Hasrat Ali
Université de Sherbrooke
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Featured researches published by Hasrat Ali.
Photochemistry and Photobiology | 1986
R. Langlots; Hasrat Ali; Nicole Brasseur; J. R. Wagner; J. E. van Lier
Abstract— Sulfonated phthalocyanine and a series of its metal chelates in combination with red light irradiation led to the degradation of L‐tryptophan in oxygenated aqueous solution. The photoproducts and the rate of transformation of L‐tryptophan are compared with hematoporphyrin and rose bengal sensitized photooxidation. In all cases the primary photoproducts are characterized as cis and trans‐3a‐hydroperoxy‐l,2,3,3a,8,8a‐hexahydropyrrolo[2,3‐b]indole‐2‐carboxylic acid. Support for the involvement of singlet excited oxygen is obtained from azide inhibition and the formation of the specific singlet oxygen product with cholesterol. We observed the contribution of another pathway in the case of the manganese complex.
Photochemistry and Photobiology | 1988
Hasrat Ali; Réjean Langlois; Richard Wagner; Nicole Brasseur; Benoit Paquette; Johannes E. Van Lier
Abstract— Synthetic methods to obtain selectively sulfonated metallo phthalocyanines are compared. Both condensation and direct sulfonation procedures lead to mixtures of mono‐ to tetrasulfonated products which are resolved by reverse phase liquid chromatography in buffered aqueous‐methanol. The proportion of sulfonated derivatives is examined as a function of the starting reagents in the case of the condensation method, and as a function of the temperature and reaction time in the case of the direct sulfonation procedure. The number of sulfonate groups per phthalocyanine molecule is determined by oxidative degradation of the phthalocyanine ring followed by quantitative chromatographic analysis of the sulfophthalamide and phthalamide fragments.
Photochemistry and Photobiology | 1987
J. Richard Wagner; Hasrat Ali; Réjean Langlois; Nicole Brasseur; Johan E. Van Ller
Abstract— The photosensitized oxidation of L‐tryptophan by gallium phthalocyanines sulfonated to different degrees is studied as a function of both substrate and sensitizer concentrations in water and 50% MeOH‐H2O solutions. The maximum quantum yield of singlet oxygen was found to be nearly 0.5 for all sulfonated gallium complexes. The effect of adding sulfonate groups in the phthalocyanine backbone is to change the tendency of dye molecules to dimerize or aggregate in a particular solvent. A shift in the chemical equilibrium away from the monomeric state, which occurs at high dye concentrations and at lower degrees of dye sulfonation, results in a reduced photochemical yield. The variation of quantum yields in different solvent systems and at several wavelengths is similarly accounted for by the fraction of light absorbed by the productive monomer state.
Photochemistry and Photobiology | 1988
Benoit Paquette; Hasrat Ali; Réjean Langlois; Johannes E. Van Lier
Abstract— Water soluble chloro aluminum phthalocyanines sulfonated to different degrees are studied for phototoxicity and cellular distribution inV–79 Chinese hamster cells. The more hydrophobic disulfonated dyes, with sulfonate substituents on adjacent benzyl groups of the phthalocyanine ring structure, exhibited the best cell penetrating properties and the highest phototoxicity. Fluorescence microscopy revealed that the dye was uniformly distributed in the cytoplasm but absent in the nucleus. The greater cell membrane penetrating properties of the lower as compared to the higher sulfonated dyes are attributed to the amphiphilic nature of the former.
Photochemistry and Photobiology | 1988
Nicole Brasseur; Hasrat Ali; Réjean Langlois; Johan E. van Lier
Abstract— Zinc phthalocyanines sulfonated to different degrees are tested for their ability to sensitizeV–79 Chinese hamster cells andEMT–6 mouse mammary tumors to red light. In vitro, the lower sulfonated derivatives were the most active with the exception of the poorly water‐soluble monosulfonated dye. An isomeric mixture of tetrasulfonated derivatives obtained via direct sulfonation was ten times more active than the homogeneous tetrasulfo derivative prepared via the condensation of sulfophthalic acid. In vivo, the latter dye was completely inactive, whereas the remainder of the sulfonated preparations exhibited a similar structure‐activity pattern as observed with theV–79 cells in vitro. The disulfonated zinc phthalocyanine showed the best tumoricidal activity in the series and also appeared to be a more efficient photosensitizer of cell inactivation and tumor cure than the aluminum or gallium complexes as well as hematoporphyrin derivative preparations. No significant differences in skin phototoxicity were observed among the various dyes.
