Photophysical properties of Hypericum perforatum L. extracts--novel photosensitizers for PDT

Hypericum Perforatum-Derived Exosomes-Like Nanovesicles: A Novel Natural Photosensitizer for Effective Tumor Photodynamic Therapy

Background

Natural photosensitizers hold potential for photodynamic therapy (PDT) but are often limited by poor visible light absorption. Plant-derived exosome-like nanovesicles offer an innovative platform for enhancing photosensitizer performance.

Methods

Hypericum perforatum-derived nanovesicles (HPDENs) were characterized using electron microscopy, dynamic light scattering, and proteomic and miRNA sequencing. High-performance liquid chromatography confirmed hypericin content. PDT efficacy was assessed in vitro and in vivo.

Results

HPDENs exhibited robust photosensitizing properties, generating reactive oxygen species (ROS) through both Type I and Type II pathways upon light activation. In vitro, HPDENs showed light dose-dependent cytotoxicity against human melanoma cells, characterized by elevated ROS production and apoptosis induction. In vivo, HPDEN-mediated PDT significantly suppressed tumor growth and induced extensive tumor necrosis, with no observable toxicity to major organs.

Conclusion

HPDENs represent a novel plant-derived photosensitizer with dual ROS generation pathways and significant therapeutic efficacy, providing a promising platform for enhancing photodynamic therapy.

Hypocrellin: A Natural Photosensitizer and Nano-Formulation for Enhanced Molecular Targeting of PDT of Melanoma

Nano-formulation has generated attention in the battle against cancer, because of its great flexibility, reduced adverse side effects, and accuracy in delivering drugs to target tissues dependent on the size and surface characteristics of the disease. The field of photodynamic treatment has advanced significantly in the past years. Photodynamic techniques that use nano-formulations have surfaced to further the field of nanotechnology in medicine, especially in cancer treatment. The pharmaceutical industry is seeing a growing trend toward enhanced drug formulation using nano-formulations such as liposomes, polymeric nanoparticles, dendrimers, nano-emulsions, and micelles. Natural extracts have also shown adverse effects when employed as photosensitizers in cancer therapy because they are cytotoxic when activated by light. Still, natural photosensitizers are a big part of cancer treatment. However, some shortcomings can be minimized by combining nano-formulations with these natural photosensitizers. The synergistic improvement in medication delivery that maintains or increases the mechanism of cell death in malignant cells has also been demonstrated by the combination of photodynamic therapy with nano-formulations and natural photosensitizers. Lastly, this review assesses the feasibility and potential of a photodynamic therapy system based on nano-formulations and natural photosensitizers in clinical treatment applications and briefly discusses the removal of toxic compounds associated with nano-formulations within cells.

Chitosan/Hyaluronate Complex-Coated Electrospun Poly(3-hydroxybutyrate) Materials Containing Extracts from Melissa officinalis and/or Hypericum perforatum with Various Biological Activities: Antioxidant, Antibacterial and In Vitro Anticancer Effects

The present study aimed to fabricate innovative fibrous materials with various biological activities from poly(3-hydroxybutyrate), sodium hyaluronate (HA), chitosan (Ch), Melissa officinalis (MO), Hypericum perforatum (HP) extract, or a combination of both extracts. Electrospinning or electrospinning followed by dip coating and the subsequent formation of a polyelectrolyte complex were the methods used to prepare these materials. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) were applied for investigating the morphology of materials, their thermal characteristics, and their surface chemical composition. The composition and design of the mats had an influence on the in vitro release behavior of the main bioactive compounds present in the MO and HP extracts incorporated in the materials. It was found that as-created materials comprising a combination of both extracts and a Ch/HA complex exerted higher antioxidant activity than that of (non-)coated MO-containing mats and Ch/HA-coated mats containing HP. The novel materials manifested antibacterial efficacy towards the pathogenic bacteria S. aureus and E. coli, as evidenced by the performed microbiological screening. Furthermore, the mats possessed a great growth inhibitory effect on HeLa cancer cells but had a less pronounced effect on the growth of normal mouse BALB/3T3 fibroblasts. The loading of both extracts in the mats and the formation of coating led to the enhancement of the in vitro anticancer and antibacterial activities of the materials. Thus, the novel materials have potential for use in local cancer therapy as well as for use as wound dressings.

