An In Vitro Comparison of Antimicrobial Effects of Curcumin-Based Photodynamic Therapy and Chlorhexidine, on Aggregatibacter actinomycetemcomitans

Non-Thermal Treatment Mediated by Curcumin for Enhancing Food Product Quality

Increasing antibiotic resistance is one of the world's greatest health problems, and biocide use in food disinfection, alongside other application fields, could increase antibiotic resistance. Effective and eco-friendly food decontamination treatment with minimal chemical intervention in food production is urgently needed. Synergistic antimicrobial interaction of photoactive compounds and blue-light-emitting diodes have recently been proven effective in agricultural and environmental applications. Curcumin-based non-thermal treatment has been reviewed in this work for the development of a safe and effective decontamination tool that could be adapted to the food industry. The antimicrobial mechanism of the synergistic interaction and the inhibitory efficacy against foodborne pathogens (bacteria in both vegetative form and spore, as well as in biofilms) are discussed. Further studies on curcumin and its derivative, as well as light illumination patterns, were compared for enhanced bactericidal efficacy. Moreover, studies relating to photodynamic inactivation treatment for food sanitation and food quality enhancement (cereal grains and other food products) were summarized, as well as the impact on food organoleptic and nutritional quality.

Curcumin-mediated photodynamic disinfection strategy with specific spectral range for mucoid Pseudomonas Aeruginosa from hospital water

BACKGROUND

Hospital water systems represent critical environments for the transmission of pathogens, including multidrug-resistant strains like mucoid Pseudomonas aeruginosa (M-PA). Conventional disinfection methods often struggle to eradicate these pathogens effectively, highlighting the need for innovative approaches.

OBJECTIVE

This study aimed to develop an enhanced photodynamic disinfection strategy targeting M-PA from hospital water systems, using curcumin-mediated photodynamic inactivation (PDI) with specific spectral range.

METHODS

An M-PA strain isolated from hospital water was subjected to photodynamic treatment using curcumin as the photosensitizer. The efficacy of different wavelengths of light and varying concentrations of curcumin, with and without Tris-EDTA adjuvants, was evaluated through bacterial enumeration, ROS level measurements, transcriptome analysis, and assessment of virulence factors and biofilm formation. In vivo experiments utilizing a DSS-induced colitis mouse model assessed the protective effects of the photodynamic treatment against M-PA infection.

RESULTS

Our findings demonstrated that the combination of curcumin-mediated PDI with specific spectral range effectively reduced M-PA counts in water, particularly when supplemented with Tris-EDTA. Transcriptome analysis revealed significant downregulation of virulence-related genes under sublethal photodynamic conditions. Furthermore, photodynamic treatment inhibited pyocyanin production and biofilm formation in M-PA, highlighting its potential to disrupt pathogenicity mechanisms. In vivo experiments showed that PDI attenuated M-PA-induced colitis in mice, indicating its protective efficacy.

CONCLUSION

This study presents a promising photodynamic disinfection strategy for combating M-PA from hospital water. By optimizing curcumin-mediated PDI with specific spectral range and adjuvants, our approach demonstrates substantial efficacy in reducing bacterial counts, inhibiting virulence factors, and preventing M-PA-associated colitis.

Reactive Oxygen Species (ROS)-Mediated Antibacterial Oxidative Therapies: Available Methods to Generate ROS and a Novel Option Proposal

The increasing emergence of multidrug-resistant (MDR) pathogens causes difficult-to-treat infections with long-term hospitalizations and a high incidence of death, thus representing a global public health problem. To manage MDR bacteria bugs, new antimicrobial strategies are necessary, and their introduction in practice is a daily challenge for scientists in the field. An extensively studied approach to treating MDR infections consists of inducing high levels of reactive oxygen species (ROS) by several methods. Although further clinical investigations are mandatory on the possible toxic effects of ROS on mammalian cells, clinical evaluations are extremely promising, and their topical use to treat infected wounds and ulcers, also in presence of biofilm, is already clinically approved. Biochar (BC) is a carbonaceous material obtained by pyrolysis of different vegetable and animal biomass feedstocks at 200-1000 °C in the limited presence of O2. Recently, it has been demonstrated that BC's capability of removing organic and inorganic xenobiotics is mainly due to the presence of persistent free radicals (PFRs), which can activate oxygen, H2O2, or persulfate in the presence or absence of transition metals by electron transfer, thus generating ROS, which in turn degrade pollutants by advanced oxidation processes (AOPs). In this context, the antibacterial effects of BC-containing PFRs have been demonstrated by some authors against Escherichia coli and Staphylococcus aureus, thus giving birth to our idea of the possible use of BC-derived PFRs as a novel method capable of inducing ROS generation for antimicrobial oxidative therapy. Here, the general aspects concerning ROS physiological and pathological production and regulation and the mechanism by which they could exert antimicrobial effects have been reviewed. The methods currently adopted to induce ROS production for antimicrobial oxidative therapy have been discussed. Finally, for the first time, BC-related PFRs have been proposed as a new source of ROS for antimicrobial therapy via AOPs.

Photodynamic therapy in periodontitis: A narrative review

BACKGROUND

Periodontitis, a chronic infectious disease, is primarily caused by a dysbiotic microbiome, leading to the destruction of tooth-supporting tissues and tooth loss. Photodynamic therapy (PDT), which combines excitation light with photosensitizers (PS) and oxygen to produce antibacterial reactive oxygen species, is emerging as a promising adjuvant treatment for periodontitis.

METHODS

This review focuses on studies examining the antibacterial effects of PDT against periodontal pathogens. It also explores the impact of PDT on various aspects of periodontal health, including periodontal immune cells, human gingival fibroblasts, gingival collagen, inflammatory mediators, cytokines in the periodontium, vascular oxidative stress, vascular behavior, and alveolar bone health. Clinical trials assessing the types of PSs and light sources used in PDT, as well as its effects on clinical and immune factors in gingival sulcus fluid and the bacterial composition of dental plaque, are discussed.

RESULTS

The findings indicate that PDT is effective in reducing periodontal pathogens and improving markers of periodontal health. It has shown positive impacts on periodontal immune response, tissue integrity, and alveolar bone preservation. Clinical trials have demonstrated improvements in periodontal health and alterations in the microbial composition of dental plaque when PDT is used alongside conventional treatments.

CONCLUSIONS

PDT offers a promising adjunctive treatment for periodontitis, with benefits in bacterial reduction, tissue healing, and immune modulation. This article highlights the potential of PDT in periodontal therapy and emphasizes the need for further research to refine its clinical application and efficacy.

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.

The effect of photodynamic therapy in controlling the oral biofilm: A comprehensive overview

Several resistance mechanisms are involved in dental caries, including oral biofilms. An accumulation of bacteria on the surface of teeth is called plaque. Periodontitis and gingivitis are caused by dental plaque. In this review article, we aimed to review the studies associated with the application of photodynamic therapy (PDT) to prevent and treat various microbial biofilm-caused oral diseases in recent decades. There are several studies published in PubMed that have described antimicrobial photodynamic therapy (APDT) effects on microorganisms. Several in vitro and in vivo studies have demonstrated the potential of APDT for treating endodontic, periodontal, and mucosal infections caused by bacteria as biofilms. Reactive oxygen species (ROS) are activated in the presence of oxygen by integrating a nontoxic photosensitizer (PS) with appropriate wavelength visible light. By causing irreversible damage to microorganisms, ROS induces some biological and photochemical events. Testing several wavelengths has been conducted to identify potential PS for APDT. A standard protocol is not yet available, and the current review summarizes findings from dental studies on APDT.

