Showing papers in "Journal of Photochemistry and Photobiology B-biology in 2012"

The antimicrobial activity of photodynamic therapy against Streptococcus mutans using different photosensitizers.

Abstract: Several photosensitizers have been used against oral bacteria without standardization. Singlet oxygen and the decay constant was estimated. Results were analyzed by one-way ANOVA and the Tukey-Kramer test (p < 0.05). PDT with irradiation in the presence of the photosensitizers TBO and MG was effective in reducing S. mutans counts by 3 and 1.4 logs, respectively (p < 0.01), compared to their respective untreated controls. MB generated 1.3 times more 1 O2 than TBO, and both produced significantly higher

Fluorescence parameters as early indicators of light stress in barley.

Abstract: Photosynthetic efficiency of two Syrian barley landraces Arabi Aswad and Arabi Abiad grown under different light intensities were studied by the application of qualitative and quantitative analysis of chlorophyll a fluorescence. Different values of fluorescence parameters, quantum efficiencies, specific and phenomenological energy fluxes were obtained for each cultivar. Both low and high light stresses decreased photosystem II (PSII) activity in barley seedlings depending on the stress type and its duration. Cultivar Arabi Aswad was more tolerant to high light while Arabi Abiad was more tolerant to low light stress. The results allowed us to select chlorophyll a fluorescence parameters related to energy flux within PSII which were specifically affected under low or high light stress. We found that the performance index parameter is a sensitive indicator to explore the effect of light changes on PSII activity immediately after stress application, while maximal quantum yield of PSII and phenomenological parameters were only modified after a long period of stress application indicating PSII damage. Thus, we recommend the former parameter for early detection of light stress.

Spectroscopic, structural and thermodynamic properties of chlorpyrifos bound to serum albumin: A comparative study between BSA and HSA.

Abstract: Chlorpyrifos (CPF) is a widely used organophosphate insecticide which could bind with human serum albumin (HSA) and bovine serum albumin (BSA). The binding behavior was studied employing fluorescence, three-dimensional fluorescence, Circular dichroism (CD) spectroscopy, UV-vis absorption spectroscopy, electrochemistry and molecular modeling methods. The fluorescence spectra revealed that CPF causes the quenching of the fluorescence emission of serum albumin. Stern-Volmer plots were made and quenching constants were thus obtained. The results suggested the formation of the complexes of CPF with serum albumins, which were in good agreement with the results from electrochemical experiments. Association constants at 25°C were 3.039 × 10(5) mol L(-1) for HSA, and 0.3307 × 10(5) mol L(-1) for BSA, which could affect the distribution, metabolism, and excretion of pesticide. The alterations of protein secondary structure in the presence of CPF were confirmed by the evidences from UV and CD spectra. Site competitive experiments also suggested that the primary binding site for CPF on serum albumin is close to tryptophan residues 214 of HSA and 212 of BSA, which was further confirmed by molecular modeling.

Synthesis, characterization and interaction studies of copper based drug with Human Serum Albumin (HSA): spectroscopic and molecular docking investigations.

Abstract: A new water soluble copper(II) complex, [Cu(glygly)(ssz)(H(2)O)]⋅6H(2)O, 1 derived from dipeptide (glycyl glycine anion) and sulfasalazine was synthesized and characterized by elemental analysis (CHN), molar conductance measurements and spectroscopic methods (IR, UV-vis, ESI-MS). The complex 1 is non-ionic in nature and possess octahedral geometry around Cu(II) metal ion. The interaction of complex 1 with Human Serum Albumin (HSA) was investigated under physiological condition in Tris-HCl buffer solution at pH 7.4 by means of various spectroscopic methods (fluorescence, CD and FTIR) and molecular docking technique. The results of fluorescence titration revealed that the complex 1 strongly quench the intrinsic fluorescence of HSA through a static quenching procedure. Binding constants (K(b)) and the number of binding sites (n≈1) were calculated using modified Stern-Volmer equations. The thermodynamic parameters ΔG at different temperatures were calculated subsequently the value of ΔH and ΔS was also calculated which revealed that the hydrophobic and hydrogen bonding interactions play a major role in HSA-complex 1 association. The distance r between donor (HSA) and acceptor (complex 1) was obtained according to fluorescence resonance energy transfer and the alterations of HSA secondary structure induced by complex 1 were confirmed by FT-IR and CD measurements.

