Fur glowing under ultraviolet: in situ analysis of porphyrin accumulation in the skin appendages of mammals

Examples of photoluminescence (PL) are being reported with increasing frequency in a wide range of organisms from diverse ecosystems. However, the chemical basis of this PL remains poorly defined, and our understanding of its potential ecological function is still superficial. Among mammals, recent analyses have identified free-base porphyrins as the compounds responsible for the reddish ultraviolet-induced photoluminescence (UV-PL) observed in the pelage of springhares and hedgehogs. However, the localization of the pigments within the hair largely remains to be determined. Here, we use photoluminescence multispectral imaging emission and excitation spectroscopy to detect, map, and characterize porphyrinic compounds in skin appendages in situ. We also document new cases of mammalian UV-PL caused by free-base porphyrins in distantly related species. Spatial distribution of the UV-PL is strongly suggestive of an endogenous origin of the porphyrinic compounds. We argue that reddish UV-PL is predominantly observed in crepuscular and nocturnal mammals because porphyrins are photodegradable. Consequently, this phenomenon may not have a specific function in intra- or interspecific communication but rather represents a byproduct of potentially widespread physiological processes.

Bactericidal efficiency of porphyrin systems

Photodynamic Inactivation is an innovative technique used to combat bacterial and viral infections which involves the use of photosensitizing agents along with light to generate cytotoxic reactive oxygen species able to kill bacteria and viruses. In the first section of this minireview, porphyrin-based fluorophores are shown to be remarkable dye candidates for PDI (photodynamic inactivation) applications. The second section is dedicated to the description of porphyrin-based antimicrobial materials and their potentialities for industrial applications such as in food packaging or antimicrobial medical devices and hygiene. Finally, the failings and perspectives of PDI are analyzed to demonstrate how the PDI technique could be an efficient and ecologically friendly antimicrobial technique.

Terbium-Based AGuIX-Design Nanoparticle to Mediate X-ray-Induced Photodynamic Therapy

X-ray-induced photodynamic therapy is based on the energy transfer from a nanoscintillator to a photosensitizer molecule, whose activation leads to singlet oxygen and radical species generation, triggering cancer cells to cell death. Herein, we synthesized ultra-small nanoparticle chelated with Terbium (Tb) as a nanoscintillator and 5-(4-carboxyphenyl succinimide ester)-10,15,20-triphenyl porphyrin (P1) as a photosensitizer (AGuIX@Tb-P1). The synthesis was based on the AGuIX@ platform design. AGuIX@Tb-P1 was characterised for its photo-physical and physico-chemical properties. The effect of the nanoparticles was studied using human glioblastoma U-251 MG cells and was compared to treatment with AGuIX@ nanoparticles doped with Gadolinium (Gd) and P1 (AGuIX@Gd-P1). We demonstrated that the AGuIX@Tb-P1 design was consistent with X-ray photon energy transfer from Terbium to P1. Both nanoparticles had similar dark cytotoxicity and they were absorbed in a similar rate within the cells. Pre-treated cells exposure to X-rays was related to reactive species production. Using clonogenic assays, establishment of survival curves allowed discrimination of the impact of radiation treatment from X-ray-induced photodynamic effect. We showed that cell growth arrest was increased (35%-increase) when cells were treated with AGuIX@Tb-P1 compared to the nanoparticle doped with Gd.

Some activities of PorphyChem illustrated by the applications of porphyrinoids in PDT, PIT and PDI

Photodynamic therapy is an innovative approach to treat diverse cancers and diseases that involves the use of photosensitizing agents along with light of an appropriate wavelength to generate cytotoxic reactive oxygen species.

Obsessive-Compulsive Disorder Due to Neuroacanthocytosis Treated with Citalopram

Neuroacanthocytois is a rare hereditary disease, which causes a degeneration of the striatum. Patients develop a choreatic movement disorder and also complex psychiatric symptoms, such as psychosis or Tourette's syndrome. We report a case of obsessive-compulsive disorder due to neuroacanthocytosis. The striatum plays an important role in the pathophysiology of obsessive-compulsive disorder. In Huntington's disease we also find obsessive-compulsive disorders, due to impairment of the fronto-striatal loop. Encouraged by similar pathophysiology and promising reports of selective serotonin reuptake inhibitors in this disease, we started a treatment with citalopram to which the patient responded very well.

[Glutamate antagonists for treatment of neuropathic pain]

An altered glutamatergic transmission within the central nervous system is supposed to be involved in the generation and propagation of neuropathic pain. Results from experimental studies with animal models of neuropathic pain demonstrate that glutamate antagonists have a positive effect on various parameters. Clinical studies with the NMDA-receptor antagonists ketamine, amantadine, memantine and dextromethorphan and with the antiepileptics gabapentin and lamotrigine, which reduce presynaptic release of glutamate,have been performed. They have shown that most of these substances can reduce neuropathic pain. Important side effects of the NMDA receptor antagonists are hallucination and agitation, whereas tiredness and dizziness are the ones of the antiepileptics. Till now, glutamate antagonists are not drugs of first choice for the treatment of neuropathic pain. However, they are an effective alternative in case the established drugs are not helpful or are not tolerated well.