Application of Different Wavelengths of LED Lights in Antimicrobial Photodynamic Therapy for the Treatment of Periodontal Disease

Therapeutic light has been increasingly used in clinical dentistry for surgical ablation, disinfection, bio-stimulation, reduction in inflammation, and promotion of wound healing. Photodynamic therapy (PDT), a type of phototherapy, has been used to selectively destroy tumor cells. Antimicrobial PDT (a-PDT) is used to inactivate causative bacteria in infectious oral diseases, such as periodontitis. Several studies have reported that this minimally invasive technique has favorable therapeutic outcomes with a low probability of adverse effects. PDT is based on the photochemical reaction between light, a photosensitizer, and oxygen, which affects its efficacy. Low-power lasers have been predominantly used in phototherapy for periodontal treatments, while light-emitting diodes (LEDs) have received considerable attention as a novel light source in recent years. LEDs can emit broad wavelengths of light, from infrared to ultraviolet, and the lower directivity of LED light appears to be suitable for plaque control over large and complex surfaces. In addition, LED devices are small, lightweight, and less expensive than lasers. Although limited evidence exists on LED-based a-PDT for periodontitis, a-PDT using red or blue LED light could be effective in attenuating bacteria associated with periodontal diseases. LEDs have the potential to provide a new direction for light therapy in periodontics.

Dual Action of Curcumin as an Anti- and Pro-Oxidant from a Biophysical Perspective

Curcumin, a natural polyphenol widely used as a spice, colorant and food additive, has been shown to have therapeutic effects against different disorders, mostly due to its anti-oxidant properties. Curcumin also reduces the efficiency of melanin synthesis and affects cell membranes. However, curcumin can act as a pro-oxidant when blue light is applied, since upon illumination it can generate singlet oxygen. Our review aims to describe this dual role of curcumin from a biophysical perspective, bearing in mind its concentration, bioavailability-enhancing modifications and membrane interactions, as well as environmental conditions such as light. In low concentrations and without irradiation, curcumin shows positive effects and can be recommended as a beneficial food supplement. On the other hand, when used in excess or irradiated, curcumin can be toxic. Therefore, numerous attempts have been undertaken to test curcumin as a potential photosensitizer in photodynamic therapy (PDT). At that point, we underline that curcumin-based PDT is limited to the treatment of superficial tumors or skin and oral infections due to the weak penetration of blue light. Additionally, we conclude that an increase in curcumin bioavailability through the using nanocarriers, and therefore its concentration, as well as its topical use if skin is exposed to light, may be dangerous.

In vitro study of nanoliposomes containing curcumin and doxycycline for enhanced antimicrobial photodynamic therapy against Aggregatibacter actinomycetemcomitans

The excessive inappropriate use of systemic antibiotics has contributed to the emergence of antibiotic-resistant pathogens, which pose a significant risk to the success of treatment. This study has approached this problem by developing doxycycline-loaded liposome doped with curcumin (NL-Cur^+Dox) for combination antibacterial therapy against Aggregatibacter actinomycetemcomitans. The characterization of formulation revealed encapsulation of both drugs in NL-Cur^+Dox with an average size of 239 nm and sustained release behavior. Transmission electron microscopy analysis confirmed the vesicular-shaped nanocarriers without any aggregation or crystallization. The cytotoxic and hemolytic activities of NL-Cur^+Dox were evaluated. The anti-biofilm and anti-metabolic effects of NL-Cur^+Dox -mediated antimicrobial photodynamic therapy (aPDT) were examined. The data indicated that NL-Cur^+Dox -mediated aPDT led to a significant reduction of biofilm (82.7%, p = 0.003) and metabolic activity (75%, p < 0.001) of A. actinomycetemcomitans compared to the control. NL-Cur^+Dox had no significant cytotoxicity to human gingival fibroblast cells under selected conditions (p = 0.074). In addition, the hemolytic activity of NL-Cur^+Dox were negligible (< 5%). These findings demonstrate the potential application of such potent formulations in reducing one of the main bacteria causing periodontitis where the NL-Cur^+Dox could be exploited to achieve an improved phototherapeutic efficiency.

A Bibliometric Study on the Top 101 Most-Cited Articles of Dental Journals of the Middle East/North Africa Countries From 2011 to 2021

Introduction: This retrospective descriptive study evaluated the Scopus-indexed dental journals and their most-cited documents affiliated with the Middle East and North Africa (MENA) countries from 2011 to 2021. Methods: Dental journals affiliated with MENA countries, their bibliometric indicators (SJR, CiteScore, SNIP, and H-index), and the 101 most cited articles of the considered journals were extracted and studied through descriptive statistics. In addition, the "citation per year" of each top 101 articles was calculated. Spearman's rho test was used for pairwise comparisons of the correlation coefficient values between each two of the considered bibliometric indicators. Results: The number of citations of the 101 most-cited papers ranged from 35 to 203. The mean (SD) citations of studied articles were 61.33 (37.58) and the median was 46. Furthermore, CiteScore had the highest significant correlation with SJR (r=0.828, P˂0.001). Moreover, the citation per year of the top 101 documents had no significant relationship with any of the journals' bibliometric indicators. Conclusion: Because journal performance and citation rate are multi-dimensional concepts, a single metric cannot express them thoroughly despite correlations between indices. "European Journal of Dentistry" from Turkey, "Saudi Dental Journal" from Saudi Arabia, and "Iranian Endodontic Journal" and "Journal of Lasers in Medical Sciences" both from Iran had the highest ranks in the SCImago portal and the highest scores in bibliometric indices amongst the MENA dental journals.

The Influence of Photodynamic Antimicrobial Chemotherapy on the Microbiome, Neuroendocrine and Immune System of Crustacean Post Larvae

Photodynamic antimicrobial chemotherapy (PACT), employing a combination of light and natural photosensitizer molecules such as curcumin, has been accepted as a safe modality for removing aquatic pathogens which cause diseases such as cholera in humans and vibriosis in aquatic animals. Curcumin and its photodegradation products are generally considered as safe to animals, but the impact of reactive oxygen species (ROS) generated by these products on the growth and survival of organisms at a cellular level has not been studied in detail. The ROS generated by curcumin on photoexcitation using blue light (λ_max 405 nm, 10 mW cm^-2) disinfects more than 80% of free-living Vibrio spp. in the rearing water of Penaeus monodon. However, it is less effective against Vibrio spp. colonized inside P. monodon because the carapace of the animal prevents the transmission of more than 70% of light at the 400-450 nm range and thus reduces the formation of ROS. The influence of curcumin and photoexcited curcumin on the microbiome of P. monodon were revealed by nanopore sequencing. The photoexcited curcumin induced irregular expression of genes coding the moult-inhibiting hormone (MIH), Crustacean hyperglycaemic hormone (CHH)), prophenoloxidase (ProPO), and crustin, which indicates toxic effects of ROS generated by photoexcited curcumin on the neuroendocrine and immune systems of crustaceans, which could alter their growth and survival in aquaculture settings. The study proposed the cautious use of photodynamic therapy in aquaculture systems, and care must be taken to avoid photoexcitation when animals are experiencing moulting or environmental stress.