Synthesis of phthalocyanine conjugates with gold nanoparticles and liposomes for photodynamic therapy

Abstract: The efficiency of [2,9,17,23-tetrakis-(1,6-hexanedithiol)phthalocyaninato]zinc(II) as a photodynamic therapy (PDT) agent was investigated. This compound belongs to the second generation of photosensitizers currently tested for the cellular photo-damage of cancer cells. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizer were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J cm(-2). The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.

Synthesis, characterization, biological studies (DNA binding, cleavage, antibacterial and topoisomerase I) and molecular docking of copper(II) benzimidazole complexes

Abstract: To explore the therapeutic potential of copper-based benzimidazole complexes, tetranuclear Cu(II) complex 1 and dinuclear ternary amino acid complexes 2 and 3 {L-trp and L-val, respectively} were synthesized and thoroughly characterized. In vitro DNA binding studies of complexes 1–3 were carried out employing UV–vis titrations, fluorescence, circular dichroic and viscosity measurements which revealed that the complexes 1–3 bind to CT DNA preferably via groove binding. Complex 1 cleaved pBR322 DNA via hydrolytic pathway (validated by T4 DNA ligase assay), accessible to major groove while 2 followed oxidative mechanism, binding to minor groove of DNA double helix; binding events were further validated by molecular docking studies. Additionally, the complexes 1 and 2 exhibit high Topo-I inhibitory activity at different concentrations. The complexes 1–3 were evaluated for antibacterial activity against Escherichia coli and Staphylococcus aureus, and 2 was found to be most effective against Gram-positive bacteria.

Bio-mediated synthesis of TiO2 nanoparticles and its photocatalytic effect on aquatic biofilm.

Abstract: The nano-TiO(2) was synthesized biologically employing Bacillus subtilis (FJ460362). These nanoparticles were characterized by FTIR, TGA-DTA, UV-Visible spectroscopy, XRD and TEM. FTIR and TGA results confirm that the organic impurities were completely removed while calcinating the resultant products. Band gap value was estimated from the UV-Visible spectrum and anatase crystal phase was confirmed by XRD. TEM images reveal that these particles were agglomerated; mostly spherical in shape with an average particle size of 10-30nm. The synthesized nano-TiO(2) particles were coated on glass slides, biofilm were grown and subjected to irradiation of polychromatic light to understand photocatalytic activity in controlling the aquatic biofilm. The bacterial killing process was established by Epi-fluorescence microscopy. The results reveal that biogenic TiO(2) nanomaterial acts as good photocatalyst by the generation of H(2)O(2) in the vicinity of the TiO(2)-biofilm interfaces to suppress the growth of the aquatic biofilm.

Genotypic variations in photosynthetic and physiological adjustment to potassium deficiency in cotton (Gossypium hirsutum).

Abstract: A hydroponic culture experiment was conducted to determine genotypic variation in photosynthetic rate and the associated physiological changes in response to potassium (K) deficiency in cotton (Gossypium hirsutum L.) seedlings with contrasting two cotton cultivars in K efficiency. The K-efficient Liaomian18 produced 66.7% more biomass than the K-inefficient NuCOTN99(B) under K deficiency, despite their similar biomass under K sufficiency. Compared with NuCOTN99(B), Liaomian18 showed 19.4% higher net photosynthetic rate (P(n), per unit leaf area) under K deficient solutions and this was associated with higher photochemical efficiency and faster export of soluble sugars from the phloem. The lower net P(n) of NuCOTN99(B) was attributed to higher capacity for nitrate assimilation and lower export of soluble sugars. Furthermore, NuCOTN99(B) showed 38.4% greater ETR/P(n) than Liaomian18 under K deficiency, indicating that more electrons were driven to other sinks. Higher superoxide dismutase (SOD) and lower catalase (CAT) and ascorbate peroxidase (APX) activities resulted in higher levels of reactive oxygen species (ROS; e.g. O(2)(-)and H(2)O(2)) in NuCOTN99(B) relative to Liaomian18. Thus, the K inefficiency of NuCOTN99(B), indicated by lower biomass and net P(n) under K deficiency, was associated with excessively high nitrogen assimilation, lower export of carbon assimilates, and greater ROS accumulation in the leaf.