Hypericin supramolecular assembles: A way to increase the skin availability and photodynamic efficiency in tumor cells

Cyclodextrins (CDs) are molecules approved by the FDA and show promise in increasing the solubility of hydrophobic molecules and making them more available to the skin. These CDs have been used to form complexes with some photosensitizers for Photodynamic Therapy (PDT), such as Hypericin (HY). HY is a lipophilic photosensitizer known for its exceptional fluorescence and singlet oxygen quantum yield generation of over 20 % under 590 nm irradiation. In this study, we found a six-fold increase in the release of HY in vitro after complexation with β-CD. The β-CDHY assembly also demonstrated better skin retention, which is crucial for the topical application of this photosensitizer. Furthermore, the β-CD complexation led to a significant increase in the phototoxicity of HY at three different light doses (3, 6, and 10 J cm-2) due to its improved water solubility and higher in vitro accumulation (approximately two times compared with free HY) in HeLa and Vero cell lines.

Pharmacokinetic and pharmacodynamic herb-drug interactions-part I. Herbal medicines of the central nervous system

Unlike conventional drug substances, herbal medicines are composed of a complex of biologically active compounds. Therefore, the potential occurrence of herb-drug interactions is even more probable than for drug-drug interactions. Interactions can occur on both the pharmacokinetic and pharmacodynamic level. Herbal medicines may affect the resulting efficacy of the concomitantly used (synthetic) drugs, mainly on the pharmacokinetic level, by changing their absorption, distribution, metabolism, and excretion. Studies on the pharmacodynamic interactions of herbal medicines and conventional drugs are still very limited. This interaction level is related to the mechanism of action of different plant constituents. Herb-drug interactions can cause changes in drug levels and activities and lead to therapeutic failure and/or side effects (sometimes toxicities, even fatal). This review aims to provide a summary of recent information on the potential drug interactions involving commonly used herbal medicines that affect the central nervous system (Camellia, Valeriana, Ginkgo, Hypericum, Humulus, Cannabis) and conventional drugs. The survey databases were used to identify primary scientific publications, case reports, and secondary databases on interactions were used later on as well. Search keywords were based on plant names (botanical genera), officinal herbal drugs, herbal drug preparations, herbal drug extracts.

Hypericum perforatum L. and the Underlying Molecular Mechanisms for Its Choleretic, Cholagogue, and Regenerative Properties

Any defects in bile formation, secretion, or flow may give rise to cholestasis, liver fibrosis, cirrhosis, and hepatocellular carcinoma. As the pathogenesis of hepatic disorders is multifactorial, targeting parallel pathways potentially increases the outcome of therapy. Hypericum perforatum has been famed for its anti-depressive effects. However, according to traditional Persian medicine, it helps with jaundice and acts as a choleretic medication. Here, we will discuss the underlying molecular mechanisms of Hypericum for its use in hepatobiliary disorders. Differentially expressed genes retrieved from microarray data analysis upon treatment with safe doses of Hypericum extract and intersection with the genes involved in cholestasis are identified. Target genes are located mainly at the endomembrane system with integrin-binding ability. Activation of α5β1 integrins, as osmo-sensors in the liver, activates a non-receptor tyrosine kinase, c-SRC, which leads to the insertion of bile acid transporters into the canalicular membrane to trigger choleresis. Hypericum upregulates CDK6 that controls cell proliferation, compensating for the bile acid damage to hepatocytes. It induces ICAM1 to stimulate liver regeneration and regulates nischarin, a hepatoprotective receptor. The extract targets the expression of conserved oligomeric Golgi (COG) and facilitates the movement of bile acids toward the canalicular membrane via Golgi-derived vesicles. In addition, Hypericum induces SCP2, an intracellular cholesterol transporter, to maintain cholesterol homeostasis. We have also provided a comprehensive view of the target genes affected by Hypericum's main metabolites, such as hypericin, hyperforin, quercitrin, isoquercitrin, quercetin, kaempferol, rutin, and p-coumaric acid to enlighten a new scope in the management of chronic liver disorders. Altogether, standard trials using Hypericum as a neo-adjuvant or second-line therapy in ursodeoxycholic-acid-non-responder patients define the future trajectories of cholestasis treatment with this product.

