Quinones as photosensitizer for photodynamic therapy: ROS generation, mechanism and detection methods

TiO2-ZnPc nanoparticles functionalized with folic acid as a target photosensitizer for photodynamic therapy against glioblastoma cells

The use of TiO2 as a photosensitizer in photodynamic therapy is limited due to TiO2 generates reactive oxygen species only under UV irradiation. The TiO2 surface has been modified with different functional groups to achieve activation at longer wavelengths (visible light). This work reports the synthesis, characterization, and biological toxicity assay of TiO2 nanoparticles functionalized with folic acid and combined with a zinc phthalocyanine to obtain a nano-photosensitizer for its application in photodynamic therapy for glioblastoma cancer treatment. The nano-photosensitizer was prepared using the sol-gel method. Folic acid and zinc phthalocyanine were added during the hydrolysis and condensation of titanium butoxide, which was the TiO2 precursor. The samples obtained were characterized by several microscopy and spectroscopy techniques. An in vitro toxicity test was performed using the MTT assay and the C6 cellular line. The results of the characterization showed that the structure of the nanoparticles corresponds mainly to the anatase phase. Successful functionalization with folic acid and an excellent combination with phthalocyanine was also achieved. Both folic acid-functionalized TiO2 and phthalocyanine-functionalized TiO2 had no cytotoxic effect on C6 cells (even at high concentrations) in comparison to Cis-Pt, which was very toxic to C6 cells. The materials behaved similarly to the control (untreated cells). The cell viability and light microscopy images suggest that both materials could be considered biocompatible and mildly phototoxic in these cells when activated by light.

Porphyrin-BODIPY Dyad: Enhancing Photodynamic Inactivation via Antenna Effect

A porphyrin-BODIPY dyad (P-BDP) was obtained through covalent bonding, featuring a two-segment design comprising a light-harvesting antenna system connected to an energy acceptor unit. The absorption spectrum of P-BDP resulted from an overlap of the individual spectra of its constituent parts, with the fluorescence emission of the BODIPY unit experiencing significant quenching (96 %) due to the presence of the porphyrin unit. Spectroscopic, computational, and redox investigations revealed a competition between photoinduced energy and electron transfer processes. The dyad demonstrated the capability to sensitize both singlet molecular oxygen and superoxide radical anions. Additionally, P-BDP effectively induced the photooxidation of L-tryptophan. In suspensions of Staphylococcus aureus cells, the dyad led to a reduction of over 3.5 log (99.99 %) in cell survival following 30 min of irradiation with green light. Photodynamic inactivation caused by P-BDP was also extended to the individual bacterium level, focusing on bacterial cells adhered to a surface. This dyad successfully achieved the total elimination of the bacteria upon 20 min of irradiation. Therefore, P-BDP presents an interesting photosensitizing structure that takes advantage of the light-harvesting antenna properties of the BODIPY unit combined with porphyrin, offering potential to enhance photoinactivation of bacteria.

Research Progress of Natural Product Photosensitizers in Photodynamic Therapy

Photodynamic therapy is a noninvasive cancer treatment that utilizes photosensitizers to generate reactive oxygen species upon light exposure, leading to tumor cell apoptosis. Although photosensitizers have shown efficacy in clinical practice, they are associated with certain disadvantages, such as a certain degree of toxicity and limited availability. Recent studies have shown that natural product photosensitizers offer promising options due to their low toxicity and potential therapeutic effects. In this review, we provide a summary and evaluation of the current clinical photosensitizers that are commonly used and delve into the anticancer potential of natural product photosensitizers like psoralens, quinonoids, chlorophyll derivatives, curcumin, chrysophanol, doxorubicin, tetracyclines, Leguminosae extracts, and Lonicera japonica extract. The emphasis is on their phototoxicity, pharmacological benefits, and effectiveness against different types of diseases. Novel and more effective natural product photosensitizers for future clinical application are yet to be explored in further research. In conclusion, natural product photosensitizers have potential in photodynamic therapy and represent a promising area of research for cancer treatment.

The Synthesis and Reactivity of Naphthoquinonynes

The first systematic exploration of the synthesis and reactivity of naphthoquinonynes is described. Routes to two regioisomeric Kobayashi-type naphthoquinonyne precursors have been developed, and the reactivity of the ensuing 6,7- and 5,6-aryne intermediates has been investigated. Remarkably, these studies have revealed that a broad range of cycloadditions, nucleophile additions and difunctionalizations can be achieved while maintaining the integrity of the highly sensitive quinone unit. The methodologies offer a powerful diversity oriented approach to C6 and C7 functionalized naphthoquinones, which are typically challenging to access. From a reactivity viewpoint, the study is significant because it demonstrates that aryne-based functionalizations can be utilized strategically in the presence of highly reactive and directly competing functionality.

Impacts of electric field-magnetic powder coupled membrane bioreactor on phenol wastewater treatment: Performance, synergistic mechanism, antibiotic resistance genes, and eco-environmental benefit evaluation

A novel electric field-magnetic powder coupled membrane bioreactor (EM-MBR) was constructed, which was superior on improvement of phenol treatment performance and sludge characteristics, and mitigation of membrane fouling. EM-MBR enhanced the phenol degradation via the improvement activity of phenol degrading enzymes. The EPS contents and SVI of EM-MBR were significantly reduced by 49.3 % and 58.7 % than that of the conventional MBR, respectively. Moreover, EM-MBR successfully reduced fouling rate by 57.0 %, delaying the membrane resistance. The EPS contents were positively correlated with the SVI and fouling rate, implying that the sludge settleability was strengthened by improving the properties of EPS with the assistance of electromagnetic, thus mitigating the membrane fouling. Microbial co-occurrence network demonstrated that EM-MBR enriched phenol-degrading and EPS-degrading genera correlated to Fe redox cycle. Furthermore, the activation of the antioxidant system in the EM-MBR resulted in the suppression of reactive oxygen species (ROS) generation, consequently impeding the dissemination of antibiotic resistance genes (ARGs). Co-occurrence patterns of MGEs and ARGs revealed that intercellular binding facilitated by ist and Integrase may account for the horizontal transfer of ARGs. The reduction of unit capital costs (15.63 %), running costs (53.00 %), and total average carbon emissions (15.18 %) indicated that EM-MBR was environmentally beneficial.