Synthesis and antibacterial activity of novel cationic BODIPY photosensitizers

Abstract: BODIPYs are versatile dyes never tested before in photodynamic application against prokaryotes. We specifically synthesized two cationic BODIPYs (compounds 3 and 4) with structural features suitable for this pourpose. The novel BODIPYs are both characterized by the presence of one pyridinium cationic group on position 8 and two iodine atoms on 2,6-positions of the dipyrrolylmethene structure, thus ensuring solubility in 1/1 water/organic solvent mixture and a good singlet oxygen formation rate. These two photosensitizers differ only in the moiety linked on pyridine nitrogen atom as 3 and 4 bear a methyl and a benzyl group, respectively. BODIPYs 3 and 4 were tested against two bacterial model strains, the Gram positive Staphylococcus xylosus and the Gram negative Escherichia coli. Despite the small structural modification between 3 and 4, a remarkable difference in photocatalyzed efficacy against the model microorganisms was observed. In particular methylated compound 3 was found much more efficient with respect to the benzylated one (4). As consequence, in-depth examination of the antibacterial activity was performed using the more efficient compound 3. A high degree of phototoxicity (>6 log units) was observed with the photosensitizer 0.5 μM against S. xylosus and 5.0 μM against E. coli, following 5 min irradiation with a green LED device (light dose 1.38 J/cm2). No dark toxicity was observed up to 40 μM. Further studies indicate that the phototoxic efficacy induced by BODIPY 3 depends both on its concentration and on light dose, which can be specifically modulated to achieve the eradication of the tester strains.

Photocatalytic degradation of toluene using sprayed N-doped ZnO thin films in aqueous suspension.

Abstract: Thin films of N-doped ZnO are synthesized via spray pyrolysis technique in aqueous medium using zinc acetate and ammonium acetate as precursors. Influence of N doping onto photochemical, structural, morphological, optical and thermal properties have been investigated. Structural analysis depicts hexagonal (wurtzite) crystal structure. The effect of N doping on the photocatalytic activity of N-doped ZnO in the degradation of toluene is studied and results are compared with pure ZnO. The results show that the rate of degradation of toluene over N-doped ZnO is higher as compared to that of pure ZnO and increases with increasing N doping up to 10 at.% and then decreases. The enhancement of photocatalytic activity of N-doped ZnO thin films is mainly due to their capability for reducing the electron hole pair recombination. The photocatalytic mineralization of toluene in aqueous solution has been studied by measuring COD and TOC. Possible reaction mechanism pathways during toluene degradation over N-doped ZnO has been proposed.

Chemistry of DNA minor groove binding agents.

Abstract: Most of the clinically used anticancer drugs exert their antitumor effect by damaging the replication machinery of DNA either by covalent or non-covalent binding. Intercalation and groove fitting are the major modes of non-covalent interaction. Small crescent shaped molecules have been claimed to bind with DNA via minor grooves. A plethora of hybrid molecules based on distamycin or netropsin have been synthesised with the objectives of improved selectivity and specificity with no/reduced unwanted side effects. This review critically and objectively describes the previously known hybrid DNA minor groove binding agents based on five membered, distamycin or netropsin. Moreover, the future use of six-membered benzamides has also been highlighted. Special emphasis has been put on developing structure-activity relationships of DNA minor groove binding agents.

Photodegradation of thermally modified wood.

Abstract: Natural wood, being biological material, undergoes rapid degradation by ultraviolet (UV) radiations and other environmental factors under outdoor exposure. In order to protect wood from such degradation, the chemical structure of wood is altered by chemical modification or heat treatment. In the present study, heat treated specimens of rubberwood (Hevea brasiliensis) were exposed to xenon light source in a weather-o-meter for different periods up to 300 h. Photostability of modified and unmodified wood was evaluated in terms of colour and chemical changes. Light coloured untreated wood became dark upon UV irradiation whereas, dark colour of heat treated wood lightened on UV exposure. CIE lightness parameter (L*) decreased for untreated wood whereas its value increased for heat treated wood upon irradiation. Other colour coordinates a* and b* increased with exposure duration for both untreated and heat treated wood. The overall colour change (ΔE*) increased for both untreated and heat treated wood. The Fourier Transform Infrared (FTIR) spectroscopic studies revealed severe lignin degradation of heat treated wood due to UV light exposure. Colour changes and FTIR measurements indicate that thermal modification of wood was ineffective in restricting light induced colour changes and photodegradation of wood polymers.

