Controlled Aggregation of a Perylene-Derived Probe for Near-Infrared Fluorescence Imaging and Phototherapy.

The design and synthesis of water-soluble phototherapeutic agents with near-infrared (NIR) fluorescence emission is highly desirable for cancer diagnosis and treatment. Here, we report the construction of an amphiphilic perylene-derived photosensitizer, AP. AP shows NIR emission with large Stokes shift (130 nm) and high 1O2 quantum yield (22%). It can self-assemble into nanoparticles in aqueous solution with quenched fluorescence emission due to aggregation-induced quenching. Upon membrane anchoring, AP is able to disassemble into free monomer molecules and specifically "light up" the cell membrane without the usually required washing procedures. Furthermore, AP is subsequently used for the efficient photodynamic therapy against cancer cells and solid tumors. The in vitro and in vivo experiments clearly indicate that AP is suitable for biological imaging and can serve as a promising photosensitizer for tumor suppression.

Naturally available hypericin undergoes electron transfer for type I photodynamic and photothermal synergistic therapy.

Naturally available compounds with bioactivity are potential candidates for cancer treatment. In this paper, we isolated hypericin (HC) from Hypericum sinense L. and investigated its antitumor activity both in vitro and in vivo. The nanoparticles (NPs) of HC were prepared by a nanoprecipitation process with 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG-2000). With light irradiation, HC NPs not only undergo efficient electron transfer to generate the superoxide radical (O2-˙) and the hydroxyl radical (OH˙) as well as energy transfer producing singlet oxygen (1O2) for photodynamic therapy (PDT), but also non-radiative decay to produce heat for photothermal therapy (PTT) with a photothermal conversion efficiency of 29.3%. This synergistic therapy, therefore, largely boosts the phototherapy efficacy of HC NPs on human cervical cancer cells (HeLa), guaranteeing a low half maximal inhibitory concentration (IC50) of only 5.6 µg mL-1. Furthermore, in vivo studies suggest that HC NPs are capable of inhibiting tumor proliferation after laser irradiation, and the main organs remain healthy, including the heart, kidneys, liver, lungs and spleen. Our results indicate that HC NPs derived from nature with excellent phototherapy efficacies are biocompatible candidates for type I PDT/PTT synergistic cancer therapy.

Natural-Origin Hypocrellin-HSA Assembly for Highly Efficient NIR Light-Responsive Phototheranostics against Hypoxic Tumors.

Tumor hypoxia severely limits the therapeutic efficacy of solid tumors in photodynamic therapy. One strategy is to develop photosensitizers with simultaneously high efficiency in photodynamic (PDT) and photothermal therapies (PTT) in a single natural-origin phototheranostic agent to overcome this problem. However, less attention has been paid to the natural-origin phototheranostic agent with high PDT and PTT efficiencies even though they have negligible side effects and are environmentally sustainable in comparison with many reported phototheranostic agents. In addition, almost all clinical applied photosensitizers are of natural origin so far. Herein, we synthesized a natural product-based hypocrellin derivative (AETHB), with a high singlet oxygen quantum yield of 0.64 as an efficient photosensitizer different from commercially available porphyrin-based photosensitizers. AETHB is further assembled with human serum albumin to construct nanoparticles (HSA-AETHB NPs) with a high photothermal conversion efficiency (more than 50%). As-prepared HSA-AETHB NPs have shown good water solubility and biocompatibility, pH and light stability, wide absorption (400-750 nm), and NIR emission centered at 710 nm. More importantly, HSA-AETHB NPs can be applied for fluorescent/photoacoustic dual-mode imaging and simultaneously highly efficient PDT/PTT in hypoxic solid tumors. Therefore, this natural-origin multifunctional phototheranostic agent is showing very promising for effective, precise, and safe cancer therapy in clinical applications.

Enhancing Breast Cancer Treatment Using a Combination of Cannabidiol and Gold Nanoparticles for Photodynamic Therapy.

Indisputably, cancer is a global crisis that requires immediate intervention. Despite the use of conventional treatments over the past decades, it is acceptable to admit that these are expensive, invasive, associated with many side effects and, therefore, a reduced quality of life. One of the most possible solutions to this could be the use of gold nanoparticle (AuNP) conjugated photodynamic therapy (PDT) in combination with cannabidiol (CBD), a Cannabis derivative from the Cannabis sativa. Since the use of Cannabis has always been associated with recreation and psychoactive qualities, the positive effects of Cannabis or its derivatives on cancer treatment have been misunderstood and hence misinterpreted. On the other hand, AuNP-PDT is the most favoured form of treatment for cancer, due to its augmented specificity and minimal risk of side effects compared to conventional treatments. However, its use requires the consideration of several physical, biologic, pharmacologic and immunological factors, which may hinder its effectiveness if not taken into consideration. In this review, the role of gold nanoparticle mediated PDT combined with CBD treatment on breast cancer cells will be deliberated.