Photoactivity of hypericin: from natural product to antifungal application

Considering the multifaceted and increasing application of photodynamic therapy (PDT), in recent years the antimicrobial employment of this therapy has been highlighted, because of the antiviral, antibacterial, antiparasitic, and antifungal activities that have already been demonstrated. In this context, research focussed on antimycological action, especially for treatment of superficial infections, presents promising growth due to the characteristics of these infections that facilitate PDT application as new therapeutic options are needed in the field of medical mycology. Among the more than one hundred classes of photosensitizers the antifungal action of hypericin (Hyp) stands out due to its ability to permeate the lipid membrane and accumulate in different cytoplasmic organelles of eukaryotic cells. In this review, we aim to provide a complete overview of the origin, physicochemical characteristics, and optimal alternative drug deliveries that promote the photodynamic action of Hyp (Hyp-PDT) against fungi. Furthermore, considering the lack of a methodological consensus, we intend to compile the best strategies to guide researchers in the antifungal application of Hyp-PDT. Overall, this review provides a future perspective of new studies and clinical possibilities for the advances of such a technique in the treatment of mycoses in humans.

Light-Activated Phytochemicals in Photodynamic Therapy for Cancer: A Mini Review

Background: Cancer is a serious life-threatening disease often thought of as a deadly and painful disease with no permanent cure. With the advancement of medical science, there have been several clinically approved treatment options developed over the past decade. Photodynamic therapy (PDT) is one such approved minimally invasive light-based therapeutic option for many cancers. Selection of a suitable photosensitizer (PS) is an important step in PDT for improved therapeutic outcomes. Efforts to discover more efficient PSs continue for optimal PDT. Objective: This review discusses the available natural PS of plant origin, the role of phytochemicals in the application of PDT of cancer, specific localization of PS in various cell organelles, and photochemical reactions. Materials and methods: Owing to the substantial side effects, many biomedical research fields are currently focusing on natural compounds with chemotherapeutic potential with environmentally sustainable green approaches. Medicinal plant extracts have been used since ancient times for the treatment of various ailments. Plants are a natural source of many bioactive compounds with pharmaceutical potential and there have been some efforts made to discover potential new compounds from plants with photosensitizing properties for effective PDT outcomes. Results and conclusions: The PDT application in the current scenario raises some questions, such as most effective PS, its administration, the time of irradiation, light source, sensitivity of cells toward PS, and so forth. PDT effects can be direct or indirect. Owing to the direct effect of the PDT, most of the tumoral mass is destroyed. In the cancer cells that were not directly affected, secondary effects such as vascular effects, apoptosis induction, inflammation, and generation of an immune response may occur; however, the complex nature of PDT tissue response is not fully established.

Role of Photoactive Phytocompounds in Photodynamic Therapy of Cancer

Cancer is one of the greatest life-threatening diseases conventionally treated using chemo- and radio-therapy. Photodynamic therapy (PDT) is a promising approach to eradicate different types of cancers. PDT requires the administration of photosensitisers (PSs) and photoactivation using a specific wavelength of light in the presence of molecular oxygen. This photoactivation exerts an anticancer effect via apoptosis, necrosis, and autophagy of cancer cells. Recently, various natural compounds that exhibit photosensitising potentials have been identified. Photoactive substances derived from medicinal plants have been found to be safe in comparison with synthetic compounds. Many articles have focused on PDT mechanisms and types of PSs, but limited attention has been paid to the phototoxic activities of phytocompounds. The reduced toxicity and side effects of natural compounds inspire the researchers to identify and use plant extracts or phytocompounds as a potent natural PS candidate for PDT. This review focusses on the importance of common photoactive groups (furanocoumarins, polyacetylenes, thiophenes, curcumins, alkaloids, and anthraquinones), their phototoxic effects, anticancer activity and use as a potent PS for an effective PDT outcome in the treatment of various cancers.

Shedding Light on Bladder Cancer Diagnosis in Urine

Blue light cystoscopy (BLC) is the most recent clinical approach in the detection and diagnosis of bladder cancer, a common type of cancer with a high rate of recurrence. Representing a significant advance over previous approaches, this photodynamic diagnostic technique uses a photosensitiser prodrug as an adjunct to white light cystoscopy to enhance the in vivo detection of malignant tissues in the bladder based on their distinctive fluorescence. Whilst it does improve detection rates, BLC remains an invasive and costly procedure. Meanwhile, a variety of noninvasive urine detection methods and related microdevices have been developed, none of which have yet entered routine clinical use due to unsatisfactory sensitivity. Following a brief description of the current approaches and their limitations, we provide here a systematic review of a newer niche research aiming to develop a noninvasive adaptation of photodynamic diagnosis. The research to date surrounding the ex situ use of photosensitiser prodrugs for urinary diagnosis of bladder cancer is also discussed.

