Inhibitory effect of aloe emodin mediated photodynamic therapy on human oral mucosa carcinoma in vitro and in vivo

Nanomaterials-based advanced systems for photothermal / photodynamic therapy of oral cancer

The traditional clinical approaches for oral cancer consist of surgery, chemotherapy, radiotherapy, immunotherapy, and so on. However, these treatments often induce side effects and exhibit limited efficacy. Photothermal therapy (PTT) emerges as a promising adjuvant treatment, utilizing photothermal agents (PTAs) to convert light energy into heat for tumor ablation. Another innovative approach, photodynamic therapy (PDT), leverages photosensitizers (PSs) and specific wavelength laser irradiation to generate reactive oxygen species (ROS), offering an effective and non-toxic alternative. The relevant combination therapies have been reported in the field of oral cancer. Simultaneously, the advancement of nanomaterials has propelled the clinical application of PTT and PDT. Therefore, a comprehensive understanding of PTT and PDT is required for better application in oral cancer treatment. Here, we review the use of PTT and PDT in oral cancer, including noble metal materials (e.g., Au nanoparticles), carbon materials (e.g., graphene oxide), organic dye molecules (e.g., indocyanine green), organic molecule-based agents (e.g., porphyrin-analog phthalocyanine) and other inorganic materials (e.g., MXenes), exemplify the advantages and disadvantages of common PTAs and PSs, and summarize the combination therapies of PTT with PDT, PTT/PDT with chemotherapy, PTT with radiotherapy, PTT/PDT with immunotherapy, and PTT/PDT with gene therapy in the treatment of oral cancer. The challenges related to the PTT/PDT combination therapy and potential solutions are also discussed.

Hydrazyl hydroxycoumarins as new potential conquerors towards Pseudomonas aeruginosa

A class of unique hydrazyl hydroxycoumarins (HHs) as novel structural scaffold was developed to combat dreadful bacterial infections. Some HHs could effectively suppress bacterial growth at low concentrations, especially, pyridyl HH 7 exhibited a good inhibition against Pseudomonas aeruginosa 27853 with a low MIC value of 0.5 μg/mL, which was 8-fold more active than norfloxacin. Furthermore, pyridyl HH 7 with low hemolytic activity and low cytotoxicity towards NCM460 cells showed much lower trend to induce the drug-resistant development than norfloxacin. Preliminarily mechanism exploration indicated that pyridyl HH 7 could eradicate the integrity of bacterial membrane, result in the leakage of intracellular proteins, and interact with bacterial DNA gyrase via non-covalent binding, and ADME analysis manifested that compound 7 gave good pharmacokinetic properties. These results suggested that the newly developed hydrazyl hydroxycoumarins as potential multitargeting antibacterial agents should be worthy of further investigation for combating bacterial infection.

The effects of antimicrobial photocatalytic nanoparticles on the flexural strength of orthodontic acrylic resins: A systematic review and meta-analysis

BACKGROUND/PURPOSE

Orthodontic acrylic resins containing antimicrobial photocatalytic nanoparticles aims to reduce oral lesions including denture stomatitis and white spot lesions but they should not imperil its mechanical properties. This systematic review was done to evaluate the effect of various photocatalytic nanoparticles on the flexural strength (FS) of acrylic resins.

MATERIALS AND METHODS

We systematically searched the PubMed/Medline, Cochrane Library, and Scopus databases from January 2018 to October 2023. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and the quality of the studies was evaluated using the QUIN tool, which is specifically designed to assess the risk of bias in vitro studies.

RESULTS

Following screening of 1016 initial records, 23 studies were deemed eligible for inclusion. The addition of photocatalytic nanoparticles, such as emodin (Emo), curcumin (Cur), Cur nisin (CurNis), zeolite/zinc oxide (Zeo/ZnO), and Ulva lactuca (U. lactuca), to acrylic resins resulted in a reduction in FS, with the extent of reduction dependent on the nanoparticle concentration. Specifically, the addition of Emo (≥0.5 %), Cur (≥0.5 %), CurNis (≥5 %), Zeo/ZnO (≥2), and U. lactuca (≥1 %) to acrylic resins significantly decreased FS. Conversely, the inclusion of ZnO and titanium dioxide (TiO2) in acrylic resins improved FS, but higher concentrations (≥5 % for TiO2) had a limited positive effect.