In vitro evaluation of combined hyperthermia and photodynamic effects using magnetoliposomes loaded with cucurbit[7]uril zinc phthalocyanine complex on melanoma

Abstract: The aims of this study were two fold; to develop magnetoliposomes (MLs) loaded with zinc phthalocyanine (ZnPc) complexed with cucurbituril (CB) (CB:ZnPc-MLs) and to evaluate their in vitro photodynamic (PD) and/or hyperthermia (HT) effects while using melanoma cells (B16-F10) as model. The liposomal formulations were characterized by both average diameter and zeta potential. The vesicle average size ranged from 150 to 200 nm and the polydispersity index (PdI) from 0.093 to 0.230. The zeta potential was significantly positive with values between 48 and 57 mV. The cell viability (CV) after PD and HT treatments was assessed by colorimetric MTT method. Melanoma cells were initially treated with the liposome formulation without light and magnetic field application, revealing cell viability not different from the control cells ( p > 0.05). Photodynamic and hyperthermia assays were also applied separately, demonstrating that PD is more effective than HT in reducing the CV of the neoplastic cells. Combined application of both PD and HT treatments was even more effective in reducing the CV of B16-F10 cells. At the highest light dose (2 J/cm 2 ) and under magnetic field activation the CV was about half than PD applied alone. Therefore, the use of the photosensitizer-loaded magnetoliposome for combined photodynamic therapy (PDT) and magnetohyperthermia (MHT) application can be considered as a potential tool to treat malignant melanoma.

The responses of trichome mutants to enhanced ultraviolet-B radiation in Arabidopsis thaliana.

Abstract: To gain a better understanding of the protective function of the trichome in Arabidopsis against UV-B radiation, we performed a study using several Arabidopsis trichome mutants (gl1, gis, gis2, zfp8, try82, and gl3), overexpressing trichome positive regulator lines (35S:GIS and 35S:GIS2), and wild-types (WT) under simulated enhanced UV-B radiation conditions. The flowering time, height, diameter of rosette, leaf size, trichome density, and expression levels of GL3 gene were measured. Significant decreases in height, diameter of rosette, leaf size, and a notable delay in flowering time were observed in all mutants and wild-types after exposure to UV-B. Moreover, the trichome density showed a significant increase, suggesting a clear induction of trichome formation by UV-B. Comparing the mutants and WT, we found that the mutants that had more trichomes showed a lower sensitivity to UV-B than the WT, whereas the mutants that had fewer trichomes were more sensitive to UV-B. These results indicated that the trichome plays a key shielding role against UV-B radiation. qRT-PCR analysis indicated that UV-B radiation induced expression of GL3 and an increase in GL3 transcript level correlated with the increase in trichome density and, suggesting a possible role of GL3 by integrating the environmental signal to control trichome initiation.

Spectroscopic studies on the interaction between carbaryl and calf thymus DNA with the use of ethidium bromide as a fluorescence probe

Abstract: The interaction between carbaryl and calf thymus DNA (ctDNA) was investigated under simulated physiological conditions (Tris-HCl buffer of pH 7.4) using ethidium bromide (EB) dye as a probe by UV-vis absorption, fluorescence and circular dichroism (CD) spectroscopy, as well as DNA melting studies and viscosity measurements. It can be concluded that carbaryl molecules could intercalate into the base pairs of DNA as evidenced by hyperchromic effect of absorption spectra, decreases in iodide fluorescence quenching effect, induced CD spectral changes, and significant increases in melting temperature and relative viscosity of DNA. The binding constants and thermodynamic parameters of carbaryl with DNA were obtained by the fluorescence quenching method. Furthermore, a chemometrics approach, parallel factor analysis (PARAFAC), was applied to resolve the measured three-way synchronous fluorescence spectral data matrix of the competitive interaction between carbaryl and EB with DNA, and the results provided simultaneously the concentration profiles and corresponding pure spectra for three reaction components (carbaryl, EB and DNA-EB complex) of the kinetic system at equilibrium. This PARAFAC analysis demonstrated the intercalation of carbaryl to the DNA helix by substituting for EB in the DNA-EB complex.

Study of DNA-emodin interaction by FTIR and UV-vis spectroscopy.

Abstract: Emodin, a plant- and fungus-derived anthraquinone, exerts genotoxic and antioxidative effects and shows promise in antitumor and antibacterial therapies. The aim of this study was to examine the molecular interactions of emodin with DNA in aqueous solution at physiological pH using spectroscopic methods. Fourier Transform Infrared (FTIR) Spectroscopy and UV absorption spectra were used to determine the structural features, the binding mode and the association constants. Our UV-spectroscopic results indicate that emodin interacts with DNA by intercalation and by external binding. FTIR results suggest that emodin interaction occurs preferably via adenine and thymine base pairs and also weakly with the phosphate backbone of the DNA double helix. The binding constant for emodin-DNA complex formation is estimated to be K=5.59×10(3)M(-1). No significant changes of DNA conformation were observed upon emodin-DNA complexation.