Antitumoral photoinduced effects of crude extract, fractions, and naphthoquinones from Sinningia magnifica (Otto & A. Dietr.) Wiehler (Gesneriaceae) in a bioguided study

Photodynamic therapy (PDT) has been used for various purposes, including as an antitumor resource in a noninvasive therapy with minimal side effects. Sinningia magnifica (Otto & A. Dietr.) Wiehler is a rupicolous plant found in rock crevices in Brazilian tropical forests. Initial studies indicate the presence of phenolic glycosides and anthraquinones in species of the genus Sinningia (Generiaceae family). It is known that anthraquinones are natural photosensitizers with potential PDT applications. This led us to investigate the potential compounds of S. magnifica for use as a natural photosensitizer against the melanoma (SK-MEL-103) and the prostate cancer (PC-3) cell lines in a bioguided study. Our results showed that singlet oxygen production by the 1,3-DPBF photodegradation assay greatly increased in the presence of crude extract and fractions. The biological activity evaluation showed photodynamic action against melanoma cell line SK-MEL-103 and prostate cell line PC-3. These results suggest the presence of potential photosensitizing substances, as demonstrated in this in vitro antitumor PDT study by the naphthoquinones Dunniol and 7-hydroxy-6-methoxy-α-dunnione for the first time. Naphthoquinones, anthraquinones and phenolic compounds were identified in the crude extract by UHPLC-MS/MS analysis, motivating us to continue with the bioguided phytochemical study aiming to discover more photochemically bioactive substances in Gesneriaceae plants.

Novel chlorin e6-based conjugates of tyrosine kinase inhibitors: Synthesis and photobiological evaluation as potent photosensitizers for photodynamic therapy

Since tyrosine kinase inhibitor (TKI) could reverse ABCG2-mediated drug-resistance, novel chlorin e6-based conjugates of Dasatinib and Imatinib as photosensitizer (PS) were designed and synthesized. The results demonstrated that conjugate 10b showed strongest phototoxicity against HepG2 and B16-F10 cells, which was more phototoxic than chlorin e6 and Talaporfin. It could reduce efflux of intracellular PS by inhibiting ABCG2 in HepG2 cells, and localize in mitochondria, lysosomes, golgi and ER, resulting in higher cell apoptosis rate and ROS production than Talaporfin. Moreover, it could induce cell autophagy and block cell cycle in S phase, and significantly inhibit tumor growth and prolong survival time on BALB/c nude mice bearing HepG2 xenograft tumor to a greater extent than chlorin e6. Consequently, compound 10b could be applied as a promising candidate PS due to its good water-solubility and stability, low drug-resistance, high quantum yield of 1O2 and excellent antitumor efficacy in vitro and in vivo.

Quinones: Biosynthesis, Characterization of 13 C Spectroscopical Data and Pharmacological Activities

Quinones are natural products widely distributed in nature, which are involved in stages of several vital biological processes, with mostly having a variety of pharmacological properties. The main groups comprising most of these compounds are benzoquinones, naphthoquinones, anthraquinones, and phenanthraquinones. Quinone isolation has been a focus of study around the world in recent years; for this reason, this study approaches the junction of natural quinones identified by 13 C Nuclear Magnetic Resonance (NMR) spectroscopic analytical techniques. The methodology used to obtain the data collected articles from various databases on quinones from 2000 to 2022. As a result, 137 compounds were selected, among which 70 were characterized for the first time in the period investigated; moreover, the study also discusses the biosynthetic pathways of quinones and the pharmacological activities of the compounds found, giving an overview of the various applications of these compounds.

Evaluation of the effect of photodynamic therapy with Curcumin and Riboflavin on implant surface contaminated with Aggregatibacter actinomycetemcomitans

BACKGROUND

Peri-implantitis is a destructive inflammatory disease affecting both hard and soft tissues of the osseointegrated implant and causing bone loss and envelope surrounding the implant. The study aimed at evaluating the effect of Photodynamic therapy with Curcumin and Riboflavin on the level of decontamination of implant surface impregnated with Aggregatibacter actinomycetemcomitans (A.a) biofilm.

MATERIALS AND METHODS

In this experimental and laboratory study, 42 implants (4.3 mm in diameter and 8 mm in length) were infected with A.a. bacterial suspension. Then, the implants carrying A.a biofilm were randomly divided into seven groups (n = 6). The groups included: 1- a negative control group (without treatment), 2- a positive control group of Chlorhexidine 0.12 %, 3- a Curcumin (5 mg/ ml) group, 4- a Riboflavin (0.5 %) group, 5- an LED irradiation group (390-480 nm), 6- a photodynamic therapy with Curcumin group, and 7- a photodynamic therapy with Riboflavin group. Then, the implants were sonicated and the amount of CFU/mL of each sample was calculated. One-way ANOVA and Tamhane tests were used to analyze the data.

RESULTS

The lowest mean number of colonies of A.a (CFU/ mL) were seen in the following groups, respectively: the positive control group of Chlorhexidine 0.12 %, the photodynamic therapy with Curcumin group, the photodynamic therapy with Riboflavin group, the Curcumin (5 mg/ ml) group, the Riboflavin (0.5 %) group, the LED radiation group, and the negative control group. The use of photodynamic therapy with Curcumin significantly reduced the number of colonies of A.a (CFU/ mL) in comparison with the photodynamic therapy with Riboflavin group (p = 0.004), the Riboflavin group (p = 0.045), the LED radiation group (p = 0.012), and the negative control group (p = 0.007).

CONCLUSION

aPDT with Curcumin and LED can reduce A.a biofilm on implant surfaces and can be used as a safe and non-invasive disinfection method to reduce A.a biofilm on implant surfaces.

Ultraefficient OG-Mediated Photodynamic Inactivation Mechanism for Ablation of Bacteria and Biofilms in Water Augmented by Potassium Iodide under Blue Light Irradiation

While photodynamic inactivation (PDI) has emerged as a novel sterilization strategy for drinking water treatment that recently attracted tremendous attention, its efficiency needs to be further improved. In this study, we aimed to clarify the ultraefficient mechanism by which potassium iodide (KI) potentiates octyl gallate (OG)-mediated PDI against bacteria and biofilms in water. When OG (0.15 mM) and bacteria were exposed to blue light (BL, 420 nm, 210 mW/cm2), complete sterilization (>7.5 Log cfu/mL of killing) was achieved by the addition of KI (250 mM) within only 5 min (63.9 J/cm2). In addition, at lower doses of OG (0.1 mM) with KI (100 mM), the biofilm was completely eradicated within 10 min (127.8 J/cm2). The KI-potentiated mechanism involves in situ rapid photogeneration of a multitude of reactive oxygen species, especially hydroxyl radicals (•OH), reactive iodine species, and new photocytocidal substances (quinone) by multiple photochemical pathways, which led to the destruction of cell membranes and membrane proteins, the cleavage of genomic DNA and extracellular DNA within biofilms, and the degradation of QS signaling molecules. This multitarget synergistic strategy provided new insights into the development of an environmentally friendly, safe, and ultraefficient photodynamic drinking water sterilization technology.

