Photodynamic inactivation of E. coli with cationic imidazolyl-porphyrin photosensitizers and their synergic combination with antimicrobial cinnamaldehyde.

Bacterial infections are a global health concern, particularly due to the increasing resistance of bacteria to antibiotics. Multi-drug resistance (MDR) is a considerable challenge, and novel approaches are needed to treat bacterial infections. Photodynamic inactivation (PDI) of microorganisms is increasingly recognized as an effective method to inactivate a broad spectrum of bacteria and overcome resistance mechanisms. This study presents the synthesis of a new cationic 5,15-di-imidazolyl porphyrin derivative and the impact of n-octanol/water partition coefficient (logP) values of this class of photosensitizers on PDI efficacy of Escherichia coli. The derivative with logP = -0.5, IP-H-OH2+, achieved a remarkable 3 log CFU reduction of E. coli at 100 nM with only 1.36 J/cm2 light dose at 415 nm, twice as effective as the second-best porphyrin IP-H-Me2+, of logP = -1.35. We relate the rapid uptake of IP-H-OH2+ by E. coli to improved PDI and the very low uptake of a fluorinated derivative, IP-H-CF32+, logP ≈ 1, to its poor performance. Combination of PDI with cinnamaldehyde, a major component of the cinnamon plant known to alter bacteria cell membranes, offered synergic inactivation of E. coli (7 log CFU reduction), using 50 nM of IP-H-OH2+ and just 1.36 J/cm2 light dose. The success of combining PDI with this natural compound broadens the scope of therapies for MDR infections that do not add drug resistance. In vivo studies on a mouse model of wound infection showed the potential of cationic 5,15-di-imidazolyl porphyrins to treat clinically relevant infected wounds.

Selective, broad-spectrum antiviral photodynamic disinfection with dicationic imidazolyl chlorin photosensitizers.

The COVID-19 pandemic exposes our vulnerability to viruses that acquire the ability to infect our cells. Classical disinfection methods are limited by toxicity. Existing medicines performed poorly against SARS-CoV-2 because of their specificity to targets in different organisms. We address the challenge of mitigating known and prospective viral infections with a new photosensitizer for antimicrobial photodynamic therapy (aPDT). Photodynamic inactivation is based on local oxidative stress, which is particularly damaging to enveloped viruses. We synthesized a cationic imidazolyl chlorin that reduced by > 99.999% of the percentage inhibition of amplification of SARS-CoV-2 collected from patients at 0.2 µM concentration and 4 J cm-2. Similar results were obtained in the prevention of infection of human ACE2-expressing HEK293T cells by a pseudotyped lentiviral vector exhibiting the S protein of SARS-CoV-2 at its surface. No toxicity to human epidermal keratinocytes (HaCaT) cells was found under similar conditions. aPDT with this chlorin offers fast and safe broad-spectrum photodisinfection and can be repeated with low risk of resistance.

Avoiding ventilator-associated pneumonia: Curcumin-functionalized endotracheal tube and photodynamic action.

Hospital-acquired infections are a global health problem that threatens patients' treatment in intensive care units, causing thousands of deaths and a considerable increase in hospitalization costs. The endotracheal tube (ETT) is a medical device placed in the patient's trachea to assist breathing and delivering oxygen into the lungs. However, bacterial biofilms forming at the surface of the ETT and the development of multidrug-resistant bacteria are considered the primary causes of ventilator-associated pneumonia (VAP), a severe hospital-acquired infection for significant mortality. Under these circumstances, there has been a need to administrate antibiotics together. Although necessary, it has led to a rapid increase in bacterial resistance to antibiotics. Therefore, it becomes necessary to develop alternatives to prevent and combat these bacterial infections. One possibility is to turn the ETT itself into a bactericide. Some examples reported in the literature present drawbacks. To overcome those issues, we have designed a photosensitizer-containing ETT to be used in photodynamic inactivation (PDI) to avoid bacteria biofilm formation and prevent VAP occurrence during tracheal intubation. This work describes ETT's functionalization with curcumin photosensitizer, as well as its evaluation in PDI against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli A significant photoinactivation (up to 95%) against Gram-negative and Gram-positive bacteria was observed when curcumin-functionalized endotracheal (ETT-curc) was used. These remarkable results demonstrate this strategy's potential to combat hospital-acquired infections and contribute to fighting antimicrobial resistance.