CONCLUSION

Our study supports the use of low concentrations of photocatalytic nanoparticles, such as ZnO (≤2 %), TiO2 (≤3 %), Emo (≤0.5 %), Cur (≤0.5 %), CurNis (≤5 %), and U. lactuca (≤1 %), in orthodontic acrylic resins without compromising FS.

Molecular Nanoarchitectonics of Natural Photosensitizers and Their Derivatives Nanostructures for Improved Photodynamic Therapy

Natural photosensitizers (PSs) and their derivatives have drawn ever-increasing attention in photodynamic therapy (PDT) for their wild range of sources, desirable biocompatibility, and good photosensitivity. Nevertheless, many factors such as poor solubility, high body clearance rate, limited tumor targeting ability, and short excitation wavelengths severely hinder their applications in efficient PDT. In recent years, fabricating nanostructures by utilizing molecular assembly technique is proposed to solve these problems. This technique is easy to put into effect, and the assembled nanostructures could improve the physical properties of the PSs so as to meet the requirement of PDT. In this concept, we focus on the construction of natural PSs and their derivatives nanostructures through molecular assembly technique to enhance PDT efficacy (Figure 1). Furthermore, current challenges and future perspectives of natural PSs and their derivatives for efficient PDT are discussed.

Nano-emodin mediated photodynamic therapy for wound healing of donor site after free gingival graft: A parallel clinical trial

AIM

This study aimed to evaluate the effectiveness of nano-emodin (n-Emo) mediated photodynamic therapy (PDT) as an adjunctive therapy to conventional wound care in patients undergoing free gingival graft (FGG) treatment. The study employed a single-center, parallel, two-blind, randomized, controlled trial design.

METHOD AND MATERIAL

A total of 53 patients requiring FGG treatment were randomly assigned to one of three groups: the n-Emo mediated PDT group, the n-Emo gel group, and the control group. The n-Emo mediated PDT group received n-Emo gel on donor site followed by LED (450 nm, 1000 ± 1400 mW/cm2, 60-80 J/cm2, 60 s), the n-Emo gel group received only n-Emo gel on donor site, and the control group received a placebo gel on donor site. All groups received treatment immediately and 48 h after FGG surgery. Wound healing was assessed based on wound area, bleeding, color match, and epithelialization. Postoperative pain perception was evaluated using a Visual Analogue Scale (VAS), and the number of non-steroidal anti-inflammatory drug (NSAID) intakes was recorded.

RESULTS

The results showed that all groups demonstrated significant improvement in wound healing by day 28, with the n-Emo mediated PDT exhibiting significantly better healing on the 14th, 21st, and 28th day compared to the control group. Additionally, on the 28th day, the n-Emo mediated PDT showed significantly better healing than the n-Emo gel group. The n-Emo mediated PDT also had significantly lower pain scores than the control group. There were no significant differences in the number of NSAID intakes, bleeding, or color match among the groups, but all groups showed improved color match during follow-up. By the third week, all groups had fully epithelialized without significant differences, and no secondary bleeding incidents were reported.

CONCLUSION

The study concludes that n-Emo mediated PDT is an effective adjunctive therapy to conventional wound care for managing complication after surgery at donor site after FGG surgery.

Antimicrobial efficacy of aloe-emodin mediated photodynamic therapy against antibiotic-resistant Pseudomonas aeruginosa in vitro