Advances in the knowledge of light emission by firefly luciferin and oxyluciferin

Abstract: Firefly luciferase is the most important and studied bioluminescence system. Due to very interesting characteristics, this system has gained numerous biomedical, pharmaceutical and bioanalytical applications, among others. In order to improve the use of this system, various researchers have tried to understand experimentally the colour of bioluminescence, and to create ways of tuning the colour emitted. The objective of this manuscript is to review the experimental studies of firefly luciferin and oxyluciferin, and related analogues, fluorescence and bioluminescence.

Synergistic activity of luteolin and amoxicillin combination against amoxicillin-resistant Escherichia coli and mode of action.

Abstract: The purpose of this research was to investigate whether luteolin has antibacterial and synergistic activity against amoxicillin-resistant Escherichia coli (AREC) when use singly and in combination with amoxicillin. The primarily mode of action is also investigated. The susceptibility assay (minimum inhibitory concentration and checkerboard determination) was carried out by the broth macrodilution method's in Mueller-Hinton medium. MIC and checkerboard determination were carried out after 20 h of incubation at 35°C by observing turbidity. The MICs of amoxicillin and luteolin against all AREC strains were >1000 and ≥ 200 μg/ml respectively. Synergistic activity were observed on amoxicillin plus luteolin against these strains. Viable count of this combination showed synergistic effect by reducing AREC cell numbers. The results indicated that this combination altered both outer and inner membrane permeabilisation. Enzyme assay showed that luteolin had an inhibitory activity against penicillinase. Fourier Transform-Infrared (FT-IR) spectroscopy exhibited that luteolin alone and when combined with amoxicillin caused increase in fatty acid and nucleic acid, but decrease in amide I of proteins in bacterial envelops compared with control. These results indicated that luteolin has the potential to reverse bacterial resistance to amoxicillin in AREC and may operate via three mechanisms: inhibition of proteins and peptidoglycan synthesis, inhibition of the activity of certain extended-spectrum β-lactamases and alteration of outer and inner membrane permeability. These findings offer the potential to develop a new generation of phytopharmaceuticals to treat AREC.

Molecular spectroscopic studies on the interaction of morin with bovine serum albumin.

Abstract: The interaction between morin and bovine serum albumin (BSA) was studied using molecular spectroscopic approach at different temperatures under imitated physiological conditions. Quenching of intrinsic tryptophanyl fluorescence of BSA with increasing morin concentration is the actuating tool in the analysis. The obtained quenching mechanisms, binding constants, binding sites and corresponding thermodynamic parameters at different temperatures indicate that the hydrophobic interaction play a major role in the morin-BSA association. Binding affinity between morin and BSA was determined using Scatchard equation and the modified Stern–Volmer equation, and the corresponding Structure–affinity relationships of flavonoids were discussed. Site marker competitive displacement experiments demonstrated that morin binds with high affinity to site II (subdomain IIIA) of BSA. Furthermore, the circular dichroism spectral results indicated that the conformation of BSA changed in the presence of morin. In addition, the effect of some common metal ions on the binding constant between morin and BSA was examined.

Synthesis and characterization of doxorubicin modified ZnO/PEG nanomaterials and its photodynamic action.

Abstract: The aim of this study is to investigate a new strategy of combined application of ZnO/PEG nanospheres with anticancer drug of doxorubicin (DOX) in photodynamic therapy (PDT). We were able to fabricate ZnO/PEG nanospheres as the drug carrier of DOX in drug delivery system. The combination of DOX-ZnO/PEG nanocomposites induced the remarkable improvement in the anti-tumor activity, which has been demonstrated by antibacterial activity, drug release and DNA cleavage study. Furthermore, the possible mechanism was explored by optical spectroscopic studies and EPR – spin trapping technique. It was noted that the photodynamic activity of the non-cytotoxic DOX loaded ZnO/PEG nanocomposite could considerably increase cancer cell injury mediated by reactive oxygen species (ROS) under UV irradiation. In our observations demonstrated that ZnO/PEG nanosphere could obviously increase the intracellular concentration of DOX and enhance its potential anti-tumor efficiency, indicating that ZnO/PEG nanosphere could act as an efficient drug delivery carrier importing DOX into target cancer cells. Nearly 91% of loaded drug was released within 26 h of incubation of conjugates in vitro in an acidic environment. It suggests that there is an efficient drug release of DOX from DOX-ZnO/PEG nanocomposite. DOX loaded on ZnO/PEG nanomaterials showed antibacterial activity was more pronounced with Gram-positive than Gram-negative bacteria under visible light. DOX-ZnO/PEG nanocomposites were effective against HeLa cell lines under in vitro condition and photocleavage of DNA. This result indicated that ZnO/PEG nanomaterials can be used as a nanocarrier for drug delivery system for PDT.