Unraveling the Pivotal Role of Atropisomerism for Cellular Internalization.

The intrinsic challenge of large molecules to cross the cell membrane and reach intracellular targets is a major obstacle for the development of new medicines. We report how rotation along a single C-C bond, between atropisomers of a drug in clinical trials, improves cell uptake and therapeutic efficacy. The atropisomers of redaporfin (a fluorinated sulfonamide bacteriochlorin photosensitizer of 1135 Da) are separable and display orders of magnitude differences in photodynamic efficacy that are directly related to their differential cellular uptake. We show that redaporfin atropisomer uptake is passive and only marginally affected by ATP depletion, plasma proteins, or formulation in micelles. The α4 atropisomer, where meso-phenyl sulfonamide substituents are on the same side of the tetrapyrrole macrocycle, exhibits the highest cellular uptake and phototoxicity. This is the most amphipathic atropisomer with a conformation that optimizes hydrogen bonding (H-bonding) with polar head groups of membrane phospholipids. Consequently, α4 binds to the phospholipids on the surface of the membrane, flips into the membrane to adopt the orientation of a surfactant, and eventually diffuses to the interior of the cell (bind-flip mechanism). We observed increased α4 internalization by cells of the tumor microenvironment in vivo and correlated this to the response of photodynamic therapy when tumor illumination was performed 24 h after α4 administration. These results show that properly orientated aryl sulfonamide groups can be incorporated into drug design as efficient cell-penetrating motifs in vivo and reveal the unexpected biological consequences of atropisomerism.

Photodynamic therapy with redaporfin targets the endoplasmic reticulum and Golgi apparatus.

Preclinical evidence depicts the capacity of redaporfin (Redp) to act as potent photosensitizer, causing direct antineoplastic effects as well as indirect immune-dependent destruction of malignant lesions. Here, we investigated the mechanisms through which photodynamic therapy (PDT) with redaporfin kills cancer cells. Subcellular localization and fractionation studies based on the physicochemical properties of redaporfin revealed its selective tropism for the endoplasmic reticulum (ER) and the Golgi apparatus (GA). When activated, redaporfin caused rapid reactive oxygen species-dependent perturbation of ER/GA compartments, coupled to ER stress and an inhibition of the GA-dependent secretory pathway. This led to a general inhibition of protein secretion by PDT-treated cancer cells. The ER/GA play a role upstream of mitochondria in the lethal signaling pathway triggered by redaporfin-based PDT Pharmacological perturbation of GA function or homeostasis reduces mitochondrial permeabilization. In contrast, removal of the pro-apoptotic multidomain proteins BAX and BAK or pretreatment with protease inhibitors reduced cell killing, yet left the GA perturbation unaffected. Altogether, these results point to the capacity of redaporfin to kill tumor cells via destroying ER/GA function.

Photodynamic disinfection of SARS-CoV-2 clinical samples using a methylene blue formulation.

The amplitude of the coronavirus disease 2019 (COVID-19) pandemic motivated global efforts to find therapeutics that avert severe forms of this illness. The urgency of the medical needs privileged repositioning of approved medicines. Methylene blue (MB) has been in clinical use for a century and proved especially useful as a photosensitizer for photodynamic disinfection (PDI). We describe the use of MB to photo-inactivate SARS-CoV-2 in samples collected from COVID-19 patients. One minute of treatment can reduce the percentage inhibition of amplification by 99.99% under conditions of low cytotoxicity. We employed a pseudotyped lentiviral vector (LVs) encoding the luciferase reporter gene and exhibiting the S protein of SARS-CoV-2 at its surface, to infect human ACE2-expressing HEK293T cells. Pre-treatment of LVs with MB-PDI prevented infection at low micromolar MB concentrations and 1 min of illumination. These results reveal the potential of MB-PDI to reduce viral loads in the nasal cavity and oropharynx in the early stages of COVID-19, which may be employed to curb the transmission and severity of the disease.

