Aloe-emodin-mediated antimicrobial photodynamic therapy against multidrug-resistant Acinetobacter baumannii: An in vivo study

On the Photosensitizing Properties of Aloe-Emodin in Photodynamic Therapy: Insights from the Molecular Modeling

The photosensitizing properties of aloe-emodin were investigated under physiological conditions using computational chemistry tools. The neutral and monoanionic species were found to coexist in a 98:2 ratio, with dissociation causing a redshift in the absorption spectrum. Aloe-emodin exhibits high two-photon absorption cross-section values within the therapeutic window and significant transition probabilities, making it an efficient two-photon photosensitizer. Excited-state dynamics analysis revealed a triplet state quantum yield of 0.51 for the neutral species and around 0.88-0.89 for the anionic species, with triplet lifetimes of 26.0 s and 0.66 s, respectively. Both species exhibit similar Type I photoreactivity, but the neutral form more effectively oxidizes biomolecules during Type III photoreactivity. Additionally, the neutral species intercalates into DNA, particularly at the AT-TA site, inducing absorption changes and structural nucleotide rearrangements. The computational results align closely with available experimental data, further confirming their reliability.

Aloe-Emodin activated by Photodynamic therapy and diode laser on carious affected dentin and survival of S. mutans. An-invitro SEM assessment

AIMS

To evaluate the effect of different sterilizing agents i.e., Chlorhexidine (CHX), Diode laser (DL) and Aloe-emodin (AE) activated via Photodynamic therapy (PDT) on the viability of Streptococcus mutans (S. mutans) and the shear bond strength (SBS) of self-etch (SE) adhesive to carious affected dentin (CAD) MATERIAL AND METHODS: Forty-four human molars in which carious lesion extends up to the middle third of the dentin ICDAS criteria- 5 were collected and disinfected using 0.5% chloramine Tsolution. To identify the CAD, visual and tactile examinations were used. Specimens were randomly assigned into four experimental cohorts based on cavity disinfection protocol (n=11) Group 1 (No disinfection), Group 2 (CHX), Group 3 (DL), and Group 4 (AE-mediated PDT). Fresh cultures of S.mutans were cultivated on CAD and their survival rate assessment was performed following the type of disinfection. SE adhesive and composite application were performed on CAD following assessment of SBS and failure mode utilizing a universal testing machine (UTM) and stereo microscope respectively. Quantification of resin tags was performed via Scanning electron Microscopy (SEM). One-way ANOVA and Tukey post hoc test were implemented to investigate the statistical variances among different experimental groups (p≤0.05) RESULTS: The lowest survival rate was presented in Group 4 (AE mediated PDT) (1.52±1.32CFU/mL) samples. Whereas, the highest survival was established in control (3.27±0.82 CFU /mL). Group 3 (DL) treated CAD presented the lowest bond strength (7.12±0.03MPa) and shortest resin tag length (53.79±2.32μ m). Whereas, the highest SBS (9.45±0.14MP) and longest resin tags (109.21 ± 1.09μ m) were exhibited by Group 4 (AE-mediated PDT) CONCLUSION: Aloe-Emodin mediated photodynamic therapy could serve as a potent approach for CAD disinfection as it exhibits exceptional antibacterial efficiency and also enhances the bond strength of the self-etch adhesive to carious affected dentin.

Divulging the potency of naturally derived photosensitizers in green PDT: an inclusive review Of mechanisms, advantages, and future prospects

