A Cytotoxic Porphyrin from North Pacific Brittle Star Ophiura sarsii

Triple-negative breast cancer (TNBC) represents the deadliest form of gynecological tumors currently lacking targeted therapies. The ethanol extract of the North Pacific brittle star Ophiura sarsii presented promising anti-TNBC activities. After elimination of the inert material, the active extract was submitted to a bioguided isolation approach using high-resolution semipreparative HPLC-UV, resulting in one-step isolation of an unusual porphyrin derivative possessing strong cytotoxic activity. HRMS and 2D NMR resulted in the structure elucidation of the compound as (3S,4S)-14-Ethyl-9-(hydroxymethyl)-4,8,13,18-tetramethyl-20-oxo-3-phorbinepropanoic acid. Never identified before in Ophiuroidea, porphyrins have found broad applications as photosensitizers in the anticancer photodynamic therapy. The simple isolation of a cytotoxic porphyrin from an abundant brittle star species we describe here may pave the way for novel natural-based developments of targeted anti-cancer therapies.

Protoberberine compounds extracted from Chelidonium majus L. as novel natural photosensitizers for cancer therapy

BACKGROUND

It has been shown that secondary metabolites occur in Chelidonium majus L. (C. majus) crude extract and milky sap (alkaloids such as berberine, coptisine, chelidonine, chelerythrine, sanguinarine, and protopine) are biologically active compounds with a wide spectrum of pharmacological functions. Berberine, an isoquinoline alkaloid extracted from plants, possesses a wide range of biological activities, including inhibition of growth of a variety of cancer cell lines.

PURPOSE AND STUDY DESIGN

In the present study, we investigated the potential anticancer effect of a protoberberine alkaloidal fraction (BBR-F) isolated from the medicinal plant C. majus on HeLa and C33A cervical cancer cells after light irradiation (PDT treatment).

METHODS

BBR-F was prepared from an ethanolic extract of stems of C. majus. Identification of alkaloidal compounds was performed using high-performance liquid chromatography - mass spectrometry (HPLC/ESI-MS) and nuclear magnetic resonance (NMR) spectroscopy. BBR-F was then biologically evaluated for its anticancer properties. Cytotoxic activity after PDT treatment and without light irradiation (dark cytotoxicity) was determined by colorimetric WST-1 assay. The impact of the protoberberine alkaloidal fraction on the morphology and function of the cells was assessed by fluorescence and confocal microscopy as well as by flow cytometric analysis. To investigate the proinflammatory effect of the extracted natural BBR-F, nitric oxide concentration was determined using the Griess method.

RESULTS

An effective reduction in HeLa and C33A cell viability was observed after PDT treatment of BBR-F treated cells. Furthermore, microscopic analysis identified various morphological changes in the studied cells that occurred during apoptosis. Apoptosis of HeLa and C33A cells was also characterized by biochemical changes in cell membrane composition, activation of intracellular caspases, disruption of the mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS) generation.

CONCLUSION

Our results strongly suggest that the components of the natural plant protoberberine fraction (BBR-F) extracted from C. majus may represent promising novel photosensitive agents and can be applied in cancer photodynamic therapy as natural photosensitizers.

The effects of photodynamic therapy on leukemia cells mediated by KillerRed, a genetically encoded fluorescent protein photosensitizer

BACKGROUND

Leukemia is a cancer of blood and bone marrow cells, causing about 300,000 deaths worldwide. Photodynamic therapy (PDT) is a promising alternative for the treatment of malignant tumors. KillerRed is a genetically encoded red fluorescent protein photosensitizer (PS). In this study, we aimed to investigate the effects of KillerRed-mediated PDT on chronic myelogenous leukemia K562 cells, acute monocytic leukemia NB4 cells, and acute monocytic leukemia THP1 cells.

METHODS

KillerRed was expressed in Escherichia coli cells, purified by Q-Sepharose column, and confirmed by western-blotting. The PDT effect on cell proliferation was evaluated by Cell Counting Kit-8 (CCK-8). Cell apoptosis was determined by PE Annexin V/7-AAD staining and flow cytometry. The distribution of KillerRed in leukemia cells was detected by confocal laser scanning microscopy (CLSM) and western-blotting. The ROS generation was measured by flow cytometry.

