Hypocrellin A与二苄胺和N-甲基苄胺的光化学反应

为了探讨HypocrellinA (HA)与胺基衍生物反应的自由基形成机制 ,我们采用ESR谱分别研究了HA与二苄胺 (DBA)和N 甲基苄胺 (NMBA)的光化学反应 .在含胺类物质和溶解氧的溶剂系统下 ,可见光照射HA激发成HA ,然后将溶解氧转变成1O2 ,1O2 诱导DBA或NMBA的氯仿溶液都能产生半醌自由基和氮氧自由基 .氮氧自由基的信号强度随光照时间的增加而减弱 ,而半醌自由基的信号强度随光照时间的增加而增强 ,氮氧自由基的含量与光照产生的半醌自由基成反比 .在除氧条件下 ,光照含HA和DBA的氯仿溶液体系时 ,半醌自由基是主要的自由基 .结果表明 ,在有氧的氯仿溶液中 ,HA诱导胺类物质生成HA半醌自由基     

Study on sonodynamic activity of metallophthalocyanine sonosensitizers based on the sonochemiluminescence of MCLA

In this work, the chemiluminescence analysis method was used to detect the free radical during sonodynamic process. MCLA, which can specifically react with singlet oxygen ((1)O(2)) or superoxide anion to emit photon, was used to detect free radical formation in the sonosensitization of metallophthalocyanine in real time. The ultrasound-induced chemiluminescence of MCLA enhanced by sulfonated phthalocyanines Nickel did not show the expected structure-activity relationship which was well known as type II mechanism for the photodynamic therapy related to singlet oxygen production. The results showed that free radical are involved in the sonosensitization, and the catalytic performance of NiPcS(4) was the main reason for the increase of SCL.     

Sonodynamic therapy--a review of the synergistic effects of drugs and ultrasound

Sonodynamic therapy, the ultrasound dependent enhancement of cytotoxic activities of certain compounds (sonosensitizers) in studies with cells in vitro and in tumor bearing animals, is reviewed. The attractive features of this modality for cancer treatment emerges from the ability to focus the ultrasound energy on malignancy sites buried deep in tissues and to locally activate a preloaded sonosensitizer. Possible mechanisms of sonodynamic therapy include generation of sonosensitizer derived radicals which initiate chain peroxidation of membrane lipids via peroxyl and/or alkoxyl radicals, the physical destabilization of the cell membrane by the sonosensitizer thereby rendering the cell more susceptible to shear forces or ultrasound enhanced drug transport across the cell membrane (sonoporation). Evidence against the role of singlet oxygen in sonodynamic therapy is discussed. The mechanism of sonodynamic therapy is probably not governed by a universal mechanism, but may be influenced by multiple factors including the nature of the biological model, the sonosensitizer and the ultrasound parameters. The current review emphasizes the effect of ultrasound induced free radicals in sonodynamic therapy.     

EPR in the environmental control: Copper complexes and free radicals in soil and municipal solid waste compost

Quantitative EPR technique was applied to examine Cu(II) complexes and free radicals in soil and municipal solid waste composts. Production and stabilization of free radicals in humic and humic-like substances depend on transition metal containing red-ox systems in soil. Termination of the reaction pathways yields relatively stable semiquinone free radicals in the polyphenol and melanoidin matrices. EPR investigations of municipal solid waste composts in different stages of their maturity show distinct correlation between free radical concentration and microbiological activity. Copper(II) sorption by living microorganisms and formation of the copper(II) complexes by humic substances in soils (Cambisols and Luvisols) result in decrease of the concentration of the semiquinone radicals. The Cu(II) complexes formed by various natural humic and humic-like substances produced in the composts were characterized on the basis of EPR measurements. The process of solubilization of inorganic copper compounds in soil and composts, and free radical activity in soil and composts can be characterized using EPR technique as the monitoring method.     

Spectroscopic study on the sonodynamic and sonocatalytic damage of anthraquinone derivants to bovine serum albumin under ultrasonic irradiation

In this work, three anthraquinone derivants (Alizarin: 1,2-dihydroxy-9, 10-anthraquinone, Alizarin–DA: 1,2-dihydroxy-9, 10-anthraquinone-3-aminomethyl-N, N-diacetic acid and Alizarin–DA–Fe: 1,2-dihydroxy-9, 10-anthraquinone-3-aminomethyl-N, N-diacetate-Ferrous(III)) were used to study the sonodynamic and sonocatalytic damage of bovine serum albumin (BSA) molecules according to the hyperchromic effect of UV–vis spectra and quenching effect of intrinsic fluorescence. Meanwhile, some influencing factors such as ultrasonic irradiation time, anthraquinone derivants concentration and ionic strength on the damage of BSA molecules were also considered. The results show that the synergetic effect of anthraquinone derivants and ultrasonic irradiation can efficiently damage the BSA molecules. Finally, some special radical scavengers were used to determine the kind of generated reactive oxygen species (ROS) in the presence of three anthraquinone derivants under ultrasonic irradiation. The results show that the ROS, at least, including singlet oxygen (¹O₂) and hydroxyl radicals (OH) are generated during the sonodynamic and sonocatalytic processes. It is wished that this paper could offer some valuable references for the application of anthraquinone derivants in sonodynamic therapy (SDT) and sonocatalytic therapy (SCT) for tumor treatment.     