Effect of curcumin-loaded photoactivatable polymeric nanoparticle on peri-implantitis-related biofilm

Curcumin has been used as a photosensitizer (PS) for antimicrobial photodynamic chemotherapy (PACT). However, its low solubility, instability, and poor bioavailability challenge its in vivo application. This study aimed to synthesize curcumin-loaded polymeric nanoparticles (curcumin-NP) and determine their antimicrobial and cytotoxic effects. Nanoparticles (NP) were synthesized using polycaprolactone (PCL) as a polymer by the nanoprecipitation method. Curcumin-NP was characterized by particle size, polydispersity index and zeta potential, scanning electron microscopy, and curcumin encapsulation efficiency (EE). Curcumin-NP was compared to free curcumin solubilized in 10% DMSO as photosensitizers for PACT in single and multispecies Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus oralis biofilms. Chlorhexidine 0.12% (CHX) and ultrapure water were used as positive and negative controls. The cytotoxic effect of curcumin-NP was evaluated on human periodontal ligament fibroblast cells (HPLF). Data were analyzed by ANOVA (α=0.05). Curcumin-NP exhibited homogeneity and stability in solution, small particle size, and 67.5% EE of curcumin. Curcumin-NP presented reduced antibiofilm activity at 500 µg/ml, although in planktonic cultures it showed inhibitory and bactericidal effect. Curcumin-NP and curcumin with and without photoactivation were not cytotoxic to HPLF cells. Curcumin-NP has antimicrobial and antibiofilm properties, with better effects when associated with blue light, being a promising therapy for preventing and treating peri-implant diseases.

Photodynamic therapy for treatment of infected burns

Burns are among the most debilitating and devastating forms of trauma. Such injuries are influenced by infections, causing increased morbidity, mortality, and healthcare costs. Due to the emergence of multidrug-resistant infectious agents, efficient treatment of infections in burns is a challenging issue. Antimicrobial photodynamic therapy (aPDT) is a promising approach to inactivate infectious agents, including multidrug-resistant. In this review, studies on PubMed were gathered, aiming to summarize the achievements regarding the applications of antimicrobial photodynamic therapy for the treatment of infected burns. A literature search was carried out for aPDT published reports assessment on bacterial, fungal, and viral infections in burns. The collected data suggest that aPDT could be a promising new approach against multidrug-resistant infectious agents. However, despite important results being obtained against bacteria, experimental and clinical studies are necessary yet on the effectiveness of aPDT against fungal and viral infections in burns, which could reduce morbidity and mortality of burned patients, mainly those infected by multidrug-resistant strains.

Biomedical Applications and Bioavailability of Curcumin-An Updated Overview

Curcumin, a yellow-colored molecule derived from the rhizome of Curcuma longa, has been identified as the bioactive compound responsible for numerous pharmacological activities of turmeric, including anticancer, antimicrobial, anti-inflammatory, antioxidant, antidiabetic, etc. Nevertheless, the clinical application of curcumin is inadequate due to its low solubility, poor absorption, rapid metabolism and elimination. Advancements in recent research have shown several components and techniques to increase the bioavailability of curcumin. Combining with adjuvants, encapsulating in carriers and formulating in nanoforms, in combination with other bioactive agents, synthetic derivatives and structural analogs of curcumin, have shown increased efficiency and bioavailability, thereby augmenting the range of applications of curcumin. The scope for incorporating biotechnology and nanotechnology in amending the current drawbacks would help in expanding the biomedical applications and clinical efficacy of curcumin. Therefore, in this review, we provide a comprehensive overview of the plethora of therapeutic potentials of curcumin, their drawbacks in efficient clinical applications and the recent advancements in improving curcumin's bioavailability for effective use in various biomedical applications.

Antimicrobial Effect of Phytochemicals from Edible Plants

Current strategies of combating bacterial infections are limited and involve the use of antibiotics and preservatives. Each of these agents has generally inadequate efficacy and a number of serious adverse effects. Thus, there is an urgent need for new antimicrobial drugs and food preservatives with higher efficacy and lower toxicity. Edible plants have been used in medicine since ancient times and are well known for their successful antimicrobial activity. Often photosensitizers are present in many edible plants; they could be a promising source for a new generation of drugs and food preservatives. The use of photodynamic therapy allows enhancement of antimicrobial properties in plant photosensitizers. The purpose of this review is to present the verified data on the antimicrobial activities of photodynamic phytochemicals in edible species of the world’s flora, including the various mechanisms of their actions.

Blue Light Photodynamic Therapy With Curcumin and Riboflavin in the Management of Periodontitis: A Systematic Review

Introduction: The aim of this article was to evaluate reports in the scientific literature that used antimicrobial photodynamic therapy (aPDT) with a blue light source and curcumin and riboflavin as photosensitizers in the management of periodontitis. Methods: The search was conducted in electronic databases, including PubMed, Web of Science, and Scopus, with the keywords "photodynamic therapy", "antimicrobial photodynamic therapy", "laser activated disinfection", "photoactivated disinfection", "light activated disinfection" "LED", "Periodontitis", "Curcumin", "Riboflavin", and "periodontitis" from 2012 to 2020. Results: After evaluating a total of 24 relevant articles, 13 articles were selected, full texts were read, and the data were extracted and placed in a table. Conclusion: Reviewing articles showed that curcumin as a photosensitizer activated by a blue wavelength is effective in the elimination of the various bacterial species involved in periodontal disease, and to the best of our knowledge, there is no study that has shown this substance does not reduce bacteria. According to the result of the articles, riboflavin as a photosensitizer activated by blue light can reduce bacteria that are involved in periodontitis, but other studies have reported that blue light alone can also reduce bacteria significantly. Therefore, more in-vitro and clinical trial studies are needed to give a more conclusive opinion on the effectiveness of riboflavin as a photosensitizer in the treatment of periodontitis.

Antimicrobial photodynamic therapy against Acinetobacter baumannii

Acinetobacter baumannii (A. baumannii) has emerged as a pathogen of global importance able to cause opportunistic infections on the skin, urinary tract, lungs, and bloodstream, being frequently involved in hospital outbreaks. Such bacterium can resist a variety of environmental conditions and develop resistance to different classes of antibiotics. Antimicrobial photodynamic therapy (aPDT) has been considered a promising approach to overcome bacterial resistance once it does not cause selective environmental pressure on bacteria. In this review, studies on aPDT were accessed on PubMed, and their findings were summarized regarding its efficacy against A. baumannii. The data obtained from the literature show that exogenous photosensitizers belonging to different chemical classes are effective against multidrug-resistant A. baumannii strains. However, most of such data is from in vitro studies, and additional studies are necessary to evaluate if the exogenous photosensitizers may induce selective pressure on A. baumannii and the effectiveness of such photosensitizers in clinical practice.