Photodynamic Therapy (PDT) offers a minimally invasive approach for treating various health conditions, employing a photosensitizer (PS) and specific light. Recent enhancements make PDT outpatient-friendly and less discomforting. Effectiveness hinges on selecting the appropriate PS. This article delves into natural and synthetic PSs, emphasizing the rising interest in natural alternatives for their safety. It explores their mechanisms, characteristics, and applications, offering insights into their potential contributions to advancing PDT. This extensive review delves into the preclinical and clinical landscape of natural PSs for PDT, shedding light on their diverse applications and promising outcomes. Compounds like curcumin, piperine, riboflavin, psoralen, hypericin, and others show significant potential in preclinical in vitro studies across various cell lines. In vivo, these photosensitizers prove effective against skin tumors, carcinomas, and sarcomas, inducing apoptosis, autophagy, and ROS generation for therapeutic efficacy. The review underscores the critical role of proper dosing and monitoring in balancing therapeutic benefits and risks. It highlights the advantages and limitations of natural PSs, emphasizing their specific targeting, bioavailability, and limited side effects. The future of PDT holds promising breakthroughs, taking from some evidence like Bergamot oil in nanostructured lipid carriers for dermatological conditions. Second-generation photosensitizer Tookad shows potential in prostate cancer treatment, while Tripterygium wilfordii Hook. F. emerges as an antimicrobial PDT source etc. Thus, environmental concerns in PDT prompt a shift to plant extracts for PS purification. The evidence-supported focus on natural PSs establishes this article as a key resource for advancing natural compounds in PDT and their therapeutic applications.

Aloe-emodin plus TIENAM ameliorate cecal ligation and puncture-induced sepsis in mice by attenuating inflammation and modulating microbiota

Despite the high sepsis-associated mortality, effective and specific treatments remain limited. Using conventional antibiotics as TIENAM (imipenem and cilastatin sodium for injection, TIE) is challenging due to increasing bacterial resistance, diminishing their efficacy and leading to adverse effects. We previously found that aloe-emodin (AE) exerts therapeutic effects on sepsis by reducing systemic inflammation and regulating the gut microbiota. Here, we investigated whether administering AE and TIE post-sepsis onset, using a cecal ligation and puncture (CLP)-induced sepsis model, extends survival and improves physiological functions. Survival rates, inflammatory cytokines, tissue damage, immune cell populations, ascitic fluid microbiota, and key signaling pathways were assessed. Combining AE and TIE significantly enhanced survival rates, and reduced inflammation and bacterial load in septic mice, indicating potent antimicrobial properties. Moreover, substantial improvements in survival rates of AE + TIE-treated mice (10% to 60%) within 168 h were observed relative to the CLP group. This combination therapy also effectively modulated inflammatory marker (interleukin [IL]-6, IL-1β, and tumor necrosis factor [TNF]-α) levels and immune cell counts by decreasing those of B, NK, and TNFR2+ Treg cells, while increasing that of CD8+ T cells; alleviated tissue damage; reduced bacterial load in the peritoneal cavity; and suppressed the NF-κB signaling pathway. We also observed a significantly altered peritoneal cavity microbiota composition post-treatment, characterized by reduced pathogenic bacteria (Bacteroides) abundance. Our findings underscore the potential of AE + TIE in treating sepsis, and encourage further research and possible clinical implementations to surmount the limitations of TIE and amplify the therapeutic potential of AE.

Potential of using medicinal plant extracts as photosensitizers for antimicrobial photodynamic therapy

Antimicrobial photodynamic therapy (APDT) is a promising approach to overcome antimicrobial resistance. However, for widespread implementation of this approach, approved photosensitizers are needed. In this study, we used commercially available preparations (Calendulae officinalis floridis extract, Chamomillae recutitae floridis extract, Achillea millefolii herbae extract; Hypericum perforatum extract; Eucalyptus viminalis folia extract) as photosensitizers for inactivation of gram-negative (Pseudomonas aeruginosa) and gram-positive (Staphylococcus aureus) bacteria. Spectral-luminescent analysis has shown that the major chromophores are of chlorophyll (mainly chlorophyll a and b) and hypericin nature. The extracts are efficient generators of singlet oxygen with quantum yield (γΔ) from 0.40 to 0.64 (reference compound, methylene blue with γΔ = 0.52). In APDT assays, bacteria before irradiation were incubated with extracts for 30 min. After irradiation and 24 h of incubation, colony-forming units (CFU) were counted. Upon exposure of P. aeruginosa to radiation of 405 nm, 590 nm, and 660 nm at equal energy dose of 30 J/cm2 (irradiance - 100 mW/cm2, exposure time - 5 min), the most pronounced effect is observed with blue light (>3 log10 reduction); in case of S. aureus, the effect is approximately equivalent for light of indicated wavelengths and dose (>4 log10 reduction).

