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Synthesis, Spectral and Photodynamic Properties of Lithium Phthalocyanine
Abstract
The aim of this paper was to synthesize lithium phthalocyanine Li2Pc, to characterize and to test it on culture
media from HepG-2 (human hepatocellular carcinoma), by photodynamic test, under irradiation with λ=632.8 nm, He-Ne laser (30 mW, 25°C, total irradiation time = 30 min, in O2 saturated solution). During irradiation, cells are actively destroyed, especially those loaded with Li2Pc. Some parameters as viability were significantly lowered in culture media from HepG-2 cells in the presence of 25 μg/mL Li2Pc, after irradiation with laser, as compared to control cells (non-irradiated, but treated with Li2Pc). The synthesized phthalocyanine has been characterized from spectral (UV-Vis, FTIR,1H NMR), photophysical (fluorescence lifetimes and triplet quantum yields) and photochemical point of view, too (singlet oxygen generation).
... It is also a very cheap form of treatment, that is well tolerated by all categories of patients and can be used in pregnancy, for which there are many potential applications (48,49). Complementary and alternative medical therapies, including plant extracts have been used for the treatment of various diseases since ancient times, even during periods of economic downturn and their characteristics have been analysed in detail (50)(51)(52)(53)(54)(55)(56)(57)(58)(59)(60). Informed consent obliges us to fully disclose all positive and potential adverse effects of the therapies we propose to our patients. ...
Lichen planus (LP) is an idiopathic, cell-mediated immune disorder, accompanied by itching. Spontaneous remission occurs. Topical and systemic therapies are utilised. Four cases of generalized LP with and without mucosal involvement treated homeopathically are presented. Case 1: A 48-year-old female presented with a 7-month history of generalized itchy rash, which had been diagnosed as LP, treated unsuccessfully with topical steroids and removal of dental fillings. Examination revealed violaceous papules on upper and lower limbs, oral mucosal lesions and an irregular, erythematous, blanching, macular rash on the chest. She received homeopathic Ignatia amara at medication dilution factor (MK) potency, weekly dose and went into remission at 3 months. Patient remains in remission. Case 2: A 65-year-old female presented with a 27-year history of generalized, LP, which had been unresponsive to topical steroids. Examination showed generalized, violaceous papules, with no mucosal involvement. She received homeopathic Aurum metallicum, MK potency, weekly, and went into remission. She relapsed at 8 months after onset of therapy, following a very stressful incident, but gained remission again with Aurum metal-licum after 1 month of therapy. She remains in remission. Case 3: A 38-year-old male presented with a 21-year history of generalized LP. Medical history was significant for hepatitis B and asthma. Topical steroid therapy was only partially successful. Examination revealed generalized, violaceous papules, with oral and genital involvement. He received homeopathic Lycopodium at MK potency, weekly, and remitted by 2 months. He remains in remission. Case 4: A 41-year-old male presented with a 12-year history of generalized hypertrophic LP, which had responded partially to topical steroids and ultraviolet A therapy. Medical history was significant for reduced sense of smell. Examination revealed generalized, violaceous, hypertrophic papules and nodules. He received homeopathic Carcinosinum at MK potency and remitted at 6-months. In its long-standing, generalized form, with mucosal involvement, LP may respond to individualized homeopathy. More research may clarify homeopathy's place in LP therapy.
... The therapeutic options in vitiligo include: topical potent or very potent corticosteroids, topical immunomodulators (1,2,10); narrow-band UVB phototherapy (11,12); oral corticosteroid mini-pulse therapy (2), surgical treatment (skin grafting); depigmentation with p-benzyloxyphenol, laser treatment, cryotherapy (1,2), and long-term methotrexate (13). The side effects of those therapies may include: Skin atrophy, striae, telangiectasia, acne, scales, pustules, local endosymbiosis proliferation, contact allergy, immunosuppression, weight gain, sleep disturbances and others cited unpredictable effects (2,10,(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26), so the treatment, as in other diseases, should be closely monitored (27)(28)(29)(30)(31). ...
Although vitiligo is one of the most frequently occurring depigmentary disorder, its pathophysiology is still not fully clarified, resulting in the incapacity to find a targeted cure. Most of the treatment options available at the time have an anti-inflammatory or immunosuppressive effect, influencing the immune factor in vitiligo but without having a direct effect on melanocyte differentiation, migration or proliferation. This study shows that Piper nigrum (PN) extract and its main alkaloid, piperine, promote melanocyte proliferation in vivo, being consistent with previous study. A PN fruit extract and pure piperine were integrated in two different ointments and tested on human subjects affected by vitiligo. A number of 9 areas were treated: 3 using the extract, 3 using pure piperine, 1 using travoprost solution, and 2 using an association of travoprost (prostaglandin F2α analogue) solution and our products. Pigmentation was achieved in all the treated areas. The extract caused faster and more remarkable results than the pure piperine. The association of the travoprost solution speed up the process and changed the pigmentation pattern, especially when associated with the PN extract. Our early studies suggest that PN extract may represent, in the future, a new treatment option for vitiligo, especially considering the mild side effects of the tested products and the reduced amount of time needed for repigmentation. However, more studies are needed to validate this experimental data.