Organic disulfide-modified folate carbon dots for tumor-targeted synergistic chemodynamic/photodynamic therapy

Carbon dots (CDs) have great potential for cancer diagnosis and treatment. Photodynamic therapy and chemodynamic therapy are promising treatments mediated by reactive oxygen species (ROS), which have the advantages of being minimally invasive, having no multi-drug resistance, and having no systemic toxic side effects. However, the tumor microenvironment (TME) and poor targetability often reduce the therapeutic effect. In this work, we have successfully prepared folate-based carbon dots (FCP-CDs) from folic acid (FA), citric acid (CA), and polyethyleneimine (PEI) for tumor-targeting. The surface of FCP-CDs was modified using organic disulfide, 3,3'-dithiodipropionic acid (DTPA), and a photosensitizer (PS) pyropheophorbide-a (PPa) to form a tumor microenvironment-responsive nanoplatform, FCP-CDs@DTPA@PPa (named FCPPD), for synergistic cancer therapy. The results showed that FCPPD effectively preserved the tumor target specificity of folic acid and the photodynamic therapeutic (PDT) activity of PPa, and could provide additional chemodynamic therapeutic (CDT) function by reacting with hydrogen peroxide (H₂O₂) to generate ˙OH. The introduction of DTPA, which contains disulfide bonds, endows FCPPD with an excellent ability to deplete glutathione (GSH) in tumors via intracellular redox reactions, amplifying intracellular oxidative strain and enhancing ROS-based therapeutic effects. Systematic in vitro and in vivo studies under various conditions have shown that the obtained FCPPD nanoparticles have good biocompatibility and could be a promising therapeutic agent for imaging-guided PDT/CDT combination therapy.

Tuning the Molecular Structure of Corroles to Enhance the Antibacterial Photosensitizing Activity

The increase in the antibiotic resistance of bacteria is a serious threat to public health. Photodynamic inactivation (PDI) of micro-organisms is a reliable antimicrobial therapy to treat a broad spectrum of complex infections. The development of new photosensitizers with suitable properties is a key factor to consider in the optimization of this therapy. In this sense, four corroles were designed to study how the number of cationic centers can influence the efficacy of antibacterial photodynamic treatments. First, 5,10,15-Tris(pentafluorophenyl)corrole (Co) and 5,15-bis(pentafluorophenyl)-10-(4-(trifluoromethyl)phenyl)corrole (Co-CF₃) were synthesized, and then derivatized by nucleophilic aromatic substitution with 2-dimethylaminoethanol and 2-(dimethylamino)ethylamine, obtaining corroles Co-3NMe₂ and Co-CF₃-2NMe₂, respectively. The straightforward synthetic strategy gave rise to macrocycles with different numbers of tertiary amines that can acquire positive charges in an aqueous medium by protonation at physiological pH. Spectroscopic and photodynamic studies demonstrated that their properties as chromophores and photosensitizers were unaffected, regardless of the substituent groups on the periphery. All tetrapyrrolic macrocycles were able to produce reactive oxygen species (ROS) by both photodynamic mechanisms. Uptake experiments, the level of ROS produced in vitro, and PDI treatments mediated by these compounds were assessed against clinical strains: methicillin-resistant Staphylococcus aureus and Klebsiella pneumoniae. In vitro experiments indicated that the peripheral substitution significantly affected the uptake of the photosensitizers by microbes and, consequently, the photoinactivation performance. Co-3NMe₂ was the most effective in killing both Gram-positive and Gram-negative bacteria (inactivation > 99.99%). This work lays the foundations for the development of new corrole derivatives having pH-activable cationic groups and with plausible applications as effective broad-spectrum antimicrobial photosensitizers.

Mode of action of p-quinone derivatives with trypanocidal activity studied by experimental and in silico models

Quinones are attractive pharmacological scaffolds for developing new agents for the treatment of different transmissible and non-transmissible human diseases due to their capacity to alter the cell redox homeostasis. The bioactivity and potential mode of action of 19 p-quinone derivatives fused to different aromatic rings (carbo or heterocycles) and harboring distinct substituents were investigated in infective Trypanosoma brucei brucei. All the compounds, except for a furanequinone (EC₅₀₌38 μM), proved to be similarly or even more potent (EC₅₀ = 0.5-5.5 μM) than the clinical drug nifurtimox (EC₅₀ = 5.3 μM). Three furanequinones and one thiazolequinone displayed a higher selectivity than nifurtimox. Two of these selective hits resulted potent inhibitors of T. cruzi proliferation (EC₅₀₌0.8-1.1 μM) but proved inactive against Leishmania infantum amastigotes. Most of the p-quinones induced a rapid and marked intracellular oxidation in T. b. brucei. DFT calculations on the oxidized quinone (Q), semiquinone (Q^•-) and hydroquinone (QH₂) suggest that all quinones have negative ΔG for the formation of Q^•-. Qualitative and quantitative structure-activity relationship analyses in two or three dimensions of different electronic and biophysical descriptors of quinones and their corresponding bioactivities (killing potency and oxidative capacity) were performed. Charge distribution over the quinone ring carbons of Q and Q^.- and the frontier orbitals energies of SUMO (Q^.-) and LUMO (Q) correlate with their oxidative and trypanocidal activity. QSAR analysis also highlighted that both bromine substitution in the p-quinone ring and a bulky phenyl group attached to the furane and thiazole rings (which generates a negative charge due to the π electron system polarized by the nearby heteroatoms) are favorable for activity. By combining experimental and in silico procedures, this study disclosed important information about p-quinones that may help to rationally tune their electronic properties and biological activities.

In Vitro Evaluation of Photodynamic Activity of Plant Extracts from Senna Species against Microorganisms of Medical and Dental Interest

Background: Bacterial resistance requires new treatments for infections. In this context, antimicrobial photodynamic therapy (aPDT) is an effective and promising option. Objectives: Three plant extracts (Senna splendida, Senna alata, and Senna macranthera) were evaluated as photosensitizers for aPDT. Methods: Cutibacterium acnes (ATCC 6919), Streptococcus mutans (ATCC 35668), Staphylococcus aureus (ATCC 25923), Escherichia coli (ATCC 25922), and Candida albicans (ATCC 90028) were evaluated. Reactive oxygen species production was also verified. Oral keratinocytes assessed cytotoxicity. LC-DAD-MS analysis identified the chemical components of the evaluated extracts. Results: Most species cultured in the planktonic phase showed total microbial reduction (>6 log10 CFU/mL/p < 0.0001) for all extracts. C. albicans cultured in biofilm showed total microbial reduction (7.68 log10 CFU/mL/p < 0.0001) for aPDT mediated by all extracts. Extracts from S. macranthera and S. alata produced the highest number of reactive oxygen species (p < 0.0001). The S. alata extract had the highest cell viability. The LC-DAD-MS analysis of active extracts showed one naphthopyrone and seven anthraquinones as potential candidates for photoactive compounds. Conclusion: This study showed that aPDT mediated by Senna spp. was efficient in microbial suspension and biofilm of microorganisms of medical and dental interest.

Nanomaterials-Functionalized Hydrogels for the Treatment of Cutaneous Wounds

Hydrogels have been utilized extensively in the field of cutaneous wound treatment. The introduction of nanomaterials (NMs), which are a big category of materials with diverse functionalities, can endow the hydrogels with additional and multiple functions to meet the demand for a comprehensive performance in wound dressings. Therefore, NMs-functionalized hydrogels (NMFHs) as wound dressings have drawn intensive attention recently. Herein, an overview of reports about NMFHs for the treatment of cutaneous wounds in the past five years is provided. Firstly, fabrication strategies, which are mainly divided into physical embedding and chemical synthesis of the NMFHs, are summarized and illustrated. Then, functions of the NMFHs brought by the NMs are reviewed, including hemostasis, antimicrobial activity, conductivity, regulation of reactive oxygen species (ROS) level, and stimulus responsiveness (pH responsiveness, photo-responsiveness, and magnetic responsiveness). Finally, current challenges and future perspectives in this field are discussed with the hope of inspiring additional ideas.