Photodamage on Staphylococcus aureus by natural extract from Tetragonia tetragonoides (Pall.) Kuntze: Clean method of extraction, characterization and photophysical studies

Photodynamic therapy (PDT) is a clinical modality that allows the destruction of tumor cells and microorganisms by reactive oxygen species, formed by the combination of photosensitizer (PS), molecular oxygen and adequate wavelength light. This research, through a clean methodology that involves pressurized liquids extraction (PLE), obtained a highly antimicrobial extract of Tetragonia tetragonoides, which rich in chlorophylls as photosensitizers. The Chlorophylls-based extract (Cbe-PLE) presented pharmacological safety, through the maintenance of cellular viability. In addition, Cbe-PLE showed great efficacy against Staphylococcus aureus, with severe dose-dependent damage to the cell wall of the pathogen. The obtained product has a high potential for the development of photostimulated phytotherapic formulations for clinical applications in localized infections, as a complementary therapeutic alternative to antibiotics.

Nanocarriers in photodynamic therapy-in vitro and in vivo studies

Photodynamic therapy (PDT) is a minimally invasive technique which has proven to be successful in the treatment of several types of tumors. This relatively simple method exploits three inseparable elements: phototoxic compound (photosensitizer [PS]), light source, and oxygen. Upon irradiation by light with specified wavelength, PS generates reactive oxygen species, which starts the cascade of reactions leading to cell death. The positive therapeutic outcome of PDT may be limited due to several aspects, including low water solubility of PSs, hampering their effective administration and blood circulation, as well as low tumor specificity, inefficient cellular uptake and activation energies requiring prolonged illumination times. One of the promising approaches to overcome these obstacles involves the use of carrier systems modulating pharmacokinetics and pharmacodynamics of the PSs. In the present review, we summarized current in vitro and in vivo studies regarding the use of nanoparticles as potential delivery devices for PSs to enhance their cellular uptake and cytotoxic properties, and thus-the therapeutic outcome of PDT. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Influence of the electron donor properties of hypericin on its sensitizing ability in DSSCs

Rising demands for renewable energy sources have led to the development of dye sensitized solar cells. It is a challenge to find a good and low cost sensitizer, which has a low environmental impact. In this work, we conducted spectroscopic and electrochemical experiments, as well as quantum-chemical calculations of the natural pigment hypericin, in order to provide insight into its sensitizing efficiency. To this end, three identical cells were made and characterized. Although this pigment exhibited good adsorption onto a semiconductor surface, a high molar absorption coefficient (43 700 L mol^-1 cm^-1) and favorable alignment of energy levels and provided a long lifetime of electrons (17.8 ms) in the TiO₂ photoanode, it was found that the efficiency of hypericin-sensitized solar cells was very low, only 0.0245%. We suggest that this inefficiency originated from a low injection of electrons into the conduction band of TiO_2. This conclusion is supported by the density functional theory calculations which revealed a low electron density in the anchoring groups of electronically excited hypericin. The results of this work could be valuable not only in the photovoltaic aspect, but also for application of hypericin in medicine in photodynamic therapy.

Photodynamic therapy for cancer: Role of natural products

Photodynamic therapy (PDT) is a promising modality for the treatment of cancer. PDT involves administering a photosensitizing dye, i.e. photosensitizer, that selectively accumulates in tumors, and shining a light source on the lesion with a wavelength matching the absorption spectrum of the photosensitizer, that exerts a cytotoxic effect after excitation. The reactive oxygen species produced during PDT are responsible for the oxidation of biomolecules, which in turn cause cell death and the necrosis of malignant tissue. PDT is a multi-factorial process that generally involves apoptotic death of the tumor cells, degeneration of the tumor vasculature, stimulation of anti-tumor immune response, and induction of inflammatory reactions in the illuminated lesion. Numerous compounds with photosensitizing activity have been introduced commercially. Although many papers have been published with regard to PDT in the last decade, there has been relatively little focus on natural medicinal plant extracts and compounds derived therefrom. Herbal plants and their extracts are natural substances, and in comparison with synthetic chemicals are considered "green". This review focuses on the different mechanisms of PDT and discusses the role of various plant extracts and natural compounds either alone or in combination for carrying out PDT on different types of cancers.

