adenocarcinoma cells have been compared to those of tetra(meta-hydroxyphenyl) chlorin (m-THPC, Foscan®). The tetra glucoconjugated chlorin, TPC(m-O-GluOH)4, was found to be poorly internalized and weakly photoactive. In contrast, the asymmetric and more amphiphilic compound TPC(m-O-GluOH)3, exhibited superior phototoxicity compared to m-THPC. Drug concentration, temperature and sodium azide effects indicated that TPC(m-O-GluOH)3 internalization partly proceeds via an active receptor-mediated endocytosis mechanism. Cellular uptake appeared as a saturable process and remained 30% lower than for mTHPC. However, a maximum phototoxicity in HT29 cells (survival fraction of 2±0.6%) were observed for concentration as low as 2μM. A 4-fold higher concentration of m-THPC was necessary to observe the same level of photoactivity. This higher phototoxicity has been correlated to a greater mitochondrial affinity. On the basis of these results, work is in progress to further evaluate the potential of glycosylated chlorins in photodynamic therapy (PDT).

We report a convenient solid-phase synthesis and characterisation of a new class of glycosylated porphyrins bearing the RGD tripeptide, designed for photodynamic cancer therapy. The photocytotoxicities of these compounds against the K562 leukemia cell line are also presented and compared to the effect of Photofrin II(R). ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).

The aim of this work is the synthesis of a new family of glycosylated porphyrins in which the sugar moieties are linked to the tetrapyrrole ring by a thioglycosidic bond. Two series have been designed. The first one corresponds to meso-aryl porphyrin derivatives. The second one has been obtained from protoporphyrin IX derivatization. Aryl-porphyrins were prepared from tristolyl o- and p-hydroxyporphyrins followed by bromoallylation and thioglycosylation with peracetylated S-glucose, mannose and galactose and deprotection. The other series has been synthesized from protoporphyrin IX dimethylester with a regioselective glycosylation of terminal alkenyl carbon. The UV-visible, NMR and MALDI mass spectra are presented. Photocytotoxicities of the synthesized compounds against K562 chronic leukaemia cell line has been evaluated.

meta-Tetra(hydroxyphenyl)chlorin (mTHPC), a second generation photosensitizer used in photodynamic therapy (PDT), was incorporated into long circulating carriers with the aim of improving the tumor selectivity by limiting the reticuloendothelial system (RES) uptake. Biodistribution of mTHPC (0.06 mg kg−1) was studied directly in nude mice bearing HT29 human tumor by optical fiber fluorimetry and tissue drug contents were determined by HPLC after extraction. The drug was incorporated in the oily core of nanocapsules surrounded by poly(d,l lactic acid) (PLA NCs), PLA grafted with polyethylene glycol (PLA-PEG) or PLA coated with poloxamer 188 (polox PLA). Compared to PLA NCs, incorporation of mTHPC in surface-modified nanocapsules resulted in strong modifications of the drug biodistribution and tumoral retention with a three-fold increase of drug level as early as 24 h post-administration. A reduced liver uptake was observed at early times post-administration indicating that surface-modified NCs are effective in limiting the RES uptake and could be potential carriers to enhance the therapeutic ratio of lipophilic photosensitizers. Furthermore, in situ fluorescence measurements and concentration data were found in broad agreement showing that optical fiber fluorimetry is a very sensitive method that can be used to follow the biodistribution of fluorescent drugs in real-time.

The 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (m-THPC) (Foscan) is a photosensitizer used in the photodynamic therapy (PDT) of cancers which is currently under clinical trial. The formation of a m-THPC inclusion complex with dimethyl-beta-cyclodextrin (Me-beta-CD) in solution was demonstrated on the basis of circular dichroism experiments. A 1:2 complex stoichiometry was found and an inclusion constant beta 2 = 2.8(+/- 0.4) x 10(10) M-2 was determined. The formation of such a complex was shown to enhance the m-THPC fluorescence intensity. It could be exploited to improve the sensitivity of the direct m-THPC detection in human plasma. Optimization of the operating conditions shows that the best results were obtained by the addition of 100 microL of a concentrated Me-beta-CD solution (3.2 x 10(-2) M) to 1 mL plasma samples. Compared to the standard conditions, a 90% increase in sensitivity was obtained. The proposed analytical method which showed a linear response function [0-300 ng mL-1 (440 pM)] and a low limit of detection [1.5 ng mL-1 (2 pM) (S/N = 3)] appears, especially due to the absence of metabolism, a simple and specific method suitable for pharmacokinetics studies in patients.

An original, rapid and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the detection of 5, 10, 15, 20 tetra-meso-hydroxyphenylchlorine (m-THPC), a photosensitizer used in the photodynamic therapy (PDT) of cancers. Chromatographic separation was carried out on a C(8) Zorbax column (80 x 4 mm, 5 microm). The mobile phase was an ethanol/aqueous sulphuric acid, pH 2.0 (65/35 v/v), in an isocratic mode yielding to rapid analysis (3.1 min) with narrow peaks. As the fluorescence intensity was found to be highly pH-dependent and to increase with pH values, a post-column device prior to the fluorescence detection (lambda(exc) = 423 nm, lambda(em) = 650 nm) was used to allow the addition of a 0.05 mol/L Na(2)HPO(4) solution to the mobile phase. Compared to standard conditions, a 300% increase of the fluorescence intensity was obtained for optimized operating conditions using experimental design. The validation of this analytical method showed that the response function was linear for concentrations up to 1000 microg/L (1.47 x 10(-6) mol/L) with a detection limit of 188 pg (S/N = 3).

The synthesis and characterisation of symmetrical glycosylated neutral and cationic porphyrin dimers linked at the meso-position via a flexible hydrocarbon chain to improve targeting on malignant cells is reported. Photocytotoxicity of these compounds against the K562 leukemia cell line compared to the effect of hematoporphyrin is also presented.