Hypericin in cancer treatment: more light on the way

Fagopyrin F fraction from Fagopyrum tataricum demonstrates photodynamic inactivation of skin infecting bacterium and squamous cell carcinoma (A431) cells

Photodynamic therapy (PDT) stands out as a noteworthy development as an alternative targeted treatment against skin ailments. While PDT has advanced significantly, research into photo-activatable "Green drugs" derived from plants which are less toxic than the synthetic drugs has not kept pace. This study investigates the potential of Fagopyrin F Containing Fraction (FCF) derived from Fagopyrum tataricum in mediating PDT against Staphylococcus aureus and skin cancer cells (A431). FCF was isolated from the plant extract using thin-layer chromatography, followed by identification of the compound through high-performance liquid chromatography and high-resolution liquid chromatography-mass spectrometry. FCF was tested to determine its antibacterial and anticancer efficacy. Results revealed that FCF-mediated PDT exhibited potent action against S. aureus, significantly reducing bacterial viability (MIC 19.5 μg/100 μL). Moreover, FCF-mediated PDT showed good efficacy against A431 cells, resulting in a notable reduction in cell viability (IC50 29.08 μg/mL). Given the known association between S. aureus and squamous cell carcinoma (SCC), FCF shows the potential to effectively target and eradicate both SCC and the related S. aureus present within the lesions. In silico study reveals that Fagopyrin F effectively binds with the epidermal growth factor (EGFR), one among the highly expressed proteins in the A431 cells, with a binding energy of - 9.6 kcal/mol. The affinity of Fagopyrin F for EGFR on A431 cancer cells along with its cytotoxicity against skin cancer cells while safeguarding the normal cells (L929) plays a major part in the way it targets cancer cells. However, its safety, efficacy, and long-term advantages in treating skin conditions require more investigation, including in vivo investigations and clinical trials.

Hypericin as a promising natural bioactive naphthodianthrone: A review of its pharmacology, pharmacokinetics, toxicity, and safety

Hypericin can be derived from St. John's wort, which is widely spread around the world. As a natural product, it has been put into clinical practice such as wound healing and depression for a long time. In this article, we review the pharmacology, pharmacokinetics, and safety of hypericin, aiming to introduce the research advances and provide a full evaluation of it. Turns out hypericin, as a natural photosensitizer, exhibits an excellent capacity for anticancer, neuroprotection, and elimination of microorganisms, especially when activated by light, potent anticancer and antimicrobial effects are obtained after photodynamic therapy. The mechanisms of its therapeutic effects involve the induction of cell death, inhibition of cell cycle progression, inhibition of the reuptake of amines, and inhibition of virus replication. The pharmacokinetics properties indicate that hypericin has poor water solubility and bioavailability. The distribution and excretion are fast, and it is metabolized in bile. The toxicity of hypericin is rarely reported and the conventional use of it rarely causes adverse effects except for photosensitization. Therefore, we may conclude that hypericin can be used safely and effectively against a variety of diseases. We hope to provide researchers with detailed guidance and enlighten the development of it.

Advanced application of nanotechnology in active constituents of Traditional Chinese Medicines

Traditional Chinese Medicines (TCMs) have been used for centuries for the treatment and management of various diseases. However, their effective delivery to targeted sites may be a major challenge due to their poor water solubility, low bioavailability, and potential toxicity. Nanocarriers, such as liposomes, polymeric nanoparticles, inorganic nanoparticles and organic/inorganic nanohybrids based on active constituents from TCMs have been extensively studied as a promising strategy to improve the delivery of active constituents from TCMs to achieve a higher therapeutic effect with fewer side effects compared to conventional formulations. This review summarizes the recent advances in nanocarrier-based delivery systems for various types of active constituents of TCMs, including terpenoids, polyphenols, alkaloids, flavonoids, and quinones, from different natural sources. This review covers the design and preparation of nanocarriers, their characterization, and in vitro/vivo evaluations. Additionally, this review highlights the challenges and opportunities in the field and suggests future directions for research. Nanocarrier-based delivery systems have shown great potential in improving the therapeutic efficacy of TCMs, and this review may serve as a comprehensive resource to researchers in this field.

The Functional Implications of Broad Spectrum Bioactive Compounds Targeting RNA-Dependent RNA Polymerase (RdRp) in the Context of the COVID-19 Pandemic

BACKGROUND

As long as COVID-19 endures, viral surface proteins will keep changing and new viral strains will emerge, rendering prior vaccines and treatments decreasingly effective. To provide durable targets for preventive and therapeutic agents, there is increasing interest in slowly mutating viral proteins, including non-surface proteins like RdRp.

METHODS

A scoping review of studies was conducted describing RdRp in the context of COVID-19 through MEDLINE/PubMed and EMBASE. An iterative approach was used with input from content experts and three independent reviewers, focused on studies related to either RdRp activity inhibition or RdRp mechanisms against SARS-CoV-2.

RESULTS

Of the 205 records screened, 43 studies were included in the review. Twenty-five evaluated RdRp activity inhibition, and eighteen described RdRp mechanisms of existing drugs or compounds against SARS-CoV-2. In silico experiments suggested that RdRp inhibitors developed for other RNA viruses may be effective in disrupting SARS-CoV-2 replication, indicating a possible reduction of disease progression from current and future variants. In vitro, in vivo, and human clinical trial studies were largely consistent with these findings.

CONCLUSIONS

Future risk mitigation and treatment strategies against forthcoming SARS-CoV-2 variants should consider targeting RdRp proteins instead of surface proteins.

Skin cancer: understanding the journey of transformation from conventional to advanced treatment approaches

Skin cancer is a global threat to the healthcare system and is estimated to incline tremendously in the next 20 years, if not diagnosed at an early stage. Even though it is curable at an early stage, novel drug identification, clinical success, and drug resistance is another major challenge. To bridge the gap and bring effective treatment, it is important to understand the etiology of skin carcinoma, the mechanism of cell proliferation, factors affecting cell growth, and the mechanism of drug resistance. The current article focusses on understanding the structural diversity of skin cancers, treatments available till date including phytocompounds, chemotherapy, radiotherapy, photothermal therapy, surgery, combination therapy, molecular targets associated with cancer growth and metastasis, and special emphasis on nanotechnology-based approaches for downregulating the deleterious disease. A detailed analysis with respect to types of nanoparticles and their scope in overcoming multidrug resistance as well as associated clinical trials has been discussed.

Hypericin: A natural anthraquinone as promising therapeutic agent

BACKGROUND

Hypericin is a prominent secondary metabolite mainly existing in genus Hypericum. It has become a research focus for a quiet long time owing to its extensively pharmacological activities especially the anti-cancer, anti-bacterial, anti-viral and neuroprotective effects. This review concentrated on summarizing and analyzing the existing studies of hypericin in a comprehensive perspective.

METHODS

The literature with desired information about hypericin published after 2010 was gained from electronic databases including PubMed, SciFinder, Science Direct, Web of Science, China National Knowledge Infrastructure databases and Wan Fang DATA.

RESULTS

According to extensive preclinical and clinical studies conducted on the hypericin, an organized and comprehensive summary of the natural and artificial sources, strategies for improving the bioactivities, pharmacological activities, drug combination of hypericin was presented to explore the future therapeutic potential of this active compound.

CONCLUSIONS

Overall, this review offered a theoretical guidance for the follow-up research of hypericin. However, the pharmacological mechanisms, pharmacokinetics and structure activity relationship of hypericin should be further studied in future research.