RESULTS

Pure KillerRed was obtained with a yield of about 37 mg per liter of bacterial cells. KillerRed photodynamic inactivated the leukemia cells in a concentration-dependent manner, but exhibited no obvious dark toxicity. PDT mediated by KillerRed could also induce apoptotic response (mainly early apoptosis) in the three cell lines. The CLSM imaging indicated that KillerRed was distributed within the cytoplasm and nuclei of leukemia cells, causing damages to the cytoplasm and leaving the nuclear envelope intact during light irradiation. KillerRed distributed both in the cytosol and nuclei was confirmed by western blotting, and ROS significantly increased in PDT treated cells compared to the cells treated with KillerRed alone.

CONCLUSIONS

Our studies demonstrated that KillerRed-mediated PDT could effectively inactivate K562, NB4, and THP1 leukemia cells and trigger cell apoptosis, and it has potential to be used individually or complementally, in the treatment of leukemia.

Photodynamic therapy with Bixa orellana extract and LED for the reduction of halitosis: study protocol for a randomized, microbiological and clinical trial

BACKGROUND

Halitosis is an unpleasant breath odour that can interfere with the professional life, social life and quality of life of people who suffer from it. A modality of treatment that has been increasing in dentistry is antimicrobial photodynamic therapy (aPDT). Bixa orellana, popularly known as "urucum" is a plant native to Brazil. The seeds are used to produce a dye that is largely used in the food, textile, paint and cosmetic industries. The aim of this study is to verify whether aPDT with Bixa orellana extract and blue light-emitting diodes (LEDs) is effective in reducing halitosis. This method will also be compared with tongue scraping, the most commonly used conventional method for tongue coating removal, and the association of both methods will be evaluated.

METHODS/DESIGN

A randomized clinical trial will be conducted at the dental clinic of the Universidade Nove de Julho. Thirty-nine patients will be divided by block randomization into three groups (n = 13) according to the treatment to be performed. In Group 1, tongue scraping will be performed by the same operator in all patients for analysis of the immediate results. Patients will also be instructed on how to use the scraper at home. Group 2 will be treated with aPDT with Bixa orellana extract and the LED light curing device: Valo Cordless Ultradent®. Six points in the tongue dorsum with a distance of 1 cm between them will be irradiated. The apparatus will be pre-calibrated at wavelength 395-480 nm for 20 s and 9.6 J per point. In Group 3, patients will be submitted to the tongue scraping procedure, as well as to the previously explained aPDT. Oral air collection with the Oral Chroma™ and microbiological collections of the tongue coating shall be done before, immediately after and 7 days after treatment for comparison.

DISCUSSION

Halitosis treatment is a topic that still needs attention. The results of this trial could support decision-making by clinicians regarding aPDT using blue LEDs for treating halitosis on a daily basis, as most dentists already have this light source in their offices.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03346460 . Registered on 17 November 2017.

Photo-induced antibacterial activity of a porphyrin derivative isolated from the harmful dinoflagellate Heterocapsa circularisquama