Comparative in vitro study of photodynamic activity of hypericin and hypericinates in MCF-7 cells

In this work we present a comparative in vitro study of photodynamic activity between hypericin (HYP) and some hypericinates (hypericin ionic pair with lysine or N-methylglucamine) in human mammary adenocarcinoma cells (MCF-7). The toxicity and phototoxicity of hypericin and hypericinates were compared, as well as their cellular uptake and localization and mutagenic, genotoxic and clonogenic capacity. Our results demonstrate that different cationic moieties promote differences in the hypericinate solubility in a biological environment, and can influence the cellular localization and the phototoxicity of the photosensitizer. It was verified that hypericinates have better efficiency to generate singlet oxygen than HYP, and a lower aggregation in biological medium. In vitro assays have shown that HYP and the hypericinates are able to permeate the MCF-7 cell membrane and accumulated in organelles near the nucleus. The difference in location, however, was not determinant to the cell death mechanism, and a higher prevalence of apoptosis for all studied compounds occurred. The photodynamic studies indicated that hypericinates were more effective than HYP and were able to inhibit the formation of cellular colonies, suggesting a possible ability to prevent the recurrence of tumors. It also appears that all compounds have relative safety for mutagenicity and genotoxicity, which opens up a further safe route for application in in vivo studies.

Investigating the effect of poly-l-lactic acid nanoparticles carrying hypericin on the flow-biased diffusive motion of HeLa cell organelles

OBJECTIVES

In this study, we investigate in human cervical epithelial HeLa cells the intracellular dynamics and the mutual interaction with the organelles of the poly-l-lactic acid nanoparticles (PLLA NPs) carrying the naturally occurring hydrophobic photosensitizer hypericin.

METHODS

Temporal and spatiotemporal image correlation spectroscopy was used for the assessment of the intracellular diffusion and directed motion of the nanocarriers by tracking the hypericin fluorescence. Using image cross-correlation spectroscopy and specific fluorescent labelling of endosomes, lysosomes and mitochondria, the NPs dynamics in association with the cell organelles was studied. Static colocalization experiments were interpreted according to the Manders' overlap coefficient.

KEY FINDINGS

Nanoparticles associate with a small fraction of the whole-organelle population. The organelles moving with NPs exhibit higher directed motion compared to those moving without them. The rate of the directed motion drops substantially after the application of nocodazole. The random component of the organelle motions is not influenced by the NPs.

CONCLUSIONS

Image correlation and cross-correlation spectroscopy are most appropriate to unravel the motion of the PLLA nanocarrier and to demonstrate that the rate of the directed motion of organelles is influenced by their interaction with the nanocarriers. Not all PLLA-hypericin NPs are associated with organelles.

Reduced Graphene Oxide/Amaranth Extract/AuNPs Composite Hydrogel on Tumor Cells as Integrated Platform for Localized and Multiple Synergistic Therapy

Integration of multimodal treatment strategies combined with localized therapy to enhance antitumor efficacy and reduce side effects is still a challenge. Herein, a novel composite hydrogel containing rGO, amaranth extract (AE) and gold nanoparticles (AuNPs) was prepared by using AE as both reductant and cross-linking agent. The chlorophyll derivatives in AE were also employed as a photodynamic therapy drug. Meanwhile, AuNPs and rGO both have obvious photothermal effects and can accelerate the generation of cytotoxic singlet oxygen (1O2). The temperature increase of rGO/AE/AuNPs precursor is up to 6.3 °C under 808 nm laser irradiation at a power density of 200 mW·cm(-2). The hydrogel shell on in situ tumor cells was easily formed and regulated by near-infrared irradiation within 10 min, which could both retain a high concentration of drugs on the lesion site and prevent them from migrating to normal tissue, thus reducing the side effects. Compared with rGO/AE and AE, rGO/AE/AuNPs showed a remarkably improved and synergistic antitumor effect. The hydrogel possesses good biocompatibility and high hydrophilicity and could be used for loading chemotherapeutics, which provides a new approach for located and multiple antitumor therapies.