Synergistic chemotherapy and phototherapy based on red blood cell biomimetic nanomaterials

Novel drug delivery systems (DDSs) have become the mainstay of research in targeted cancer therapy. By combining different therapeutic strategies, potential DDSs and synergistic treatment approaches are needed to effectively deal with evolving drug resistance and the adverse effects of cancer. Nowadays, developing and optimizing human cell-based DDSs has become a new research strategy. Among them, red blood cells can be used as DDSs as they significantly enhance the pharmacokinetics of the transported drug cargo. Phototherapy, as a novel adjuvant in cancer treatment, can be divided into photodynamic therapy and photothermal therapy. Phototherapy using erythropoietic nanocarriers to mimic the unique properties of erythrocytes and overcome the limitations of existing DDSs shows excellent prospects in clinical settings. This review provides an overview of the development of photosensitizers and research on bio-nano-delivery systems based on erythrocytes and erythrocyte membranes that are used in achieving synergistic outcomes during phototherapy/chemotherapy.

Potent Virucidal Activity In Vitro of Photodynamic Therapy with Hypericum Extract as Photosensitizer and White Light against Human Coronavirus HCoV-229E

The emergent human coronavirus SARS-CoV-2 and its high infectivity rate has highlighted the strong need for new virucidal treatments. In this sense, the use of photodynamic therapy (PDT) with white light, to take advantage of the sunlight, is a potent strategy for decreasing the virulence and pathogenicity of the virus. Here, we report the virucidal effect of PDT based on Hypericum extract (HE) in combination with white light, which exhibits an inhibitory activity of the human coronavirus HCoV-229E on hepatocarcinoma Huh-7 cells. Moreover, despite continuous exposure to white light, HE has long durability, being able to maintain the prevention of viral infection. Given its potent in vitro virucidal capacity, we propose HE in combination with white light as a promising candidate to fight against SARS-CoV-2 as a virucidal compound.

Unravelling Phytochemical and Bioactive Potential of Three Hypericum Species from Romanian Spontaneous Flora: H. alpigenum, H. perforatum and H. rochelii

Hypericum perforatum L., also known as St. John’s Wort, is recognized worldwide as a valuable medicinal herb; however, other Hypericum species were intensively studied for their bioactive potential. To fill the research gap that exists in the scientific literature, a comparative evaluation between H. alpigenum Kit., H. perforatum L. and H. rochelii Griseb. & Schenk was conducted in the present study. Two types of herbal preparations obtained from the aerial parts of these species were analyzed: extracts obtained through maceration and extracts obtained through magnetic-stirring-assisted extraction. LC-DAD-ESI-MSn analysis revealed the presence of phenolic acids, flavan-3-ols and flavonoid derivatives as the main constituents of the above-mentioned species. Moreover, all extracts were tested for their antioxidant, enzyme-inhibitory and antimicrobial potential. Our work emphasizes for the first time a detailed description of H. rochelii phenolic fractions, including their phytochemical and bioactive characterization. In comparison with the other two studied species, H. rochelii was found as a rich source of phenolic acids and myricetin derivatives, showing important antioxidant, anticholinesterase and antibacterial activity. The study offers new perspectives regarding the chemical and bioactive profile of the less-studied species H. alpigenum and H. rochelii.

Hypericin, a potential new BH3 mimetic

Many types of cancer such as prostate cancer, myeloid leukemia, breast cancer, glioblastoma display strong chemo resistance, which is supported by enhanced expression of multiple anti-apoptotic Bcl-2, Bcl-XL and Mcl-1 proteins. The viable anti-cancer strategies are based on developing anti-apoptotic Bcl-2 proteins inhibitors, BH3 mimetics. Our focus in past years has been on the investigating a new potential BH3 mimetic, Hypericin (Hyp). Hyp is a naturally occurring photosensitive compound used in photodynamic therapy and diagnosis. We have demonstrated that Hyp can cause substantial effects in cellular ultrastructure, mitochondria function and metabolism, and distribution of Bcl2 proteins in malignant and non-malignant cells. One of the possible mechanisms of Hyp action could be the direct interactions between Bcl-2 proteins and Hyp. We investigated this assumption by in silico computer modelling and in vitro fluorescent spectroscopy experiments with the small Bcl2 peptide segments designed to correspond to Bcl2 BH3 and BH1 domains. We show here that Hyp interacts with BH3 and BH1 peptides in concentration dependent manner, and shows the stronger interactions than known BH3 mimetics, Gossypol (Goss) and ABT-263. In addition, interactions of Hyp, Goss and ABT263, with whole purified proteins Bcl-2 and Mcl-1 by fluorescence spectroscopy show that Hyp interacts stronger with the Bcl-2 and less with Mcl-1 protein than Goss or ABT-263. This suggest that Hyp is comparable to other BH3 mimetics and could be explore as such. Hyp cytotoxicity was low in human U87 MG glioma, similar to that of ABT263, where Goss exerted sufficient cytotoxicity, suggesting that Hyp acts primarily on Bcl-2, but not on Mcl-1 protein. In combination therapy, low doses of Hyp with Goss effectively decreased U87 MG viability, suggesting a possible synergy effect. Overall, we can conclude that Hyp as BH3 mimetic acts primarily on Bcl-2 protein and can be explored to target cells with Bcl-2 over-expression, or in combination with other BH3 mimetics, that target Mcl-1 or Bcl-XL proteins, in dual therapy.

Photobiomodulation and photodynamic therapy-induced switching of autophagy and apoptosis in human dermal fibroblasts

Nowadays, photobiomodulation (PBM) in combination with chemotherapy or other therapeutic approaches is an attractive adjuvant modality for cancer treatment. Targeted destruction of cancer cells is one of the main advantages of photodynamic therapy (PDT). We have shown in previous studies that the combination of PBM at 808 nm and hypericin-mediated PDT increases PDT efficacy in human glioblastoma cells U87 MG. The study presented here shows significant differences between U87 MG and non-cancerous human dermal fibroblasts (HDF) cells treated by PBM and PDT. This study focuses on mitochondria because PBM mainly affects these organelles. We demonstrated that an interplay between mitochondrial and autophagic proteins plays a crucial role in the response of HDF cells to PBM and PDT. Fluorescence microscopy, flow cytometry, and Western blot analysis were used to examine the autophagic profile of HDF cells after these treatments. An increase in ubiquitin, SQSTM1, LC3BII, and cytochrome c was accompanied by a decrease in M6PR, ATG16L1, and Opa1 in HDF cells exposed to PBM and PDT. Overall, we observed that the switching of autophagy and apoptosis is dose-dependent and also occurs independently of PBM in HDF cells after hypericin-mediated PDT. However, PBM might preferentially induce autophagy in noncancer cells, which might escape apoptosis under certain conditions.

A new valid rhabdomyosarcoma spheroid culture model for in vitro evaluation of hypericin-based photodynamic therapy

BACKGROUND

Advanced stages of pediatric alveolar rhabdomyosarcoma (RMA) are associated with an unfavorable outcome at established therapeutic strategies, accentuating the need for novel treatment options. Photodynamic therapy (PDT) with hypericin (HYP) has shown strong cytotoxic effects in two-dimensional (2D) cell culture. In order to more accurately mimic in vivo tissue architecture and better predict pharmaceutical response, the aim of this study was to establish a spheroid culture model by which PDT efficacy could be assessed in a three-dimensional (3D) context.

MATERIALS AND METHODS

3D multicellular tumor spheroids were generated using various scaffold-based and scaffold-free techniques. On two reproducible methods, HYP-PDT was performed varying spheroid sizes, photosensitizer concentrations, and illumination times. The ability for HYP uptake within the spheroid was analyzed assessing the substrate's autofluorescence. Antitumorigenic treatment effects were evaluated investigating cell viability, spheroid morphology, proliferative activity, and induction of apoptosis.