Nanotherapeutic Intervention in Photodynamic Therapy for Cancer

The clinical need for photodynamic therapy (PDT) has been growing for several decades. Notably, PDT is often used in oncology to treat a variety of tumors since it is a low-risk therapy with excellent selectivity, does not conflict with other therapies, and may be repeated as necessary. The mechanism of action of PDT is the photoactivation of a particular photosensitizer (PS) in a tumor microenvironment in the presence of oxygen. During PDT, cancer cells produce singlet oxygen (¹O₂) and reactive oxygen species (ROS) upon activation of PSs by irradiation, which efficiently kills the tumor. However, PDT's effectiveness in curing a deep-seated malignancy is constrained by three key reasons: a tumor's inadequate PS accumulation in tumor tissues, a hypoxic core with low oxygen content in solid tumors, and limited depth of light penetration. PDTs are therefore restricted to the management of thin and superficial cancers. With the development of nanotechnology, PDT's ability to penetrate deep tumor tissues and exert desired therapeutic effects has become a reality. However, further advancement in this field of research is necessary to address the challenges with PDT and ameliorate the therapeutic outcome. This review presents an overview of PSs, the mechanism of loading of PSs, nanomedicine-based solutions for enhancing PDT, and their biological applications including chemodynamic therapy, chemo-photodynamic therapy, PDT-electroporation, photodynamic-photothermal (PDT-PTT) therapy, and PDT-immunotherapy. Furthermore, the review discusses the mechanism of ROS generation in PDT advantages and challenges of PSs in PDT.

Parent anion radical formation in coenzyme Q0: Breaking ubiquinone family rules

We report electron attachment (EA) measurements for the parent anion radical formation from coenzyme Q0 (CoQ0) at low electron energies (<2 eV) along with quantum chemical calculations. CoQ0 may be considered a prototype for the electron withdrawing properties of the larger CoQ n molecules, in particular ubiquinone (CoQ10), an electron carrier in aerobic cell respiration. Herein, we show that the mechanisms for the parent anion radical formation of CoQ0 and CoQ n (n = 1,2,4) are remarkably distinct. Reported EA data for CoQ1, CoQ2, CoQ4 and para-benzoquinone indicated stabilization of the parent anion radicals around 1.2-1.4 eV. In contrast, we observe for the yield of the parent anion radical of CoQ0 a sharp peak at ∼ 0 eV, a shoulder at 0.07 eV and a peak around 0.49 eV. Although the mechanisms for the latter feature remain unclear, our calculations suggest that a dipole bound state (DBS) would account for the lower energy signals. Additionally, the isoprenoid side chains in CoQ n (n = 1,2,4) molecules seem to influence the DBS formation for these compounds. In contrast, the side chains enhance the parent anion radical stabilization around 1.4 eV. The absence of parent anion radical formation around 1.4 eV for CoQ0 can be attributed to the short auto-ionization lifetimes. The present results shed light on the underappreciated role played by the side chains in the stabilization of the parent anion radical. The isoprenoid tails should be viewed as co-responsible for the electron-accepting properties of ubiquinone, not mere spectators of electron transfer reactions.

The Quinone-Derived Small Molecule M5N32 Is an Effective Anti-Helicobacter pylori Agent Both In Vivo and In Vitro

BACKGROUND

Helicobacter pylori has become increasingly resistant to all commonly used clinical antibiotics. Therefore, new anti-H. pylori drugs need to be identified. Recently, quinones were found to inhibit growth of H. pylori with quinone-derived small-molecule compounds identified as having antitumor effects.

METHODS

The minimum inhibitory concentrations of the compounds against H. pylori were measured by agar plate dilution method. The inhibition of biofilm formation by the compounds was assessed by SYTO9-PI double staining. The reactive oxygen species induced by the compounds were detected by DCFH-DA stain. The clearance effects of the compounds for H. pylori in mouse were evaluated by counting colony-forming units and hematoxylin and eosin staining.

RESULTS

Our results revealed strong inhibition of M5N32 in vitro against H. pylori in both the planktonic and biofilm-forming states. Resistance to M5N32 was not developed in successive generations of the bacteria. In vivo, the combination of M5N32 and omeprazole showed enhanced effects in comparison to the standard triple therapy. M5N32 was nontoxic to normal tissues.

CONCLUSIONS

M5N32 is effective in the treatment of H. pylori infections, providing potential development of anti-H. pylori medicines in the treatment of H. pylori infections.

PARP inhibitors diminish DNA damage repair for the enhancement of tumor photodynamic therapy

Pancreatic cancer is a lethal malignancy and only around 4% of patients will live 5 years post-diagnosis. Photodynamic therapy (PDT) is a promising strategy for treating malignant tumors because of its high selectivity. Through the colocalization of light, oxygen and photosensitizer, a large number of reactive oxygen species (ROS) are generated under excitation at a specific wavelength of a laser, which can induce DNA damage and destroy cancer cells. However, the repair mechanism of cell will repair part of the damaged DNA, which could reduce the efficiency of PDT. The poly (ADP-Ribose) polymerase (PARP) plays a wide and multifaceted role in the cellular response to DNA damage, with growing evidence for participation in multiple pathways of DNA damage repair and genome maintenance. Cells require PARP to resolve single-strand DNA breaks (SSBs) induced by chemotherapy agents. Its inhibition is thought to result in the accumulation of damage in DNA, which may eventually lead to cell death. The combination therapy of PDT and PARP inhibitors may benefit patients. In this study, we design and synthesize a zeolitic imidazolate framework-8 (ZIF-8) to co-deliver DNA damaging agent Chlorin e6 (Ce6) and PARP inhibitor Olaparib (Ola). Ce6 and Ola demonstrate strong synergistic actions, providing a novel approach for the treatment of pancreatic cancer.