Group IA alkaline-metal phthalocyanine (Pc) complexes (Li2Pc, Na2Pc, K2Pc, Rb2Pc, Cs2Pc) have been synthesized and purified to study their excited state behavior. Their UV-Vis electronic absorption spectra, fluorescence emission and excitation spectra, fluorescence quantum yields and lifetimes, as well as singlet oxygen formation quantum yields have been measured in DMF. These photophysical properties are compared with that of H2Pc. The fluorescence and singlet oxygen formation properties reveal that alkaline metal Pcs show weak heavy atom effect. The results also reveal that alkaline-metal Pcs (Na2Pc, K2Pc, Rb2Pc, and Cs2Pc) show very different excited singlet state (S1) behavior from that of Li2PC and H2Pc. While S1 decay of Li2PC is mainly via intersystem crossing and fluorescence, the S1 decay of M2Pc (M=Na, K, Rb, Cs) is mainly metal ion dissociation: M2Pc(S1) → 2M⁺ + [Pc]²⁻(S1), in addition to the intersystem crossing.
This paper is meant at studying the kinetics and the reaction mechanism for the tetraphenyl-porphyrin (TPP) preparation from pyrrol and benzaldehyde in acetic acid medium. Unlike the literature date, which provide for the porphyrin synthesis free bases (with molecular oxygen present) yields of 5-50%, this paper deals with the same TPP synthesis reaction by using either a reducing agent (sodium dithionite), or an oxidant (ammonium persulphate), with a substantial increase of the reaction yield (i.e. 67%). The paper also presents the utilization of acetic acid as reaction solvent, thus proposing the replacement of the propionic acid, used in the literature. The reaction mechanism involves a porphyrinogen intermediate (P) which passes quickly to porphyrodimethene (D), the latter leading to tetra-phenylporphyrin by a pseudo-zero-order reaction.
The porphyrins and related compounds occur an important place into the present high-technologies, practical not existing any area where such compounds to be used. In spite of their high price and the preparation difficulties, despite the fact that porphyrin compounds and the methods to produce them are well established, there still exists a need for an improved technique for synthesizing porphyrin compounds. In this paper is presented a comparative study between the conventional methods (chemical) and the non-conventional (microwave, radiochemical, photochemical) for porphyrins synthesis. The experimental conditions and analytical proofs are discussed, too.
Porphyrins can form a variety of structures from linear head-to-tail or J-aggregates to fractal aggregates with different and specific photophysical properties. In this paper, the controlled aggregation of meso-5 ,10, 15, 20-sulfonato-phenyl porphyrin (H 2 TPPS 4 4-) was studied at room temperature. Structure of the aggregates was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-visible spectroscopy. TEM and SEM results indicated the formation of organized nanostructures from the porphyrin derivative. UV-visible-NIR spectroscopic data showed broad red-shifted Soret band, indicating J-aggregation among the monomer units. Conjugate effect of lateral π-π interaction among the tetrapyrrole cores and hydrophobic interaction among the peripheral phenyl rings is believed to lead to the organized nanostructures. Such aggregates have the size of 5-6 nm in solution. The columnar structure formed by porphyrins has a length of 5 to 27 porphyrin unities.
Porphyrins can form a variety of structures from linear head-to-tail or J-aggregates to fractal aggregates with different and specific photophysical properties. The aggregation process of some sensitizers such as tetrakis(4-sulphonatophenyl) porphyrin (TSPP) and chlorophyll (ChL) are investigated by different spectral techniques: absorption, fluorescence, transmission and scanning microscopy. The excited states lifetimes and the aggregation process for these hvo essential porphyrins are discussed in this paper. Also, the transmission electron microscopy (TEM) images are analized in order to obtain fractal dimensions of 3-dimensional porphyrin objects obtained by aggregation and a correlation with the transient absorption studies is achieved for the studied porphyrin.
The present paper is a concise material of a literature data in pbotodynamic therapy of cancel area using as drugs synthetic porphyrias. The paper treats the optímal porphyrin's structure, the physical properties, and photopbysical and pharmakinetical properties of porphyrins and distinguished the advantages of this treatment method, as well as the achievements in this field.