RESULTS

Magnetic spheroid printing and orbital shaking methods were established as reproducible culturing systems producing uniform spheroids. Within assessed incubation times, HYP showed good penetration depth in spheroids containing 50,000 cells. PDT was causing metabolic and molecular impairment of RMA cells, resulting in viability decrease, reduction of cell proliferation, and induction of apoptosis.

CONCLUSION

Assessing HYP-based PDT in a 3D culture model, we were able to gain an insight on how parameters like photosensitizer, oxygen, and light distribution contribute to the phototoxic effect. Compared to 2D cell culture, a higher treatment resistance was detected, which can be related to spheroid structure and mechanisms of intercellular communication, signal transduction, and gene expression.

Ultrasound Triggers Hypericin Activation Leading to Multifaceted Anticancer Activity

The use of ultrasound (US) in combination with a responsive chemical agent (sonosensitizer) can selectively trigger the agent's anticancer activity in a process called sonodynamic therapy (SDT). SDT shares some properties with photodynamic therapy (PDT), which has been clinically approved, but sets itself apart because of its use of US rather than light to achieve better tissue penetration. SDT provides anticancer effects mainly via the sonosensitizer-mediated generation of reactive oxygen species (ROS), although the precise nature of the underpinning mechanism is still under debate. This work investigates the SDT anticancer activity of hypericin (Hyp) in vitro in two- (2D) and three-dimensional (3D) HT-29 colon cancer models, and uses PDT as a yardstick due to its well-known Hyp phototoxicity. The cancer cell uptake and cellular localization of Hyp were investigated first to determine the proper noncytotoxic concentration and incubation time of Hyp for SDT. Furthermore, ROS production, cell proliferation, and cell death were evaluated after Hyp was exposed to US. Since cancer relapse and transporter-mediated multidrug resistance (MDR) are important causes of cancer treatment failure, the US-mediated ability of Hyp to elicit immunogenic cell death (ICD) and overcome MDR was also investigated. SDT showed strong ROS-mediated anticancer activity 48 h after treatment in both the HT-29 models. Specific damage-associated molecular patterns that are consistent with ICD, such as calreticulin (CRT) exposure and high-mobility group box 1 protein (HMGB1) release, were observed after SDT with Hyp. Moreover, the expression of the ABC transporter, P-glycoprotein (P-gp), in HT-29/MDR cells was not able to hinder cancer cell responsiveness to SDT with Hyp. This work reveals, for the first time, the US responsiveness of Hyp with significant anticancer activity being displayed, making it a full-fledged sonosensitizer for the SDT of cancer.

Accumulation and penetration behavior of hypericin in glioma tumor spheroids studied by fluorescence microscopy and confocal fluorescence lifetime imaging microscopy

Glioblastoma WHO IV belongs to a group of brain tumors that are still incurable. A promising treatment approach applies photodynamic therapy (PDT) with hypericin as a photosensitizer. To generate a comprehensive understanding of the photosensitizer-tumor interactions, the first part of our study is focused on investigating the distribution and penetration behavior of hypericin in glioma cell spheroids by fluorescence microscopy. In the second part, fluorescence lifetime imaging microscopy (FLIM) was used to correlate fluorescence lifetime (FLT) changes of hypericin to environmental effects inside the spheroids. In this context, 3D tumor spheroids are an excellent model system since they consider 3D cell-cell interactions and the extracellular matrix is similar to tumors in vivo. Our analytical approach considers hypericin as probe molecule for FLIM and as photosensitizer for PDT at the same time, making it possible to directly draw conclusions of the state and location of the drug in a biological system. The knowledge of both state and location of hypericin makes a fundamental understanding of the impact of hypericin PDT in brain tumors possible. Following different incubation conditions, the hypericin distribution in peripheral and central cryosections of the spheroids were analyzed. Both fluorescence microscopy and FLIM revealed a hypericin gradient towards the spheroid core for short incubation periods or small concentrations. On the other hand, a homogeneous hypericin distribution is observed for long incubation times and high concentrations. Especially, the observed FLT change is crucial for the PDT efficiency, since the triplet yield, and hence the O₂ activation, is directly proportional to the FLT. Based on the FLT increase inside spheroids, an incubation time > 30 min is required to achieve most suitable conditions for an effective PDT.

Polyamine Metabolism in Leishmania Parasites: A Promising Therapeutic Target

Parasites of the genus Leishmania cause a variety of devastating and often fatal diseases in humans and domestic animals worldwide. The need for new therapeutic strategies is urgent because no vaccine is available, and treatment options are limited due to a lack of specificity and the emergence of drug resistance. Polyamines are metabolites that play a central role in rapidly proliferating cells, and recent studies have highlighted their critical nature in Leishmania. Numerous studies using a variety of inhibitors as well as gene deletion mutants have elucidated the pathway and routes of transport, revealing unique aspects of polyamine metabolism in Leishmania parasites. These studies have also shed light on the significance of polyamines for parasite proliferation, infectivity, and host-parasite interactions. This comprehensive review article focuses on the main polyamine biosynthetic enzymes: ornithine decarboxylase, S-adenosylmethionine decarboxylase, and spermidine synthase, and it emphasizes recent discoveries that advance these enzymes as potential therapeutic targets against Leishmania parasites.

Hypericin-mediated photodynamic therapy enhances gemcitabine induced Capan-2 cell apoptosis via inhibiting NADPH level

OBJECTIVES

The combination of gemcitabine (Gem) and hypericin (HY) enhances the apoptosis of Capan-2 cells, providing a promising option for the treatment of pancreatic cancer. Our study further explored the cytotoxic mechanism of HY combined with chemotherapy drugs on pancreatic cancer.

METHODS

The proliferation rate of the cells assayed with the MTT method. The ROS (reactive oxygen species) levels of each treatment were evaluated by DCFH-DA oxidisation methods. The activity of glutathione reductase and the levels of reduced glutathione (GSH) and oxidised glutathione (GSSG) were assessed using assay kits. The expression levels of apoptosis-related proteins were analysed by western blotting.

KEY FINDINGS

The activity of glucose-6-phosphate dehydrogenase (G6PDH), a key enzyme of the pentose phosphate pathway, significantly decreased in Gem + HY groups, however, the ROS level enhanced accompanying with GSH depleting, mitochondrial membrane depolarisation and cytochrome C release. Gem + HY inhibits the expression of Bcl-2 but stimulates Bax level, triggering caspase activation and PARP cleavage and thus promoted apoptosis of Capan-2 cells.

CONCLUSIONS

We demonstrated that Gem combined HY-PDT could inhibit the proliferation of Capan-2 cells and induce cell apoptosis. HY-PDT combined with Gem had a great potential on pancreatic cancer treatment clinically.

Some Natural Photosensitizers and Their Medicinal Properties for Use in Photodynamic Therapy

Despite significant advances in early diagnosis and treatment, cancer is one of the leading causes of death. Photodynamic therapy (PDT) is a therapy for the treatment of many diseases, including cancer. This therapy uses a combination of a photosensitizer (PS), light irradiation of appropriate length and molecular oxygen. The photodynamic effect kills cancer cells through apoptosis, necrosis, or autophagy of tumor cells. PDT is a promising approach for eliminating various cancers but is not yet as widely applied in therapy as conventional chemotherapy. Currently, natural compounds with photosensitizing properties are being discovered and identified. A reduced toxicity to healthy tissues and a lower incidence of side effects inspires scientists to seek natural PS for PDT. In this review, several groups of compounds with photoactive properties are presented. The use of natural products has been shown to be a fruitful approach in the discovery of novel pharmaceuticals. This review focused on the anticancer activity of furanocoumarins, polyacetylenes, thiophenes, tolyporphins, curcumins, alkaloid and anthraquinones in relation to the light-absorbing properties. Attention will be paid to their phototoxic and anti-cancer effects on various types of cancer.