Novel Ru(II)-bipyridine/phenanthroline-lapachol complexes as potential anti-cancer agents

For the first time, we herein report on the syntheses of two new Ru(II)/bipyridine/phenanthroline complexes containing lapachol as ligand: complex (1), [Ru (bipy)₂(Lap)]PF₆ and complex (2), [Ru(Lap)(phen)₂]PF₆, where bipy = 2,2'-bipyridine and ph en = 1,10-phenanthroline; Lap = lapachol (2-hydroxy-3-(3-methylbut-2-en-1- yl)naphthalene-1,4-dione). The complexes were synthesized and characterized by elemental analyses, molar conductivity, mass spectrometry, ultraviolet-visible and infrared spectroscopies, nuclear magnetic resonance (¹H, ¹³C), and single crystal X-ray diffraction, for complex (2). In addition, in vitro cytotoxicity was tested against six cancer cells: A549 (lung carcinoma); DU-145 (human prostate carcinoma); HepG2 (human hepatocellular carcinoma), PC-3 (human prostate adenocarcinoma); MDA-MB-231 (human breast adenocarcinoma); Caco-2 (human colorectal adenocarcinoma), and against two non-cancer cells, FGH (human gingival normal fibroblasts) and PNT-2 (prostate epithelial cells). Complex (1) was slightly more toxic and selective than complex (2) for all cell lines, except against the A549 cells, where (2) was more potent than complex (1). The complexes induced an increase in the reactive oxygen species, and the co-treatment with N-acetyl-L-cysteine remarkably suppressed the ROS generation and prevented the reduction of cell viability, suggesting that the cytotoxicity of the complexes is related to the ROS-mediated pathway. Further studies indicated that the complexes may bind to DNA via minor groove interaction. Our studies also revealed that free Lap induces gene mutations in Salmonella Typhimurium, nevertheless, the complexes demonstrated the absence of genotoxicity by the Ames test. The present study provides a relevant contribution to understanding the anti-cancer potential and genetic toxicological events of new ruthenium complexes containing the lapachol molecule as a ligand.

Effect of Substituents on the Photodynamic Action of Anthraquinones: EPR, Computational and In Vitro Studies

Anthraquinone class of compounds possesses a broad spectrum of therapeutic applications. Cancer cell targeting ability, together with photogeneration of reactive oxygen species, renders anthraquinones an interesting class of photosensitizers for photodynamic therapy (PDT). Screening of newer compounds for better singlet oxygen generation is of current interest to improve the practical usability in PDT. In this study, we investigate the photodynamic activity of nine commercially available anthraquinones, using EPR spectroscopy and computational techniques, to identify the role of substituents on singlet oxygen yield. Three anthraquinone derivatives, 1,5-diaminoanthraquinone, 15-dihydroxyanthraquinone and 1,2,7-trihydroxyanthraquinone, showed highest singlet oxygen quantum yield (0.21, 0.18 and 0.15, respectively) relative to Rose Bengal. Time-dependent density functional theory calculations indicate the singlet oxygen quantum yield of anthraquinones inversely correlate well with the excited singlet-triplet (S1-T1) energy gap. Electron-donating substituents present at positions 1, 2 and 5 of anthraquinone seem to reduce the S1-T1 energy gap, facilitating inter-system crossing and the production of singlet oxygen. This would greatly aid in the design of newer anthraquinone-based photosensitizers. This study also highlights the suitability of 1,5-diaminoanthraquinone for PDT applications as demonstrated by in vitro experiments of photoinduced DNA cleavage and photocytotoxicity in Dalton's lymphoma ascites.

Application of Fullerenes as Photosensitizers for Antimicrobial Photodynamic Inactivation: A Review

Antimicrobial photodynamic inactivation (aPDI) is a newly emerged treatment approach that can effectively address the issue of multidrug resistance resulting from the overuse of antibiotics. Fullerenes can be used as promising photosensitizers (PSs) for aPDI due to the advantages of high triplet state yields, good photostability, wide antibacterial spectrum, and permissibility of versatile functionalization. This review introduces the photodynamic activities of fullerenes and the up-to-date understanding of the antibacterial mechanisms of fullerene-based aPDI. The most recent works on the functionalization of fullerenes and the application of fullerene derivatives as PSs for aPDI are also summarized. Finally, certain remaining challenges are emphasized to provide guidance on future research directions for achieving clinical application of fullerene-based aPDI.

The Application of Antimicrobial Photodynamic Therapy (aPDT) in the Treatment of Peri-Implantitis

Background

This literature review evaluates the mechanisms and efficacy of different types of antimicrobial photodynamic therapy (aPDT) for treating peri-implantitis by reviewing existing experimental studies to provide guidance for the clinical application of antibacterial photodynamic therapy (aPDT) in oral implants.

Materials and Methods

From February 2001 to February 2021, we have collected 152 randomized controlled trials of aPDT for peri-implantitis by searching the experimental studies and clinical trials published in PubMed, Embase, Web of Science, and Google Scholar databases via online search. After screening the retrieved literature, we finally selected 10 statistically significant literature for evaluation and review.

Results

Compared with the traditional nonsurgical treatment of peri-implantitis, the aPDT was superior to the traditional mechanical irrigation treatment group in terms of periodontal indexes PD, BOP, PLI, and postoperative effect, and the difference was statistically significant (P < 0.05). Furthermore, the combination of the aPDT and other treatments shows the synergistic antibacterial effect, signifying better clinical effect in many aspects (P < 0.05). In these 10 papers, by comparing the probe depth (PD), bleeding on probing (BOP), synosteosis, and periodontal pathogenic bacteria detection, etc., obtained after treating peri-implantitis by application of the antimicrobial photodynamic therapy, and using the SPSS data analysis software for statistical data processing, we found that the antimicrobial photodynamic therapy combined with other periodontal treatments has a more prominent postoperative effect. Meanwhile, the antibacterial photodynamic therapy with targeted action of photosensitizer has strong specificity to some bacteria, while the synthetic photosensitize for antibacterial photodynamic therapy can show good inactivation effect on broad-spectrum periodontal anaerobes without side effect.

Conclusion

The experimental studies and clinical data of antibacterial photodynamic therapy for treating peri-implantitis show a good postoperative treatment effect. In addition, it did not develop resistance due to the use of antibiotic drugs. Owing to multiple advantages from combining antibacterial photodynamic therapy and other treatments, it is applicable for clinical treatment.

New phthalonitrile/metal phthalocyanines-gold nanoparticle conjugates for biological applications

The appearance of nanoscience and its effect on the development of the scientific fields particularly materials chemistry have been well-known today. In this study, a new di-substituted phthalonitrile derivative namely...

From main chain conjugated polymer photosensitizer to hyperbranched one: the expansion of polymerization-enhanced photosensitization effect for photodynamic therapy

Three conjugated polymers with the same donor-acceptor structure but totally different architectures are design to show both Type-I and Type-II photosensitization abilities simultaneously, among which the hyperbranched polymer shows the...

Injectable Micromotor@hydrogel system for antibacterial therapy

The drug delivery system based on nano/micromotors has become a research hot spot in recent years. However, naked micromotors may be ruptured or passivated under the complex biological environment, which will result in the leakage of drugs in advance or limited self-propulsion performance. Here, we propose an injectable micromotor@hydrogel drug delivery system to protect micromotors from the external environment. The micromotors were prepared through layer-by-layer assembly technology. The asymmetric decomposition of hydrogen peroxide catalyzed by the locally distributed platinum nanoparticles enabled efficient propulsion of the micromotors in low concentration of hydrogen peroxide. In order to protect micromotors, they were loaded into the Schiff base hydrogel. The micromotor@hydrogel system can be injected directly into the lesion to release micromotors in response to the environment, reducing external influence on micromotors and improving the sustained-release effect. Erythromycin (Ery) was loaded into the micromotors and the micromotor@hydrogel system demonstrated excellent antibacterial effect. Micromotors released from the hydrogel underwent enhanced diffusion in the surroundings of bacteria without addition of exogenous hydrogen peroxide, which was manifested by their appearance in edge of the inhibition zone. The proposed micromotor@hydrogel drug delivery system offers a new strategy for the treatment of bacterial infections.