Potential antioxidant and anti-inflammatory action of Hypericum hookerianum extracts in a liposome system evaluated with zebrafish embryos.

The purpose of this study was to assess the antioxidant and anti-inflammatory potential of liposomal formulations enriched with Hypericum hookerianum (Hyp) aqueous extracts. Cotyledon segments derived from protocorms of H. hookerianum were cultured on Murashige and Skoog (MS) media supplemented with Kinetin (KN, 1 mgl-1) and Naphthalene acetic acid (NAA, 0.1 mgl-1) to induce hypericin-rich red shoots (HypR, 0.87 mg/G DW). Highly stable liposomes (-29.4 mV) were successfully developed which encapsulated 63 ± 0.8% Hyp extracts, respectively. MTT assay subsequently confirmed the biocompatibility of liposome compositions using fibroblast cell lines. This work also evaluated acute toxicity of L-HypR and L-HypG formulations using Danio rerio (Zebrafish) embryos for 96 hpf. The expression of antioxidant and anti-inflammatory genes were found to be upregulated for L-HypR than L-HypG (green shoots without hypericin) formulations. These properties of L-HypR may be extremely useful for incorporating lipophilic substances into the food or pharmaceutical industry.

The potential of hypericin and hyperforin for antiadhesion therapy to prevent metastasis of parental and oxaliplatin-resistant human adenocarcinoma cells (HT-29).

Cancer cells disseminate to other parts of the body during metastasis through the process of intravasation. The hypericin and hyperforin effect has been described to understand the signal mechanisms that stimulate or stunt cancer cell sprouting to metastasis on colon adenocarcinoma cells HT-29 and its resistant form HT-29-OxR. We focused on the key points of adhesion proteins (cadherin, integrin, selectin and syndecan) and also proteins participating in or contributing to the process of cancer cell migration and adhesion through genes expression and proteins levels. Treatment effects were identified as a consequence of decreased cell adhesion, changes of expression in the adhesive proteins as well as basal membrane degradation associated with changes in the expression of matrix proteinases and in their activity. Finally, the cells affected by hypericin or hyperforin were evaluated by monitoring the cancer cell adhesion properties and proliferation processes. Supplementary Fig. (Supplemental digital content 1, http://links.lww.com/ACD/A267).

Liposomal hypocrellin B as a potential photosensitizer for age-related macular degeneration: pharmacokinetics, photodynamic efficacy, and skin phototoxicity in vivo.

Photodynamic therapy (PDT) has been successfully implemented as a treatment for wet age-related macular degeneration (AMD), but very few photosensitizers have been developed for clinical use. Herein, we describe a novel formulation of liposomal hypocrellin B (LHB) that was prepared by high-pressure homogenization. The encapsulation efficiency and PDT efficacy in vitro of this new preparation were found to remain nearly constant over 1 year. Moreover, LHB is rapidly cleared from the blood, with a half-life of 2.319 ± 0.462 h and a very low serum concentration at 24 h after injection. Testing in a rat model of choroidal neovascularization (CNV) showed that leakage of blood vessels in CNV lesions was significantly reduced when LHB PDT was given at a dose of 1 mg kg(-1) along with yellow laser irradiation; the damage to the collateral retina and the retinal pigment epithelium was minimal. Skin phototoxicity assays showed that only two of the 200 mice given a 4 mg per kg dose of LHB experienced an inflammatory reaction in the auricle irradiated at 24 h after dosing. These data collectively indicate that LHB may be a safe and effective photosensitizer for vascular-targeted PDT of AMD.

Photodynamic therapy for psoriasis.