Advances in Management of Bladder Cancer-The Role of Photodynamic Therapy

Photodynamic therapy (PDT) is a non-invasive and modern form of therapy. It is used in the treatment of non-oncological diseases and more and more often in the treatment of various types of neoplasms in various locations including bladder cancer. The PDT method consists of local or systemic application of a photosensitizer, i.e., a photosensitive compound that accumulates in pathological tissue. Light of appropriate wavelength is absorbed by the photosensitizer molecules, which in turn transfers energy to oxygen or initiates radical processes that leads to selective destruction of diseased cells. The technique enables the selective destruction of malignant cells, as the photocytotoxicity reactions induced by the photosensitizer take place strictly within the pathological tissue. PDT is known to be well tolerated in a clinical setting in patients. In cited papers herein no new safety issues were identified. The development of anti-cancer PDT therapies has greatly accelerated over the last decade. There was no evidence of increased or cumulative toxic effects with each PDT treatment. Many modifications have been made to enhance the effects. Clinically, bladder cancer remains one of the deadliest urological diseases of the urinary system. The subject of this review is the anti-cancer use of PDT, its benefits and possible modifications that may lead to more effective treatments for bladder cancer. Bladder cancer, if localized, would seem to be a good candidate for PDT therapy since this does not involve the toxicity of systemic chemotherapy and can spare normal tissues from damage if properly carried out. It is clear that PDT deserves more investment in clinical research, especially for plant-based photosensitizers. Natural PS isolated from plants and other biological sources can be considered a green approach to PDT in cancer therapy. Currently, PDT is widely used in the treatment of skin cancer, but numerous studies show the advantages of related therapeutic strategies that can help eliminate various types of cancer, including bladder cancer. PDT for bladder cancer in which photosensitizer is locally activated and generates cytotoxic reactive oxygen species and causing cell death, is a modern treatment. Moreover, PDT is an innovative technique in oncologic urology.

Monitoring tautomerization of single hypericin molecules in a tunable optical λ/2 microcavity

Hypericin tautomerization that involves the migration of the labile protons is believed to be the primary photophysical process relevant to its light-activated antiviral activity. Despite the difficulty in isolating individual tautomers, it can be directly observed in single-molecule experiments. We show that the tautomerization of single hypericin molecules in free space is observed as an abrupt flipping of the image pattern accompanied with fluorescence intensity fluctuations, which are not correlated with lifetime changes. Moreover, the study can be extended to a λ/2 Fabry-Pérot microcavity. The modification of the local photonic environment by a microcavity is well simulated with a theoretical model that shows good agreement with the experimental data. Inside a microcavity, the excited state lifetime and fluorescence intensity of single hypericin molecules are correlated, and a distinct jump of the lifetime and fluorescence intensity reveals the temporal behavior of the tautomerization with high sensitivity and high temporal resolution. The observed changes are also consistent with time-dependent density functional theory calculations. Our approach paves the way to monitor and even control reactions for a wider range of molecules at the single molecule level.

Photosensitizers Mediated Photodynamic Inactivation against Fungi

Superficial and systemic fungal infections are essential problems for the modern health care system. One of the challenges is the growing resistance of fungi to classic antifungals and the constantly increasing cost of therapy. These factors force the scientific world to intensify the search for alternative and more effective methods of treatment. This paper presents an overview of new fungal inactivation methods using Photodynamic Antimicrobial Chemotherapy (PACT). The results of research on compounds from the groups of phenothiazines, xanthanes, porphyrins, chlorins, porphyrazines, and phthalocyanines are presented. An intensive search for a photosensitizer with excellent properties is currently underway. The formulation based on the existing ones is also developed by combining them with nanoparticles and common antifungal therapy. Numerous studies indicate that fungi do not form any specific defense mechanism against PACT, which deems it a promising therapeutic alternative.

Hypericin-loaded oil-in-water nanoemulsion synthesized by ultrasonication process enhances photodynamic therapy efficiency

Hypericin (Hy) is a hydrophobic photosensitizer used in photodynamic therapy for cancer therapeutic. In this study, Hy-loaded oil-in-water (O/W) nanoemulsions (NEs) were produced by the ultrasonication method combing different biocompatible oils and surfactants to enhance Hy aqueous solubility and bioavailability. Experimental parameters were optimized by the characterization of droplet size, zeta potential, and physicochemical properties. In vitro studies based on the release profile, cytotoxicity, cell morphology, and Hy intracellular accumulation were assayed. Hy at 100 mg L^-1 was incorporated into the low viscosity (~0.005 Pa s) NEs with spherical droplets averaging 20-40 nm in size and polydispersity index <0.02. Hy release from the NE was significantly higher (4-fold) than its suspension (p < 0.001). The NEs demonstrated good physical stability during storage at 5 °C for at least six months. The Hy-loaded NEs exhibited an IC50 value 6-fold lower than Hy suspension during PDT against breast cancer cell lines (MCF-7). Cell microscopy imaging confirmed the increased cytotoxic effects of Hy-loaded NEs, showing damaged and apoptotic cells. Confocal laser scanning microscopy evidenced greater Hy delivery through NE into MCF-7 cells followed by improved intracellular ROS generation. Our results suggest that the Hy-loaded NEs can improve hypericin efficacy and assist Hy-PDT's preclinical development as a cancer treatment.

Hypericin Enhances Paclitaxel-Induced B16-F10 Cell Apoptosis by Activating a Cytochrome c Release-Dependent Pathway

The enhanced inhibitory effect of paclitaxel (PTX) combined with hypericin (HY) on B16-F10 cells may be realized through the ROS-related cytochrome c release pathway. The apoptotic characteristics of the B16-F10 cells, such as DNA fragmentation, chromatin condensation, and apoptotic body formation, were all enhanced in the combined treatment group. Further investigation showed that the combination of paclitaxel and HY could increase the level of mitochondrial damage and the concentration of cytochrome c, causing the expression of caspase-3 and the cleavage of PARP.¹. Compared with paclitaxel or HY alone, the level of reactive oxygen species (ROS) increased significantly, while glutathione reductase (GR) activity and intracellular glutathione (GSH) levels decreased significantly in the combination group.

Hypericin in photobiological assays: An overview

Hypericin is considered a potent photosensitizer for use in antitumor and antimicrobial photodynamic therapy (PDT). This review presents the primary biological results obtained with hypericin in photodynamic therapy applications, such as photodynamic cancer treatment, photoinactivation of microorganisms (PDI), tissue scarring, and photo diagnosis. We present a compilation of in vitro results that have been published thus far; for these studies, we highlight the hypericin concentration, light dose, and other experimental conditions to evaluate the efficiency of photodynamic treatment like cell death, cell viability, or cell proliferation. The results indicate that different hypericin phototoxicity levels can be observed according to the specific light dose and concentration. Furthermore, it was shown that cellular localization and cell death mechanisms (apoptosis and necrosis) are dependent on the cell type.