Follow-up of pressure ulcer treatment with photodynamic therapy, low level laser therapy and cellulose membrane

OBJECTIVE

A pressure ulcer (PU) is an area of tissue trauma caused by continuous and prolonged pressure, often associated with hospitalised patients immobilised due to neurological problems, negatively affecting their quality of life, and burdening the public budget. The aim of this study was to report the follow-up, for 45 weeks, of three patients with neurological lesions due to trauma who subsequently developed PUs, and who were treated with a combination of photodynamic therapy (PDT), low level laser therapy (LLLT) and cellulose membrane (CM).

METHOD

PDT was mediated by the photosensitiser curcumin on a 1.5% emulsion base. Blue LED light at 450 nm was delivered continuously for 12 minutes at an irradiance of 30mW/cm² and total energy delivered to the tissue was 22J/cm². LLLT was performed with 660 nm laser, punctuated and continuous, twice a week with parameters: spot size 0.04cm², power of 40mW, 10 seconds per point, fluence of 10J/cm² and irradiance of 1000mW/cm².

RESULTS

All PUs had a significant reduction (range: 95.2-100%) of their area after 45 weeks of follow-up and two PUs had complete healing at 20 weeks and 30 weeks. All of the PUs showed a reduction in contamination with the PDT treatments in different proportions.

CONCLUSION

From the results obtained, we conclude that the combination of PDT, LLLT and CM is a promising treatment for PU healing.

Effects of Curcumin and Silymarin on the Shigella dysenteriae and Campylobacter jejuni In vitro

OBJECTIVE

Antimicrobial properties of silymarin and curcumin have been assessed against several infectious agents. The aim of this study was to investigate the anti-apoptotic and antibacterial effects of both compounds on the expression of genes among Shigella dysenteriae ATCC 12022 and Campylobacter jejuni subsp. jejuni strain ATCC 33560 standard strains.

METHODS

S. dysenteriae and C. jejuni standard strains were prepared from reference laboratory. Additionally, two clinical multidrug-resistant (MDR) isolates were adopted. Silymarin and curcumin stocks were purchased from Sigma Corporation (USA), and after preparation of dilutions (0.5-512 μg/ml), the minimum inhibitory concentration (MIC) and minimum bactericidal concentrations (MBC) were determined. Furthermore, the effect of 100 μg/ml of each compound was also evaluated on the expression of two gyrB and 16S rRNA housekeeping genes by quantitative real-time PCR (qRT-PCR).

RESULTS

Silymarin MIC and MBC were 512 μg/ml and > 512 μg/ml against S. dysenteriae and > 512μg/ml against C. jejuni standard strains, respectively. Moreover, curcumin MIC and MBC concentrations were 256 μg/ml and 512 μg/ml, respectively for ATCC strains. Silymarin down-expressed the expression of gyrB gene in S. dysenteriae and gyrB and 16srRNA gene in C. jejuni significantly (p < 0.05) compared with unexposed strains. In addition, curcumin could down-express the both gyrB and 16S rRNA genes in both strains significantly (p < 0.05). For two MDR clinical isolates, both MIC and MBC of compounds were > 512 μg/ml. Addition of 100 μg/ml curcumin and silymarin to ampicillin (10 μg/ml) lowered the MIC of MDR S. dysenteriae to 256 μg/ml and 512 μg/ml, respectively. However, no MIC change was observed with regard to C. jejuni.

CONCLUSION

In this study, curcumin and silymarin could inhibit the growth of S. dysenteriae and C. jejuni and 100 μg/ml sub-MIC levels exhibited the suppression of housekeeping genes. Combating pathogenic bacteria by compounds alternative to antibiotics in the era of antibiotic resistance is a proper strategy, though more studies using combinations of them are needed.

Adjuvant effects of curcumin as a photoantimicrobial or irrigant in the non-surgical treatment of periodontitis: Systematic review and meta-analysis

AIM

Curcumin (CUR) has been used clinically in several studies as a subgingival irrigant or as a photoantimicrobial in combination with a blue light-emitting diode (LED) in antimicrobial photodynamic therapy (aPDT) adjuvant to scaling and root planing (SRP). The aim of this study was to assess the effectiveness of CUR as an irrigant or as a photoantimicrobial in conjunction with the blue LED in aPDT adjuvant to SRP, compared to SRP as conventional mechanical treatment.

MATERIALS AND METHODS

Fifteen randomized controlled trials (RCT) were included in a qualitative analysis after researching the databases: PubMed / MEDLINE, SCOPUS, EMBASE, Cochrane Central, Web of Science and Scielo. Manual searches were also performed. Five studies were submitted to quantitative analysis, evaluating periodontal clinical parameters such as probing depth (PD) and clinical attachment level (CAL).

RESULTS

The obtained results have shown clinical benefits in PD reduction and CAL gains at 3 months with the use of CUR as adjuvant therapy to SRP, both as an irrigant or photoantimicrobial, in comparison with SRP monotherapy.

CONCLUSION

Currently, there is evidence that treatment with CUR applied as irrigant or in conjunction with the blue LED as aPDT presents superior clinical results in the short term, for clinical periodontics parameters like as PD reduction and CAL gain, when compared to SRP monotherapy in the non-surgical treatment of periodontitis. However, these results cannot be proven in the long term.

Targeted Photodynamic Treatment of Bacterial Biofilms Using Curcumin Encapsulated in Cells and Cell Wall Particles

Efficient inactivation and removal of pathogenic biofilms in food and biomedical environments remain a significant challenge for food safety applications and medical facilities. This research aims to develop food-grade microcarriers for the targeted delivery of a photosensitizer, curcumin, and photodynamic inactivation of a model pathogenic bacterial biofilm. The microcarriers evaluated in this study include alive yeast cell carriers, deactivated yeast cell carriers, and yeast cell wall particles. The microcarriers were evaluated based on the encapsulation yield of a model photosensitizer (curcumin), binding of the microcarriers to biofilms, and inactivation of the bacteria in the biofilms. The results illustrate that the combination of binding affinity, encapsulation yield, and the intracellular composition of the microcarriers influenced the overall inactivation of bacteria in the biofilms. All of the selected compositions achieved more than 93% inactivation of the bacteria in the biofilm using the photodynamic treatment, and the yeast cell wall particles with curcumin achieved over 99% inactivation of the bacteria in the biofilm matrix. In addition, all of the selected compositions demonstrated significant potential to remove the biofilm from the plastic surface, suggesting the role of binding affinity of the microcarriers in removal of the biofilm from surfaces. Overall, this study developed biomaterial formulations for targeted photodynamic inactivation and potential removal of biofilms.

In vitro antibacterial activity and durability of a nano-curcumin-containing pulp capping agent combined with antimicrobial photodynamic therapy

BACKGROUND

Considering the antibacterial properties of nano-curcumin (nCur) reinforced with antimicrobial photodynamic therapy (aPDT), this study aimed to assess the antibacterial activity and durability of Activa BioActive Base/Liner (ABBL) containing nCur (nCur-ABBL) as a pulp capping agent against Streptococcus mutans, the most common cause of secondary caries.

MATERIALS AND METHODS

In this in vitro experimental study, ABBL discs containing 0.5 %, 1%, 2%, and 5% (w/w) concentrations of nCur were fabricated. After aPDT using light emitting diode (LED) at 435 ± 20 nm wavelength for 5 min, the discs were undergone aging in artificial saliva for 90 days. The antibacterial activity of the discs against S. mutans was evaluated by the disc agar diffusion test, and the number of bacterial colonies present in the biofilm formed on the disc surfaces was counted after 0, 15, 30, and 60 days of aging.