INTRODUCTION: Photodynamic therapy for psoriasis showed promise in the early 1990s with reports of plaque clearance following topical aminolevulinic acid - photodynamic therapy (ALA-PDT). METHODS: In December 2013, we conducted a systematic search of the PubMed Medline database using the keywords "psoriasis" and "photodynamic therapy". RESULTS: Numerous clinical studies have failed to demonstrate a consistent, efficacious response to topical ALA-PDT. Furthermore, severe pain and burning sensations were repeatedly reported, many cases being intolerable for patients. DISCUSSION: The variability in clinical response and the painful side effects have made topical ALA-PDT an unsuitable treatment option for chronic plaque psoriasis. Nonetheless, early clinical studies of other modalities such as topical hypericin and methylene blue, as well as systemic ALA and verteporfin, have shown that these photosensitizers are efficacious and much better tolerated than topical ALA. CONCLUSION: With the current landscape of phototherapy dominated by psoralen combined with ultraviolet A (PUVA) and narrow-band ultraviolet B (NB-UVB), an alternative light therapy utilizing the visible spectrum is certainly promising and a worthwhile endeavor to pursue.

PKC-mediated potentiation of morphine analgesia by St. John's Wort in rodents and humans.

Our purpose was to combine the use of morphine with clinically available inhibitors of protein kinase C (PKC), finally potentiating morphine analgesia in humans. Thermal tests were performed in rodents and humans previously administered with acute or chronic morphine combined or not with increasing doses of the PKC-blocker St. John's Wort (SJW) or its main component hypericin. Phosphorylation of the γ subunit of PKC enzyme was assayed by western blotting in the periaqueductal grey matter (PAG) from rodents co-administered with morphine and hypericin and was prevented in rodent PAG by SJW or hypericin co-administration with morphine, inducing a potentiation of morphine analgesia in thermal pain. The score of pain assessment in healthy volunteers were decreased by 40% when morphine was co-administered with SJW at a dose largely below those used to obtain an antidepressant or analgesic effect in both rodents and humans. The SJW/hypericin potentiating effect lasted in time and preserved morphine analgesia in tolerant mice. Our findings indicate that, in clinical practice, SJW could reduce the dose of morphine obtaining the same analgesic effect. Therefore, SJW and one of its main components, hypericin, appear ideal to potentiate morphine-induced analgesia.

Photodynamic effect of hypericin after topical application in the ex ovo quail chorioallantoic membrane model.

Photosensitizing properties of hypericin are well known, and the chicken chorioallantoic membrane has previously been used to test photodynamic effects of hypericin and other substances. In our study the photodynamic effect of hypericin in the ex ovo quail chorioallantoic membrane model was evaluated. Steady-state and time-resolved fluorescence spectroscopy of hypericin solution in PEG-400 and its mixture in PBS was performed to assess and characterize the process of aggregation and disaggregation of hypericin during the drug formulation preparation. A therapeutical formulation (2 µg/g of embryo weight) was topically applied on CAM into the silicone ring. Hypericin was excited by diode laser with wavelength 405 nm, fluence rate 140 mW/cm2, and fluence 16.8 J/cm2. Hypericin in 100% PEG-400 exhibits typical fluorescence spectra with a maximum of about 600 nm, while hypericin 10% PEG-400 formulation exhibits almost no fluorescence. Time resolved spectra analysis showed fluorescence decay of hypericin in 100% PEG-400 solution with a mean lifetime of 5.1 ns and in 10% PEG 4.1 ns. Damage of quail chorioallantoic membrane vasculature after photodynamic therapy ranged from hemorrhage and vanishing of capillary vessels to thrombosis, lysis, and hemorrhage of larger vessels.The presented findings suggest that quail embryos can be used as a suitable model to test the effect of hypericin and other photodynamic compounds.

Biodistribution and radiation dosimetry of radioiodinated hypericin as a cancer therapeutic.