Multidrug-resistant Pseudomonas aeruginosa is a common pathogen that causes topical infections following burn injuries. Antimicrobial photodynamic therapy (aPDT) has emerged as a promising approach for treating antibiotic-resistant bacterial infections. The objective of this study was to evaluate the aPDT efficacy of aloe-emodin (AE), which is a photosensitizer extracted from traditional Chinese herbs, on antibiotic-sensitive and antibiotic-resistant P. aeruginosa in vitro. In this study, we confirmed the effectiveness of AE-mediated aPDT against both standard and MDR P. aeruginosa, explored the effects of irradiation time and AE concentration on bacterial survival in AE-mediated aPDT, and observed the structural damage of P. aeruginosa by using transmission electron microscope. Our results showed that neither AE nor light irradiation alone caused cytotoxic effects on P. aeruginosa. However, AE-mediated aPDT effectively inactivated both antibiotic-sensitive and antibiotic-resistant P. aeruginosa. The transmission electron microscope investigation showed that aPDT mediated by AE primarily caused damage to the cytoplasm and cell membrane. Our findings suggest that AE is a photosensitizer in the aPDT of MDR P. aeruginosa-caused topical infections following burn injuries. Future investigations will concentrate on the safety and efficacy of AE-mediated aPDT in animal models and clinical trials.

A promising natural anthraquinones mediated by photodynamic therapy for anti-cancer therapy

BACKGROUND

Experimental studies emphasize the therapeutic potential of plant-derived photosensitizers used in photodynamic therapy. Moreover, several in vitro and in vivo research present the promising roles of less-known anthraquinones that can selectively target cancer cells and eliminate them after light irradiation. This literature review summarizes the current knowledge of chosen plant-based-photosensitizers in PDT to show the results of emodin, aloe-emodin, parietin, rubiadin, hypericin, and soranjidiol in photodynamic therapy of cancer treatment and describe the comprehensive perspective of their role as natural photosensitizers.

METHODS

Literature searches of chosen anthraquinones were conducted on PubMed.gov with keywords: "emodin", "aloe-emodin", "hypericin", "parietin", "rubiadin", "soranjidiol" with "cancer" and "photodynamic therapy".

RESULTS

According to literature data, this review concentrated on all existing in vitro and in vivo studies of emodin, aloe-emodin, parietin, rubiadin, soranjidiol used as natural photosensitizers emphasizing their effectiveness and detailed mechanism of action in anticancer therapy. Moreover, comprehensive preclinical and clinical studies on hypericin reveal that the above-described substances may be included in the phototoxic treatment of different cancers.

CONCLUSIONS

Overall, this review presented less-known anthraquinones with their promising molecular mechanisms of action. It is expected that in the future they may be used as natural PSs in cancer treatment as well as hypericin.

Aloe-Emodin Derivative, an Anthraquinone Compound, Attenuates Pyroptosis by Targeting NLRP3 Inflammasome in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is widely recognized as a major contributing factor to the development of heart failure in patients with diabetes. Previous studies have demonstrated the potential benefits of traditional herbal medicine for alleviating the symptoms of cardiomyopathy. We have chemically designed and synthesized a novel compound called aloe-emodin derivative (AED), which belongs to the aloe-emodin (AE) family of compounds. AED was formed by covalent binding of monomethyl succinate to the anthraquinone mother nucleus of AE using chemical synthesis techniques. The purpose of this study was to investigate the effects and mechanisms of AED in treating DCM. We induced type 2 diabetes in Sprague-Dawley (SD) rats by administering a high-fat diet and streptozotocin (STZ) injections. The rats were randomly divided into six groups: control, DCM, AED low concentration (50 mg/kg/day), AED high concentration (100 mg/kg/day), AE (100 mg/kg/day), and positive control (glyburide, 2 mg/kg/day) groups. There were eight rats in each group. The rats that attained fasting blood glucose of ˃16.7 mmol/L were considered successful models. We observed significant improvements in cardiac function in the DCM rats with both AED and AE following four weeks of intragastric treatment. However, AED had a more pronounced therapeutic effect on DCM compared to AE. AED exhibited an inhibitory effect on the inflammatory response in the hearts of DCM rats and high-glucose-treated H9C2 cells by suppressing the pyroptosis pathway mediated by the nucleotide-binding oligomerization domain (NOD)-like receptor pyrin domain 3 (NLRP3) inflammasome. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis of differentially expressed genes showed a significant enrichment in the NOD-like receptor signaling pathway compared to the high-glucose group. Furthermore, overexpression of NLRP3 effectively reversed the anti-pyroptosis effects of AED in high-glucose-treated H9C2 cells. This study is the first to demonstrate that AED possesses the ability to inhibit myocardial pyroptosis in DCM. Targeting the pyroptosis pathway mediated by the NLRP3 inflammasome could provide a promising therapeutic strategy to enhance our understanding and treatment of DCM.

