<Emphasis Type="Italic">Ab initio</Emphasis> study of the aromaticity of hydrogenated fullerenes

An analysis of the global and local aromaticity was made for a series of hydrogenated fullerenes of the type C₆₀H_2n (n=1–6) at the ab initio HF(Hartree-Fock)/3–21G level of theory, the isomers considered being obtained with an octahedral addition pattern. The relation between this addition pattern and the magnetic properties was established, showing low aromatic regions to be preferred for addition. These results show that local aromaticity, as shown in the nucleus-independent chemical shift, can be used to predict addition sites in these systems.     

化橘红与其它产地橘红元素含量的比较分析

用原子吸收分光光度法测定了三个不同产地橘红的元素含量，并比较了它们之间各种元素含量的差异。结果表明，化州橘红的Ｃｕ，Ｃａ含量显著低于其它产地橘红，而其它元素含量差异不大。     

In vivo FLUORESCENCE KINETICS OF PHTHALOCYANINES IN A SKIN-FOLD OBSERVATION CHAMBER MODEL: ROLE OF CENTRAL METAL ION AND DEGREE OF SULFONATION

Abstract— The fluorescence pharmacokinetics of a series of metallosulfophthalocyanines, chelated with either aluminum or zinc and sulfonated to different degrees, was studied by fluorescence measurements in vivo . Dyes were administered systemically to female WAG/RIJ rats with an isogeneic mammary carcinoma transplanted into the subcutis in a transparent observation chamber located on their backs. Following an intravenous injection of 2.5 μmol/ kg of the dye, fluorescence dynamics was observed up to 7 h postinjection. The phthalocyanines were excited at 610 nm with a power density of 0.1 mW/cm² without causing photodynamic damage to the vasculature. Fluorescence was detected above 665 nm using a fluorescence imaging system based on an image intensifier. Dye retention in the blood vessels and tumor tissue was expressed as ratios relative to the fluorescence signal of the surrounding subcutaneous tissue. Phthalocyanincs chelated with aluminum gave the highest fluorescence signal with tumor-over-subcutis ratios of up to a value of 4. The zinc complexes exhibited the highest vascular-over-subcutis ratios with maximum values exceeding a value of 6. They also displayed the longest retention times in the vascular system of well over 7 h. Overall, decreasing the degree of sulfonation of the metallophthalocyanines results in lower tumor-over-normal tissue fluorescence ratios, and furthermore aluminum-based dyes seem superior tumor localizers over zinc-based dyes. The advantages of phthalocyanines over porphyrins with respect to tumor localization and photodynamic therapy are discussed.     

不同产地及不同生长期高良姜中总黄酮的测定

不同产地及不同生长期高良姜中总黄酮的测定＊罗辉张建和莫丽儿（广东医学院化学教研室湛江５２４０２３）关键词高良姜总黄酮柱层析－分光光度法中图分类号Ｏ６５７．３２高良姜系姜科植物高良姜ＡｌｐｉｎｉａｏｆｉｃｉｎａｒｕｍＨａｎｃｅ的根状茎，其药性温中散寒，...     

Quinone sensitized electron transfer photooxidation of nucleic acids: chemistry of thymine and thymidine radical cations in aqueous solution

The 2-methyl-1,4-naphthoquinone (MQ) sensitized photooxidation of nucleic acid derivatives has been studied by laser flash photolysis and steady state methods. Thymine and thymidine, as well as other DNA model compounds, quench triplet MQ by electron transfer to give MQ radical anions and pyrimidine or purine radical cations. Although the pyrimidine radical cations cannot be directly observed by flash photolysis, the addition of N,N,N',N'-tetramethyl-1,4-phenylenediamine (TMPD) results in the formation of the TMPD radical cation via scavenging of the pyrimidine radical cation. The photooxidation products for thymine and thymidine are shown to result from subsequent chemical reactions of the radical cations in oxygenated aqueous solution. The quantum yield for substrate loss at limiting substrate concentrations is 0.38 for thymine and 0.66 for thymidine. The chemistry of the radical cations involves hydration by water leading to C(6)-OH adduct radicals of the pyrimidine and deprotonation from the N(1) position in thymine and the C(5) methyl group for thymidine. Superoxide ions produced via quenching of the quinone radical anion with oxygen appear to be involved in the formation of thymine and thymidine hydroperoxides and in the reaction with N(1)-thyminyl radicals to regenerate thymine. The effects of pH were examined in the range pH 5-8 in both the presence and absence of superoxide dismutase. Initial C(6)-OH thymine adducts are suggested to dehydrate to give N(1)-thyminyl radicals.     

BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES-XL PHOTOTOXICITY OF SULFONATED ALUMINUM NAPHTHALOCYANINES TOWARDS V-79 CHINESE HAMSTER CELLS

The phototoxicity of sulfonated aluminum naphthalocyanines towards V-79 Chinese hamster cells is investigated. The disulfonated naphthalocyanine exhibits similar photostability, but better cell penetrating properties than the tetrasulfonated dyes. The capacity of the naphthalocyanines to generate singlet oxygen is comparable to that of the corresponding phthalocyanines. However, in contrast to the phthalocyanine dyes, the sulfonated aluminum naphthalocyanines show very little phototoxicity towards the V-79 cells, suggesting close association with non-vital cell constituents or extensive formation of photoinactive adducts and aggregates.     

BIOLOGICAL ACTIVITIES OF PHTHALOCYANINES—IV. TYPE II SENSITIZED PHOTOOXIDATION OF L-TRYPTOPHAN AND CHOLESTEROL BY SULFONATED METALLO PHTHALOCYANINES

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.     

Metallophthalocyanines photosensitize the breakdown of (hydro)peroxides in solution to yield hydroxyl or alkoxyl and peroxyl free radicals via different interaction pathways

Interactions of organic peroxides (R'OOR) and hydroperoxides (R'OOH), including H2O2, with excited triplet and singlet state metallophthalocyanines (MPc, M = Zn, Al) have been studied by T-T absorption decay and fluorescence quenching. The ensuing photochemical processes result in decomposition of (hydro)peroxides as assessed by photo-EPR (electron paramagnetic resonance) and spin trapping. In argon-saturated apolar solutions and low MPc concentrations, alkoxyl free radicals (*OR) were identified as the primary products of (hydro)peroxide breakdown. Similarly, photosensitized decomposition of symmetric disulfides results in the formation of sulfur-centered radicals. In air-free aqueous solutions, ROOH photosensitization always gave rise to a mixture of hydroxyl and peroxyl radical (*OOR) adducts in varying molar ratios. At high MPc concentrations, both in polar and in apolar solutions, the most abundant products of ROOH decomposition were identified as *OOR. This indicates a change in the predominant interaction pathway, most likely mediated by MPc exciplexes and involving H-atom abstraction from ROOH by MPc-cation radicals. The prevalence of MPc singlet vs. triplet state interactions was confirmed by the much higher singlet quenching rate constants (log kq up to 9.5; vs. log kT < or = 4.5). In contrast to the triplet quenching, singlet quenching rates were found to depend on the (hydro)peroxide structure, following closely the trend of varying *OR yields for different substrates. Thermodynamic calculations were performed to correlate experimental results with models for electronic energy and charge transfer processes in agreement with the Marcus theory (Rhem and Weller approximation) and Savéant's model for a concerted dissociative electron transfer mechanism.