Efficient dermal delivery of ascorbic acid 2-glucoside with photoacoustic waves.

OBJECTIVE: Ascorbic acid (i.e., vitamin C) is an important antioxidant present in skin. The protective role of vitamin C against photoaging motivated numerous attempts to promote its topical delivery, with a success limited by its chemical instability and poor skin permeability. Vitamin C precursors, such as ascorbic acid 2-glucoside (AA2G), which are metabolized to vitamin C by enzymes present in the skin, solve the problem of stability but are limited by low skin permeability. We developed a 2% (w/v) gel formulation of AA2G application (viscosity 4.30 × 104 Pa.s, pH 5.94) and compared its passive dermal delivery with the delivery promoted by photoacoustic waves that transiently perturb the skin barrier. METHODS: Photoacoustic (PA) waves were generated by laser pulses absorbed by piezophotonic (light-to-pressure) transducers. Pig skin samples were exposed to the 2% AA2G formulation alone or combined with 5 min of PA waves. One hour later, AA2G was extracted from the skin and quantified by reverse-phase HPLC. AA2G transdermal fluxes using Franz cells with 760 µm thick pig skin samples were also measured. RESULTS: Photoacoustic waves transiently enhanced skin permeability and increased dermal delivery of AA2G. AA2G was released from the formulation nearly quantitatively (92.6 ± 6.2%) in 24 h, showing a non-Fickian behaviour controlled by diffusion and swelling. AA2G dermal delivery with exposure for 5 min to PA waves was compared with passive delivery to pig skin. PA waves increased the delivery of AA2G to the skin by a factor of 15-fold with respect to passive delivery, as measured from skin extracts after 1 h of contact of the formulation with the skin. CONCLUSION: Five minutes of exposure to PA waves is a safe and effective method to deliver large quantities of AA2G to the skin.

OBJECTIF: L'acide ascorbique (c.-à-d. la vitamine C) est un antioxydant important présent dans la peau. Le rôle protecteur de la vitamine C contre le photovieillissement a motivé de nombreuses tentatives pour favoriser son administration topique, avec un succès limité par son instabilité chimique et sa mauvaise perméabilité cutanée. Les précurseurs de la vitamine C, tels que l'acide ascorbique 2-glucoside (AA2G), qui sont métabolisés en vitamine C par les enzymes présentes dans la peau, résolvent le problème de stabilité, mais sont limités par une faible perméabilité de la peau. Nous avons développé une formulation type gel à 2 % (p/v) d'AA2G (viscosité 4,30 × 104 Pa.s, pH 5,94) et comparé son administration dermique passive à l'administration favorisée par des ondes photoacoustiques qui perturbent transitoirement la barrière cutanée. MÉTHODES: Les ondes photoacoustiques (PA) ont été générées par des impulsions laser absorbées par des transducteurs piézophotoniques (lumière vers pression). Des échantillons de peau de porc ont été exposés à la formulation d'AA2G à 2 % seule ou associée à 5 min d'ondes PA. Une heure plus tard, l'AA2G a été extrait de la peau et quantifié par chromatographie en phase liquide à haute performance en phase inverse. Les flux transdermiques d'AA2G utilisant des cellules de Franz avec des échantillons de peau de porc épaisse de 760 µm ont également été mesurés. RÉSULTATS: Les ondes photoacoustiques ont amélioré transitoirement la perméabilité de la peau et augmenté l'administration dermique d'AA2G. L'AA2G a été libéré de la formulation presque quantitativement (92,6 ± 6,2 %) en 24 h, montrant un comportement non-Fickian contrôlé par diffusion et gonflement. L'administration cutanée d'AA2G avec une exposition de 5 min aux ondes PA a été comparée à l'administration passive sur peau de porc. Les ondes PA ont augmenté l'administration d'AA2G dans la peau d'un facteur de 15 concernant l'administration passive, mesurée à partir d'extraits cutanés après 1 h de contact de la formulation avec la peau. CONCLUSIONS: Cinq minutes d'exposition aux ondes PA est une méthode sûre et efficace pour administrer de grandes quantités d'AA2G dans la peau.

Photodynamic disinfection and its role in controlling infectious diseases.