The Comparison of the Efficiency of Emodin and Aloe-Emodin in Photodynamic Therapy

Skin cancer (melanoma and non-melanoma) is the most frequent type of malignancy in the Caucasian population. Photodynamic therapy (PDT) as an interesting and unique strategy may potentially boost standard therapeutic approaches. In the present study, the potential of emodin and aloe-emodin as photosensitizers in photodynamic therapy has been investigated. The conducted research presents for the first-time comparison of the phototoxic and anti-cancerous effects of emodin and aloe-emodin on skin cancer cell lines, including SCC-25 representing cutaneous squamous cell carcinoma, MUG-Mel2 representing a melanoma cell line, and normal human keratinocytes HaCaT representing control normal skin cells. To assess the effectiveness of emodin and aloe-emodin as a photosensitizer in PDT on different skin cell lines, we performed MTT assay measuring cytotoxicity of natural compounds, cellular uptake, apoptosis with flow cytometry, and a wound-healing assay. Although emodin and aloe-emodin are isomers and differ only in the position of one hydroxyl group, our phototoxicity and apoptosis detection results show that both substances affect skin cancer cells (SSC-25 squamous cell carcinoma and MUG-Mel2 melanoma) and normal keratinocytes (HaCaT cell line) in other ways. In conclusion, our study provides evidence suggesting that emodin and aloe-emodin mediated PDT exhibits the potential for clinical development as a new effective and safe photosensitizer to treat skin cancer.

Natural aloe emodin-hybridized sulfonamide aminophosphates as novel potential membrane-perturbing and DNA-intercalating agents against Enterococcus faecalis

The dramatic rise in drug resistance accelerated the desire for new antibacterial agents to safeguard human health. This work constructed a novel type of aloe emodin-hybridized sulfonamide aminophosphates as unique potential antibacterial agents. The biological assay revealed that some target hybrids possessed potent inhibitory activity. Particularly, ethyl aminophosphate-hybridized sulfadiazine aloe emodin 7a (EASA-7a) not only displayed preponderant antibacterial efficiency against drug-resistant E. faecalis at low concentration as 0.25 μg/mL but also possessed strong bacteriostatic capacity and low propensity to develop resistance toward E. faecalis. The weak hemolysis toward human red blood cells and efficient biofilm-disruptive ability further implied the therapeutic potential of EASA-7a. Preliminary studies disclosed that the excellent antibacterial behavior of EASA-7a might be attributed to its capacity to permeate and depolarize the bacterial membrane, as well as promote ROS accumulation and intercalate with DNA. These findings manifested that EASA-7a was worthy of further development to combat life-threatening bacterial infections.

pH-responsive and CD44-targeting polymer micelles based on CD44p-conjugated amphiphilic block copolymer PEG-b-HES-b-PLA for delivery of emodin to breast cancer cells

Herein, an amphiphilic block copolymer CD44-targeting peptide-conjugated polyethylene glycol-block-hydroxyethyl starch-block-poly (L-lactic acid) (CD44p-conjugated PEG-b-HES-b-PLA) are synthesized, which could self-assemble into the pH-responsive and CD44-targeting polymer micelles against breast cancer cells MDA-MB-231. Emodin (Emo) is a natural anthraquino with pharmacological activities in anti-tumor effects. However, Emo suffers from poor water solubility, low biocompatibility, rapid systemic elimination, and off-target side effects, resulting in unsatisfactory treatment outcomes. Nanotechnology-based drug delivery systems have proven great potential for cancer chemotherapy. The constructed polymeric micelles Emo@CD44p-PM have exhibited an average size of 154.5 ± 0.9 nm characterized by DLS and TEM. Further, the Emo@CD44p-PM have effective Emo-loading capacity, good thermal stability, and pH responsiveness. Intracellular uptake study shows the enhanced cellular internalization of Emo@CD44p-PM due to the increased exposure of CD44p enhances the cellular internalization of Emo@CD44p-PM effectively. Furthermore, thein vitroresults showed Emo@CD44p-PM has been observed good biocompatibility and anti-tumor effects. Therefore, the polymeric micelles Emo@CD44p-PM provide a promising delivery strategy of targeted therapy for breast cancer.