Iodine-131­labeled monoiodohypericin (131I­Hyp) is a necrosis avid compound used as a complementary anticancer agent. Herein, the biodistribution in rats with re-perfused partial liver infarction (RPLI) was used to estimate its human internal radiation dosimetry. Iodine-123­labeled monoiodohypericin (123I-Hyp) as a safer surrogate for 131I-Hyp was prepared with iodogen as oxidant. Determination of radiochemical yield and purification was performed by high performance liquid chromatography (HPLC). To control aggregation, the formulation was macroscopically and microscopically examined. Biodistribution of 123I-Hyp was studied in RPLI rats (n=18) at 4, 24 and 48 h post-injection. Tissue gamma counting (TGC), autoradiography and histology were performed. Dosimetry of 131I-Hyp in hepatic necrosis and in normal human organs was estimated using biodistribution data of 123I-Hyp, the Organ Level Internal Dose Assessment/Exponential Modeling (OLINDA/EXM®), a sphere model and male and female phantoms. A radiochemical yield of 95% was achieved in labeling of 123I-Hyp with a radiochemical purity of 99% after HPLC purification. In the Hyp added formulation, no macroscopic but minimal microscopic aggregation was observed. By TGC, selective accumulation in hepatic infarction and low uptake in viable liver of 123I­Hyp/Hyp were detected, as confirmed by autoradiography and histology. Significantly higher doses of 131I-Hyp were delivered to necrotic (276­93,600 mGy/MBq) than to viable (4.2 mGy/MBq) liver (P<0.05). In normal organs, 123I­Hyp was eliminated within 24 h except for relatively high levels in the lungs and thyroid. Hepatobiliary elimination was a major pathway of 123I-Hyp causing high activity in the intestines. For both genders, dosimetry showed the longest residence time of 131I-Hyp in the remainder, followed by the lungs, intestines and thyroid. The highest absorbed radiation dose was seen in necrotic tissues and the shortest residence times and lowest absorbed radiation dose were found in the brain. 131I-Hyp selectively delivers higher radiation dose to necrosis compared with the rest of the body. Among normal organs, thyroids, lungs and intestines receive considerable radiation dose, which deserves cautious attention in developing this anticancer approach.

A phase II placebo-controlled study of photodynamic therapy with topical hypericin and visible light irradiation in the treatment of cutaneous T-cell lymphoma and psoriasis.

BACKGROUND: Hypericin is a known photodynamic agent that has been demonstrated to induce apoptosis in normal and malignant B and T lymphocytes, and has potential to treat benign and malignant disorders of the skin, including psoriasis and cutaneous T-cell lymphoma. OBJECTIVE: We wished to test whether topical hypericin was an effective, safe, and well-tolerated therapy for patch or plaque phase mycosis fungoides and for plaque psoriasis. METHODS: We conducted a phase II placebo-controlled clinical study in patients who had either patch or plaque phase mycosis fungoides or plaque type psoriasis vulgaris. Representative lesions were treated twice weekly for 6 weeks with topically applied hypericin or placebo followed 24 hours later by exposure to visible light at 8 to 20 J/cm(2). RESULTS: After 6 weeks of twice-weekly therapy, several concentrations of hypericin resulted in the significant improvement of treated skin lesions among the majority of patients with cutaneous T-cell lymphoma and psoriasis whereas the placebo vehicle was ineffective. LIMITATIONS: The clinical trial involved a small number of patients. CONCLUSIONS: Overall, the data from this study support the conclusion that topical hypericin/visible light photodynamic therapy is an effective and well-tolerated alternative to standard psoralen plus ultraviolet A treatment of these disorders.

Determination of total hypericins in St. John's wort and herbal medicinal products.

The work aimed to determine the levels of hypericins expressed as hypericin in the herbal substance of St. John's wort, in capsules and tablets containing the extract of St. John's wort, tablets containing powdered herb and in tincture and juice from fresh St. John's wort, by HPLC method with spectrophotometric detection. In addition, the amount of hypericins in the infusion prepared from St. John's wort was determined by HPLC and spectrophotometry methods. According to traditional indications aqueous infusions from St. John's wort containing mainly hydrophilic components are used in gastrointestinal diseases. On the other hand, ethanolic extracts containing hypericin and hyperforin affect the CNS and are indicated for the treatment of episodes of mild depressive disorders. The results obtained in the work indicate that the daily dose of hypericins taken by a patient as infusions is 0.328 mg on average for herbs in sachets and in bulk form. It can be compared to the daily dose of hypericins contained in tablets and capsules based on the alkoholic extract of St. John's wort and tablets containing powdered St. John's wort herb. For solid dosage forms, this dose ranges from 0.288 mg to 0.636 mg. The assays were performed using consistent analytical methods for all tested pharmaceutical products and consequently it was possible to compare doses taken by patients and their strength of action.

Quenching-induced deactivation of photosensitizer by nanoencapsulation to improve phototherapy of cancer.

Photodynamic therapy has emerged as a promising alternative to current cancer treatment. However, conventional photosensitizers have several limitations due to their unsuitable pharmaceutical formulations and lack of selectivity. Our strategy was to exploit the advantages of nanoparticles and the quenching-induced deactivation of the model photosensitizer hypericin to produce "activatable" drug delivery systems. Efficient fluorescence and activity quenching were achieved by increasing the drug-loading rate of nanoparticles. In vitro assays confirmed the reversibility of hypericin deactivation, as the hypericin fluorescence and photodynamic activity were recovered upon cell internalization.