Photodynamic inactivation of edible photosensitizers for fresh food preservation: Comprehensive mechanism of action and enhancement strategies

Foodborne harmful bacteria not only cause waste of fresh food, but also pose a major threat to human health. Among many new sterilization and preservation technologies, photodynamic inactivation (PDI) has the advantages of low-cost, broad-spectrum, energy-saving, nontoxic, and high efficiency. In particular, PDI based on edible photosensitizers (PSs) has a broader application prospect due to edible, accessible, and renewable features, it also can maximize the retention of the nutritional characteristics and sensory quality of the food. Therefore, it is meaningful and necessary to review edible PSs and edible PSs-mediated PDI, which can help to arouse interest and concern and promote the further development of edible PSs-mediated PDI in the future field of nonthermally sterilized food preservation. Herein, the classification and modification of edible PSs, PS-mediated in vivo and PS-mediated in vitro mechanism of PDI, strengthening strategy to improve PDI efficiency by the structure change synergistic and multitechnical means, as well as the application in fresh food preservation were reviewed systematically. Finally, the deficiency and possible future perspectives of edible PSs-mediated PDI were articulated. This review aimed to provide new perspective for the future food preservation and microbial control.

New opportunities and perspectives on biosynthesis and bioactivities of secondary metabolites from Aloe vera

Historically, the genus Aloe has been an indispensable part of both traditional and modern medicine. Decades of intensive research have unveiled the major bioactive secondary metabolites of this plant. Recent pandemic outbreaks have revitalized curiosity in aloe metabolites, as they have proven pharmacokinetic profiles and repurposable chemical space. However, the structural complexity of these metabolites has hindered scientific advances in the chemical synthesis of these compounds. Multi-omics research interventions have transformed aloe research by providing insights into the biosynthesis of many of these compounds, for example, aloesone, aloenin, noreugenin, aloin, saponins, and carotenoids. Here, we summarize the biological activities of major aloe secondary metabolites with a focus on their mechanism of action. We also highlight the recent advances in decoding the aloe metabolite biosynthetic pathways and enzymatic machinery linked with these pathways. Proof-of-concept studies on in vitro, whole-cell, and microbial synthesis of aloe compounds have also been briefed. Research initiatives on the structural modification of various aloe metabolites to expand their chemical space and activity are detailed. Further, the technological limitations, patent status, and prospects of aloe secondary metabolites in biomedicine have been discussed.

Photodynamic therapy for treatment of burns: A system review and meta-analysis of animal study

BACKGROUND AND AIM

Burns are common in both everyday life and war. Shock, infection, and organ dysfunction are major complications, among which infection is the most common and has the highest mortality rate. The aim of this study was to evaluate the effect of photodynamic therapy(PDT) on animals suffering from burns.

METHODS

Through searching Embase, PubMed, Web of Science, and the Cochrane Library, only controlled trials were collected to study the effects of PDT on animals with burns. The included studies were evaluated for methodological quality by the MINORS (Methodological Index for Non-Randomized Studies) assessment tool, and the data analysis software was used to analyze the data accordingly.

RESULTS

16 articles were collected between the earliest available date and August 2022. The results of the meta-analysis showed that PDT effectively reduces TNF-α and IL-6 levels in wounds, and increases bFGF and VEGF levels, PDT can also reduce bacterial colonization at the injury site, accelerate the healing of burn wounds, and improve the survival rate.

CONCLUSION

PDT has been shown to have positive effects as a treatment for animals suffering from burns. It affects the levels of cytokines, reduces bacterial counts in wounds, promotes wound healing, and improves animal survival rates.