Antifungal Effect of Antimicrobial Photodynamic Therapy Mediated by Haematoporphyrin Monomethyl Ether and Aloe Emodin on Malassezia furfur

Infectious dermatological diseases caused by Malassezia furfur are often chronic, recurrent, and recalcitrant. Current therapeutic options are usually tedious, repetitive, and associated with adverse effects. Alternatives that broaden the treatment options and reduce side effects for patients are needed. Antimicrobial photodynamic therapy (aPDT) is an emerging approach that is quite suitable for superficial infections. The aim of this study is to investigate the antimicrobial efficacy and effect of aPDT mediated by haematoporphyrin monomethyl ether (HMME) and aloe emodin (AE) on clinical isolates of M. furfur in vitro. The photodynamic antimicrobial efficacy of HMME and AE against M. furfur was assessed by colony forming unit (CFU) assay. The uptake of HMME and AE by M. furfur cells was investigated by fluorescence microscopy. Reactive oxygen species (ROS) probe and flow cytometry were employed to evaluate the intracellular ROS level. The effect of HMME and AE-mediated aPDT on secreted protease and lipase activity of M. furfur was also investigated. The results showed that HMME and AE in the presence of light effectively inactivated M. furfur cells in a photosensitizer (PS) concentration and light energy dose-dependent manner. AE exhibited higher antimicrobial efficacy against M. furfur than HMME under the same irradiation condition. HMME and AE-mediated aPDT disturbed the fungal cell envelop, significantly increased the intracellular ROS level, and effectively inhibited the activity of secreted protease and lipase of M. furfur cells. The results suggest that HMME and AE have potential to serve as PSs in the photodynamic treatment of dermatological diseases caused by M. furfur, but further ex vivo or in vivo experiments are needed to verify that they can meet the requirements for clinical practice.

Lactose-conjugated porphyrin: synthesis and photobiological evaluation as potential agents for photodynamic therapy

Porphyrin-based photosensitizers are conventional photodynamic agents that are used clinically. However, their clinical applications have been overshadowed by poor water solubility. In addition, they have weak tumor selectivity, which may cause undesirable side effects. The preparation of novel porphyrin derivatives has been explored for potential applications in photodynamic therapy (PDT). To achieve this goal, lactose-conjugated porphyrin nanoparticles (Lac-Por NPs) have been synthesized and characterized. PDT with Lac-Por NPs exhibited tumor-specific cytotoxicity in lactose receptor-overexpressing HepG2 cells in vitro and in vivo. In summary, we designed and synthesized lactose conjugate porphyrins with enhanced water solubility and tumor selectivity. This work expands the application range of porphyrin-based photosensitizers for cancer treatment.

Betulinic acid and its spray dried microparticle formulation: In vitro PDT effect against ovarian carcinoma cell line and in vivo plasma and tumor disposition

The race against ovarian cancer continue to motivate the research worldwide. It is known that many antitumor drugs have limited penetration into solid tumor tissues due to its microenvironment, thus contributing to their low efficacy. Therapeutic modalities have been exploited to elicit antitumor effects based on microenvironment of tumor, including Photodynamic therapy (PDT). Prospection of natural small molecules and nanotechnology are important tools in the development of new ways of obtaining photoactive compounds that are biocompatible. The Betulinic acid (BA) has shown potential biological effect as bioactive drug, but it has low water solubility. Thus, in the present study, owing to the poor solubility of the BA, its free form (BAF) was compared to a spray dried microparticle betulinic acid/HP-β-CD formulation (BAC) aiming to assess the BAF and BAC efficacy as a photosensitizer in PDT for application in ovarian cancer. BAF and BAC were submitted to assays in the presence of LED (λ = 420 nm) under different conditions (2.75 J/cm2, 5.5 J/cm2, and 11 J/cm2) and in absence of irradiation, after 5 min or 4 h of contact with ovarian carcinoma cells (A2780) or fibroblast murine cells (3T3). Furthermore, HPLC-MS/MS and MALDI-MSI methods were developed and validated in plasma and tumor of mice proving suitable for in vivo studies. The results found a greater photoinduced cytotoxic effect for the BAC at low concentration for A2780 when irradiated with LED with similar results for fluorescence microscopy. The results motivate us to continue the studies with the BA as a potential antitumor bioactive compound.

Charge density distribution effect in pyrrolidine-fused chlorins on microbial uptake and antimicrobial photoinactivation of microbial pathogens

Two novels structurally related pyrrolidine-fused chlorins were synthesized from 5,10,15,20-tetrakis(pentafluorophenyl)chlorin by nucleophilic aromatic substitution of the para-fluoro groups. The reaction with 2-dimethylaminoethanol produced TPCF₁₆-NMe₂ in 77% yield, while TPCF₁₆-NBu was obtained using butylamine in 87% yield. The latter was extensively methylated to form TPCF₁₆-N⁺Bu in 92% yield. The synthetic strategy was designed to compare the effect of charge density distribution on chlorin in the efficacy to induce photodynamic inactivation of pathogens. TPCF₁₆-NMe₂ has five tertiary amines that can acquire positive charges in aqueous medium by protonation. Furthermore, four of the cationic groups are located in amino groups linked to the chlorine macrocycle by an aliphatic structure of two carbon atoms, which gives it greater movement capacity. In contrast, TPCF₁₆-N⁺Bu presents intrinsic positive charges on aromatic rings. Absorption and fluorescence emission properties were not affected by the peripheral substitution on the chlorin macrocycle. Both photosensitizers (PSs) were able to form singlet molecular oxygen and superoxide anion radical in solution. Uptake and photodynamic inactivation mediated by these chlorins were examined on Staphylococcus aureus and Escherichia coli. Both phototherapeutic agents produced efficient photoinactivation of S. aureus. However, only TPCF₁₆-NMe₂ was rapidly bound to E. coli cells and this chlorin was effective to photoinactivate both strains of bacteria using lower concentrations and shorter irradiation periods. Our outcomes reveal that the charge density distribution is a key factor to consider in the development of new PSs. Accordingly, this work stands out as a promising starting point for the design of new tetrapyrrolic macrocycles with application in PDI.