Topical anti-inflammatory activity of extracts and compounds from Hypericum perforatum L.

Three preparations of Hypericum perforatum L. (a hydroalcoholic extract, a lipophilic extract and an ethylacetic fraction) and the pure compounds hypericin, adhyperforin, amentoflavone, hyperoside, isoquercitrin, hyperforin dicyclohexylammonium (DHCA) salt and dicyclohexylamine were evaluated for their topical anti-inflammatory activity. H. perforatum preparations provoked a dose-dependent reduction of Croton-oil-induced ear oedema in mice, showing the following rank order of activity: lipophilic extract > ethylacetic fraction > hydroalcoholic extract (ID50 (dose that inhibited oedema by 50%) 220, 267 and >1000 microg cm(-2), respectively). Amentoflavone (ID50 0.16 micromol cm(-2)), hypericin (ID50 0.25 micromol cm(-2)), hyperforin DHCA salt (ID50 0.25 micromol cm(-2)) and adhyperofrin (ID50 0.30 micromol cm(-2)) had anti-inflammatory activity that was more potent or comparable to that of indometacin (ID50 0.26 micromol cm(-2)), whereas isoquercitrin and hyperoside were less active (ID50 about 1 micromol cm(-2)). As dicyclohexylamine alone was inactive, the effect of hyperforin DHCA salt can be attributed completely to the phloroglucinol moiety. The pharmacological activity and phytochemical profile of the tested extracts and fraction suggest that different constituents are involved in the topical antiphlogistic property of H. perforatum in-vivo.

Histomorphological changes in murine fibrosarcoma after hypericin-based photodynamic therapy.

Histomorphological changes in murine fibrosarcoma after photodynamic therapy (PDT) based on the natural photosensitizer hypericin were evaluated. C3H/DiSn mice were inoculated with fibrosarcoma G5:1:13 cells. When the tumour reached a volume of 40-80 mm(3) the mice were intraperitoneally injected with hypericin, either in a single dose (5 mg/kg; 1 or 6 h before laser irradiation) or two fractionated doses (2.5 mg/kg; 6 and 1 h before irradiation with laser light; 532 nm, 70 mW/cm(2), 168 J/cm(2)). All groups of PDT-treated animals with single and fractionated hypericin dosing presented primary vascular reactions including vascular dilatation, congestion, thrombosis and oedema. Two hours after PDT there were necrotic changes with small, rather focal appearance. One day after therapy the necrotic areas were enhanced, often affecting a complete superficial layer of tumour tissue. Necrotic areas were accompanied with inflammation and haemorrhages.

Investigation of pharmacokinetic data of hypericin, pseudohypericin, hyperforin and the flavonoids quercetin and isorhamnetin revealed from single and multiple oral dose studies with a hypericum extract containing tablet in healthy male volunteers.

Hypericins, hyperforin and flavonoids are discussed as the main components contributing to the antidepressant action of St. John's wort (Hypericum perforatum). Therefore, the objective of the two open phase I clinical trials was to obtain pharmacokinetic data of these constituents from a hypericum extract containing tablet: hypericin, pseudohypericin, hyperforin, the flavonoid aglycone quercetin, and its methylated form isorhamnetin. Each trial included 18 healthy male volunteers who received the test preparation, containing 900 mg dry extract of St John's wort (STW 3-VI, Laif 900), either as a single oral dose or as a multiple once daily dose over a period of 14 days. Concentration/time curves were determined for the five constituents, for 48 h after single dosing and for 24 h on day 14 at the end of 2 weeks of continuous daily dosing. After single dose intake, the key pharmacokinetic parameters were determined as follows: Hypericin: Area under the curve (AUC(0-infinity)) = 78.33 h x ng/ml, maximum plasma concentration (Cmax) = 3.8 ng/ml, time to reach Cmax (tmax) = 7.9 h, and elimination half-life (t1/2) = 18.71 h; pseudohypericin: AUC(0-infinity) = 97.28 h x ng/ml, Cmax = 10.2 ng/ml, tmax = 2.7 h, t1/2 = 17.19 h; hyperforin: AUC(0-infinity) = 1550.4 h x ng/ml, Cmax = 122.0 ng/ml, tmax = 4.5 h, t1/2 = 17.47 h. Quercetin and isorhamnetin showed two peaks of maximum plasma concentration separated by about 3-3.5 h. Quercetin: AUC(0-infinity) = 417.38 h x ng/ml, Cmax (1) = 89.5 ng/ml, tmax (1) = 1.0 h, Cma (2) = 79.1 ng/ml, tmax (2) = 4.4 h, t1/2 = 2.6 h; isorhamnetin: AUC(0-infinity) = 155.72 h x ng/ml, Cmax (1) = 12.5 ng/ml, tmax (1) = 1.4 h, Cmax (2) = 14.6 ng/ml, tmax (2) = 4.5 h, t1/2 = 5.61 h. Under steady state conditions reached during multiple dose administration similar results were obtained. Further pharmacokinetic characteristics calculated from the obtained data were the mean residence time (MRT), the lag-time, the peak-trough fluctuation (PTF), the lowest observed plasma concentration (Cmin), and the average plasma concentration (Cav). The data obtained for the five consitituents generally corresponded well with values previously published. The trial preparation was well tolerated.