The dinoflagellate Heterocapsa circularisquama is highly toxic to bivalves. However, significant toxicity to finfish species has not been reported. We previously found that H. circularisquama has light-dependent haemolytic agents. Purification and chemical structural analyses revealed that the haemolytic agent H2-a is a porphyrin derivative, which exhibits light-dependent cytotoxicity toward tumour cells. To clarify the biological activity of H2-a further, its antibacterial activities against Gram-positive and Gram-negative bacteria were investigated in this study. A fraction (F5) equivalent to H2-a purified from the methanol extract of H. circularisquama showed potent light-dependent bactericidal activity toward Staphylococcus aureus, and the activity was concentration- and light illumination time-dependent; however, Escherichia coli was highly resistant to F5. Electron microscopic observation suggested that F5 induces morphological changes in S. aureus in a light-dependent manner. Further analysis using other bacterial species showed that the Gram-positive bacterium Bacillus subtilis was more sensitive than the Gram-negative bacteria Pseudomonas aeruginosa and Vibrio alginolyticus. These results indicate that F5 is a photo-induced antibacterial agent with relatively higher specificity to Gram-positive bacteria. Iodometric assay suggested that singlet oxygen was generated from light-illuminated F5. Histidine, a specific singlet oxygen scavenger, markedly inhibited the photosensitising antibacterial activity of F5 against S. aureus, suggesting the involvement of singlet oxygen in antibacterial activity. The antibacterial spectrum of F5 was evidently different from that of 5,10,15,20-tetra (N,N,N-trimethylanilinium) porphyrin tetratosylate, a commercially available porphyrin compound with antibacterial activity. Our results demonstrate that H. circularisquama has a novel antibacterial photosensitiser, a porphyrin derivative, with relatively higher specificity to Gram-positive bacteria. To the best of our knowledge, this is the first study to discover a porphyrin derivative with antibacterial activity in marine microalga.

Photosensitizing anthraquinones from Heterophyllaea lycioides (Rubiaceae)

Seven anthraquinones were isolated from aerial parts of Heterophyllaea lycioides (Rusby) Sandwith (Rubiaceae), including three derivatives that have not been described before: a hetero-bianthraquinone identified as (R)-2-hydroxymethyl-2'methyl-1,1',6,6'-tetrahydroxy-5,5' bianthraquinone (lycionine), and two mono-chlorinated derivatives related to soranjidiol. One of them is a homo-bianthraquinone: (R)-7-chloro-2,2'-dimethyl-1,1',6,6'-tetrahydroxy-5,5' bianthraquinone (7-chlorobisoranjidiol), whereas the second halogenated derivative corresponds to a monomeric structure: 5-chloro-1,6-dihydroxy-2-methyl anthraquinone (5-chlorosoranjidiol). The four known compounds were already isolated from another species of this genus, H. pustulata, and they were identified as 5,5'-bisoranjidiol, soranjidiol, pustuline and heterophylline. Structural elucidation was performed by means of an extensive spectroscopic analysis, including 1D and 2D NMR data as well as by HRMS analysis. Chemical structures of 7-chlorobisoranjidiol and 5-chlorosoranjidiol were confirmed by their synthesis from 5,5'-bisoranjidiol and soranjidiol, respectively. Type I photosensitizing properties (superoxide anion radical generation, O₂^-) were assessed by using the nitroblue tetrazolium assay. When lycionine and chlorinated derivatives were irradiated, they enhanced the O₂^- production with respect to the control; 7-chlorobisoranjidiol stood out by generating an increase of 20%, whereas the other anthraquinones only produced a slight increase of 7%.

Quantification of a Novel Photosensitizer of Chlorin e6-C15-Monomethyl Ester in Beagle Dog Plasma Using HPLC: Application to Pharmacokinetic Studies

Chlorin e6-C15-monomethyl ester (CMME) is a novel photosensitizer, which is synthetized from the degradation products of silkworm excrement. Preclinical studies on the promising photosensitizer CMME are necessary to determine its therapeutic efficacy and druglikeness. A high-performance liquid chromatography with UV detection (HPLC–UV) method was established for the determination of CMME in beagle dog plasma. The sample preparation involved a protein-precipitation method with acetonitrile after the addition of tanshinone IIA as an internal standard (IS). CMME and the IS were separated on a Diamonsil C18 (2) column (100 mm × 4.6 mm, 5 μm) with a isocratic system of methanol–water containing 20 mM ammonium acetate with 0.3% glacial acetic acid (85:15, v/v). The flow rate was 1.0 mL/min with UV detection using a wavelength of 400 nm. The method was sensitive enough with a lower limit of quantitation (LLOQ) of 0.05 μg/mL and had a good linearity (r² > 0.999) over the linear range of 0.05–5.00 μg/mL. The intra-day and inter-day accuracies ranged from 98.5% to 102.8% and precisions (RSD) were within 6.8%. The validated method was successfully applied to the pharmacokinetic study of CMME after intravenous administration of single and multiple doses in beagle dogs.