Aloe-emodin: Progress in Pharmacological Activity, Safety, and Pharmaceutical Formulation Applications

Aloe-emodin (AE) is an anthraquinone derivative and a biologically active component sourced from various plants, including Rheum palmatum L. and Aloe vera. Known chemically as 1,8-dihydroxy-3-hydroxymethyl-anthraquinone, AE has a rich history in traditional medicine and is esteemed for its accessibility, safety, affordability, and effectiveness. AE boasts multiple biochemical and pharmacological properties, such as strong antibacterial, antioxidant, and antitumor effects. Despite its array of benefits, AE's identity as an anthraquinone derivative raises concerns about its potential for liver and kidney toxicity. Nevertheless, AE is considered a promising drug candidate due to its significant bioactivities and cost efficiency. Recent research has highlighted that nanoformulated AE may enhance drug delivery, biocompatibility, and pharmacological benefits, offering a novel approach to drug design. This review delves into AE's pharmacological impacts, mechanisms, pharmacokinetics, and safety profile, incorporating insights from studies on its nanoformulations. The goal is to outline the burgeoning research in this area and to support the ongoing development and utilization of AE-based therapies.

Polyphenolic natural products as photosensitizers for antimicrobial photodynamic therapy: recent advances and future prospects

Antimicrobial photodynamic therapy (aPDT) has become a potent contender in the fight against microbial infections, especially in the context of the rising antibiotic resistance crisis. Recently, there has been significant interest in polyphenolic natural products as potential photosensitizers (PSs) in aPDT, given their unique chemical structures and inherent antimicrobial properties. Polyphenolic natural products, abundant and readily obtainable from natural sources, are generally regarded as safe and highly compatible with the human body. This comprehensive review focuses on the latest developments and future implications of using natural polyphenols as PSs in aPDT. Paramount polyphenolic compounds, including curcumin, hypericin, quercetin, hypocrellin, celastrol, riboflavin, resveratrol, gallic acid, and aloe emodin, are elaborated upon with respect to their structural characteristics, absorption properties, and antimicrobial effects. Furthermore, the aPDT mechanism, specifically its targeted action on microbial cells and biofilms, is also discussed. Polyphenolic natural products demonstrate immense potential as PSs in aPDT, representing a promising alternate approach to counteract antibiotic-resistant bacteria and biofilm-related infections.

Effect of photodynamic therapy on multidrug-resistant Acinetobacter baumannii: A scoping review

BACKGROUND

Acinetobacter baumannii is a Gram-negative, non-fermenting coccobacillus of the Moraxellaceae family. It is an opportunistic pathogen responsible for several hospital-acquired infections (HAIs) associated with skin and tissue infections at surgical sites, catheter-associated urinary tract infections, and central line catheters. Multidrug-resistant (MDR) A. baumannii has caused hospital outbreaks that are difficult to eradicate and represent one of the leading producers of HAIs. MDR-A. baumannii presents a broad range of resistance to different antimicrobials, including carbapenems. Due to the low sensitivity to conventional antibiotic therapies, it is necessary to identify other therapeutic options. Antimicrobial photodynamic therapy (aPDT) is a promising alternative and complementary approach to address the shortage of antimicrobials in MDR-A. baumannii. APDT combines a photosensitizer agent, light, and oxygen to achieve a bactericidal/bacteriostatic effect. The effect is given by producing reactive oxygen species (ROS) that produce photooxidative stress over bacterial structures, such as the envelope and the DNA.

METHODS

This study aims to systematically collect bibliographic information from databases such as PubMed, Scopus, and google scholar to analyze the relevant articles critically.

RESULTS

An increasing body of evidence demonstrates the efficacy of photodynamic inactivation in eliminating A. baumannii strains, both in vitro and in vivo.

CONCLUSIONS

The evidence supports that photodynamic inactivation is an alternative capable of eliminating strains of Acinetobacter baumannii and may considerably improve the treatment of MDR strains. Although they do exist, aPDT studies on MDR strains of A. baumannii are scarce and should increase since it is on these strains that photodynamic therapy becomes attractive.