Photodynamic therapy is witnessing a revival of its origins as a response to the rise of multi-drug resistant infections and the shortage of new classes of antibiotics. Photodynamic disinfection (PDDI) of microorganisms is making progresses in preclinical models and in clinical cases, and the perception of its role in the clinical armamentarium for the management of infectious diseases is changing. We review the positioning of PDDI from the perspective of its ability to respond to clinical needs. Emphasis is placed on the pipeline of photosensitizers that proved effective to inactivate biofilms, showed efficacy in animal models of infectious diseases or reached clinical trials. Novel opportunities resulting from the COVID-19 pandemic are briefly discussed. The molecular features of promising photosensitizers are emphasized and contrasted with those of photosensitizers used in the treatment of solid tumors. The development of photosensitizers has been accompanied by the fabrication of a variety of affordable and customizable light sources. We critically discuss the combination between photosensitizer and light source properties that may leverage PDDI and expand its applications to wider markets. The success of PDDI in the management of infectious diseases will ultimately depend on the efficacy of photosensitizers, affordability of the light sources, simplicity of the procedures, and availability of fast and efficient treatments.

Singlet Exciton Fission and Associated Enthalpy Changes with a Covalently Linked Bichromophore Comprising TIPS-Pentacenes Held in an Open Conformation.

A covalently linked bichromophore, embracing 6,13-bis(triisopropylsilylethinyl)pentacene (TIPS-pentacene) terminals bridged by a rigid fluorene spacer, generates a relatively high yield (i.e., 65 ± 6%) of the spin-correlated, triplet biexciton upon illumination in toluene. Under the same conditions, the extent of fluorescence quenching relative to the parent TIPS-pentacene approaches 97% and is insensitive to temperature. The biexciton, having overall singlet spin multiplicity, undergoes internal conversion in competition to spin decorrelation. These latter processes occur on the relatively slow time scale of a hundred or so nanoseconds, possibly reflecting the restricted level of electronic communication between the terminals. Spin decorrelation leads to evolution of an independent triplet pair with an overall quantum yield of 0.50 ± 0.06 and a lifetime of 8 ± 2 µs in deaerated toluene. Photoacoustic calorimetry (PAC) indicates three separate enthalpy changes: a very fast step associated with intramolecular singlet exciton fission to form the correlated triplet biexciton, a fast step essentially reflecting spin decorrelation, and a slow step associated with relaxation of the independent triplet pair. Analysis of the PAC data, in conjunction with the transient absorption results, establishes excitation energies for both spin-correlated and independent triplet pairs. Polar solvent enhances both fluorescence quenching and triplet formation at the expense of radiationless decay while temperature effects have been recorded for all important intermediate species.

Enhanced Cellular Uptake and Photodynamic Effect with Amphiphilic Fluorinated Porphyrins: The Role of Sulfoester Groups and the Nature of Reactive Oxygen Species.

A class of amphiphilic photosensitizers for photodynamic therapy (PDT) was developed. Sulfonate esters of modified porphyrins bearing-F substituents in the ortho positions of the phenyl rings have adequate properties for PDT, including absorption in the red, increased cellular uptake, favorable intracellular localization, low cytotoxicity, and high phototoxicity against A549 (human lung adenocarcinoma) and CT26 (murine colon carcinoma) cells. Moreover, the role of type I and type II photochemical processes was assessed by fluorescent probes specific for various reactive oxygen species (ROS). The photodynamic effect is improved not only by enhanced cellular uptake but also by the high generation of both singlet oxygen and oxygen-centered radicals. All of the presented results support the idea that the rational design of photosensitizers for PDT can be further improved by better understanding the determinants affecting its therapeutic efficiency and explain how smart structural modifications can make them suitable photosensitizers for application in PDT.

Translating phototherapeutic indices from in vitro to in vivo photodynamic therapy with bacteriochlorins.