Preclinical Study of Antineoplastic Sinoporphyrin Sodium-PDT via In Vitro and In Vivo Models

Photodynamic therapy (PDT) investigations have seen stable increases and the development of new photosensitizers is a heated topic. Sinoporphyrin sodium is a new photosensitizer isolated from Photofrin. This article evaluated its anticancer effects by clonogenic assays, MTT assays and xenograft experiments in comparison to Photofrin. The clonogenicity inhibition rates of sinoporphyrin sodium-PDT towards four human cancer cell lines ranged from 85.5% to 94.2% at 0.5 μg/mL under 630 nm irradiation of 30 mW/cm² for 180 s. For MTT assays, the IC₅₀ ranges of Photofrin-PDT and sinoporphyrin sodium-PDT towards human cancer cells were 0.3 μg/mL to 5.5 μg/mL and 0.1 μg/mL to 0.8 μg/mL under the same irradiation conditions, respectively. The IC₅₀ values of Photofrin-PDT and sinoporphyrin sodium-PDT towards human skin cells, HaCaT, were 10 μg/mL and 1.0 μg/mL, respectively. Esophagus carcinoma and hepatoma xenograft models were established to evaluate the in vivo antineoplastic efficacy. A control group, Photofrin-PDT group (20 mg/kg) and sinoporphyrin sodium group at three doses, 0.5 mg/kg, 1 mg/kg and 2 mg/kg, were set. Mice were injected with photosensitizers 24 h before 60 J 630 nm laser irradiation. The tumor weight inhibition ratio of 2 mg/kg sinoporphyrin sodium-PDT reached approximately 90%. Besides, the tumor growths were significantly slowed down by 2 mg/kg sinoporphyrin sodium-PDT, which was equivalent to 20 mg/kg Photofrin-PDT. In sum, sinoporphyrin sodium-PDT showed great anticancer efficacy and with a smaller dose compared with Photofrin. Further investigations are warranted.

Reduction of Candida tropicalis biofilm by photoactivation of a Heterophyllaea pustulata extract

CONTEXT

Biofilm formation is an important problem, since this growth mode confers resistance to drugs usually used in therapeutics.

OBJECTIVE

In vitro antifungal activity of extracts obtained from Heterophyllaea pustulata Hook f. (Rubiaceae) were studied against Candida tropicalis biofilms, evaluating the effect of irradiation and the oxidative and nitrosative stresses as possible mechanisms of action.

MATERIALS AND METHODS

Hexane, benzene, ethyl acetate and ethanol extracts were evaluated at three concentrations (0.2, 0.1 and 0.05 mg/mL) over mature biofilm, under darkness and irradiation. After 48 h of incubation, biofilm quantitation was performed by the O'Toole and Kolter method. Reactive oxygen species (ROS) was measured by nitro-blue tetrazolium (NBT) reaction and reactive nitrogen intermediates (RNI) by the Griess reagent. Superoxide dismutase activation (SOD, NBT assay) and total antioxidant system (FRAP test) were studied.

RESULTS

Only the benzene extract at 0.2 mg/mL reduced the biofilms formation. The slight decrease achieved in darkness (17.06 ± 2.80% reduction) was increased by light action (39.31 ± 3.50% reduction), clearly observing a photostimulation. This great reduction was confirmed by confocal microscopy. In darkness, biofilm reduction was mediated by an increase in RNI, whereas under irradiation, the ROS action was most important. Although no SOD activation was observed, a strong stimulation of the total antioxidant system was detected. HPLC analysis established a high content of several anthraquinones in this extract.

DISCUSSION AND CONCLUSION

Biofilm reduction by benzene extract was mainly mediated by oxidative stress triggered under light action, confirming a photodynamic sensitization, which could be attributed to its high content of photosensitizing anthraquinones.