Advances in Understanding the Role of Aloe Emodin and Targeted Drug Delivery Systems in Cancer

Cancer is one of the important causes of death worldwide. Despite remarkable improvements in cancer research in the past few decades, several cancer patients still cannot be cured owing to the development of drug resistance. Natural sources might have prominence as potential drug candidates. Among the several chemical classes of natural products, anthraquinones are characterized by their large structural variety, noticeable biological activity, and low toxicity. Aloe emodin, an anthraquinone derivative, is a natural compound found in the roots and rhizomes of many plants. This compound has proven its antineoplastic, anti-inflammatory, antiangiogenic, and antiproliferative potential as well as ability to prevent cancer metastasis and potential in reversing multidrug resistance of cancer cells. The anticancer property of aloe emodin, a broad-spectrum inhibitory agent of cancer cells, has been detailed in many biological pathways. In cancer cells, these molecular mechanisms consist of inhibition of cell growth and proliferation, cell cycle arrest deterioration, initiation of apoptosis, antimetastasis, and antiangiogenic effect. In accordance with the strategy of developing potential drug candidates from natural products, aloe emodin's low bioavailability has been tried to be overcome by structural modifications and nanocarrier systems. Consequently, this review summarizes the antiproliferative and anticarcinogenic properties of aloe emodin, as well as the enhanced activity of its derivatives and the advantages of drug delivery systems on bioavailability.

Feature-Based Molecular Networking-An Exciting Tool to Spot Species of the Genus Cortinarius with Hidden Photosensitizers

Fungi have developed a wide array of defense strategies to overcome mechanical injuries and pathogen infections. Recently, photoactivity has been discovered by showing that pigments isolated from Cortinarius uliginosus produce singlet oxygen under irradiation. To test if this phenomenon is limited to dermocyboid Cortinarii, six colourful Cortinarius species belonging to different classical subgenera (i.e., Dermocybe, Leprocybe, Myxacium, Phlegmacium, and Telamonia) were investigated. Fungal extracts were explored by the combination of in vitro photobiological methods, UHPLC coupled to high-resolution tandem mass spectrometry (UHPLC-HRMS2), feature-based molecular networking (FBMN), and metabolite dereplication techniques. The fungi C. rubrophyllus (Dermocybe) and C. xanthophyllus (Phlegmacium) exhibited promising photobiological activity in a low concentration range (1-7 µg/mL). Using UHPLC-HRMS2-based metabolomic tools, the underlying photoactive principle was investigated. Several monomeric and dimeric anthraquinones were annotated as compounds responsible for the photoactivity. Furthermore, the results showed that light-induced activity is not restricted to a single subgenus, but rather is a trait of Cortinarius species of different phylogenetic lineages and is linked to the presence of fungal anthraquinones. This study highlights the genus Cortinarius as a promising source for novel photopharmaceuticals. Additionally, we showed that putative dereplication of natural photosensitizers can be done by FBMN.

Aloe and its Effects on Cancer: A Narrative Literature Review

Many years ago, Aloe Vera was cited to have a lot of therapeutic properties including; anti-microbial, anti-viral, anti-cancer, anti-oxidant, anti-inflammatory, skin protection, wound healing, and regulation of blood glucose and cholesterol. However, Aloe could present some side effects. This review focused on the latest discoveries regarding the therapeutic role of Aloe plant or its compounds on the acquired biological capabilities for tumour growth and progression namely; evading growth suppressor, avoiding immune destruction, enabling replicative immortality, tumour promoting inflammation, activating invasion and metastasis, inducing angiogenesis, genome instability and mutation, resisting cell death, deregulating cellular energetics and sustaining proliferating signalling. It clarified the anti-cancer activities it exerts on different types of cancer and also highlighted some pro-oncogenic pathways that can be disrupted by different compounds of Aloe.

Antioxidant and anticancer potentials of edible flowers: where do we stand?