RESULTS

The maximum growth inhibition zone was noted around the 5% nCur-ABBL discs. Increasing the concentration of nCur from 0.5 % to 5% combined with aPDT significantly decreased the number of S. mutans colonies in the biofilm over time (P < 0.05). nCur-ABBL discs containing 2% and 5% nCur had no difference in antibacterial activity at any time point up to 60 days (P > 0.05).

CONCLUSION

According to our data, 5% nCur-ABBL revealed the largest growth inhibition zone in S. mutans culture. Moreover, 5% nCur can serve as an excellent ABBL additive in aPDT producer against S. mutans biofilms up to 60 days of aging period.

Local application of curcumin-loaded nanoparticles as an adjunct to scaling and root planing in periodontitis: Randomized, placebo-controlled, double-blind split-mouth clinical trial

OBJECTIVE

Assess a single local application of curcumin-loaded nanoparticles as an adjunct to scaling and root planing (SRP) in nonsurgical periodontal treatment (NPT).

MATERIALS AND METHODS

Twenty healthy subjects with periodontitis received SRP+PLGA/PLA nanoparticles loaded with 50 μg of curcumin (N-Curc) or SRP+empty nanoparticles. Probing pocket depth (PPD), clinical attachment level (CAL), and bleeding on probing (BOP) were monitored at baseline, 30, 90, and 180 days. IL-1α, IL-6, TNFα, and IL-10 in the gingival crevicular fluid (GCF) were assessed by ELISA, and counts of 40 bacterial species were determined by DNA hybridization at baseline, 3, 7, and 15 days post-therapy.

RESULTS

PPD, CAL, and BOP were similarly and significantly improved in both experimental groups. There was no difference in GCF cytokine levels between experimental groups, although IL-6 was decreased at 3 days only in the N-Curc group. NPT reduced counts of red complex bacterial species in both groups. Veillonella Parvula counts increased significantly only in N-Curc group at 7 days, whereas Aggregatibacter actinomycetemcomitans counts increased significantly only in the control group from day 3 to day 15.

CONCLUSION

We conclude that a single local administration of nanoencapsulated curcumin in periodontally diseased sites had no additive benefits to NPT.

CLINICAL RELEVANCE

Our results showed that a single local application of curcumin-loaded nanoparticles associated with nonsurgical periodontal therapy did not improve clinical outcomes. Hence, our findings do not support the use of curcumin as an adjunct to nonsurgical periodontal therapy.

In vitro antimicrobial effect of curcumin-based photodynamic therapy on Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans

BACKGROUND

Photodynamic therapy (PDT) is a bactericidal method, which has recently been introduced in the field of dental medicine and therapy. Curcumin, a compound isolated from Curcuma longa L., exerts potent phototoxic effects at micromolar concentrations. The aim of our study was to explore the in vitro antimicrobial effect of curcumin-based PDT on two major etiological agents of periodontitis, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans.

METHODS

P. gingivalis ATCC33277 and A. actinomycetemcomitans ATCC24523 suspension was irradiated with blue LED (BL) (450-470 nm, output power density 1.2 W/cm²) for 20-60 s (6-18 J/cm²), treated with curcumin (2 min), or subjected to a combination of curcumin treatment and BL irradiation (60 s, 18 J/cm²). A suspension of chlorhexidine gluconate (CHG) was used as the positive control. All bacterial suspensions used were serially diluted, plated, and incubated anaerobically or microaerobically. The numbers of colony-forming units (CFUs) were counted on day 7. One-way analysis of variance (ANOVA) and Tukey's HSD tests were used for statistical analysis.

RESULTS

BL irradiation at 6, 12, and 18 J/cm² alone reduced the number of CFUs of both P. gingivalis and A. actinomycetemcomitans, but the reduction was not statistically significant. Compared with BL irradiation alone, curcumin solution at 20 μmol/L used alone achieved a lower reduction in the number of CFUs. Combined use of BL at 18 J/cm² 20 μmol/L curcumin treatment yielded a log reduction of 0.43 and 1.51 for P. gingivalis and A. actinomycetemcomitans CFUs, respectively. Suspensions treated with 0.12 % CHG showed a log reduction of 0.29 and 0.28 for P. gingivalis and A. actinomycetemcomitans CFUs, respectively.

CONCLUSIONS

Although the bactericidal and growth-inhibitory effects of BL alone on P. gingivalis and A. actinomycetemcomitans were not significant, A. actinomycetemcomitans was susceptible to photodynamic inactivation by the combination of BL and curcumin.

Biofilm Inactivation using Photodynamic Therapy in Dentistry: a review of literature

Introduction: Photodynamic therapy (PDT) is a therapy involving light and a photosensitising chemical substance, used in conjunction with molecular oxygen in order to elicit cell death (photo-toxicity) and thus ability to kill microbial cells, including bacteria, fungi and viruses. Photodynamic therapy is an alternative method of biofilm disruption and it is considered a new way of microorganism inactivation. It is also an additional procedure to reduce the infection rate in patients, caused by the increasing antimicrobials resistance of bacteria. The aim of this literature review was to evaluate the specific effects and the antibacterial effectiveness of photodynamic therapy using different types of photosensitizers (Erythrosine, Rose Bengal, Toluidine blue, Methylene blue, Ozone, Riboflavin, Curcumin, Chlorhexidine, SAPYR) and a visible light of a specific wavelength for each photosensitizer and to reveal the applications of PDT in periodontics, endodontics, prosthodontics and dental caries. Methods: A research of literature was performed in an attempt to find all the articles published on this topic in the last 10 years. The articles was searched by using a certain combination of different keywords (photodynamic therapy ) and (diode laser ) and (teeth) in PubMed database. Results: A total number of 83 articles were found. After applying inclusion and exclusion criteria, 35 articles were taken into consideration for our study and among them 4 were a manuscript, 3 was a review of literature, 1 was an in vivo evaluation and 27 were in vitro studies. Conclusion: Considering that none of the disinfection methods can completely remove the biofilm, PDT is a therapeutic tool complementary to conventional disinfection, with great applicability in dentistry. PDT showed significantly efficacy in reduction of biofilms. Exposure to light in the presence of a photosensitizing chemical substance helps in the reduction of microbes and the protocols could be recommended for clinical usage, but only together with ‘classic ‘ disinfection.

Photodisinfection effects of silver sulfadiazine nanoliposomes doped-curcumin on Acinetobacter baumannii: a mouse model

Aim: To evaluate the antimicrobial effects of photoexcited silver sulfadiazine nanoliposomes (AgSD-NLs) doped by curcumin (AgSD-NLs@Cur) on Acinetobacter baumannii. Materials & methods: Following characterization, the cytotoxic and hemolytic activities of AgSD-NLs@Cur were evaluated. The antimicrobial activities of AgSD-NLs@Cur-mediated antimicrobial photodynamic therapy (aPDT) were determined. Histopathological examination of the burn wound sites of infected mice treated with photoexcited AgSD-NLs@Cur was assessed. Results: No significant cytotoxic and hemolytic activities were observed. There was a decrease in the Acinetobacter baumannii count in planktonic and biofilm forms and the gene expression level using AgSD-NLs@Cur-aPDT (p < 0.05). Histopathological analysis indicated the epidermis developed markedly and the bacterial load decreased significantly after aPDT. Conclusion: Photoexcited AgSD-NLs@Cur has an antimicrobial potential against A. baumannii.