Visible light absorption and photo-sensitizing properties of spinach leaves and beetroot extracted natural dyes

Herein, chlorophyll and betalain dyes are extracted from fresh spinach leaves and beetroots. Fourier transform infrared spectra are used to identify the characteristic peaks of the extracted dyes. UV-vis light absorption characteristics of the dyes and their mixed counterpart are investigated by varying their pH and temperature. These dyes are used as photo sensitizer for fabrication of zinc oxide photo-anode based dye sensitized solar cells (DSSCs). The photo-voltaic characteristics of the developed DSSCs are measured under simulated solar light (power of incident light 100 mW cm(-2) from Air Mass 1.5G). The solar to electric conversion efficiencies for the chlorophyll, betalain and mixed dye based solar cells are estimated as 0.148%, 0.197% and 0.294% respectively. The highest conversion efficiency for mixed dye based solar cell is attributed due to the absorption of wider range of solar spectrum.

Characterization and evaluation of the efficiency of SiO2/tetra-α-(2,4-di-tert-butylphenoxy)-phthalocyaninato zinc nanocomposite as photosensitizers for oxidation of 2,4,6-trichlorophenol

A photosensitizer tetra-α-(2,4-di-tert-butylphenoxy)-phthalocyaninato zinc [ZnPc(OAr)4] was successfully encapsulated in SiO2 nanoparticle by the microemulsion method. The photosensitized composite nanoparticle was able to degrade 2,4,6-trichlorophenol (TCP) in aqueous solution. Under visible light irradiation, the nanoparticles efficiently generated reactive oxygen species; 95.4% of TCP was degraded after 270 min of reaction. Some aromatic compounds and aliphatic carboxylic acids were detected by mass spectrometry as the reaction intermediates. The results were different from those of previously reported photocatalytic reactions, in which valence band holes or hydroxyl radicals functioned as the main oxidants. The photosensitizing composite nanoparticle is potentially applicable to the oxidation of phenol.

In situ Assessment of Porphyrin Photosensitizers in Propionibacterium acnes

Porphyrins are known to be efficient photosensitizer molecules and the combined action of light and porphyrins in Propionibacterium acnes have a lethal action on the cells. Identification and quantification of in situ porphyrins in P. acnes have been done using an integrating sphere connected to an ordinary absorption spectrophotometer, and the amounts of porphyrins in the cells were quantified by measuring scattering free absorption spectra of the cell suspensions. The concentration of porphyrins in P. acnes cells were increased in either of two ways; by the addition of δ-aminolevulinic acid (ALA), which lead to the formation of coproporphyrin III under the incubation conditions used in these experiments, or by the addition of protoporphyrin IX (PPIX) to the cell suspension. In the latter case, PPIX molecules are taken up by the cells in a membrane-mediated uptake mechanism, and accumulate in the cells either on a monomeric or a particular aggregate form. The fraction of porphyrins on aggregate form increased with increasing PPIX additions. In the case of ALA induced porphyrin production, only monomeric porphyrins were stored in the cells. In both cases, the cells have a limited binding capacity of monomeric porphyrins, which is estimated to be 3 × 105 molecules/cell, or one porphyrin molecule to every 100st lipid molecule in the cell membrane.

Rapid identification of cyclic tetrapyrrolic photosensitisers for photodynamic therapy using on-line hyphenated LC-PDA-MS coupled with photo-cytotoxicity assay

INTRODUCTION

Photodynamic therapy is a treatment modality that involves site-directed generation of cytotoxic reactive oxygen species by light-activated photosensitisers.

OBJECTIVE

In order to rapidly identify new photosensitisers from natural extracts, we developed a liquid chromatography-photodiode array-mass spectrometry (LC-PDA-MS) method to rapidly identify plant extracts that contain photosensitisers, particularly those possessing a cyclic tetrapyrrole structure.

METHOD

Six previously isolated compounds (1-6) were identified in bioactive fractions derived from 15 plant extracts on the basis of their chromatographic retention times, UV-visible profiles, accurate mass and fragmentation patterns.