Role of curcumin on the determination of the critical micellar concentration by absorbance, fluorescence and fluorescence anisotropy techniques.

Abstract: Curcumin (C(21)H(20)O(6)) is a natural antioxidant which has a wide range of physiological and pharmacological actions Here, first time this is employed for the determination of the critical micellar concentration (cmc) of both ionic and nonionic surfactants using the measurements of UV absorption, fluorescence spectroscopy and fluorescence polarization anisotropy Results on a number of surfactants have agreed with those evaluated from conductometric, tensiometric and calorimetric methods The absorbance and fluorescence intensities of curcumin are enhanced by different micellar solutions The profiles of the absorbance and fluorescence intensities as a function of concentration of surfactant can be described by sigmoidal function to evaluate the cmc of the studied amphiphiles However, we have found that some of the anisotropy profiles are sigmoidal in nature

Photo-corrosion inhibition and photoactivity enhancement with tailored zinc oxide thin films.

Abstract: The nanocrystalline ZnO, TiO2 and ZnO/TiO2 films are deposited onto FTO-coated glass substrates by using spray pyrolysis technique. The structural, morphological, optical and photoelectrochemical properties of the ZnO, TiO2 and ZnO/TiO2 are investigated by X-ray diffraction, scanning electron microscopy, UV–Vis spectroscopy and photoelectrochemical techniques. XRD analysis shows that films are polycrystalline and having hexagonal and tetragonal crystal structure for pure ZnO and TiO2. The photocatalytic degradation of methylene blue has been investigated with ZnO, TiO2 and ZnO/TiO2 photocatalysts. ZnO/TiO2 thin films have proved quite effective mineralization of methylene blue, while pure ZnO and TiO2 do not lead complete mineralization of methylene blue. The metabolites produced during degradation are analyzed by HPLC and Fourier transforms infrared spectroscopy. The by-products detected during degradation have been identified by GCMS technique.

Binding of fullerol to human serum albumin: Spectroscopic and electrochemical approach

Abstract: The potential impact of human exposure to carbonaceous nanomaterials in the environment becomes a concerning issue. Here we report on the interaction of fullerol with human serum albumin (HSA) using spectroscopic and electrochemical methods. The water-soluble fullerene derivative (fullerol) was synthesized and characterized by IR, 1H NMR, TG-DSC, XRD, HR-TEM, etc. The spectroscopic methods show that the fluorescence quenching of HSA by fullerol is the result of the formation of an HSA-fullerol complex. Binding parameters such as ΔG, ΔH and ΔS were calculated, and the quenching constant Ka at different temperatures was determined using the modified Stern–Volmer equation. The electrochemical experiments further confirmed the conclusions. In addition, the influences of coexisting heavy metal ions have also been studied in the present system. The circular dichroism spectra (CD), 3D fluorescence spectra and FT-IR spectra results suggest that the secondary structure of HSA was changed by fullerol. Based on the site marker competitive experiments, we can predict the possible binding position of fullerol on the HSA was located at the site of sub domain II A. Furthermore, the distance r between donor (HSA) and acceptor (fullerol) was obtained according to the famous fluorescence resonance energy transfer (FRET) mechanism.

Assessment of amsacrine binding with DNA using UV-visible, circular dichroism and Raman spectroscopic techniques.

Abstract: Proper understanding of the mechanism of binding of drugs to their targets in cell is a fundamental requirement to develop new drug therapy regimen. Amsacrine is a rationally designed anticancer drug, used to treat leukemia and lymphoma. Binding with cellular DNA is a crucial step in its mechanism of cytotoxicity. Despite numerous studies, DNA binding properties of amsacrine are poorly understood. Its reversible binding with DNA does not permit X-ray crystallography or NMR spectroscopic evaluation of amsacrine–DNA complexes. In the present work, interaction of amsacrine with calf thymus DNA is investigated at physiological conditions. UV–visible, FT-Raman and circular dichroism spectroscopic techniques were employed to determine the binding mode, binding constant, sequence specificity and conformational effects of amsacrine binding to native calf thymus DNA. Our results illustrate that amsacrine interacts with DNA by and large through intercalation between base pairs. Binding constant of the amsacrine–DNA complex was found to be K = 1.2 ± 0.1 × 10 4 M −1 which is indicative of moderate type of binding of amsacrine to DNA. Raman spectroscopic results suggest that amsacrine has a binding preference of intercalation between AT base pairs of DNA. Minor groove binding is also observed in amsacrine–DNA complexes. These results are in good agreement with in silico investigation of amsacrine binding to DNA and thus provide detailed insight into DNA binding properties of amsacrine, which could ultimately, renders its cytotoxic efficacy.