Photoinduced antitumour effect of hypericin can be enhanced by fractionated dosing.

The in vivo antitumour activity of the natural photosensitizer hypericin was evaluated. C3H/DiSn mice were inoculated with fibrosarcoma G5:1:13 cells. When the tumour reached a volume of 40-80mm3 the mice were intraperitoneally injected with hypericin, either in a single dose (5mg/kg; 1 or 6h before laser irradiation) or two fractionated doses (2.5 mg/kg; 6 and 1 h before irradiation with laser light; 532 nm, 70mW/cm2, 168 J/cm2). All tumours in control groups treated with hypericin alone as well as those irradiated with laser light alone had similar growth rates and none of these tumours regressed spontaneously. Complete remission of tumour in photodynamic therapy (PDT)-treated groups was similar (14-17% single dose vs. 33% fractionated dose), but the fractionated schedule of hypericin dosing was found to be more efficient than the single dose, measured by survival assay (p < 0.05). Our experimental model showed that fractionated administration of hypericin can produce a better therapeutic response than single administration.

In vivo accumulation of different hypericin ion pairs in the urothelium of the rat bladder.

OBJECTIVE: To optimise the diagnostic and phototherapeutic efficacy of hypericin in superficial bladder cancer, by developing a bladder instillation fluid that does not depend on the presence of plasma proteins for an appropriate and reliable urothelial uptake of hypericin. MATERIALS AND METHODS: Sodium hypericinate (in distilled water, in sodium phosphate buffer, or in polyethylene glycol) and several other hypericinate salts (potassium, lysine, TRIS or hexylamine) were instilled with no plasma constituents into the rat bladder. The accumulation of hypericin was assessed with fluorescence microscopy. RESULTS: The diagnostic and phototherapeutic efficacy of hypericin depends on its ability to penetrate the tumour lesions sufficiently to show a fluorescent signal or elicit a photodynamic response. Several instillation fluids meet the purpose, as the urothelial accumulation of hypericin was similar to that obtained with the instillation fluid supplemented with plasma proteins, used in clinical practice. The highest concentrations of hypericin in the urothelium of the rat bladder were obtained with hypericin instillation solutions prepared with distilled water or 20% polyethylene glycol 400 in distilled water. Fluorescence microscopy showed that hypericin was selectively localized in the urothelium. Furthermore, all variables investigated (hydrophilic/lipophilic balance, pH, saline, presence of organic solvent) can dramatically influence the in vivo accumulation of hypericin. CONCLUSION: An appropriate and reliable urothelial uptake of hypericin does not depend on the presence of plasma protein supplements in the bladder instillation fluid.

Cytotoxic activity of Hypericum perforatum L. on K562 erythroleukemic cells: differential effects between methanolic extract and hypericin.

The influence of a methanolic extract of Hypericum perforatum L. and of purified hypericin has been comparatively tested on the growth of a human erythroleukemic cell line (K562). After 1 h exposure to increasing concentrations (as hypericin content) of both agents in the dark, leukemic cells were grown for 24 h and 48 h. The effects on cell growth were determined by viable cell count, flow cytometry analysis and fluorescence microscopy. Our data show that purified hypericin has only a weak inhibitory effect on cell growth and no effect in inducing apoptotic cell death. In contrast, the Hypericum flower extract shows a significant concentration-dependent and long-lasting inhibition of cell growth, and induces apoptotic cell death. This work con fi rms the interesting role of Hypericum perforatum L. in cancer therapy and strongly supports the hypothesis that agents, other than hypericin, present in the total extract can impair tumor cell growth acting separately or in a combined manner.