Non-Polymeric Nanogels as Versatile Nanocarriers: Intracellular Transport of the Photosensitizers Rose Bengal and Hypericin for Photodynamic Therapy

The use of nanocarriers for intracellular transport of actives has been extensively studied in recent years and represents a central area of nanomedicine. The main novelty of this paper lies on the use of nanogels formed by a low-molecular-weight gelator (1). Here, non-polymeric, molecular nanogels are successfully used for intracellular transport of two photodynamic therapy (PDT) agents, Rose Bengal (RB) and hypericin (HYP). The two photosensitizers (PSs) exhibit different drawbacks for their use in clinical applications. HYP is poorly water-soluble, while the cellular uptake of RB is hindered due to its dianionic character at physiological pH values. Additionally, both PSs tend to aggregate precluding an effective PDT. Despite the different nature of these PSs, nanogels from gelator 1 provide, in both cases, an efficient intracellular transport into human colon adenocarcinoma cells (HT-29) and a notably improved PDT efficiency, as assessed by confocal laser scanning microscopy and flow cytometry. Furthermore, no significant dark toxicity of the nanogels is observed, supporting the biocompatibility of the delivery system. The developed nanogels are highly reproducible due to their non-polymeric nature, and their synthesis is easily scaled up. The results presented here thus confirm the potential of molecular nanogels as valuable nanocarriers, capable of entrapping both hydrophobic and hydrophilic actives, for PDT of cancer.

An Alternating Irradiation Strategy-Driven Combination Therapy of PDT and RNAi for Highly Efficient Inhibition of Tumor Growth and Metastasis

Hypoxia and hypoxia induced overexpression of vascular endothelial growth factor (VEGF) not only seriously affects the treatment effects of photodynamic therapy (PDT) but also promotes tumor metastasis. Herein, an alternating irradiation strategy (referred to as alternate use of low/high dose of light [ALHDL] irradiation)-driven combination therapy of PDT and RNA interference (RNAi) is developed to synergistically inhibit tumor growth and metastasis. A cationic amphipathic peptide (ALS) served as a carrier in the co-delivery system of photochlor (HPPH) and siVEGF (ALSH/siVEGF). At the beginning of ALHDL-driven ALSH/siVEGF treatment, short-term LDL irradiation can facilitate the tumor penetration, cellular uptake, and endosome escape of ALSH/siVEGF. Moreover, accompanied by HDL-mediated rapid cell apoptosis and LDL-mediated efficient VEGF silencing, the joint use of PDT and RNAi achieved remarkable antitumor effects both in vitro and in vivo. Importantly, benefited from the excellent performance of ALHDL in slowing the rapid deterioration of the anoxic environment of tumors, and ALSH/siVEGF treatment-mediated highly improved VEGF silencing efficacy and inhibitory effect on angiogenesis, the liver and lung metastases of HeLa cells have been successfully suppressed. Together, this study clearly indicates that ALHDL-driven combination therapy of PDT and RNAi is a highly effective modality for inhibition of tumor growth and metastasis.

Photophysical characterization of Hypericin-loaded in micellar, liposomal and copolymer-lipid nanostructures based F127 and DPPC liposomes

Hypericin (Hy) compound presents a high photoactivity in photodynamic therapy (PDT), photodiagnosis and theranostics applications. The maintenance of this compound in monomeric form could undermine the potential benefits of its photophysical and photodynamic activity. In this study, we demonstrated that the Hy formulated in a system based on the use of the F127 copolymer and the 1,2-dipalmitoyl-sn-3-glycerol-phosphatidylcholine (DPPC) as micelles, liposomal vesicles and Copolymer-Lipid coated systems, have improved its photophysical properties for many clinical modalities. Based on the results of the triplet state lifetime values (τ_t), the singlet oxygen quantum yield (Φ_Δ¹O₂), the fluorescence lifetime (τ_F) and the fluorescence quantum yield (Φ_F), all Hy formulations had its photophysical properties described in different models of drug delivery systems (DDS). In addition, the transient spectra profile of those formulations was unaffected by the Hy incorporation process, except for the liposomal system, which demonstrated to be the less stable one by flash photolysis technique. The cytotoxic effects of those formulations were also investigated for CaCo-2 and HaCat cells line. The cytotoxic concentrations for 50% (CC₅₀) were 0.56, 1.05, 1.33 and 4.80 µmol L^-1 for Copolymer-Lipid/Hy, DPPC/Hy, F127/Hy and ethanol/Hy for CaCo-2 cells, respectively, and 0.69, 2.02, 1.45 and 1.16 µmol L^-1 for Copolymer-Lipid/Hy, DPPC/Hy, F127/Hy and ethanol/Hy for HaCat cells, respectively. The F127 copolymer had a significant role in many photophysical parameters determined for Copolymer-Lipid/Hy coated system. Although all those formulations had shown satisfactory results, Copolymer-Lipid/Hy proved to be superior in many aspects, being the most promising formulation for PDT, photodiagnosis and theranostics applications.

Whole-genome sequence data of Hypericum perforatum and functional characterization of melatonin biosynthesis by N-acetylserotonin O-methyltransferase

Hypericum perforatum is among the most commonly used herbal remedies and supplements. The aerial plant parts are often used to treat depression. Due to the lack of genomic information of H. perforatum, the gene networks regulating secondary metabolite synthesis remain unclear. Here, we present a high-quality genome for H. perforatum with a 2.3-Mb scaffold N50. The draft assembly covers 91.9% of the predicted genome and represents the fourth sequenced genus in the order Malpighiales. Comparing this sequence with model or related species revealed that Populus trichocarpa and Hevea brasiliensis could be grouped into one branch, while H. perforatum and Linum usitatissimum are grouped in another branch. Combined with transcriptome data, 40 key genes related to melatonin, hyperforin, and hypericin synthesis were screened and analyzed. Five N-acetylserotonin O-methyltransferases (HpASMT1-HpASMT5) were cloned and functionally characterized. Purified HpASMT3 protein converted N-acetylserotonin into melatonin with a V_max of about 1.35 pkat/mg protein. HpASMT1 and HpASMT3 overexpression in Arabidopsis mutants caused 1.5-2-fold higher melatonin content than in mutant and wild-type plants. The endogenous reactive oxygen species (ROS) in transgenic plants was significantly lower than ROS in mutant and wild-type plants, suggesting higher drought tolerance. The obtained genomic data offer new resources for further study on the evolution of Hypericaceae family, but also provide a basis for further study of melatonin biosynthetic pathways in other plants.

Viral Nanoparticle System: An Effective Platform for Photodynamic Therapy

Photodynamic therapy (PDT) is a promising therapy due to its efficiency and accuracy. The photosensitizer is delivered to the target lesion and locally activated. Viral nanoparticles (VNPs) have been explored as delivery vehicles for PDT in recent years because of their favorable properties, including simple manufacture and good safety profile. They have great potential as drug delivery carriers in medicine. Here, we review the development of PDT photosensitizers and discuss applications of VNP-mediated photodynamic therapies and the performance of VNPs in the treatment of tumor cells and antimicrobial therapy. Furthermore, future perspectives are discussed for further developing novel viral nanocarriers or improving existing viral vectors.

Direct Observation of Structural Heterogeneity and Tautomerization of Single Hypericin Molecules

Tautomerization is a fundamental chemical reaction which involves the relocation of a proton in the reactants. Studying the optical properties of tautomeric species is challenging because of ensemble averaging. Many molecules, such as porphines, porphycenes, or phenanthroperylene quinones, exhibit a reorientation of the transition dipole moment (TDM) during tautomerization, which can be directly observed in single-molecule experiments. Here, we study single hypericin molecules, which is a prominent phenanthroperylene quinone showing antiviral, antidepressive, and photodynamical properties. Observing abrupt flipping of the image pattern combined with time-dependent density functional theory calculations allows drawing conclusions about the coexistence of four tautomers and their conversion path. This approach allows the unambiguous assignment of a TDM orientation to a specific tautomer and enables the determination of the chemical structure in situ. Our approach can be applied to other molecules showing TDM reorientation during tautomerization, helping to gain a deeper understanding of this important process.