Antitumor activity of photo-stimulated zinc oxide nanoparticles combined with paclitaxel or cisplatin in HNSCC cell lines

Abstract: Zinc oxide nanoparticles (ZnO-NPs) exhibit photocatalytic properties and are used in sunscreen cosmetics and for the degradation of environmental pollutants. Furthermore, ZnO-NPs have proven to induce tumor-selective cell death in human squamous cell carcinoma (HNSCC) in vitro. The aim of the current study was to evaluate cytotoxic effects of UVA-1-activated ZnO-NPs in combination with paclitaxel and cisplatin in HNSCC. Three HNSCC cell lines (HLaC-78, Cal-27 and PJ-41) were incubated with ZnO-NPs at concentrations of 0.02 and 0.2 μg/ml in combination with paclitaxel (0.5-5 nM) or cisplatin (0.03-3 μM) for 24 h. Afterwards, cells were irradiated with UVA-1 for 15 min. Viability was measured by MTT assay, fluorescein-diacetate (FDA) test and annexin/propidiumiodide flow cytometry. A significant decrease in viable cells could be observed in all three HNSCC cell lines treated by photocatalytic therapy with 0.2 μg/cm(2) ZnO-NPs alone. A combination with paclitaxel or cisplatin at low concentrations resulted in a further increase in cytotoxicity in vitro revealing a synergistic effect. Flow cytometry revealed a combination of apoptosis and necrosis. These results indicate that photocatalytic therapy of HNSCC with ZnO-NPs could enhance the cytotoxic action of chemotherapeutic agents synergistically, indicating a promising potential for ZnO-NPs in antitumor applications.

Chlorophyll index, photochemical reflectance index and chlorophyll fluorescence measurements of rice leaves supplied with different N levels

Abstract: Rapid and non-destructive diagnosis of plant N status is highly required in order to optimise N fertilizer management and use-efficiency Additionally to handheld devices for measurements of chlorophyll indices (eg, SPAD meter) parameters of canopy reflectance via remote sensing approaches are intensively investigated and the photochemical reflectance index (PRI) appears to be a reliable indicator for changes of the epoxidation state of xanthophyll cycle pigments In order to assess the suitability of a handheld PRI as an additional tool for N diagnosis, rice plants were grown in a nutrient solution experiment with seven N-supply levels (018-571 mM) and CI (SPAD) and PRI values and chlorophyll fluorescence parameters measured 20 and 28 days after onset of treatments N-supply had effects on both CI (SPAD) and PRI values with a more reliable differentiation between levels Maximum quantum yield of PSII (F(v)/F(m)), actual efficiency of PSII photochemistry (Ф(PSII)) and regulated non-photochemical quenching (Ф(NPQ)) did not differ significantly between N levels Non-photochemical quenching (NPQ) and fast- relaxing NPQ (NPQ(F)) were significantly affected by N-supply NPQ and NPQ(F), but not the slow-relaxing component (NPQ(S)), were correlated with CI (SPAD) and PRI values This finding which has not been reported for N-supply effects so far is indirect evidence that low N-supply induced xanthophyll cycle activity and that PRI values are able to indicate this at least in plants subject to severe N deficiency

Effects of pulsed infra-red low level-laser irradiation on open skin wound healing of healthy and streptozotocin-induced diabetic rats by biomechanical evaluation.

Abstract: Diabetes is one of the most common causes of delayed wound healing. Low-level laser therapy (LLLT) are one of the therapeutic modalities used for the treatment of wounds. The aim of present study is to evaluate the effect of LLLT in experimentally-induced diabetic rats. Two full thickness skin incisions were made on dorsal regions of each rat. The wounds were randomly divided into laser-treated and placebo. Laser-treated wounds of the healthy (non-diabetic) animals were submitted to a pulsed-infrared 890nm laser with an 80Hz frequency and 0.03J/cm(2) for each wound point in the first healthy group and 0.2J/cm(2) in the second healthy group. Laser-treated wounds of the diabetic animals received the same pulsed-infrared laser treatments as the second group for each wound point. On day 15, a sample from each wound was extracted and submitted for tensile strength evaluation. Laser irradiation with 0.03J/cm(2) significantly decreased the maximum load for wound repair in healthy rats (p=0.015). Laser irradiation with 0.2J/cm(2) significantly increased the maximum load in wounds from the healthy control (p=0.021) and diabetic (p<001) groups. Laser treatments with a pulsed infrared laser at 0.2J/cm(2) significantly accelerated wound healing in both healthy and diabetic rats.