Review of natural compounds for potential skin cancer treatment

Most anti-cancer drugs are derived from natural resources such as marine, microbial and botanical sources. Cutaneous malignant melanoma is the most aggressive form of skin cancer, with a high mortality rate. Various treatments for malignant melanoma are available, but due to the development of multi-drug resistance, current or emerging chemotherapies have a relatively low success rates. This emphasizes the importance of discovering new compounds that are both safe and effective against melanoma. In vitro testing of melanoma cell lines and murine melanoma models offers the opportunity for identifying mechanisms of action of plant derived compounds and extracts. Common anti-melanoma effects of natural compounds include potentiating apoptosis, inhibiting cell proliferation and inhibiting metastasis. There are different mechanisms and pathways responsible for anti-melanoma actions of medicinal compounds such as promotion of caspase activity, inhibition of angiogenesis and inhibition of the effects of tumor promoting proteins such as PI3-K, Bcl-2, STAT3 and MMPs. This review thus aims at providing an overview of anti-cancer compounds, derived from natural sources, that are currently used in cancer chemotherapies, or that have been reported to show anti-melanoma, or anti-skin cancer activities. Phytochemicals that are discussed in this review include flavonoids, carotenoids, terpenoids, vitamins, sulforaphane, some polyphenols and crude plant extracts.

Evidence for contributions of interactions of constituents to the anti-inflammatory activity of Hypericum perforatum

Hypericum perforatum (Hp) extracts contain many different classes of constituents including flavonoids and biflavonoids, phloroglucinols, naphthodianthrones, caffeic acid derivatives, and unknown and/or unidentified compounds. Many constituents may be responsible for the anti-inflammatory activity of Hp including quercetin and derivatives, hyperforin, pseudohypericin, and amentoflavone. In line with antidepressant data, it appears that the interactions of constituents may be important for the anti-inflammatory activity of Hp. Interactions of constituents, tested in bioavailability models, may explain why synergistic mechanisms have been found to be important for antidepressant and antiproliferative bioactivities. This review highlights the relationship among individual constituents and the anti-inflammatory activity of Hp extracts and proposes that interactions of constituents may be important for the anti-inflammatory activity of botanical extracts, although the exact mechanisms of the interactions are still unclear.

Hypericum perforatum: Influences of the habitat on chemical composition, photo-induced cytotoxicity, and antiradical activity

CONTEXT

Hypericin, isolated from Hypericum perforatum L. and about another 300 Hypericum species (Guttiferae), is one of the most powerful photosensitizers found in nature.

OBJECTIVE

The aim of this study was to assess the variability of chemical composition and biological activities of four H. perforatum samples, collected at different altitudes in the South Apennine of Italy.

MATERIALS AND METHODS

MTT assay was used to evaluate the antiproliferative activity of different samples concentrations (0.6-100 µg/mL) after irradiation at 365 nm. The inhibition of nitric oxide production was evaluated after 24 h of incubation using the macrophage cell line RAW 264.7 and sample solutions ranging from 12.5 to 1000 µg/mL. Antioxidant activities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and β-carotene bleaching test (ranges were 12.5-1000 and 1-400 µg/mL, respectively). Chemical composition was evaluated through HPTLC, and different contents of hypericin and rutin have been observed.

RESULTS

The most phototoxic sample was collected from Zumpano (no. 1 at 370 m), with IC50 values of 24.61 ± 0.02 μg/mL. Sample no. 1 showed also the best radical scavenging activity (IC50 value of 9.18 ± 0.03 μg/mL) and the best antioxidant activity (IC50 value of 10.04 ± 0.03 μg/mL after 30 min of incubation). Best activity of extract no. 1 was well in accordance with chemical data, including the phenolic total content and particular metabolome profile.

DISCUSSION AND CONCLUSION

This paper confirms the usefulness in maintaining the exploration of H. perforatum activities, in order to confirm its potentiality as a multipurpose plant.