Enzymatic dimerization in the biosynthetic pathway of microbial natural products

Covering: up to August 2020The dramatic increase in the identification of dimeric natural products generated by microorganisms and plants has played a significant role in drug discovery. The biosynthetic pathways of these products feature inherent dimerization reactions, which are valuable for biosynthetic applications and chemical transformations. The extraordinary mechanisms of the dimerization of secondary metabolites should advance our understanding of the uncommon chemical rules for natural product biosynthesis, which will, in turn, accelerate the discovery of dimeric reactions and molecules in nature and provide promising strategies for the total synthesis of natural products through dimerization. This review focuses on the enzymes involved in the dimerization in the biosynthetic pathway of microbial natural products, with an emphasis on cytochrome P450s, laccases, and intermolecular [4 + 2] cyclases, along with other atypical enzymes. The identification, characterization, and catalytic landscapes of these enzymes are also introduced.

Hypericin-mediated photodynamic therapy for the treatment of cancer: a review

OBJECTIVES

Hypericin is a polycyclic aromatic naphthodianthrone that occurs naturally. It is also an active ingredient in some species of the genus Hypericum. Emerging evidence suggests that hypericin has attracted great attention as a potential anticancer drug and exhibits remarkable antiproliferative effect upon irradiation on various tumour cells. This paper aims to summarise the anticancer effect and molecular mechanisms modulated by hypericin-medicated photodynamic therapy and its potential role in the cancer treatment.

KEY FINDINGS

Hypericin-medicated photodynamic therapy could inhibit the proliferation of various tumour cells including bladder, colon, breast, cervical, glioma, leukaemia, hepatic, melanoma, lymphoma and lung cancers. The effect is primarily mediated by p38 mitogen-activated protein kinase (MAPK), JNK, PI3K, CCAAT-enhancer-binding protein homologous protein (CHOP)/TRIB3/Akt/mTOR, TRAIL/TRAIL-receptor, c-Met and Ephrin-Eph, the mitochondria and extrinsic signalling pathways. Furthermore, hypericin-medicated photodynamic therapy in conjunction with chemotherapeutic agents or targeted therapies is more effective in inhibiting the growth of tumour cells.

SUMMARY

During the past few decades, the anticancer properties of photoactivated hypericin have been extensively investigated. Hypericin-medicated photodynamic therapy can modulate a variety of proteins and genes and exhibit a great potential to be used as a therapeutic agent for various types of cancer.

Biophysical Characterization and Anticancer Activities of Photosensitive Phytoanthraquinones Represented by Hypericin and Its Model Compounds

Photosensitive compounds found in herbs have been reported in recent years as having a variety of interesting medicinal and biological activities. In this review, we focus on photosensitizers such as hypericin and its model compounds emodin, quinizarin, and danthron, which have antiviral, antifungal, antineoplastic, and antitumor effects. They can be utilized as potential agents in photodynamic therapy, especially in photodynamic therapy (PDT) for cancer. We aimed to give a comprehensive summary of the physical and chemical properties of these interesting molecules, emphasizing their mechanism of action in relation to their different interactions with biomacromolecules, specifically with DNA.

In silico studies evidenced the role of structurally diverse plant secondary metabolites in reducing SARS-CoV-2 pathogenesis

Plants are endowed with a large pool of structurally diverse small molecules known as secondary metabolites. The present study aims to virtually screen these plant secondary metabolites (PSM) for their possible anti-SARS-CoV-2 properties targeting four proteins/ enzymes which govern viral pathogenesis. Results of molecular docking with 4,704 ligands against four target proteins, and data analysis revealed a unique pattern of structurally similar PSM interacting with the target proteins. Among the top-ranked PSM which recorded lower binding energy (BE), > 50% were triterpenoids which interacted strongly with viral spike protein-receptor binding domain, > 32% molecules which showed better interaction with the active site of human transmembrane serine protease were belongs to flavonoids and their glycosides, > 16% of flavonol glycosides and > 16% anthocyanidins recorded lower BE against active site of viral main protease and > 13% flavonol glycoside strongly interacted with active site of viral RNA-dependent RNA polymerase. The primary concern about these PSM is their bioavailability. However, several PSM recorded higher bioavailability score and found fulfilling most of the drug-likeness characters as per Lipinski's rule (Coagulin K, Kamalachalcone C, Ginkgetin, Isoginkgetin, 3,3'-Biplumbagin, Chrysophanein, Aromoline, etc.). Natural occurrence, bio-transformation, bioavailability of selected PSM and their interaction with the target site of selected proteins were discussed in detail. Present study provides a platform for researchers to explore the possible use of selected PSM to prevent/ cure the COVID-19 by subjecting them for thorough in vitro and in vivo evaluation for the capabilities to interfering with the process of viral host cell recognition, entry and replication.

St. John's Wort Suppresses Growth in Triple-Negative Breast Cancer Cell Line MDA-MB-231 by Inducing Prodeath Autophagy and Apoptosis

The rational regulation of programmed cell death by means of autophagy and apoptosis has been considered a potential treatment strategy for cancer. We demonstrated the inhibitory effect of St. John’s Wort (SJW) on growth in the triple-negative breast cancer (TNBC) cell line and xenografted mice and its target mechanism concerning autophagic and apoptotic cell death. SJW ethanol extract (SJWE) inhibited proliferation in a dose-dependent manner. SJWE treatment dramatically increased autophagy flux and apoptosis compared with the control. The autophagy inhibitor, 3-methyladenine (3-MA), reversed the SJWE-induced inhibition of cell proliferation and regulation of autophagy and apoptosis, indicating that SJWE induced apoptosis through prodeath autophagy. Furthermore, SJWE inhibited tumor growth and induced autophagy and apoptosis in the tumor of MDA-MB-231 xenografted athymic nude mice. Our results indicate that SJWE might have great potential as a new anticancer therapy for triple-negative breast cancer by inducing prodeath autophagy and apoptosis.

The Biochemical and Genetic Basis for the Biosynthesis of Bioactive Compounds in Hypericum Perforatum L., One of the Largest Medicinal Crops in Europe

Hypericum perforatum L. commonly known as Saint John's Wort (SJW), is an important medicinal plant that has been used for more than 2000 years. Although H. perforatum produces several bioactive compounds, its importance is mainly linked to two molecules highly relevant for the pharmaceutical industry: the prenylated phloroglucinol hyperforin and the naphtodianthrone hypericin. The first functions as a natural antidepressant while the second is regarded as a powerful anticancer drug and as a useful compound for the treatment of Alzheimer's disease. While the antidepressant activity of SJW extracts motivate a multi-billion dollar industry around the world, the scientific interest centers around the biosynthetic pathways of hyperforin and hypericin and their medical applications. Here, we focus on what is known about these processes and evaluate the possibilities of combining state of the art omics, genome editing, and synthetic biology to unlock applications that would be of great value for the pharmaceutical and medical industries.

Hypericin, a medicinal compound from St. John's Wort, inhibits genotoxicity induced by mutagenic agents in V79 cells

This study evaluated the cytotoxic, genotoxic, and the modulatory effects on DNA damage of hypericin in Chinese hamster lung fibroblasts (V79 cells). The hypericin is a natural polycyclic quinone, mainly extracted from St. John's Wort (Hypericum perforatum L.). Along with hyperforin, the hypericins are responsible for the antidepressant activity of St. John's Wort. Cytotoxicity was assessed by the XTT colorimetric assay and the nuclear division index (NDI). The genotoxic activity was studied by the micronucleus test at concentrations of 30, 60, 120, and 240 μg/mL. Mutagenic agents, methyl methanesulfonate (MMS, 44 μg/mL), doxorubicin (DXR, 0.5 μg/mL), and etoposide (VP16, 1 μg/mL) were used in combination with different concentrations of hypericin in order to evaluate the modulatory effect on DNA damage. Results showed that the hypericin was cytotoxic at concentrations above 156.2 μg/mL and genotoxic above 120 μg/mL. The hypericin significantly reduced DNA damage frequency induced by DXR, at concentrations of 30 and 60 μg/mL, and MMS at a concentration of 30 μg/mL, but was unable to reduce damage when combined with VP-16. These results demonstrate the non-photoactivated hypericin toxicological safety limits, its protective effect on DNA damage and provide a basis for future studies that may characterize better its chemopreventive mechanism.