OBJECTIVE: To compare hydrophilic and lipophilic bacteriochlorin photosensitizers in the photodynamic therapy of cancer, and relate their properties and in vitro phototoxicities to the efficacy of in vivo PDT treatments. MATERIALS AND METHODS: Photochemical characterization of a hydrophilic bacteriochlorin (F2 BOH) photosensitizer, and its use in PDT was compared with the performance of a closely related but water-insoluble bacteriochlorin (F2 BMet or redaporfin). Biodistribution, pharmacokinetics, skin photosensitivity, PDT efficacy and immune responses of two bacteriochlorins were compared. PDT in vitro employed CT26 colon carcinoma cells. BALB/c mice bearing CT26 cells were treated according to a protocol where the illumination of the subcutaneous tumor is performed 15 minute after intravenous administration of the photosensitizer, while it is in the vascular compartment (vascular-PDT). RESULTS: F2 BOH has photochemical properties comparable to redaporfin and both are promising photosensitizers for PDT. Although, F2 BOH is 10 times less phototoxic in vitro than redaporfin, the phototoxicity of F2 BOH in vascular-PDT is comparable to that of redaporfin. This is consistent with the fact that the vasculature is the main target of vascular-PDT. F2 BOH-PDT led to long-term cures and stimulation of the immune system. CONCLUSION: F2 BOH is soluble in aqueous media, photostable, has a convenient elimination half-life of 44 hours and leads to very low skin photosensitivity one week after administration. F2 BOH and redaporfin are both very phototoxic in vascular-PDT, but this could not be anticipated from their widely different phototherapeutic indices in vitro. PDT with F2 BOH enabled long-term cures of BALB/c mice with subcutaneously implanted CT26 tumors, and the cured mice rejected tumor re-inoculation one year after the treatment. Lasers Surg. Med. 50:451-459, 2018. © 2018 Wiley Periodicals, Inc.

Split-Face, Randomized, Placebo-Controlled, Double-Blind Study to Investigate Passive Versus Active Dermal Filler Administration.

BACKGROUND: QueryHyaluronic acid (HA) is a large polymer increasingly used as dermal filler. HA does not permeate through healthy skin and is administered using various injection techniques. As HA procedures become more popular, the number of complications in facial rejuvenation procedures is likely to increase. Alternative methods may be necessary to satisfy the increasing demand for HA procedures. High-frequency high-intensity ultrasound is a painless and noninvasive method to deliver large molecules to the skin that is expected to deliver HA with visible results. OBJECTIVE: Assess facial rejuvenation with HA delivered with high-frequency high-intensity ultrasound. METHODS: Fifteen women (mean age 55) willing to participate in a randomized, double-blind, face-split trial with HA and placebo formulations in different sides of the face, were subject to five treatment sessions with high-frequency high-intensity ultrasound. Photographs taken before the procedure and after the last procedure were evaluated by a panel of five experts, blind to which side was treated with the HA or with the placebo. RESULTS: The expert panel identified a noticeable facial rejuvenation in the HA side relative to the placebo with a very statistically significant difference between the two sides (p < 0.0001). CONCLUSIONS: Administration of HA with high-frequency high-intensity ultrasound is safe and leads to unambiguous facial rejuvenation. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Ultrafast Dynamics of Manganese(III), Manganese(II), and Free-Base Bacteriochlorin: Is There Time for Photochemistry?

Manganese(III) and manganese(II) complexes of halogenated sulfonamide tetraphenylbacteriochlorins were prepared for the first time via a transmetalation reaction and shown to be stable at room temperature. The behavior of the electronic states of the paramagnetic complexes is remarkably different from those of the metal-free bacteriochlorins or diamagnetic metallobacteriochlorins. The Mn3+ complex exhibits eight electronic transitions between different states from 300 to 1100 nm, with a very prominent band (molar absorption coefficient of ca. 50000 M-1 cm-1) at 829 nm. Ultrafast transient absorption showed the formation of an excited singquintet state that decays to a tripquintet state with a femtosecond lifetime. The tripquintet state decays in 5 ps, yielding a tripseptet state with a 570 ps lifetime. The electronic absorption of the Mn2+ complex more closely resembles those of diamagnetic metallobacteriochlorins, but the longest decay lifetime is only ca. 8 ps. The intense photoacoustic waves generated with near-infrared excitation suggest the use of these complexes in photoacoustic tomography.