Mineralization and toxicity reduction of textile dye neutral red in aqueous phase using BiOCl photocatalysis

Abstract: The BiOCl catalyst was prepared by hydrolysis method. The compound was extensively characterized by XRD, SEM, TEM, UV–vis measurements and BET surface area. The prepared material had average pore diameter about 6–13 nm. The BET surface area of the sample is about 40 m2/g. The photocatalytic degradation and toxicity reduction of textile dye neutral red (NR) was investigated in the presence of as prepared BiOCl. The analysis of OH radical formation was performed by fluorescence technique. The intermediates and the final products of degradation were detected by high-performance liquid chromatography–photodiode array-electrospray ionization-mass spectrometry (HPLC–ESI-DAD-MS) technology. Decrease in chemical oxygen demand (COD) and dye absorbance of the photodegraded dye solution revealed a complete mineralization of NR into CO2 and inorganic ions. The recycling experiments confirmed the relative stability of the catalyst. Finally, the luminescent marine bacteria Vibrio fischeri was used to assess the acute toxicity of samples prior to and after the photocatalytic treatment and it was found that toxicity was fully eliminated following photocatalytic degradation.

UVA-induced melanogenesis and modulation of glutathione redox system in different melanoma cell lines: the protective effect of gallic acid.

Abstract: Oxidative stress has been suggested to play a role in ultraviolet A (UVA)-mediated melanogenesis. Glutathione (GSH) and GSH-related enzymes including γ-glutamate cysteine ligase (γ-GCL) and glutathione S-transferase (GST) are important antioxidant defenses responsible for maintaining cellular redox balance. Hence, improving GSH redox system to cope with oxidative insults may be essential for attenuation of abnormal melanin production. Gallic acid (GA), a dietary phenolic, has been shown to provide beneficial effects against hyperpigmentation possibly through its antioxidant properties. This study thus aimed to assess the antimelanogenic action of GA with regard to modulation of GSH-GCL system and GST in two melanoma cell lines, lightly pigmented G361 human melanoma and more pigmented B16F10 mouse melanoma cells, irradiated with UVA. G361 cells were shown to have lower basal GSH content and GST activity than B16F10 cells. Moreover, GA provided antimelanogenic effects in correlation with promotion of GSH levels, GST activity as well as γ-GCL and GST mRNA in both G361 and B16F10 cells at 2-h post-irradiation. In summary, GA exhibits protective effects on UVA-mediated melanogenesis possibly through improvement of GSH-related antioxidant defenses. Furthermore, different redox state in G361 and B16F10 cells may affect the responses of melanoma cells to GA.

The effects of combined treatment with ionizing radiation and indocyanine green-mediated photodynamic therapy on breast cancer cells

Abstract: This study was undertaken to evaluate the effects of indocyanine green as a sensitizer in both photodynamic and radiation therapy on MCF-7 human breast cancer cells line. The cells were incubated with indocyanine green at different concentrations for 24 h and were then exposed in the independent treatment groups to a non-coherent light at different fluence rates and X-ray ionizing radiation at different dose rates. In addition, combination effects of this chemo, photo, and radiotherapy were evaluated. The percentage of the cell survival was investigated using the MTT assay. The results showed that indocyanine green had no significant cytotoxic effects up to 100 μM but as a photosensitizer had a strong cytotoxic effect on cancer cells. Despite, indocyanine green could not act as a radiosensitizer. Furthermore, it is surprising to find that 50 μM of indocyanine green in combination with light at 60 J/cm2 and 4 Gy of X-ray radiation astonishingly killed cancer cells and reduced the percentage of viable cancer cells to be 3.42%. According to the findings, we observed the same efficacy of treatment by adding a low dose of radiation and reducing light fluence rate. In fact, it appears from our data that the adverse effects of photodynamic therapy can be partially abated without reducing the efficacy of treatment. Obviously, this new therapeutic avenue in breast cancer therapy could be worth further investigation and elucidation and should be tested in vivo models for being applied in human therapy.