Edible flowers are attracting special therapeutic attention and their administration is on the rise. Edible flowers play pivotal modulatory roles on oxidative stress and related interconnected apoptotic/inflammatory pathways toward the treatment of cancer. In this review, we highlighted the phytochemical content and therapeutic applications of edible flowers, as well as their modulatory potential on the oxidative stress pathways and apoptotic/inflammatory mediators, resulting in anticancer effects. Edible flowers are promising sources of phytochemicals (e.g., phenolic compounds, carotenoids, terpenoids) with several therapeutic effects. They possess anti-inflammatory, anti-diabetic, anti-microbial, anti-depressant, anxiolytic, anti-obesity, cardioprotective, and neuroprotective effects. Edible flowers potentially modulate oxidative stress by targeting erythroid nuclear transcription factor-2/extracellular signal-regulated kinase/mitogen-activated protein kinase (Nrf2/ERK/MAPK), reactive oxygen species (ROS), nitric oxide (NO), malondialdehyde (MDA) and antioxidant response elements (AREs). As the interconnected pathways to oxidative stress, inflammatory mediators, including tumor necrosis factor (TNF)-α, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukins (ILs) as well as apoptotic pathways such as Bcl-2-associated X protein (Bax), Bcl-2, caspase and cytochrome C are critical targets of edible flowers in combating cancer. In this regard, edible flowers could play promising anticancer effects by targeting oxidative stress and downstream dysregulated pathways.

Exploring the Role of Phytochemicals as Potent Natural Photosensitizers in Photodynamic Therapy

BACKGROUND

Cancer is still considered a deadly disease worldwide due to difficulties in diagnosis, painful treatment procedures, costly therapies, side effects, and cancer relapse. Cancer treatments using conventional methods like chemotherapy and radiotherapy were not convincing due to its post-treatment toxicity in the host. In Photodynamic Therapy (PDT), three individual non-toxic components including a photosensitizer, light source and oxygen cause damage to the cells and tissues when they are combined.

OBJECTIVE

In recent years, phytochemicals are being increasingly recognized as potent complementary drugs for cancer because of its natural availability, less toxicity and therapeutic efficiency in par with commercial drugs. Hence, the idea of using phytochemicals as natural photosensitizers in PDT resulted in a multiple pool of research studies with promising results in preclinical and clinical investigations.

METHODS

In this review, the potential of phytochemicals to act as natural photosensitizers for PDT, their mode of action, drawbacks, challenges and possible solutions are discussed in detail.

RESULTS

In PDT, natural photosensitizers, when used alone or in combination with other photosensitizers, induced cell death by apoptosis and necrosis, increased oxidative stress, altered cancer cell death signaling pathways, increased cytotoxicity and DNA damage in cancer cells. The pro-oxidant nature of certain antioxidant polyphenols, hormesis phenomenon, Warburg effect and DNA damaging potential plays a significant role in the photosensitizing mechanism of phytochemicals in PDT.

CONCLUSION

This review explores the role of phytochemicals that can act as photosensitizers alone or in combination with PDT and its mechanism of action on different cancers.

Photodynamic therapy in the treatment of oral squamous cell carcinoma - The state of the art in preclinical research on the animal model

BACKGROUND

Oral cavity squamous cell carcinoma is a common cancer of the head and neck region. Due to the frequency of diagnoses, high rate of mortality, mutilating nature of classic therapy and numerous complications, new methods of treatment are being sought. One promising solution for treatment that is utilized in many fields of oncology is photodynamic therapy. The purpose of this article is to present a general overview of the use of photodynamic therapy in preclinical in vivo studies on the animal model.

MATERIAL AND METHODS

A literature search for articles corresponding to the topic of this review was performed using the PubMed and MEDLINE databases using the following keywords: 'oral cavity squamous cell carcinoma,' 'photodynamic therapy,' 'photosensitizer(s),' 'in vivo', and 'animal model'.

RESULTS

Based on the literature review, the two most used animal models can be distinguished in research on the use of photodynamic therapy for oral squamous cell carcinoma. Studies mainly focus on the evaluation of tumor growth inhibition after using therapies with various photosensitizers on the murine or hamster cheek pouch models.