Fungal quinones: diversity, producers, and applications of quinones from Aspergillus, Penicillium, Talaromyces, Fusarium, and Arthrinium

Quinones represent an important group of highly structurally diverse, mainly polyketide-derived secondary metabolites widely distributed among filamentous fungi. Many quinones have been reported to have important biological functions such as inhibition of bacteria or repression of the immune response in insects. Other quinones, such as ubiquinones are known to be essential molecules in cellular respiration, and many quinones are known to protect their producing organisms from exposure to sunlight. Most recently, quinones have also attracted a lot of industrial interest since their electron-donating and -accepting properties make them good candidates as electrolytes in redox flow batteries, like their often highly conjugated double bond systems make them attractive as pigments. On an industrial level, quinones are mainly synthesized from raw components in coal tar. However, the possibility of producing quinones by fungal cultivation has great prospects since fungi can often be grown in industrially scaled bioreactors, producing valuable metabolites on cheap substrates. In order to give a better overview of the secondary metabolite quinones produced by and shared between various fungi, mainly belonging to the genera Aspergillus, Penicillium, Talaromyces, Fusarium, and Arthrinium, this review categorizes quinones into families such as emodins, fumigatins, sorbicillinoids, yanuthones, and xanthomegnins, depending on structural similarities and information about the biosynthetic pathway from which they are derived, whenever applicable. The production of these quinone families is compared between the different genera, based on recently revised taxonomy. KEY POINTS: • Quinones represent an important group of secondary metabolites widely distributed in important fungal genera such as Aspergillus, Penicillium, Talaromyces, Fusarium, and Arthrinium. • Quinones are of industrial interest and can be used in pharmacology, as colorants and pigments, and as electrolytes in redox flow batteries. • Quinones are grouped into families and compared between genera according to the revised taxonomy.

A new natural detector for irradiations with blue LED light source in photodynamic therapy measurements via UV-Vis spectroscopy

Photodynamic therapy has been recently studied, bringing innovations regarding the reduction of exposure time to light by the patient. This work aimed to investigate the feasibility of using Coutarea hexandra (Jacq.) K. Schum (CHS) as a detector in photodynamic therapy measurements. For this, an irradiator containing a blue LED bulb lamp was utilized. The CHS samples were irradiated with ten doses from 0.60 up to 6.0 kJ/cm², and six concentrations were prepared (1, 2, 3, 4, 5, and 6 mg/ml) for the CHS detector samples. After irradiation, the detector samples were evaluated using UV-Vis spectrophotometry. The results showed the behavior of the CHS detector with doses and concentrations, its sensitivity, and its linearity was also evaluated both by Wavelength Method (WM) and the Kernel Principal Component Regression (KPCR) Statistical Method. The values obtained indicate that this method can be applied to the CHS sample detector. In conclusion, the CHS is a promising detector in the field of photodynamic therapy.

In Vitro Effect of Photodynamic Therapy with Indocyanine Green Followed by 660 nm Photobiomodulation Therapy on Fibroblast Viability

This in␣vitro study sought to assess the effect of repetitive PBMT on the viability of fibroblasts following aPDT with indocyanine green (ICG). In this in␣vitro experimental study, human gingival fibroblasts (HGFs) were obtained and incubated in a culture medium. After reaching 10 000 cells cm^-2 , the cells were divided into five groups of control, aPDT with ICG and 808 nm (energy density of 24 J cm^-2 ), PBMT immediately after aPDT, PBMT with 660 nm (energy density of 7.2 J cm^-2 ) immediately and 24 h after aPDT and PBMT immediately and 24 and 48 h after aPDT in 48-well plates. Cell viability was evaluated using the methyl thiazolyl tetrazolium (MTT) assay after 1, 4 and 7 days of incubation. Statistical analyses were performed using one-way ANOVA. Cell viability significantly decreased in group 2 (P < 0.002). We observed no significant increase in cell viability at any time point in group 3 (P > 0.05). Cell viability significantly increased in groups 4 and 5 after the first day of incubation (P < 0.000). Emission of 660 nm as PBMT for two and three times along with passage of time would increase the viability of HGFs following aPDT with ICG.

A visible-light-induced, metal-free bis-arylation of 2,5-dichlorobenzoquinone

A metal-free protocol for the direct bis-arylation of 2,5-dichlorobenzoquinone with aryldiazonium salts is reported. The reactive salts are generated in situ and converted to radicals through irradiation with visible light. Reaction products precipitate from the solvent, eliminating the need for purification and thus providing a novel green method for the synthesis of versatile bis-electrophiles.

A Novel Ruthenium(II) Complex With Lapachol Induces G2/M Phase Arrest Through Aurora-B Kinase Down-Regulation and ROS-Mediated Apoptosis in Human Prostate Adenocarcinoma Cells

Lapachol is a well-studied natural product that has been receiving great interest due to its anticancer properties that target oxidative stress. In the present work, two novel lapachol-containing ruthenium(II) complexes [Ru(Lap)(dppm)(bipy)]PF6 (1) and [Ru(Lap)(dppm)(phen)]PF6 (2) [Lap = lapachol, dppm = 1,1'-bis(diphosphino)methane, bipy = 2,2'-bipyridine, phen = 1,10-phenantroline] were synthesized, fully characterized, and investigated for their cellular and molecular responses on cancer cell lines. We found that both complexes exhibited a potent cytotoxic effect in a panel of cancer cell lines in monolayer cultures, as well as in a 3D model of multicellular spheroids formed from DU-145 human prostate adenocarcinoma cells. Furthermore, the complex (2) suppressed the colony formation, induced G2/M-phase arrest, and downregulated Aurora-B. The mechanism studies suggest that complex (2) stimulate the overproduction of reactive oxygen species (ROS) and triggers caspase-dependent apoptosis as a result of changes in expression of several genes related to cell proliferation and caspase-3 and -9 activation. Interestingly, we found that N-acetyl-L-cysteine, a ROS scavenger, suppressed the generation of intracellular ROS induced by complex (2), and decreased its cytotoxicity, indicating that ROS-mediated DNA damage leads the DU-145 cells into apoptosis. Overall, we highlighted that coordination of lapachol to phosphinic ruthenium(II) compounds considerably improves the antiproliferative activities of resulting complexes granting attractive selectivity to human prostate adenocarcinoma cells. The DNA damage response to ROS seems to be involved in the induction of caspase-mediated cell death that plays an important role in the complexes' cytotoxicity. Upon further investigations, this novel class of lapachol-containing ruthenium(II) complexes might indicate promising chemotherapeutic agents for prostate cancer therapy.

Cytotoxic mechanisms of primin, a natural quinone isolated from Eugenia hiemalis, on hematological cancer cell lines

Considering the high morbidity and mortality rates associated with hematological malignancies and the frequent development of drug resistance by these diseases, the search for new cytotoxic agents is an urgent necessity. The new compounds should present higher efficiency and specificity in inducing tumor cell death, be easily administered and have little or negligible adverse effects. Quinones have been reported in the literature by their several pharmacological properties, including antitumor activity, thus, the aim of this study was to investigate the cytotoxic effect of primin, a natural quinone, on hematological malignancies cell lines. Primin was highly cytotoxic against the three cell lines included in this study (K562, Jurkat and MM.1S) in a concentration- and time-dependent manner, as demonstrated by the MTT method. The compound triggered an apoptotic-like cell death, as observed by ethidium bromide/acridine orange staining, DNA fragmentation and phosphatidylserine exposure after labeling with Annexin V. Both intrinsic and extrinsic apoptosis are involved in cell death induced by primin, as well as the modulation of cell proliferation marker KI-67. The activation of intrinsic apoptosis appears to be related to a decreased Bcl-2 expression and increased Bax expression. While the increase in FasR expression signals activate extrinsic apoptosis. The results suggest that primin is a promising natural molecule that could be used in hematological malignancies therapy or as prototypes for the development of new chemotherapics.