Photosensitizing and radiosensitizing effects of hypericin on human renal carcinoma cells in vitro

The renal cell carcinoma (RCC) is extremely resistant to chemotherapy and radiotherapy. The prognosis of patients with metastatic RCC still remains poor, the median survival is less than 12 months. Therefore, new therapeutic options are desirable. The aim of this study was to investigate the photosensitizing and radiosensitizing effects of hypericin on human RCC cells in vitro. First the RCC-derived cell lines A498 and ACHN were incubated with different concentrations of hypericin. In vitro uptake and intracellular distribution of hypericin were confirmed by fluorescence microscopy. Subsequently cells were illuminated and irradiated with a dose of 2-8 Gy, respectively. Finally, metabolic activity, apoptosis and clonogenic survival were investigated. Uptake of hypericin was observed for almost all cells. Hypericin treatment combined with illumination led to a 94-97% decrease in metabolic activity and caused apoptosis in nearly 100% of RCC cells. Hypericin enhanced the radiosensitivity of A498 cells in vitro. The clonogenic survival after irradiation was significantly reduced by hypericin treatment. Taken together, the photosensitizing and radiosensitizing effects of hypericin on human RCC cells we found in this investigation could be of clinical relevance, e.g. for radiotherapy and intraoperative photodynamic therapy, respectively.

Photodynamic diagnosis in urology: state-of-the-art

OBJECTIVES

To provide an overview on the methodology and clinical relevance of fluorescence diagnosis with exogenous fluorochromes or fluorochrome prodrugs in urology.

METHODS

The methodology is summarised on the basis of our experience and the relevant literature. Clinical results and perspectives are reported and concluded after we scanned and evaluated sources from PubMed. Search items were "aminolev*" or "hypericin" or "photodyn*" or "porphyrin" or "fluorescence" or "autofluorescence" and "bladder" or "prostate" or "kidney" or "peni*" or "condylo*". Some literature was also obtained from journals not indexed.

RESULTS

A large number of clinical trials have shown that photodynamic diagnosis (PDD) improves the ability to detect inconspicuous urothelial carcinoma of the bladder. Fluorescence diagnosis has recently been approved in Europe for the detection of bladder cancer after instillation of a hexaminolevulinate (Hexvix) solution. PDD is recommended by the European Association of Urology for the diagnosis of carcinoma in situ of the bladder. To date, the major weakness of PDD for the detection of bladder cancer is its relatively low specificity. Initial results with PDD for the detection of penile carcinoma, prostate cancer, kidney tumours, and urethral condylomata are promising.

CONCLUSIONS

To determine the actual impact of PDD on recurrence and progression rates of bladder cancer, further long-term observational studies are necessary. These studies also will clarify whether PDD is cost efficient.

Hypericum perforatum L. extract – Novel photosensitizer against human bladder cancer cells

The polar methanolic fraction (PMF) of the Hypericum perforatum L. extract has recently been developed and tested as a novel, natural photosensitizer for use in the photodynamic therapy (PDT), and photodynamic diagnosis (PDD). PMF has been tested on HL-60 leukemic cells and cord blood hemopoietic progenitors. In the present study, the efficacy of PMF as a phototoxic agent against urinary bladder carcinoma has been studied using the T24 (high grade metastatic cancer), and RT4 (primary low grade papillary transitional cell carcinoma) human bladder cancer cells. Following cell culture incubation, PMF was excited using 630 nm laser light. The photosensitizer exhibited significant photocytotoxicity in both cell lines at a concentration of 60microg/ml, with 4-8 J/cm(2) light dose, resulting in cell destruction from 80% to 86%. At the concentration of 20microg/ml PMF was not active in either cell line. These results were compared with the results obtained in the same cell lines, under the same conditions with a clinically approved photosensitizer, Photofrin. Photofrin was used in the maximum clinically tolerable dose of 4microg/ml, and it was also excited with 630 nm laser light. In the T24 cell Photofrin exhibited slightly less photocytotocixity, compared with PMF, resulting in 77% cell death with 8J/cm(2) light dose. However, against the RT4 cells Photofrin resulted in minimal cell death (9%) with even 8J/cm(2) light dose. Finally, the type of cell death induced by PMF photoactivation was studied using flow cytometry and DNA laddering. Cell death by PMF photodynamic action in these two bladder cell lines is caused predominently by apoptosis. The reported significant photocytotoxicity, selective localization, natural abundance, easy, and inexpensive preparation, underscore that the PMF extract hold the promise of being a novel, effective PDT photosensitizer.