RESULTS

Samples containing uncommon photosensitisers were rapidly identified using this method, and subsequent scale-up isolation efforts led to two new compounds (7 and 8) which were confirmed to be active photosensitisers in a photo-cytotoxicity assay.

CONCLUSION

This method serves as a useful tool in prioritising samples that may contain new photosensitisers out of a larger group of photo-cytotoxic natural products extracts.

Photocytotoxic pheophorbide-related compounds from Aglaonema simplex

In our screening program for new photosensitizers from the Malaysian biodiversity, we found five pheophorbide-related compounds from the leaves and stems of Aglaonema simplex. Detailed spectroscopic analyses showed that compounds 1-3 and 5 are pheophorbide and hydroxy pheophorbide derivatives of chlorophyll a and b. Compound 4, identified as 15(1)-hydroxypurpurin-7-lactone ethyl methyl diester, was isolated for the first time from the Araceae family. An MTT-based short-term survival assay showed that all five compounds exhibit moderate-to-strong photocytotoxic activities towards human leukemia (HL60) and two oral squamous carcinoma cell lines (HSC-2 and HSC-3). Compounds 4 and 5 showed the strongest photocytotoxicities, with IC(50) values of 0.30-0.41 muM (Table 2). Compounds 1-3 with Et chains at C(17(3)) were less photocytotoxic than the parent pheophorbide a (5).

Intracellular chemiluminescence activates targeted photodynamic destruction of leukaemic cells

Photodynamic therapy (PDT) involves a two-stage process. A light-absorbing photosensitiser (Ps) is endocytosed and then stimulated by light, inducing transfer of energy to a cytoplasmic acceptor molecule and the generation of reactive oxygen species that initiate damage to cellular membrane components and cytolysis. The expanded use of PDT in the clinic is hindered by the lack of Ps target-cell specificity and the limited tissue penetration by external light radiation. This study demonstrates that bioconjugates composed of transferrin and haematoporphyrin (Tf–Hp), significantly improve the specificity and efficiency of PDT for erythroleukemic cells by a factor of almost seven-fold. Fluorescence microscopy showed that the conjugates accumulate in intracellular vesicles whereas free Hp was mostly membrane bound. Experiments with cells deliberately exposed to Tf–Hp at <LD₁₀₀ doses showed that surviving cells did not develop resistance to subsequent treatments with the conjugate. Furthermore, we show that the compound luminol induces intracellular chemiluminescence. This strategy was then used to obviate the use of external radiation for Ps activation by incubating the cells with luminol either before or together with Tf–Hp. This novel chemical means of PDT activation induced cytotoxicity in 95% of cells. These combined approaches provide an opportunity to develop broader and more effective applications of PDT.

Separation of porphyrin-based photosensitizer isomers by laser-induced fluorescence capillary electrophoresis

Methods for the separation of photosensitizer isomers, such as benzoporphyrin derivative monoacid, benzoporphyrin ethyl monoacid, 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a, diethyleneglycol diester benzoporphyrin derivative, tin ethyl etiopurpurin, and phthalocyanine tetrasulfonate, have been systematically developed by CE. Detection was accomplished by UV absorption at 214 nm or by LIF with excitation at 442/488 nm and emission at 690 nm. The effects of three major experimental parameters of buffer types, organic solvents, and surfactant additives are described. The optimized separation conditions were determined so as to provide satisfactory separation efficiency and analysis time. The methods are shown to be suitable for the separation and determination of porphyrin and phthalocyanines regioisomers, diastereoisomers, and enantiomers.

A novel porphyrin photosensitizer from bamboo leaves that induces apoptosis in cancer cell lines

BACKGROUND

In the screening of new anticancer agents, we found that a methanol extract of bamboo leaves induced rapid apoptosis in the human leukemia CMK-7 cell line.

MATERIALS AND METHODS

The active compounds in the extract were isolated by chromatographic methods and their structures were determined by NMR and mass spectroscopy. Apoptosis by the compounds were evaluated in CMK-7 and human colon adenocarcinoma Colo320 DM cells by monitoring the caspase-3 activation and DNA cleavage.