Pro-oxidant and Antioxidant Effects in Photodynamic Therapy: Cells Recognise that Not All Exogenous ROS Are Alike.

Photodynamic therapy (PDT) uses light, photosensitizer molecules and oxygen to generate reactive oxygen species (ROS) that kill cancer cells. Redaporfin, a new photosensitizer in clinical trials, generates both singlet oxygen and superoxide ions. We report the potentiation of redaporfin-PDT in combination with ascorbate and with the inhibition of antioxidant enzymes in A549 (human lung adenocarcinoma) and CT26 (mouse colon adenocarcinoma) cells. The addition of ascorbate and the inhibition of superoxide dismutase (SOD) strongly increased the phototoxicity of redaporfin towards A549 cells but not towards CT26 cells. The inhibition of catalase and the depletion of the glutathione pool also potentiate redaporfin-PDT towards A549 cells. The lower SOD activity of A549 cells might explain this difference. SOD activity levels may be explored to increase the selectivity and efficacy of PDT with photosensitizers that generate radical species.

Assessment of lifetime resolution limits in time-resolved photoacoustic calorimetry vs. transducer frequencies: setting the stage for picosecond resolution.

Time-resolved photoacoustic calorimetry (PAC) gives access to lifetimes and energy fractions of reaction intermediates by deconvolution of the photoacoustic wave of a sample (E-wave) with that of the instrumental response (T-wave). The ability to discriminate between short lifetimes increases with transducer frequencies employed to detect the PAC waves. We investigate the lifetime resolution limits of PAC as a function of the transducer frequencies using the instrumental response obtained with the photoacoustic reference 2-hydroxybenzophenone in toluene or acetonitrile. The instrumental response was obtained for a set of transducers with central frequencies ranging from 0.5 MHz up to 225 MHz. The simulated dependence of the lifetime resolution with the transducer frequencies was anchored on experimental data obtained for the singlet state of naphthalene with a 2.25 MHz transducer. The shortest lifetime resolved with the 2.25 MHz transducer was 19 ns and our modelling of the transducer responses indicates that sub-nanosecond lifetimes of photoacoustic transients can be resolved with transducers of central frequencies above 100 MHz.

Photodynamic therapy (PDT) of cancer: from local to systemic treatment.

Photodynamic therapy (PDT) requires a medical device, a photosensitizing drug and adequate use of both to trigger biological mechanisms that can rapidly destroy the primary tumour and provide long-lasting protection against metastasis. We present a multidisciplinary view of the issues raised by the development of PDT. We show how spectroscopy, photophysics, photochemistry and pharmacokinetics of photosensitizers determine the mechanism of cell death and clinical protocols. Various examples of combinations with chemotherapies and immunotherapies illustrate the opportunities to potentiate the outcome of PDT. Particular emphasis is given to the mechanisms that can be exploited to establish PDT as a systemic treatment of solid tumours and metastatic disease.

Intravenous Single-Dose Toxicity of Redaporfin-Based Photodynamic Therapy in Rodents.

We assessed the tolerability and safety in rodents of a single intravenous (i.v.) dose of redaporfin, a novel photosensitizer for Photodynamic Therapy (PDT) of cancer. Two approaches were used to evaluate acute toxicity: (i) a dose escalation study in BALB/c mice to evaluate the maximum tolerated dose of redaporfin; and (ii) a safety toxicology study in Wistar rats, of a single dose of redaporfin, with or without illumination, to evaluate possible signs of systemic toxicity. Redaporfin formulation was well tolerated by mice, with no signs of adverse reactions up to 75 mg/kg. In rats, there were no relevant changes, except for a significant, but transient, increase in the blood serum markers for hepatic function and muscle integrity, and also on neutrophil counts, observed after the application of light. The overall results showed that redaporfin-PDT is very well tolerated. No abnormalities were observed, including reactions at the injection site or skin phototoxicity, although the animals were maintained in normal indoor lighting. Redaporfin also showed a high efficacy in the treatment of male BALB/c mice with subcutaneously implanted colon (CT26) tumours. Vascular-PDT with 1.5 mg/kg redaporfin and a light dose of 74 J/cm² led to the complete tumour regression in 83% of the mice.