Modulation of virulence in Enterococcus faecalis cells surviving antimicrobial photodynamic inactivation with reduced graphene oxide-curcumin: An ex vivo biofilm model

BACKGROUND

Enterococcus faecalis, as a major microorganism in persistent/secondary infections of endodontically treated teeth, is less likely to be eliminated during endodontic therapy. In this study, the effect of root canal disinfection and anti-virulence activities of photodynamic inactivation (PDI) of E. faecalis utilizing reduced graphene oxide-curcumin (rGO-Cur) as a photosensitizing agent following irradiation with light-emitting diode (LED), as well as intracellular ROS production were evaluated on ex vivo biofilms of E. faecalis in comparison with sodium hypochlorite (NaOCl) as the traditional endodontic irrigation solution.

MATERIALS AND METHODS

After formulation and confirmation of synthesized rGO-Cur using scanning electron microscopy (SEM), Fourier transformation infrared (FT-IR), UV-Vis spectra, dynamic light scattering (DLS), and Zeta potential, the minimum biofilm inhibitory concentrations (MBICs) and in vitro anti-biofilm activity of rGO-Cur, light-emitting diode (LED) at the wavelength of 435 ± 20 nm, and rGO-Cur-PDI were determined against 4-week-old pre-formed biofilms of E. faecalis. After preparation of ex vivo biofilm model in root canals, the ex-vivo anti-biofilm potential of rGO-Cur, LED, and rGO-Cur-PDI against E. faecalis were analyzed using the XTT assay and scanning electron microscopy (SEM) in comparison with NaOCl. The effects of sub-MBIC of rGO-Cur and NaOCl, sub-lethal dose of LED, and sub-significant inhibitory (SSI) potential of rGO-Cur-PDI for E. faecalis biofilms on virulence genes (efa, esp, gel, and fsr) expression of E. faecalis were analyzed using real-time polymerase chain reaction (qRT-PCR) assay. Intracellular reactive oxygen species (ROS) level was measured in rGO-Cur-PDI-treated bacterial cells compared to control cells with 2',7'-dichlorfluorescein-diacetate (DCFH-DA) fluorescent probe.

RESULTS

The FTIR, DLS, Zeta potential, SEM, and UV-Vis spectra analysis indicated the successful synthesis of rGO-Cur. The MBIC of rGO-Cur was 250 μg/ml, which inhibited the growth ofE. faecalis. LED showed insignificant anti-biofilm activity against E. faecalis even after treating for a long irradiation time (300 s). According to checkerboard assay, the MBIC value of rGO-Cur-PDI was reduced noticeably compared to the individual MBIC values of rGO-Cur and LED for E. faecalis. The expression levels of efa, esp, gel, and fsr genes in pre-formed E. faecalis biofilms were markedly reduced after rGO-Cur, rGO-Cur-PDI, and NaOCl treatment in comparison with the control group. Conversely, LED revealed no significant change in the expression of the virulence genes. The intracellular ROS assay showed a significant increase (8.3-fold) in rGO-Cur-PDI when compared to the control.

CONCLUSION

Our data support that rGO-Cur-PDI showed dual inhibitory effects on biofilm formation ability and virulence activity of E. faecalis with potential clinical applications for infection control in endodontics.

Dual wavelength irradiation antimicrobial photodynamic therapy using indocyanine green and metformin doped with nano-curcumin as an efficient adjunctive endodontic treatment modality

BACKGROUND

Indocyanine green (ICG) doped with nano-curcumin (N-CUR) can increase photosensitivity in antimicrobial photodynamic therapy (aPDT). Since metformin (Met) provides a synergistic advantage with photosensitivity, it was conjugated with N-CUR@ICG. Aim of the study was to evaluate the photosensitizing effect of N-CUR@ICG-Met used as a new photosensitizer in dual wavelengths irradiation (diode laser and light-emitting diode, LED) aPDT in root canals infected with Enterococcus faecalis biofilm.

MATERIALS AND METHODS

Following synthesis and confirmation of N-CUR@ICG-Met by Scanning electrone microscope (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and Zetasizer analysis, the mature microbial biofilm was formed. The quantitative and qualitative evaluations of E. faecalis biofilm were made using microbial viability and SEM analysis of the following groups of treatment modalities (n = 5): 1- N-CUR, 2- ICG, 3- Met, 4- N-CUR@ICG, 5- N-CUR@ICG-Met, 6- Diode laser, 7- LED, 8- aPDT/diode, 9- aPDT/LED, 10- aPDT/diode laser + LED, 11- aPDT/LED + diode laser, 12- 2.5 % sodium hypochlorite (NaOCl). In addition, E. faecalis not treated served as negative control. Data were statistically analyzed using One-way Analysis of Variance (ANOVA) and the post-Hoc Bonferroni tests with a level of significance set at P < 0.05.

RESULTS

SEM, FT-IR, XRD, Zetasizer analysis confirmed successful doping of ICG-Met onto/into N-CUR. The treatment modality of N-CUR@ICG-Met mediated aPDT/diode laser, aPDT/LED, aPDT/diode laser + LED, and aPDT/LED + diode laser statistically decreased the cell viability of E. faecalis for 69.40 %, 75.52 %, 82.74 %, and 83.84 %, respectively compared with the negative control group (P < 0.05). The double wavelengths irradiation technique, which exposed the N-CUR@ICG-Met with diode laser irradiation and immediately after with LED (i.e. group No. 10), as well as, N-CUR@ICG-Met with LED irradiation and immediately after with diode laser (i.e. group No. 11) reduced the viable E. faecalis count in biofilm structures statistically more than the other treatment modalities (P < 0.05).

CONCLUSIONS

N-CUR@ICG-Met as a new photosensitizer in dual wavelengths irradiation method may improve anti-biofilm activity of aPDT against E. faecalis.

Comparison of different laser-based photochemical systems for periodontal treatment

PURPOSE

The main aim in periodontitis treatment is to remove supragingival and subgingival biofilm. Mechanical treatment to eliminate pathogenic bacteria is limited by morphological conditions on the root surface. This study assessed the antibacterial effectiveness of different laser-based photochemical systems, particularly a novel curcumin-based option.

METHODS

Ninety-one titanium bars were inoculated with an artificial biofilm of common pathogenic periodontal bacteria and inserted into an artificial periodontal pocket model. The following groups (n = 13) were tested: 1, curcumin solution plus SLB laser irradiation (C + L; 445 nm, 0.6 W, 25% duty cycle, 100 Hz, 10 s); 2, curcumin solution (Cur); 3, dimethyl sulfoxide solution (DMSO); 4, SiroLaser Blue (SLB) - laser irradiation (445 nm, 0.6 W, 25% duty cycle, 100 Hz, 10 s); 5, antimicrobial photodynamic therapy (aPDT); 6, antimicrobial photothermal therapy (aPTT); 7, control. The samples were stored in Eppendorf tubes and analyzed microbiologically using quantitative real-time polymerase chain reaction (PCR). The main parameter for analyzing group differences was the total bacterial load. Statistical analysis was performed with nonparametric methods.