Aloe-Emodin Ameliorates Cecal Ligation and Puncture-Induced Sepsis

Sepsis remains a major challenge owing to its severe adverse effects and high mortality, against which specific pharmacological interventions with high efficacy are limited. Mitigation of hyperactive inflammatory responses is a key factor in enhancing the likelihood of survival in patients with sepsis. The Aloe genus has several health benefits, including anti-inflammatory properties. The toxicological implications of aloe-emodin (AE), extracted from various Aloe species, remain uncertain in clinical contexts. However, AE has been shown to inhibit inflammatory responses in lipopolysaccharide-induced mice, indicating its potential as a therapeutic approach for sepsis treatment. Nonetheless, there is a paucity of data regarding the therapeutic benefits of AE in the widely recognized cecal ligation and puncture (CLP)-induced sepsis model, which is commonly used as the gold standard model for sepsis research. This study demonstrates the potential benefits of AE in the treatment of CLP-induced sepsis and investigates its underlying mechanism, along with the efficacy of postoperative AE treatment in mice with CLP-induced sepsis. The results of this study suggest that AE can mitigate sepsis in mice by diminishing systemic inflammation and regulating the gut microbiota. The study provides novel insights into the molecular mechanisms underlying the anti-inflammatory effects of AE.

Biomimetic photosensitizer nanocrystals trigger enhanced ferroptosis for improving cancer treatment

As a novel non-apoptotic cell death pathway, ferroptosis can effectively enhance the antitumor effects of photodynamic therapy (PDT) by disrupting intracellular redox homeostasis. However, the reported nanocomposites that combined the PDT and ferroptosis are cumbersome to prepare, and the unfavorable tumor microenvironment also severely interferes with their tumor suppressive effects. To address this inherent barrier, this study attempted to explore photosensitizers that could activate ferroptosis pathway and found that the photosensitizer aloe-emodin (AE) could induce cellular ferroptosis based on its specific inhibiting activity to Glutathione S-transferase P1(GSTP1), a key protein for ferroptosis. Herein, we prepared AE@RBC/Fe nanocrystals (NCs) with synergistic PDT and ferroptosis therapeutic effects by one-step emulsification to obtain AE NCs cores and further modification of red blood cells (RBC) membranes and ferritin. Benefiting from the involvement of ferritin, the prepared AE@RBC/Fe NCs provide not only sufficient oxygen for oxygen-dependent PDT, but also Fe3+ for iron-dependent ferroptosis in tumor cells. Furthermore, the biomimetic surface functionalization facilitated the prolonged circulation and cancer targeting of AE@RBC/Fe NCs in vivo. The in vitro and in vivo results demonstrate that AE@RBC/Fe NCs exhibit significantly enhanced therapeutic effects for the combined two antitumor mechanisms and provide a promising prospect for achieving PDT/ferroptosis synergistic therapy.

Photodynamic therapy and combinatory treatments for the control of biofilm-associated infections

The advent of antimicrobial resistance has added considerable impact to infectious diseases both in the number of infections and healthcare costs. Furthermore, the relentless emergence of multidrug-resistant bacteria, particularly in the biofilm state, has made mandatory the discovery of new alternative antimicrobial therapies that are capable to eradicate resistant bacteria and impair the development of new forms of resistance. Amongst the therapeutic strategies for treating biofilms, antimicrobial photodynamic therapy (aPDT) has shown great potential in inactivating several clinically relevant micro-organisms, including antibiotic-resistant 'priority bacteria' declared by the WHO as critical pathogens. Its antimicrobial effect is centred on the basis that harmless low-intensity light stimulates a non-toxic dye named photosensitizer, triggering the production of reactive oxygen species upon photostimulation. In addition, combination therapies of aPDT with other antimicrobial agents (e.g. antibiotics) have also drawn considerable attention, as it is a multi-target strategy. Therefore, the present review highlights the recent advances of aPDT against biofilms, also covering progress on combination therapy.

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.

Evaluation of antimicrobial effects of photo-sonodynamic antimicrobial chemotherapy based on nano-micelle curcumin on virulence gene expression patterns in Acinetobacter baumannii

BACKGROUND

Abaumannii baumannii rapidly resistance to a wide range of antimicrobial agents. The combination of antimicrobial photodynamic therapy (aPDT) and sonodynamic antimicrobial chemotherapy (SACT) known as photo-sonodynamic antimicrobial chemotherapy (PSACT) has received considerable attention as one of the emerging and promising strategies against microbial infections.