Bacteria-specific pro-photosensitizer kills multidrug-resistant Staphylococcus aureus and Pseudomonas aeruginosa

The emergence of multidrug-resistant bacteria has become a real threat and we are fast running out of treatment options. A combinatory strategy is explored here to eradicate multidrug-resistant Staphlococcus aureus and Pseudomonas aeruginosa including planktonic cells, established biofilms, and persisters as high as 7.5 log bacteria in less than 30 min. Blue-laser and thymol together rapidly sterilized acute infected or biofilm-associated wounds and successfully prevented systematic dissemination in mice. Mechanistically, blue-laser and thymol instigated oxidative bursts exclusively in bacteria owing to abundant proporphyrin-like compounds produced in bacteria over mammalian cells, which transformed harmless thymol into blue-laser sensitizers, thymoquinone and thymohydroquinone. Photo-excitations of thymoquinone and thymohydroquinone augmented reactive oxygen species production and initiated a torrent of cytotoxic events in bacteria while completely sparing the host tissue. The investigation unravels a previously unappreciated property of thymol as a pro-photosensitizer analogous to a prodrug that is activated only in bacteria.

Multidrug-resistant bacteria are a real threat to human health. Here, the authors investigate a combinatory strategy using blue-laser and thymol against Staphylococcus aureus and Pseudomonas aeruginosa. Blue-laser and thymol succesfully sterilized acute infected or biofilm-associated wounds and prevented systematic dissemination in mice. Compared with mammalian cells, bacteria contain abundant proporphyrin-like compounds that transform harmless thymol into blue-laser sensitizers, thymoquinone and thymohydroquinone. Photo-excitation of thymoquinone and thymohydroquinone augmented reactive oxygen species production in bacteria while completely sparing the host tissue.

Topical photodynamic therapy in the treatment of benign oral mucosal lesions: A systematic review

BACKGROUND

The introduction of photodynamic therapy (PDT) in various branches of the dental field such as endodontics, implantology, periodontology, and restorative dentistry and oral medicine has become useful in recent decades. This systematic review presents an overview of the literature to evaluate the usefulness of topical PDT for the treatment of benign oral soft tissue lesions and to identify limitations in prior studies to improve PDT applications.

METHODS

We performed a review of the literature using different search engines (PubMed, ISI Web of Science, and the Cochrane Library) employing MeSH terms such as "Photodynamic therapy" and "PDT" in conjunction with other terms. We utilized the Population, Intervention, Comparison, Outcomes, and Study design (PICOS) method to define our study eligibility criteria.

RESULTS

Initial results were 1513. Finally, there were only 21 studies that met our selection criteria. We divided the 21 selected items into two groups: inflammatory diseases and infective diseases.

CONCLUSIONS

Although topical PDT is an easy to perform and well-tolerated treatment and appears to be a valid method with promising results in the treatment of benign lesions of the oral cavity's soft tissues, further studies are needed to complete the current knowledge of this technique.

Unmodified Rose Bengal photosensitizer conjugated with NaYF4:Yb,Er upconverting nanoparticles for efficient photodynamic therapy

In photodynamic therapy (PDT), photosensitizer (PS) molecules are irradiated by light to generate reactive oxygen species (ROS), the presence of which subsequently leads to cell death. At present, the modality is limited to the treatment of skin diseases because of the low tissue penetration of visible or ultraviolet light required for producing ROS. To increase tissue penetration and extend the therapeutic possibilities of PDT to the treatment of deep-seated cancer, rare-earth doped nanoparticles capable of up-converting infrared to visible light are investigated. These up-converting nanoparticles (UCNPs) are conjugated with PS molecules to efficiently generate ROS. In this work, we employ hexagonal β-NaYF₄:Yb^3 +,Er^3 + as UCNPs and Rose Bengal (RB) as PS molecules and demonstrate efficient in vitro PDT using this nanoformulation. Covalent bonding of the RB molecules is accomplished without their functionalization-an approach which is expected to increase the efficiency of ROS generation by 30%. Spectroscopic studies reveal that our approach results in UCNP surface fully covered with RB molecules. The energy transfer from UCNPs to RB is predominantly non-radiative as evidenced by luminescence lifetime measurements. As a result, ROS are generated as efficiently as under visible light illumination. The in vitro PDT is tested on murine breast 4T1 cancer cells incubated with 250 µg ml^-1 of the nanoparticles and irradiated with NIR light under power density of 2 W cm^-2 for 10 minutes. After 24 hours, the cell viability decreased to 33% demonstrating a very good treatment efficiency. These results are expected to simplify the protocols for preparation of the PDT agents and lead to improved therapeutic effects.

Effects of graphene oxide on algal cellular stress response: Evaluating metabolic characters of carbon fixation and nutrient removal

The effects of different concentrations of graphene oxide (GO) on intracellular metabolism in Chlorella vulgaris (C. vulgaris) and removal of nitrogen and phosphorus nutrients by C. vulgaris from synthetic wastewater were studied. The results demonstrated that cell division of Chlorella vulgaris increased at 24 h and decreased at 96 h after exposure to different concentrations of GO. The removal rates of total nitrogen (TN), ammoniacal nitrogen (NH₃-N), phosphate (PO₄^3--P), and chemical oxygen demand (COD) were 24.1%, 70.0%, 37.0%, and 39.6%, respectively, when the concentration of GO was 0.01 mg/L 10 mg/L GO induced severe plasmolysis and cytoplasmic contraction. Furthermore, the protein-like exopolysaccharide (EPS) content of algal cells exposed to 10 mg/L GO decrease to 10.8% of the control group. Simultaneously, the reactive oxygen species (ROS) level was 175.4% of control group. The biological responses to 10 mg/L GO included increase in ROS level, inhibition of saccharide metabolism, and degradation of amino acids. In addition, high concentrations of 10 mg/L GO weakened the carbon fixation process in algal cells. These stress-response behaviors increased cell permeability and oxidative stress. Overall, these findings provide new insights regarding the effects of GO on algal cellular stress responses.

Photoelectrocyclization Reactions of Amidonaphthoquinones

Readily available acrylamide naphthoquinones can be converted into the corresponding aza-anthraquinones using 6π-photoelectrocyclization reactions. Not only do these reactions not proceed thermally but, as demonstrated here, they can also be used to generate a range of aza-anthraquinone and aza-tetracycline derivatives including the natural products griffithazanone A and marcanine A. Several of the aza-anthraquinones generated in this work showed antibacterial activity.