Photodynamic therapy efficacy enhanced by dynamics: the role of charge transfer and photostability in the selection of photosensitizers.

Progress in the photodynamic therapy (PDT) of cancer should benefit from a rationale to predict the most efficient of a series of photosensitizers that strongly absorb light in the phototherapeutic window (650-800 nm) and efficiently generate reactive oxygen species (ROS = singlet oxygen and oxygen-centered radicals). We show that the ratios between the triplet photosensitizer-O2 interaction rate constant (kD) and the photosensitizer decomposition rate constant (kd), kD/kd, determine the relative photodynamic activities of photosensitizers against various cancer cells. The same efficacy trend is observed in vivo with DBA/2 mice bearing S91 melanoma tumors. The PDT efficacy intimately depends on the dynamics of photosensitizer-oxygen interactions: charge transfer to molecular oxygen with generation of both singlet oxygen and superoxide ion (high kD) must be tempered by photostability (low kd). These properties depend on the oxidation potential of the photosensitizer and are suitably combined in a new fluorinated sulfonamide bacteriochlorin, motivated by the rationale.

Delivery of minoxidil encapsulated in cyclodextrins with photoacoustic waves enhances hair growth.

The current pharmacological management of androgenetic alopecia is inconvenient and requires a discipline that patients find difficult to follow. This reduces compliance with treatment and satisfaction with results. It is important to propose treatment regimens that increase patient compliance and reduce adverse effects. This work describes transdermal delivery of minoxidil partially encapsulated in ß-cyclodextrin and assisted by photoacoustic waves. Photoacoustic waves transiently increase the permeability of the skin and allow for the delivery of encapsulated minoxidil. A minoxidil gel formulation was developed and the transdermal delivery was studied in vitro in the presence and absence of photoacoustic waves. A 5-min stimulus with photoacoustic waves generated by light-to-pressure transducers increases minoxidil transdermal delivery flux by approximately 3-fold. The flux of a 1% minoxidil formulation promoted by photoacoustic waves is similar to the passive flux of a 2% minoxidil commercial formulation. Release of minoxidil from ß-cyclodextrin increases dermal exposure without increasing peak systemic exposure. This promotes hair growth with fewer treatments and reduced adverse effects. In vivo studies using encapsulated minoxidil and photoacoustic waves yielded 86% hair coat recovery (vs. 29% in the control group) and no changes in the blood pressure.

Repurposing anti-cancer porphyrin derivative drugs to target SARS-CoV-2 envelope.

Antiviral medicines to treat COVID-19 are still scarce. Porphyrins and porphyrin derivatives (PDs) usually present broad-spectrum antiviral activity with low risk of resistance development. In fact, some PDs are clinically approved to be used in anti-cancer photodynamic therapy and repurposing clinically approved PDs might be an alternative to treat COVID-19. Here, we characterize the ability of temoporfin, verteporfin, talaporfin and redaporfin to inactivate SARS-CoV-2 infectious particles. PDs light-dependent and -independent effect on SARS-CoV-2 infectivity were evaluated. PDs photoactivation successfully inactivated SARS-CoV-2 with very low concentrations and light dose. However, only temoporfin and verteporfin inactivated SARS-CoV-2 in the dark, being verteporfin the most effective. PDs treatment reduced viral load in infected Caco-2 cells, while not inducing cytotoxicity. Furthermore, light-independent treatment with temoporfin and verteporfin act on early stages of viral infection. Using lipid vehicles as membrane models, we characterized PDs interaction to the viral envelope. Verteporfin presented the lowest IC50 for viral inactivation and the highest partition coefficients (Kp) towards lipid bilayers. Curiously, although temoporfin and redaporfin presented similar Kps, redaporfin did not present light-independent antiviral activity, and only temoporfin and verteporfin caused lipid membrane disorder. In fact, redaporfin is located closer to the bilayer surface, while temoporfin and verteporfin are located closer to the centre. Our results suggest that viral envelope affinity, with penetration and destabilization of the lipid bilayer, seems critical to mediate PDs antiviral activity. Altogether, these findings open new avenues for the off-label application of temoporfin and verteporfin in the systemic treatment of COVID-19.