CONCLUDING REMARKS

The animal model is a part of preclinical research. Unfortunately, each of the models has its limitations, so it is difficult to extrapolate the results to clinical trials.

The effects of aloe emodin-mediated antimicrobial photodynamic therapy on drug-sensitive and resistant Candida albicans

The extensive and repetitive use of antifungal drugs has led to the development of drug-resistant Candida albicans. Antimicrobial photodynamic therapy (aPDT) has received considerable attention as an emerging and promising approach to combat drug-resistant microbes. This study evaluated the photodynamic effects mediated by aloe emodin (AE), a natural compound isolated from Aloe vera and Rheum palmatum, on azole-sensitive and azole-resistant C. albicans in vitro. AE exhibited no significant dark toxicity, but in the presence of light, effectively inactivated C. albicans cells in a concentration-dependent manner. The uptake of AE by fungal cells was investigated by confocal laser scanning microscopy (CLSM), and the results showed that AE possessed stronger ability to enter into C. albicans cells following light irradiation. Transmission electron microscopy analysis suggested that AE-mediated aPDT could induce damage to the cell wall, cytoplasm, and nucleus. Damage to the surface of C. albicans was observed by scanning electron microscopy. These results suggest that AE is a potential PS for use in aPDT of drug-resistant C. albicans strains, and AE-mediated aPDT shows promise as an antifungal treatment.

Antimicrobial photodynamic efficacy of selected natural photosensitizers against food pathogens: Impacts and interrelationship of process parameters

Photodynamic treatment (PDT) could be a viable option to decontaminate food or food contact surfaces. Such applications require a rigorous method to assess the efficacy of different photosensitizer-light source systems. It is also essential to determine suitable treatment conditions to achieve desirable microbial inhibition for a given process. In this connection, we evaluated and compared the antimicrobial activity of two natural photosensitizers (aloe emodin, curcumin) under PDT based on the number of absorbed photons. The degree of bacterial inactivation was then correlated to the absorbed photons as well as the process parameters through kinetics study. The results showed that aloe emodin was more effective than curcumin against both S. aureus and E. coli when the number of absorbed photons was matched. Aloe emodin reduced about 2.3 log units of S. aureus and 1.1 log units of E. coli more than curcumin. E. coli was more resistant to PDT than S. aureus. Inactivation kinetics of S. aureus and E. coli as a function of the number of absorbed photons can be described by the Weibull model with D values of 1.296 × 10¹⁷ photons/cm² and 2.446 × 10¹⁸ photons/cm², R² of 0.969 and 0.968, respectively. The interrelationship between the concentration of photosensitizer, radiant fluence, and degree of bacterial inactivation could be used to determine and optimize treatment conditions of PDT processes.

Pharmacological Update Properties of Aloe Vera and its Major Active Constituents

Aloe vera has been traditionally used to treat skin injuries (burns, cuts, insect bites, and eczemas) and digestive problems because its anti-inflammatory, antimicrobial, and wound healing properties. Research on this medicinal plant has been aimed at validating traditional uses and deepening the mechanism of action, identifying the compounds responsible for these activities. The most investigated active compounds are aloe-emodin, aloin, aloesin, emodin, and acemannan. Likewise, new actions have been investigated for Aloe vera and its active compounds. This review provides an overview of current pharmacological studies (in vitro, in vivo, and clinical trials), written in English during the last six years (2014–2019). In particular, new pharmacological data research has shown that most studies refer to anti-cancer action, skin and digestive protective activity, and antimicrobial properties. Most recent works are in vitro and in vivo. Clinical trials have been conducted just with Aloe vera, but not with isolated compounds; therefore, it would be interesting to study the clinical effect of relevant metabolites in different human conditions and pathologies. The promising results of these studies in basic research encourage a greater number of clinical trials to test the clinical application of Aloe vera and its main compounds, particularly on bone protection, cancer, and diabetes.