Photochemistry and Photobiology | 1996
Philippe Margaron; Marie-Josée Grégoire; Vladimir Ŝĉasnár; Hasrat Ali; Johan E. van Lier
Abstract— Radioiodinated zinc phthalocyanine including [125I]ZnPcI4 and differently sulfonated [65Zn]ZnPcS (ZnPcS4, ZnPcS3, ZnPcS2 and ZnPcS1.75, a mixture of adjacent di and 25% mono) were prepared in order to study cell uptake and release kinetics in EMT‐6 cells. The same compounds were evaluated for their in vitro phototoxicity and the biological parameters were compared to partition coefficients to arrive at quantitative structure‐activity relationships (QSAR). At 1 μM in 1% serum, at 37°C, all dyes showed rapid cell uptake during the first hour followed by a slow accumulation phase. After 24 h, the highest cellular concentration was observed with the lipophilic ZnPcI4, followed by the amphiphilic ZnPcS2 and ZnPcS1.75. The hydrophilic ZnPcS4 and ZnPcS3 showed lower uptake. Dye release from dyeloaded cells during incubation in dye‐free medium could reach up to 60% and was shown to depend mainly on the amount of drug incorporated rather than the type of compound. These results suggest that care should be taken in interpreting dye toxicity data, which involve in vitro cell manipulations in dye‐free medium, particularly during in vitro/in vivo protocols. The EMT‐6 cell survival after 1 h or 24 h incubation with 1 μM dye in 1% serum followed by exposure to red light was assessed by means of the colorimetric 3‐(4,5‐dimethylthiazol‐2‐yl)‐diphenyl‐tetrazolium bromide (MTT) assay. Photocytotoxicities correlated inversely with the tendencies of the dyes to aggregate. Increased dye uptake by the cells also correlated with their activities, except for the lipophilic ZnPcI4, which showed the highest cell uptake but little phototoxicity. The QSAR between phototoxicity and the log of the partition coefficients (phosphate‐buffered saline and n‐octanol) gave a parabola with optimal partition values corresponding to the adjacent sulfonated ZnPcS2.
Photochemistry and Photobiology | 1987
Nicole Brasseur; Hasrat Ali; Réjean Langlois; J. Richard Wagner; Jacques Rousseau; Johan E. van Lier
Abstract— We tested water‐soluble sulfonated phthalocyanine and three metal chelate derivatives for their tumoricidal effect on the EMT‐6 mammary tumor in mice exposed to red light. The metal‐free sulfophthalocyanine had little effect, whereas the aluminum complex and the lower sulfonated fraction of the gallium complex exhibited tumoricidal activity similar to hematoporphyrin‐based photosensitizer (Photofrin II). The higher sulfonated fractions of the gallium complex were less active as compared to the lower sulfonated fraction. The cerium complex was the most active sensitizer in terms of dye and light doses required to induce tumor necrosis and cure but also showed the highest phototoxicity towards healthy skin. These results suggest that sulfonated phthalocyanines will offer a new alternative in photodynamic therapy of light‐accessible neoplasms.
Photochemistry and Photobiology | 1985
Nicole Brasseur; Hasrat Ali; D. Autenrieth; Réjean Langlois; J. E. van Liert
Abstract— Tetrasulfophthalocyanine and a series of its metal chelates were tested for their ability to photoinactivate V‐79 Chinese hamster cells. Incubation of cells for 1 h with tetrasulfophthalocyanine at 5 μM effectively sensitized cells towards red light. At the 1% survival level, the dye was 4 x more efficient than hematoporphyrin, efficiency being defined in terms of drug concentration in the medium and incident light fluence rather than on the basis of quanta absorbed. Chelation of the dye with metal ions resulted in most cases in a greatly diminished photosensitizing effect, except for cerium. The cerium complex was about 5 x more effective for cell killing than the metal free tetrasulfophthalocyanine and 20 x more efficient as compared to hematoporphyrin. Hypoxic conditions resulted in total loss of photoactivity indicating the involvement of oxygen in the action mechanism. The inactivation by near‐UV light by these drugs was also investigated. The potential of sulfonated phthalocyanines as novel photosensitizers for photodynamic cancer therapy is discussed.
Journal of Photochemistry and Photobiology B-biology | 1990
Jacques Rousseau; Réjean Langlois; Hasrat Ali; J. E. van Lier
The biodistribution and metabolism of 14C-labeled disulfonated and trisulfonated gallium phthalocyanine (Ga-PcS) was studied in radiation-induced fibrosarcoma tumor-bearing C3H mice. The [14C]Ga-PcS compounds were prepared via the condensation of [14C]phthalic acid and sulfophthalic acid in the presence of gallium chloride and characterized by their spectroscopic and chromatographic properties. The tissue concentrations of the dyes was measured by scintillation counting of the 14C and by extraction and fluorescence measurements. Elevated dye levels were found in the liver, lungs, kidneys and spleen as well as in the tumor. Lower sulfonation of Ga-PcS favored liver and spleen uptake whereas higher dye sulfonation resulted in greater kidney uptake. Both dyes showed high tumor uptake with peak concentrations exceeding those of most tissues except for the liver in the case of Ga-PcS2. The highest tumor uptake was observed with Ga-PcS3. Both dyes were slowly excreted from the body. The liver-feces pathway was favored in the case of Ga-PcS2 with high activities persisting in the liver, even after 21 days. The Ga-PcS3 was preferentially excreted via the kidney-urine pathway. High performance liquid chromatography analysis of the liver and tumor extracts of [14C]Ga-PcS3-treated animals did not reveal desulfonation of the dye. However, urine analysis showed the presence of radioactive metabolites lacking the characteristic phthalocyanine absorption.
Photochemistry and Photobiology | 1987
Nicole Brasseur; Hasrat Ali; Réjean Langlois; Johan E. van Lier
Abstract Gallium chloride phthalocyanines sulfonated to different degrees were tested for their ability to inactivate V‐79 Chinese hamster cells in the presence of red light. The mono‐ and disulfonated compounds were the most active whereas the tri‐ and tetrasulfonated complexes were completely void of photoactivity. In addition, large variations in photoactivity were observed among the four isomeric disulfonated derivatives with the most hydrophobic isomer exhibiting the highest photoactivity. Prolonged exposure to the disulfonated complex resulted in increased photosensitization. Complexing the dye with Al instead of Ga resulted in a slightly increased photosensitizing effect.