RESULTS

Statistically significant reductions in bacterial count were observed in all experimental groups (p < 0.05). The mean percentage reductions were as follows: SLB, 95.03%; aPDT, 83.91%; DMSO, 95.69%; C + L, 97.15%. No statistically significant differences in bacteria reduction were observed for laser alone (SLB), DMSO, or curcumin with or without additional laser irradiation.

CONCLUSIONS

The greatest antibacterial efficacy was observed in samples treated with aPTT. Using curcumin as a photosensitizing agent for 445 nm laser irradiation did not result in improved antibacterial effectiveness in comparison with laser alone.

Antimicrobial photodynamic therapy (aPDT) with curcumin and LED, as an enhancement to scaling and root planing in the treatment of residual pockets in diabetic patients: A randomized and controlled split-mouth clinical trial

INTRODUCTION

Residual pockets represent a risk factor for periodontal disease progression. Diabetes Mellitus (DM) may impair prognosis after cause-related therapy, mainly due to the chronic hyperglycemia that negatively influences tissue repair. This study evaluated the clinical efficacy of antimicrobial photodynamic therapy (aPDT) with curcumin (CUR) solution (100 mg/L) and LED irradiation (465-485 nm), as an adjunctive therapy to scaling and root planing (SRP), in the treatment of residual pockets in type 2 diabetic patients.

METHODS

Individuals with type 2 DM and chronic periodontitis presenting at least one residual pocket per quadrant were selected (n = 25). In each patient, all residual pockets with probing depth (PD) ≥5 mm and bleeding on probing (BOP) were allocated to receive, according to quadrant: 1) SRP (SRP group); 2) SRP and irrigation with CUR solution (100 mg/L) (CUR group); 3) SRP and LED irradiation (InGaN, 465-485 nm, 0.78 cm², 78 mW, 100 mW/cm², 60 s) (LED group); 4) SRP, irrigation with CUR solution (100 mg/L), one minute of pre-irradiation, and LED irradiation (InGaN, 465-485 nm, 60 s) (aPDT group). Clinical parameters of PD, gingival recession (GR), clinical attachment level (CAL), BOP and visible plaque index (PI) were evaluated at baseline, three and six months post-therapies. Differences between the examination periods in each group were analyzed by Friedman's test for non-parametric data, while parametric data were submitted to analysis of variance (One-way ANOVA), followed by Tukey's test. Intergroup comparisons were performed by Kruskal-Wallis test.

RESULTS

In an intergroup comparison, the mean values for PD, GR, CAL, BOP and PI were not different at baseline, three and six months (p > 0.05). The intragroup comparison evidenced reduction in PD and BOP in all treatment groups at three and six months (p < 0.05). Significant CAL gain was notable only for the aPDT and LED groups at three months in comparison to baseline data (p < 0.05).

CONCLUSION

Treatment of residual pockets in patients with type 2 DM through association of SRP with aPDT (CUR solution 100 mg/L and LED irradiation) or LED irradiation may yield short-term (three months) clinical benefits regarding CAL gain.

Diacetylcurcumin: a new photosensitizer for antimicrobial photodynamic therapy in Streptococcus mutans biofilms

This study evaluated the effect of antimicrobial photodynamic therapy (aPDT) on S. mutans using diacetylcurcumin (DAC) and verified DAC toxicity. In vitro, S. mutans biofilms were exposed to curcumin (CUR) and DAC and were light-irradiated. Biofilms were collected, plated and incubated for colony counts. DAC and CUR toxicity assays were conducted with Human Gingival Fibroblast cells (HGF). In vivo, G. mellonella larvae were injected with S. mutans and treated with DAC, CUR and aPDT. The hemolymph was plated and incubated for colony counts. Significant reductions were observed when DAC and CUR alone were used and when aPDT was applied. HGF assays demonstrated no differences in cell viability for most groups. DAC and CUR reduced the S. mutans load in G. mellonella larvae both alone and with aPDT. Systematic toxicity assays on G. mellonella demonstrated no effect of DAC and CUR or aPDT on the survival curve.

Photosensitizers in antibacterial photodynamic therapy: an overview

Antibacterial Photodynamic therapy (APDT) is a process utilizing light and light sensitive agents (named photosensitizer (PS)) and is usually applied in an oxygen-rich environment. The energy of the photons is absorbed by the photosensitizer and subsequently transferred to surrounding molecules. Consequently, reactive oxygen species and free radicals are formed. These oxidative molecules can damage bacterial macromolecules such as proteins, lipids and nucleic acids and may result in bacterial killing. Unlike antibiotics, APDT as a novel technique does not lead to the selection of mutant resistant strains, hence it has appealed to researchers in this field. The type of PS used in APDT is a major determinant regarding outcome. In this review, various types of PS that are used in antimicrobial Photodynamic therapy will be discussed. PSs are classified based on their chemical structure and origin. Synthetic dyes such as methylene blue and toluidine blue are the most commonly used photosensitizers in Antibacterial Photodynamic therapy (APDT). Other photosensitizers including natural PSs (e.g. curcumin and hypericin) and tetra-pyrrole structures like phthalocyanines and porphyrins have also been studied. Furthermore, nanostructures and their probable contribution to APDT will be discussed.

Photodynamic therapy with Bixa orellana extract and LED for the reduction of halitosis: study protocol for a randomized, microbiological and clinical trial

BACKGROUND

Halitosis is an unpleasant breath odour that can interfere with the professional life, social life and quality of life of people who suffer from it. A modality of treatment that has been increasing in dentistry is antimicrobial photodynamic therapy (aPDT). Bixa orellana, popularly known as "urucum" is a plant native to Brazil. The seeds are used to produce a dye that is largely used in the food, textile, paint and cosmetic industries. The aim of this study is to verify whether aPDT with Bixa orellana extract and blue light-emitting diodes (LEDs) is effective in reducing halitosis. This method will also be compared with tongue scraping, the most commonly used conventional method for tongue coating removal, and the association of both methods will be evaluated.

METHODS/DESIGN

A randomized clinical trial will be conducted at the dental clinic of the Universidade Nove de Julho. Thirty-nine patients will be divided by block randomization into three groups (n = 13) according to the treatment to be performed. In Group 1, tongue scraping will be performed by the same operator in all patients for analysis of the immediate results. Patients will also be instructed on how to use the scraper at home. Group 2 will be treated with aPDT with Bixa orellana extract and the LED light curing device: Valo Cordless Ultradent®. Six points in the tongue dorsum with a distance of 1 cm between them will be irradiated. The apparatus will be pre-calibrated at wavelength 395-480 nm for 20 s and 9.6 J per point. In Group 3, patients will be submitted to the tongue scraping procedure, as well as to the previously explained aPDT. Oral air collection with the Oral Chroma™ and microbiological collections of the tongue coating shall be done before, immediately after and 7 days after treatment for comparison.

DISCUSSION

Halitosis treatment is a topic that still needs attention. The results of this trial could support decision-making by clinicians regarding aPDT using blue LEDs for treating halitosis on a daily basis, as most dentists already have this light source in their offices.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03346460 . Registered on 17 November 2017.