RESULTS

The active compounds are 201-hydroxypurpurin-7 delta-lactone ethyl methyl diester (1) and the corresponding methyl phytyl diester (2). The apoptosis by compound 1 (0.3 to 0.1 microM for CMK-7 cells) was enhanced when the culture was briefly irradiated with a fluorescent lamp. This photodynamic induction of apoptosis by compound 1 was much stronger than that by a known photosensitizer, pyropheophorbidemethyl. Compound 2 was a weaker inducer of apoptosis than compound 1, but the apoptosis occurred after light irradiation.

CONCLUSION

The 201-hydroxypurpurin-7 delta-lactone esters are promising lead compounds as photosensitizers for photodynamic therapy of cancer.

Antimicrobial DNA-binding photosensitizers from the common rush, Juncus effusus

Our continuing survey of phototoxins from higher plants has led to the isolation and identification from the common rush, Juncus effusus L., of the phenanthrene, dehydroeffusol (1), and the dihydrophenanthrene, juncusol (2), compounds that display enhanced antimicrobial activities in light. The antimicrobial activities (minimum inhibitory concentrations) for these compounds against methicillin-resistant and -sensitive Staphylococcus aureus and Candida albicans were increased 16- and two-fold, respectively, by irradiation with ultraviolet A (UVA). Photosensitized DNA-binding activities (as possible covalent bond formation) of these compounds were determined by using restriction enzymes and a specially prepared 1.5 kb DNA fragment. Under UVA irradiation, dehydroeffusol strongly inhibited all the restriction enzymes (KpnI, XbaI, PmeI, DraI, PacI and BciVI) that have at least one 5'-TpA sequence in their recognition sites. Weak inhibitions were found for the restriction enzymes EcoRI, SacI, BamHI, SalI, PstI and HindIII, which do not possess a 5'-TpA sequence at their restriction sites and the restriction site sequences of which consist of all bases, A, T, G and C. Trace or no inhibition was found for AscI and SmaI, the restriction site sequences of which are composed of only C and G. The results indicate the necessity of thymine (adenine) for the photosensitized DNA-binding activity of dehydroeffusol. A strong inhibition against SphI, which does not have a 5'-TpA sequence in the restriction sequence, indicates that there are possibly other binding sequence(s) for dehydroeffusol. With juncusol and UVA, strong inhibitions for KpnI and BciVI and trace inhibitions for PacI, XbaI, PmeI and DraI were found. This result also showed a preference of juncusol for 5'-TpA, but the preference could be more selective than that of dehydroeffusol depending on the surrounding sequences of 5'-TpA in the respective restriction sites. A strong inhibition of SphI by juncusol with UVA also indicated the existence of an unknown binding sequence for this compound. Generally, the DNA-binding activity of this compound was weaker than that of dehydroeffusol.

1,5-dihydroxyanthraquinones and an anthrone from roots of Rumex crispus

From the roots of Rumex crispus, two known anthraquinones and a new one together with a new anthrone were isolated and the structures of compounds 1-4 were elucidated by spectroscopic means. The singlet oxygen generation capacity was tested with 1,3-diphenylisobenzofuran (DPBF) for compounds 1-4.

Photosensitization and mutation induced in Escherichia coli and Saccharomyces cerevisiae strains by dorstenin, a psoralen analog isolated from Dorstenia bahiensis

Dorstenin, 5-[3-(4,5-dihydro-5,5-dimethyl-4-oxo-2-furanyl)-butoxy]-7H-furo[3, 2-g] benzopyran-7-one, is a psoralen analog recently isolated from Dorstenia species (Moraceae). In order to characterize its biological activity, its photosensitizing and mutational properties were measured in wild-type E. coli and S. cerevisiae and also in strains carrying mutations which affect DNA repair. Compared to the high activities of psoralen and bergapten, dorstenin showed lower genotoxic effect.