Metal-enhanced Singlet Oxygen Generation: A Consequence of Plasmon Enhanced Triplet Yields

In this Rapid Communication, we report the first observation of Metal-Enhanced singlet oxygen generation (ME¹O₂). Rose Bengal in close proximity to Silver Island Films (SiFs) can generate more singlet oxygen, a three-fold increase observed, as compared to an identical glass control sample but containing no silver. The enhanced absorption of the photo-sensitizer, due to coupling to silver surface plasmons, facilitates enhanced singlet oxygen generation. The singlet oxygen yield can potentially be adjusted by modifying the choice of MEF (Metal-Enhanced Fluorescence) & MEP (Metal Enhance Phosphorescence) parameters, such as distance dependence for plasmon coupling and wavelength emission of the coupling fluorophore. This is a most helpful observation in understanding the interactions between plasmons and lumophores, and this approach may well be of significance for singlet oxygen based clinical therapy.     

Pulsed EPR study on large dynamic electron polarisation created in the quenching of photo-excited xanthene dyes by nitroxide radicals in aqueous solutions

Dynamic electron polarisation (DEP) produced by the quenching of dye molecules in the triplet excited states by nitroxide radicals was investigated in aqueous solutions by pulsed electron paramagnetic resonance and transient absorption spectroscopy. An analysis of the measured quenching rate constants suggests that quenching is promoted by either exchange or charge-transfer mechanisms for a triplet dye and a doublet radical pair. An unusually large DEP on the radical was found generated in the nitroxide and Eosin Y or Rose Bengal systems in aqueous solutions. Quantitative analysis indicates that the DEP values in aqueous solutions range from ?40 to ?150 in the unit of thermal spin polarisation, which is in contrast to previously reported small DEP values of less than ?10 for organic triplet molecules in benzene solutions [22–27,29,31,32]. From the theoretical analysis of DEP, an origin of this large DEP was attributed to the notably slow diffusion motion of Eosin Y and Rose Bengal in water.     

Spectroscopic investigation on the sonodynamic activity of Safranine T to bovine serum albumin damage

In this paper, the Safranine T (ST) was used as sonosensitive compound to study the sonodynamic damage to bovine serum albumin (BSA) under ultrasonic irradiation using fluorescence and UV–vis spectroscopy. The experimental results revealed the obvious synergetic effect of Safranine T (ST) and ultrasonic irradiation during the damage of BSA molecules. In addition, some influencing factors such as ultrasonic irradiation time, Safranine T (ST) concentration, pH value and ionic strength on the sonodynamic damage of BSA molecules were also considered. Finally, the generation of reactive oxygen species (ROS) in sonodynamic process was estimated by the method of Oxidation-Extraction Photometry (OEP). Meanwhile, several radical scavengers were used to determine the kind of generated ROS. Experiments showed that under ultrasonic irradiation the Safranine T (ST) can generate several kinds of ROS at the same time, at least including singlet oxygen (¹O₂) and hydroxyl radicals (OH).     

Photocleavage reaction of bromine substituted aromatic acyl compounds studied by CIDEP and transient absorption spectroscopy

The photocleavage of the CBr bond in bromoacetylnaphthalene is investigated by transient absorption and time resolved EPR spectroscopy. In the transient absorption of 2-bromo-2′-acetylnaphthalene, the absorption band observed at λ_max ~440 nm is assigned to the triplet state of the parent molecule. After decay of the triplet absorption, a long lived absorption band is observed at λ_max ~380 nm, which is assigned to naphthoylmethyl radical. The yield of this radical is not dependent on the concentration of oxygen even though the absorption band of the triplet state was quenched by addition of oxygen. Thus we conclude that the spin multiplicity of the precursor molecule is singlet. The CW time resolved EPR spectrum shows a typical E?/A CIDEP pattern of three hyperfine lines of the naphthoylmethyl radical. This result suggests some contribution from triplet precursor molecules. However, a careful analysis of the time profile of the CIDEP intensity observed by FT-EPR revealed that the polarization is generated from the radical pair mechanism (RPM) from the encountered pair of two free naphthoylmethyl radicals and the radical-triplet pair mechanism. RPM polarization by the geminate radical pair, formed by the Br atom and the naphthoylmethyl radical, is not observed. This fact indicates that large spin-orbit coupling (Δg and/or fast spin relaxation by g anisotropy) spoils the RPM polarization. The finding is in contrast to the recent observation of RPM polarization in the Cl cleavage reaction of 1-(chloromethyl)naphthalene.     

新疆肉苁蓉多糖清除活性氧自由基

研究了肉苁蓉多糖体外抗氧化活性。以抗坏血酸为对照,以类Fenton反应产生羟自由基,多巴胺自氧化反应产生超氧阴离子自由基,次氯酸钠与过氧化氢反应产生单线态氧、二苯代苦味肼基自由基为实验模型,采用紫外-可见分光光度法和化学发光分析法,首次测定新疆肉苁蓉多糖对超氧阴离子自由基、羟自由基、DPPH.自由基（二苯代苦味肼基自由基）、单线态氧的清除作用。结果表明：新疆肉苁蓉多糖对上述自由基均有明显清除作用,且清除作用与多糖浓度呈正相关性。