The phthalocyanines and porphyrins are the most used compounds, called photosensitizers (PS) into photodynamic therapy, due to their NIR absorbing wavelenghts, non-toxicity and high photochemical efficiency. The aim of this chapter is to achieve a better understanding of the phthalocyanines and related compounds, like free bases and metallo-complexes and their sensitizer properties, especially. The photophysical properties (absorption, triplet state, singlet oxygen, photobleaching, and fluorescence quantum yields, and triplet lifetimes so on) are discussed well correlated with their photodynamic activity. Their photodynamic tests in vitro on different cells lines, is discussed properly, taking into account the huge number of existing publications. Some clinical results obtained by using phthalocyanines, porphyrins and related compounds are discussed, too, in order to provide initial data on how currently used PS differ regarding basic PDT-related properties.
The singlet oxygen luminescence method and the photochemical methods using 1,3-diphenylisobenzofuran (DPBF) or bilirubin ditaurate (BDT) as chemical quenchers were employed to determine the single oxygen quantum yields (ΦΔ) of different phthalocyanines and tris(2,2″-bipyridyl)ruthenium(II) dichloride in dimethylformamide (DMF) or aqueous micellar solution of 0.1 M CTAC (cetyltrimethylammonium chloride). Additionally, a perylenetetracarboxylic acid diimide derivative was examined in DMF. In a series of tetrasulfonated phthalocyanines (PTS) the following order was found: ZnPTS > GaPTS > AlPTS ≈ H2PTS > CoPTS. In general, the singlet oxygen quantum yields are higher in DMF than in 0.1 M CTAC/H2O. The results obtained with the photochemical systems are comparable with those obtained by the photophysical method. The photochemical DPBF method results in absolute values of ΦΔ. However, in micellar solution, chain reactions occur when DPBF is used as chemical quencher in the photo-oxidative process. This problem can be overcome by adding sodium thiosulphate which is able to destroy the endoperoxide initially formed. BDT can be used as quencher in different solvents to determine ΦΔ relative to a photosensitizer with known singlet oxygen quantum yield in the respective solvent. In comparison to the chemical methods the luminescence method exhibits the advantage that side reactions of the quencher are excluded. But normally the ΦΔ values obtained are relative to a reference, since absolute determinations need much larger efforts.
The mixture between the solutions of one anionic porphyrin-5,10,15,20-tetra(p-sulfonato-phenyl-porphyrin (TSPP) and a charged-positive phthalocyanine-4,4″-bis(4-trimethyl amino-ethyl sulphanyl) 4′,4‴-di-amino-phthalocyanine dimethyl sulphate (Pc56) in polar solvent (DMSO), yielding to a well-defined supramolecular heterodimer (Pc/P) and a supra-molecular heterotrimer (Pc/P2), are reported in this paper. The absorption spectra of such heterocomplexes are drastically changed with respect to the corresponding monomers, indicating the existence of a strong electrostatic interaction between these chromophores. The stoichiometry and formation constant of the heterocomplex are evaluated by means of Job method. The lifetimes for the first excited singlet states of the studied compounds were calculated and correlated with the singlet oxygen generation efficiency for the heterodimer and heterotrimer.
The singlet oxygen luminescence method and the photochemical methods using 1,3-diphenylisobenzofuran ( DPBF ) or bilirubin ditaurate ( BDT ) as chemical quenchers were employed to determine the single oxygen quantum yields (Φ Δ ) of different phthalocyanines and tris(2,2″-bipyridyl)ruthenium(II) dichloride in dimethylformamide ( DMF ) or aqueous micellar solution of 0.1 M CTAC (cetyltrimethylammonium chloride). Additionally, a perylenetetracarboxylic acid diimide derivative was examined in DMF . In a series of tetrasulfonated phthalocyanines ( PTS ) the following order was found: ZnPTS > GaPTS > AlPTS ≈ H 2 PTS > CoPTS . In general, the singlet oxygen quantum yields are higher in DMF than in 0.1 M CTAC/H 2 O . The results obtained with the photochemical systems are comparable with those obtained by the photophysical method.
The photochemical DPBF method results in absolute values of Φ Δ . However, in micellar solution, chain reactions occur when DPBF is used as chemical quencher in the photo-oxidative process. This problem can be overcome by adding sodium thiosulphate which is able to destroy the endoperoxide initially formed. BDT can be used as quencher in different solvents to determine Φ Δ relative to a photosensitizer with known singlet oxygen quantum yield in the respective solvent.
In comparison to the chemical methods the luminescence method exhibits the advantage that side reactions of the quencher are excluded. But normally the Φ Δ values obtained are relative to a reference, since absolute determinations need much larger efforts.