Inhibitory Effects of Antimicrobial Photodynamic Therapy with Curcumin on Biofilm-Associated Gene Expression Profile of Aggregatibacter actinomycetemcomitans

OBJECTIVES

Periodontitis is an inflammation of periodontal tissues that is caused by the biofilm of periodontal pathogens. Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) is an opportunistic periodontopathogen that can be the cause of periodontal diseases via fimbriae as a virulence factor. In this study, we aimed to determine the expression level of A. actinomycetemcomitans rcpA gene as a virulence factor associated with biofilm formation after antimicrobial photodynamic therapy (aPDT) as a relatively new therapeutic modality.

MATERIALS AND METHODS

To determine sub-lethal doses of aPDT against A. actinomycetemcomitans ATCC 33384 strain, we used curcumin (CUR) as a photosensitizer at a final concentration of 40 μmol/ml, which was excited with a light-emitting diode (LED) at the wavelength of 450 nm. Quantitative real-time polymerase chain reaction (qRT-PCR) was then applied to monitor rcpA gene expression in A. actinomycetemcomitans.

RESULTS

10-40 μmol/ml of CUR caused a significant reduction in the growth of A. actinomycetemcomitans compared to control group (P<0.05). Also, the cell viability of A. actinomycetemcomitans was significantly decreased after more than four minutes of LED irradiation. Therefore, the sub-lethal dose of aPDT against A. actinomycetemcomitans was 5 μmol/ml of CUR with three minutes of LED irradiation at a fluency of 180-240 J/cm², which reduced the expression of the rcpA gene by approximately 8.5-fold.

CONCLUSIONS

aPDT with CUR leads to decreased cell survival and virulence of A. actinomycetemcomitans. Thus, CUR-aPDT can be used as an alternative approach for the successful treatment of periodontitis in vivo.

Synthesis of Hydroxyapatite, β-Tricalcium Phosphate and Biphasic Calcium Phosphate Particles to Act as Local Delivery Carriers of Curcumin: Loading, Release and In Vitro Studies

The successful synthesis of hydroxyapatite (HA), β-Tricalcium phosphate (β-TCP) and two biphasic mixtures (BCPs) of the two was performed by means of wet precipitation. The resulting crystals were characterized and the BCP composition was analyzed and identified as 13% HA-87% TCP and 41% HA-59% TCP. All samples were treated with curcumin solutions, and the degree of curcumin loading and release was found to be proportional to the TCP content of the ceramic. No further cytotoxicity was observed upon MG-63 treatment with the curcumin-loaded ceramics. Finally, the alkaline phosphatase activity of the cells was found to increase with increasing content of TCP, which provides an encouraging proof of concept for the use of curcumin-loaded synthetic biomaterials in bone remodeling.

Photodynamic therapy of Curcuma longa extract stimulated with blue light against Aggregatibacter actinomycetemcomitans

BACKGROUND AND OBJECTIVE

Curcumin, one of an established curcuminoid substances extracted from Curcuma longa, has been used as a photosensitizer (PS) in photodynamic therapy (PDT). Curcuminoid substances has been reported to have benefits in treating dental chronic infection and inflammation diseases, such as chronic periodontitis. The purpose of this study was to find the optimum concentration of Curcuma longa (CL) extract, containing all curcuminoid substances, and the power density of blue light (BL) in photodynamic therapy against periodontally pathogenic bacteria, A. actinomycetemcomitans.

METHODS

Antibacterial activity of various concentrations of CL extract against A. actinomycetemcomitans was determined. Exponentially growing bacteria were combined with 2-fold dilution of CL extract solution ranging from 25 to 0.098 μg/ml. Co-culture bacteria treated with 0.12% chlorhexidine (CHX) served as the positive control. The effect of photostimulation with light emitting diode (LED) 420-480 nm at 16.8 J/cm² for 1 min on the selected concentration of CL extract was examined. Bacteria viability was determined by plate counting technique. In addition, production of free radicals was tested by electron spin resonance spectroscope (ESR) with 5,5-dimethyl-1-pyrroline N-oxide (DMPO).

RESULTS

The antibacterial activity of CL extract was dose dependent. Without BL, 25 μg/ml CL extract showed 6.03 ± 0.39 log₁₀A. actinomycetemcomitans. Interestingly, the combination of BL and 0.78 μg/ml CL extract solution showed complete absence of A. actinomycetemcomitans. Peak signal intensity of hydroxyl radical production was also detected with the combination of BL and CL.

CONCLUSIONS

CL extract not only had antimicrobial activity but also could be used as an effective PS when stimulated with BL in PDT. The optimal antibacterial effect of CL extract with BL was equal to the standard oral disinfectant, 0.12% CHX.

Effect of photoactivation on the reduction of composite resin contamination

Composite resins are predominantly marketed in developing countries in tube form, and the contents of the tube may be used in numerous procedures for different patients. This represents a problem because of the risk of cross-contamination. This study aimed to evaluate contamination in vitro of the internal contents of composite resin tubes in the dental clinics of a higher-education institution, as well as the effect of photoactivation on the level of contamination. Twenty-five tubes containing composite resin were randomly chosen (by lottery). From each tube, two samples of approximately 2 mm of composite resin were removed, and then one sample, but not the other, was photoactivated. These samples were plated on Brain-Heart Infusion (BHI), Sabouraud and MacConkey agars, and the plates were incubated at 37°C for 24-48 h. Colony counting and Gram staining were performed for subsequent microscopic identification of fungi and bacteria. The non-photoactivated composite resin group presented significantly higher microbial contamination in relation to the photoactivated composite resin group. The photoactivation of camphorquinone present in composite resin produces reactive oxygen species, which might promote cell death of contaminant microorganisms. Thus, although the same tube of composite resin may be used for a number of different patients in the dental clinics of developing countries, the photoactivation process potentially reduces the risk of cross-contamination.

Traditionally used herbal medicines with antibacterial effect on Aggegatibacter actinomycetemcomitans: Boswellia serrata and Nigella sativa

Background:

Since bacterial strains developed resistance against commonly used antibiotics and side effects became more serious, other alternatives have been postulated. There is an answer for this issue in ancient medicine. Many plants have been proved to provide antibacterial effect. In this study, Boswellia serrata (BS) and Nigella sativa (NS) were assessed to evaluate the antibacterial effect on Aggregatibacter actinomycetemcomitans (A.a) known as main pathogen of aggressive periodontitis.

Materials and Methods:

Broth microdilution method was used to obtain minimum inhibitory concentration (MIC) of crude extract of BS and NS. Furthermore, the logarithm of colony forming units grown in fresh brain heart infusion bacterial culture was assessed. Three groups including BS+ (containing only BS), NS+ (containing only NS), and BS-NS− (control group) were defined. For each group, the experiment was repeated 12 times.

Results:

MIC of BS and NS were 512 μg/mL and 128 μg/mL, respectively. No growth was observed in our negative control group. The mean ± standard deviation of logarithm of CFU/mL for BS, NS, and control group was 4.32 ± 0.36, 3.61 ± 0.3, and 5.57 ± 0.19, respectively. ANOVA test revealed significant difference (P values < 0.0001) of these groups which was later confirmed using the post hoc test of Tukey's honest significant difference (all P < 0.0001).

Conclusions:

Both BS and NS are effective against A.a which should be taken into account as appropriate ingredient for oral hygiene products.