Photoluminescent oxygen-release microspheres to image the oxygen release process in vivo

Cell therapy is a promising strategy to treat ischemic diseases, but the efficacy is limited due to high rate of cell death under low oxygen environment of the ischemic tissues. Sustained release of oxygen to continuously oxygenate the transplanted cells may augment cell survival and improve therapeutic efficacy. We have shown previously that oxygen released from oxygen-release microspheres stimulated cell survival in ischemic tissue [1]. To understand how oxygen is released in vivo and duration of release, it is attractive to image the process of oxygen release. Herein, we have developed photoluminenscent oxygen-release microspheres where the in vivo oxygen release can be non-invasively and real-time monitored by an In Vivo Imaging System (IVIS). In the oxygen-release microspheres, a complex of polyvinylpyrrolidone, H₂O₂ and a fluorescent drug hypericin (HYP) was used as core, and poly(N-isopropylacrylamide-co-acrylate-oligolactide-co-hydroxyethyl methacrylate-co-N-acryloxysuccinimide) conjugated with catalase was used as shell. To distinguish fluorescent signal change for different oxygen release kinetics, the microspheres with various release profiles were developed by using the shell with different degradation rates. In vitro, the fluorescent intensity gradually decreased during the 21-day oxygen release period, consistent with oxygen release kinetics. The released oxygen significantly augmented mesenchymal stem cell (MSC) survival under hypoxic condition. In vivo, the oxygen release rate was faster. The fluorescent signal can be detected for 17 days for the microspheres with the slowest oxygen release kinetics. The implanted microspheres did not induce substantial inflammation. The above results demonstrate that the developed microspheres have potential to monitor the in vivo oxygen release.

Selective photodynamic effects on cervical cancer cells provided by P123 Pluronic®-based nanoparticles modulating hypericin delivery

At present, cervical cancer is the fourth leading cause of cancer among women worldwide with no effective treatment options. In this study we aimed to evaluate the efficacy of hypericin (HYP) encapsulated on Pluronic® P123 (HYP/P123) photodynamic therapy (PDT) in a comprehensive panel of human cervical cancer-derived cell lines, including HeLa (HPV 18-positive), SiHa (HPV 16-positive), CaSki (HPV 16 and 18-positive), and C33A (HPV-negative), compared to a nontumorigenic human epithelial cell line (HaCaT). Were investigated: (i) cell cytotoxicity and phototoxicity, cellular uptake and subcellular distribution; (ii) cell death pathway and cellular oxidative stress; (iii) migration and invasion. Our results showed that HYP/P123 micelles had effective and selective time- and dose-dependent phototoxic effects on cervical cancer cells but not in HaCaT. Moreover, HYP/P123 micelles accumulated in endoplasmic reticulum, mitochondria and lysosomes, resulting in photodynamic cell death mainly by necrosis. HYP/P123 induced cellular oxidative stress mainly via type II mechanism of PDT and inhibited cancer cell migration and invasion mainly via MMP-2 inhibition. Taken together, our results indicate a potentially useful role of HYP/P123 micelles as a platform for HYP delivery to more specifically and effectively treat cervical cancers through PDT, suggesting they are worthy for in vivo preclinical evaluations.

Hypericin photodynamic activity in DPPC liposomes - part II: stability and application in melanoma B16-F10 cancer cells

Hypericin (Hyp) is considered a promising photosensitizer for Photodynamic Therapy (PDT), due to its high hydrophobicity, affinity for cell membranes, low toxicity and high photooxidation activity. In this study, Hyp photophysical properties and photodynamic activity against melanoma B16-F10 cells were optimized using DPPC liposomes (1,2-dipalmitoyl-sn-glycero-3-phosphocholine) as a drug delivery system. This nanoparticle is used as a cell membrane biomimetic model and solubilizes hydrophobic drugs. Hyp oxygen singlet lifetime (τ) in DPPC was approximately two-fold larger than that in P-123 micelles (Pluronic™ surfactants), reflecting a more hydrophobic environment provided by the DPPC liposome. On the other hand, singlet oxygen quantum yield values (Φ_Δ¹O₂) in DPPC and P-123 were similar; Hyp molecules were preserved as monomers. The Hyp/DPPC liposome aqueous dispersion was stable during fluorescence emission and the liposome diameter remained stable for at least five days at 30 °C. However, the liposomes collapsed after the lyophilization/rehydration process, which was resolved by adding the lyoprotectant Trehalose to the liposome dispersion before lyophilization. Cell viability of the Hyp/DPPC formulation was assessed against healthy HaCat cells and high-metastatic melanoma B16-F10 cells. Hyp incorporated into the DPPC carrier presented a higher selectivity index than the Hyp sample previously solubilized in ethanol under the illumination effect. Moreover, the IC₅₀ was lower for Hyp in DPPC than for Hyp pre-solubilized in ethanol. These results indicate the potential of the formulation of Hyp/DPPC for future biomedical applications in PDT treatment.

Hypericin: Single Molecule Spectroscopy of an Active Natural Drug

Hypericin is one of the most efficient photosensitizers used in photodynamic tumor therapy (PDT). The reported treatments of this drug reach from antidepressive, antineoplastic, antitumor and antiviral activity. We show that hypericin can be optically detected down to a single molecule at ambient conditions. Hypericin can even be observed inside of a cancer cell, which implies that this drug can be directly used for advanced microscopy techniques (PALM, spt-PALM, or FLIM). Its photostability is large enough to obtain single molecule fluorescence, surface enhanced Raman spectra (SERS), fluorescence lifetime, antibunching, and blinking dynamics. Sudden spectral changes can be associated with a reorientation of the molecule on the particle surface. These properties of hypericin are very sensitive to the local environment. Comparison of DFT calculations with SERS spectra show that both the neutral and deprotonated form of hypericin can be observed on the single molecule and ensemble level.

Selective Killing of Activated T Cells by 5-Aminolevulinic Acid Mediated Photodynamic Effect: Potential Improvement of Extracorporeal Photopheresis

Extracorporeal photopheresis (ECP), a modality that exposes isolated leukocytes to the photosensitizer 8-methoxypsoralen (8-MOP) and ultraviolet-A (UV-A) light, is used to treat conditions such as cutaneous T-cell lymphoma and graft-versus-host disease. However, the current procedure of ECP has limited selectivity and efficiency; and produces only partial response in the majority of treated patients. Additionally, the treatment is expensive and time-consuming, so the improvement for this modality is needed. In this study, we used the concept of photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA), a precursor of an endogenously synthesized photosensitizer protoporphyrin IX (PpIX) in combination with blue light to explore the possibility of targeting activated human blood T cells ex vivo. With various T-cell activation protocols, a high ALA-induced PpIX production took place in activated CD3⁺, CD4⁺CD25⁺, and CD8⁺ T cell populations with their subsequent killing after blue light exposure. By contrast, resting T cells were much less damaged by the treatment. The selective and effective killing effect on the activated cells was also seen after co-cultivating activated and resting T cells. Under our clinically relevant experimental conditions, ALA-PDT killed activated T cells more selectively and efficiently than 8-MOP/UV-A. Monocyte-derived dendritic cells (DCs) were not affected by the treatment. Incubation of ALA-PDT damaged T cells with autologous DCs induced a downregulation of the co-stimulatory molecules CD80/CD86 and also upregulation of interleukin 10 (IL-10) and indoleamine 2,3-dioxygenase expression, two immunosuppressive factors that may account for the generation of tolerogenic DCs. Overall, the data support the potential use of ALA-PDT strategy for improving ECP by selective and effective killing of activated T cells and induction of immune tolerance.