Lead bioactive compounds of Aloe vera as potential anticancer agent

Aloe vera (Aloe barbadensis Miller) is a perennial succulent medicinal plant. It has been used as a traditional or folk medicine for thousands of years and claimed that it possesses wound and burn healing activities, and anti-inflammatory as well as immunomodulatory effects. In recent years, the use of Aloe vera has been growing as a dietary supplement. The pre-clinical studies over the last couple of decades uncover the potential therapeutic activities of Aloe vera and its bioactive compounds, especially against neoplastic disease. Such investigations indicate the possible preventive as well as therapeutic effects of Aloe vera against cancer. Here, we discuss the crucial bioactive compounds of Aloe vera that have been harnessed against cancer and also address several mechanisms of action of these lead bioactive compounds compared to other standard drugs involved in cancer prevention and treatment.

Acanthopanacis Cortex extract: A novel photosensitizer for head and neck squamous cell carcinoma therapy

OBJECTIVES

The aim of this study was to develop a novel photosensitizer from traditional plant extracts and to investigate the photodynamic therapy (PDT) effect and mechanism of action of the novel photosensitizer on KB and Hep-2 cells.

METHODS

Fluorescence emission, cell viability, and intracellular distribution of candidates were analyzed to screen potential photosensitizers from traditional plant extracts. Cellular reactive oxygen species (ROS) quantification, Annexin V-FITC/PI staining, and western blotting were performed to explore the mechanism of cell death in KB and Hep-2 cells.

RESULT

Of 289 traditional plant extracts, 13 plant extracts with strong fluorescence were initially screened by fluorescence emission analysis. The cell viability assay and intracellular distribution of candidates showed that Acanthopanacis Cortex (AC) extract is a potential photosensitizer. Under optimal PDT conditions, high levels of ROS were produced in KB and Hep-2 cells, followed by cell death. However, there was no significant damage to HaCaT cells. Moreover, apoptosis induced by AC extract with 625 nm irradiation (IR) down-regulated the expression of Bcl-2 protein and up-regulated the expression of Bax protein, as well as that of cleaved PARP-1 protein in both KB and Hep-2 cells.

CONCLUSION

The fluorescence intensity of AC extract at 420 nm is similar to that of the commercial Hematoporphyrin (HP). AC extract with 625 nm IR could enhance the PDT effect, induce ROS generation, and trigger apoptotic pathways in KB and Hep-2 cells. Therefore, we suggest that AC is a potential novel photosensitizer for PDT in head and neck squamous cell carcinoma.

Effect of photodynamic therapy with (17R,18R)-2-(1-hexyloxyethyl)-2-devinyl chlorine E6 trisodium salt on pancreatic cancer cells in vitro and in vivo

AIM

To investigate the antitumor effects and underlying mechanisms of (17R,18R)-2-(1-hexyloxyethyl)-2-devinyl chlorine E6 trisodium salt (YLG-1)-induced photodynamic therapy (PDT) on pancreatic cancer in vitro and in vivo.

METHODS

YLG-1 is a novel photosensitizer extracted from spirulina. Its phototoxicity, cellular uptake and localization, as well as its effect on reactive oxygen species (ROS) production, apoptosis, and expression of apoptosis-associated proteins were detected in vitro. An in vivo imaging system (IVIS), the Lumina K imaging system, and mouse models of subcutaneous Panc-1-bearing tumors were exploited to evaluate the drug delivery pathway and pancreatic cancer growth in vivo.

RESULTS

YLG-1 was localized to the mitochondria, and the appropriate incubation time was 6 h. Under 650 nm light irradiation, YLG-1-PDT exerted a potent cytotoxic effect on pancreatic cancer cells in vitro, which could be abolished by the ROS scavenger N-acetyl-L-cysteine (NAC). The death mode caused by YLG-1-PDT was apoptosis, accompanied by upregulated Bax and cleaved Caspase-3 and decreased Bcl-2 expression. The results from the IVIS images suggested that the optimal administration route was intratumoral (IT) injection and that the best time to conduct YLG-1-PDT was 2 h post-IT injection. Consistent with the results in vitro, YLG-1-PDT showed great growth inhibition effects on pancreatic cancer cells in a mouse model.

CONCLUSION

YLG-1 is a potential photosensitizer for pancreatic cancer PDT via IT injection, the mechanisms of which are associated with inducing ROS and promoting apoptosis.