Hongjian Tian

Université de Sherbrooke, Sherbrooke, Quebec, Canada

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Publications (5)14.93 Total impact

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    ABSTRACT: A new series of water-soluble, mononaphthotrisulfobenzoporphyrazines, bearing an alkynyl side chain of varying lengths on the naphtho ring, were prepared and tested for their efficacy to inhibit plasma extravasation when used as photosensitizers during photodynamic therapy (PDT) of the retina in the rat. The hexynyl substituted photosensitizer was the most potent, and was able to produce complete inhibition, at low doses of photosensitizer and light.
    Journal of Medicinal Chemistry 07/2009; 52(14):4107-10. · 5.61 Impact Factor
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    ABSTRACT: To identify optimal features of metalated sulfophthalocyanine dyes for their use as photosensitizers in the photodynamic therapy of cancer, we synthesized a series of alkynyl-substituted trisulfonated phthalocyanines and compared their amphiphilic properties to a number of parameters related to their photodynamic potency. Varying the length of the substituted alkynyl side-chain modulates the hydrophobic/hydrophilic properties of the dyes providing a linear relationship between their n-octanol/water partition coefficients and retention times on reversed-phase HPLC. Aggregate formation of the dyes in aqueous solution increased with increasing hydrophobicity while monomer formation was favored by the addition of serum proteins or organic solvent. Trisulfonated zinc phthalocyanines bearing hexynyl and nonynyl substituents exhibited high cellular uptake with strong localization at the mitochondrial membranes, which coincided with effective photocytotoxicity toward EMT-6 murine mammary tumor cells. Further increase in the length of the alkynyl chains (dodecynyl, hexadecynyl) did not improve their phototoxicity, likely resulting from extensive aggregation of the dyes in aqueous medium and reduced cell uptake. Aggregation was evident from shifts in the electronic spectra and reduced capacity to generate singlet oxygen. When monomerized through the addition of Cremophor EL all sulfonated zinc phthalocyanines gave similar singlet oxygen yields. Accordingly, differences in the tendency of the dyes to aggregate do not appear to be a determining factor in their photodynamic potency. Our results confirm that the latter in particular relates to their amphiphilic properties, which facilitate cell uptake and intracellular localization at photosensitive sites such as the mitochondria. Combined, these factors play a significant role in the overall photodynamic potency of the dyes.
    Bioconjugate Chemistry 01/2005; 16(1):80-9. · 4.58 Impact Factor
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    ABSTRACT: Phthalocyanine-based photosensitizers, coupled via a 17alpha-ethynyl group to estradiol using Pd(II) as a catalyst, were synthesized and evaluated for their estrogen receptor binding affinity and in vitro photocytotoxicity. The highest receptor binding affinities (RBA=8-13) were observed with lipophilic conjugates coupled via a relative long spacer group while the sulfonated analogues showed little binding affinities (RBA <2). The highest photocytotoxicity was observed with the sulfonated conjugates, the nature of the spacer group did not have a pronounced effect.
    Bioorganic & Medicinal Chemistry Letters 04/2003; 13(7):1287-90. · 2.34 Impact Factor
  • Hongjian Tian, Hasrat Ali, Johan E. van Lier
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    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 01/2001; 32(3).
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    Hongjian Tian, Hasrat Ali, Johan E van Lier
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    ABSTRACT: A series of novel functionalized trisulfonated phthalocyanines were prepared in good to excellent yield using the monoiodo trisulfonated phthalocyanine as precursor for palladium-catalysed cross coupling reactions (Heck reaction and Buchwald amination).
    Tetrahedron Letters 01/2000; 41(44):8435-8438. · 2.40 Impact Factor