miR-7112-3p targets PERK to regulate the endoplasmic reticulum stress pathway and apoptosis induced by photodynamic therapy in colorectal cancer CX-1 cells

BACKGROUND

Colorectal cancer (CRC) is the third most common malignant tumor worldwide. Photodynamic therapy (PDT) is an emerging modality for the treatment of solid tumors. Sinoporphyrin sodium (DVDMS) is a new photosensitizer with good therapeutic killing effects on cancer cells. Recent findings have shown that microRNAs play important roles in many biological processes. However, the functions of microRNAs in DVDMS-induced PDT remain largely unclear.

MATERIALS AND METHODS

Proteins involved in endoplasmic reticulum (ER) stress and apoptosis of CX-1 cells treated with DVDMS-PDT were examined by Western blotting and cell viability assays. 15 candidate miRNAs targeting RNA-dependent protein kinase-like ER kinase (PERK) were screened and verified using the TargetScan, miRWalk and miRDB databases. The downstream pathways of candidate miRNAs with high scores were studied by cell transfection, qRT-PCR, Western blotting and dual-luciferase reporter assays. The subcellular location of DVDMS was confirmed by laser confocal microscopy.

RESULTS

DVDMS-PDT induced apoptosis via elevated ER stress and activation of the PERK/ATF4/CHOP/caspase cascade pathway in CX-1 cells. The endoplasmic reticulum was involved in the subcellular accumulation of DVDMS in CX-1 cells. Dual-luciferase reporting experiment confirmed that a direct crosslinking between miR-7112-3p and PERK. In addition, miR-7112-3p was highly expressed in CRC tissues compared with peripheral tissues.

CONCLUSION

Our work showed that miR-7112-3p directly targeted PERK and further regulated PERK/ATF4/CHOP/caspase cascade pathway, resulting in enhanced apoptosis in CX-1 cells treated with DVDMS-PDT.

Photochemical Internalization: Light Paves Way for New Cancer Chemotherapies and Vaccines

Photochemical internalization (PCI) is a further development of photodynamic therapy (PDT). In this report, we describe PCI as a potential tool for cellular internalization of chemotherapeutic agents or antigens and systematically review the ongoing research. Eighteen published papers described the pre-clinical and clinical developments of PCI-mediated delivery of chemotherapeutic agents or antigens. The studies were screened against pre-defined eligibility criteria. Pre-clinical studies suggest that PCI can be effectively used to deliver chemotherapeutic agents to the cytosol of tumor cells and, thereby, improve treatment efficacy. One Phase-I clinical trial has been conducted, and it demonstrated that PCI-mediated bleomycin treatment was safe and identified tolerable doses of the photosensitizer disulfonated tetraphenyl chlorin (TPCS_2a). Likewise, PCI was pre-clinically shown to mediate major histocompatibility complex (MHC) class I antigen presentation and generation of tumor-specific cytotoxic CD8+ T-lymphocytes (CTL) and cancer remission. A first clinical Phase I trial with the photosensitizer TPCS_2a combined with human papilloma virus antigen (HPV) was recently completed and results are expected in 2020. Hence, photosensitizers and light can be used to mediate cytosolic delivery of endocytosed chemotherapeutics or antigens. While the therapeutic potential in cancer has been clearly demonstrated pre-clinically, further clinical trials are needed to reveal the true translational potential of PCI in humans.

Photodynamic action of Hypericum perforatum hydrophilic extract against Staphylococcus aureus

Hypericin (Hyp) is one of the most effective, naturally occurring photodynamic agents, which proved effective against a wide array of microorganisms.

Phyotochemical candidates repurposing for cancer therapy and their molecular mechanisms

Though limited success through chemotherapy, radiotherapy and surgery has been obtained for efficient cancer therapy for modern decades, cancers are still considered high burden to human health worldwide to date. Recently repurposing drugs are attractive with lower cost and shorter time compared to classical drug discovery, just as Metformin from Galega officinalis, originally approved for treating Type 2 diabetes by FDA, is globally valued at millions of US dollars for cancer therapy. As most previous reviews focused on FDA approved drugs and synthetic agents, current review discussed the anticancer potential of phytochemicals originally approved for treatment of cardiovascular diseases, diabetes, infectious diarrhea, depression and malaria with their molecular mechanisms and efficacies and suggested future research perspectives.

Nanosecond Pulsed Electric Fields Induce Endoplasmic Reticulum Stress Accompanied by Immunogenic Cell Death in Murine Models of Lymphoma and Colorectal Cancer

Depending on the initiating stimulus, cancer cell death can be immunogenic or non-immunogenic. Inducers of immunogenic cell death (ICD) rely on endoplasmic reticulum (ER) stress for the trafficking of danger signals such as calreticulin (CRT) and ATP. We found that nanosecond pulsed electric fields (nsPEF), an emerging new modality for tumor ablation, cause the activation of the ER-resident stress sensor PERK in both CT-26 colon carcinoma and EL-4 lymphoma cells. PERK activation correlates with sustained CRT exposure on the cell plasma membrane and apoptosis induction in both nsPEF-treated cell lines. Our results show that, in CT-26 cells, the activity of caspase-3/7 was increased fourteen-fold as compared with four-fold in EL-4 cells. Moreover, while nsPEF treatments induced the release of the ICD hallmark HMGB1 in both cell lines, extracellular ATP was detected only in CT-26. Finally, in vaccination assays, CT-26 cells treated with nsPEF or doxorubicin equally impaired the growth of tumors at challenge sites eliciting a protective anticancer immune response in 78% and 80% of the animals, respectively. As compared to CT-26, both nsPEF- and mitoxantrone-treated EL-4 cells had a less pronounced effect and protected 50% and 20% of the animals, respectively. These results support our conclusion that nsPEF induce ER stress, accompanied by bona fide ICD.

Discovery of key regulators of dark gland development and hypericin biosynthesis in St. John's Wort (Hypericum perforatum)

Hypericin is a molecule of high pharmaceutical importance that is synthesized and stored in dark glands (DGs) of St. John's Wort (Hypericum perforatum). Understanding which genes are involved in dark gland development and hypericin biosynthesis is important for the development of new Hypericum extracts that are highly demanded for medical applications. We identified two transcription factors whose expression is strictly synchronized with the differentiation of DGs. We correlated the content of hypericin, pseudohypericin, endocrocin, skyrin glycosides and several flavonoids with gene expression and DG development to obtain a revised model for hypericin biosynthesis. Here, we report for the first time genotypes which are polymorphic for the presence/total absence (G+/G-) of DGs in their placental tissues (PTs). DG development was characterized in PTs using several microscopy techniques. Fourier transform infrared microscopy was established as a novel method to precisely locate polyaromatic compounds, such as hypericin, in plant tissues. In addition, we obtained transcriptome and metabolome profiles of unprecedented resolution in Hypericum. This study addresses for the first time the development of dark glands and identifies genes that constitute strong building blocks for the further elucidation of hypericin synthesis, its manipulation in plants, its engineering in microbial systems and its applications in medical research.