OBJECTIVE

This study aimed to investigate the antimicrobial effects of PSACT based on nano-micelle curcumin (N-MCur) on the virulence gene expression patterns in A. baumannii.

MATERIALS AND METHODS

N-MCur as a photo-sonosensitizer was synthesized and confirmed. To determine sub-significant reduction dose of PSACT, sub-significant reduction dose of N-MCur and blue laser light during aPDT, and ultrasound power output during SACT were assessed. Finally, changes in the expression of genes involved in treated A. baumannii by minimum sub-significant reduction dose of PSACT were determined using quantitative real-time-PCR (qRT-PCR).

RESULTS

PSACT using 12.5 mM N-MCur at the ultrasound power outputs of 28.7, 36.9, and 45.2 mW/cm2 with 4 min irradiation time of blue laser, as well as, 6.2 mM N-MCur at an ultrasound power output of 45.2 mW/cm2 plus 3 min blue laser irradiation time exhibited the significant dose-dependent reduction against A. baumannii cell viability compared to the control group (P<0.05). After treatment of A. baumannii using 3.1 mM N-MCur + 2 min blue laser irradiation time + 28.7 mW/cm2 ultrasound as the minimum sub-significant reduction doses of PSACT, mRNA expression was significantly upregulated to 6.0-, 11.2-, and 13.7-folds in recA, blsA, and dnaK and downregulated to 8.6-, 10.1-, and 14.5-folds in csuE, espA, and abaI, respectively.

CONCLUSIONS

N-MCur-mediated PSACT could regulate the expression of genes involved in A. baumannii pathogenesis. Therefore, PSACT can be proposed as a promising application to treat infections caused by A. baumannii.

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.

Phototherapy and optical waveguides for the treatment of infection

With rapid emergence of multi-drug resistant microbes, it is imperative to seek alternative means for infection control. Optical waveguides are an auspicious delivery method for precise administration of phototherapy. Studies have shown that phototherapy is promising in fighting against a myriad of infectious pathogens (i.e. viruses, bacteria, fungi, and protozoa) including biofilm-forming species and drug-resistant strains while evading treatment resistance. When administered via optical waveguides, phototherapy can treat both superficial and deep-tissue infections while minimizing off-site effects that afflict conventional phototherapy and pharmacotherapy. Despite great therapeutic potential, exact mechanisms, materials, and fabrication designs to optimize this promising treatment option are underexplored. This review outlines principles and applications of phototherapy and optical waveguides for infection control. Research advances, challenges, and outlook regarding this delivery system are rigorously discussed in a hope to inspire future developments of optical waveguide-mediated phototherapy for the management of infection and beyond.

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.

Natural Photosensitizers in Antimicrobial Photodynamic Therapy

Health problems and reduced treatment effectiveness due to antimicrobial resistance have become important global problems and are important factors that negatively affect life expectancy. Antimicrobial photodynamic therapy (APDT) is constantly evolving and can minimize this antimicrobial resistance problem. Reactive oxygen species produced when nontoxic photosensitizers are exposed to light are the main functional components of APDT responsible for microbial destruction; therefore, APDT has a broad spectrum of target pathogens, such as bacteria, fungi, and viruses. Various photosensitizers, including natural extracts, compounds, and their synthetic derivatives, are being investigated. The main limitations, such as weak antimicrobial activity against Gram-negative bacteria, solubility, specificity, and cost, encourage the exploration of new photosensitizer candidates. Many additional methods, such as cell surface engineering, cotreatment with membrane-damaging agents, nanotechnology, computational simulation, and sonodynamic therapy, are also being investigated to develop novel APDT methods with improved properties. In this review, we summarize APDT research, focusing on natural photosensitizers used in in vitro and in vivo experimental models. In addition, we describe the limitations observed for natural photosensitizers and the methods developed to counter those limitations with emerging technologies.