Sensitive high-performance liquid chromatographic assay for motexafin gadolinium and motexafin lutetium in human plasma

We present new HPLC methods for the quantitation in human plasma of two investigative metallotexaphyrin agents, motexafin gadolinium (Gd-Tex) and motexafin lutetium (Lu-Tex). Each assay uses: the other texaphyrin analogue as an internal standard; protein precipitation with acetonitrile:methanol (50:50, v/v); an ODS reversed-phase column; an isocratic mobile phase of 100 mM ammonium acetate, pH 4.3:acetonitrile:methanol (59:21:20, v/v/v); and absorbance detection at 470 nm. The Gd-Tex assay has a lower limit of quantitation (LLOQ) of 0.01 microM and is linear between 0.01 and 30 microM. The Lu-Tex assay has an LLOQ of 0.1 microM and is linear between 0.1 and 30 microM. The assays are suited for in vivo preclinical studies and clinical trials because they require minimal amounts of plasma, are sensitive, and involve a 30-mm run time. These assays are important tools for evaluating the potential of Gd-Tex and Lu-Tex as a radiation enhancer and photosensitizer, respectively.

Fluorescence and mass spectrometry studies of meta-tetra(hydroxyphenyl)chlorin photoproducts

The meta-tetra(hydroxyphenyl)chlorin (m-THPC), a second-generation sensitizer used in photodynamic therapy (PDT), is currently under clinical trial. In vivo fluorometry provides direct evidence that photobleaching processes are induced at the tumor site during PDT. Photoproduct formation has thus to be taken into account to fully understand PDT treatment. A preliminary step is to determine the fluorescence characteristics of photoproducts formed in solution. Solutions of m-THPC irradiated at 514 nm have been separated by HPLC using absorption and fluorescence detection. Six main photoproducts have been isolated. According to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) results, five fluorescent photoproducts emitting at 652 nm have been attributed to three mono-, one di- and one tri-hydroxy derivatives (m/z 697, 713 and 729, respectively). Fluorescence characteristics of mono-hydroxy forms were found to be similar to those of m-THPC, whereas fluorescence yields in di- and tri-hydroxy derivatives were very low. Another product, corresponding to a MALDI-TOF MS main signal at m/z 542, showed an absorption spectrum maximum at 522 nm while a weak fluorescence was detected at 480 nm. The loss of the Soret band suggests that this photoproduct results from the opening of the reduced pyrrole ring. The part played by each of these products in the photobleaching phenomenon of m-THPC is discussed.

Biochemical activities of propolis extracts. II. Photodynamic activities

Ethanolic and aqueous extracts of the "bee glue" Propolis exhibit antioxidative properties and are used as antiinflammatory drugs in folk medicine. In order to standardize the principle activities of prominent components of these extracts, simple biochemical tests have been introduced in the preceding paper. These activity tests prove the high antioxidative and inhibitory capacities of aqueous and ethanolic extracts of propolis in vitro. In the present communication we report on experiments documenting photodynamic quenching properties of these extracts. Using riboflavin, rose bengal or hematoporphyrin as photoactivators and ketomethylthiobutyric acid or crocin as indicators, the protective functions of propolis preparations can be demonstrated. The results indicate that the aqueous extracts are more active than the corresponding ethanolic preparation.

Characterisation of the photochemotherapeutic agent disulphonated aluminium phthalocyanine and its high-performance liquid chromatographic separated components

Disulphonated aluminium phthalocyanine (AlPcS2), a potential clinical photosensitiser, has been synthesised in a reproducible form and shown by reversed-phase HPLC to consist of at least eight components which are believed to be individual AlPcS2 regioisomers. These components have been isolated either as single bands or mixtures of two using preparative reversed-phase HPLC methods. The number and position of sulphonate groups per phthalocyanine macromolecule for each component has been determined using a chemical degradation and HPLC assay. Results suggest that the bulk AlPcS2 material consists mostly (> 60%) of an amphiphilic alpha-, alpha-disubstituted regioisomer, with both sulphonate groups substituted to the same side of the molecule (adjacent form). Possible structures for some of the other separated components of AlPcS2 are also presented.