UVR-induced phototoxicity mechanism of methyl N-methylanthranilate in human keratinocyte cell line.

Fragrances are used in almost every cosmetic product. International Fragrance Association (IFRA) is the regulatory body that controls the use of fragrances in cosmetic products. Methyl-N-methylanthranilate (DMA) is a naturally derived fragrance, commonly used in cosmetic products such as fine perfumes, skin care products, etc. But there is a lack of detailed study in terms of its phototoxic and photogenotoxicity mechanisms under UVA/sunlight exposure. In this study, we have shown that DMA photodegrades in 4 h under UVA (1.5 mW/cm2) and sunlight. DMA (0.0001%-0.0025%) significantly reduced the cell viability as demonstrated by NRU and MTT assays in a dose-dependent manner under UVA (5.4 J/cm2) and sunlight (1 h) exposure in the HaCaT cell line. It generated excessive intracellular ROS (superoxide anion radical via type-I photodynamic reaction), resulting in lysosomal destabilization and mitochondrial membrane depolarization. Photo-activated DMA caused DNA fragmentation as observed by olive tail moment. DNA double-strand breaks was demonstrated by phosphorylation of H2AX-histone protein and formation of photo-micronuclei in skin keratinocytes. Additionally, photo-activated DMA upregulated the oxidative stress marker gene hemeoxygenase-1 and apoptotic marker genes (cytochrome-C, caspase-3, caspase-9). Activated caspase-cascade pathway established that photo-activated DMA can potentially trigger apoptosis in the human skin cells.

Quantum Yield for the Aqueous Photochemical Degradation of Chlorantraniliprole and Simulation of Its Environmental Fate in a Model California Rice Field.

The photochemical degradation of chlorantraniliprole (3-bromo-N-[4-chloro-2-methyl-6-(methylcarbamoyl)phenyl]-1-(3-chloro-2-pyridine-2-yl)-1H-pyrazole-5-carboxamide; CAP) was characterized under simulated solar light with 2-nitrobenzaldehyde (2NB) actinometry. Overall, aqueous CAP degraded quickly via direct photodegradation with no significant difference observed between high-purity water and filtered rice field water. The 24-h average half-life normalized to summer sunlight using 2NB was 34.5 ± 4.0 h (jCAP,env = 0.020 ± 0.0023 h-1 , n = 3), and the calculated apparent quantum yield in simulated sunlight was 0.0099 ± 0.00060. These new values were used-alongside previously characterized data for air/and soil/water partitioning, degradation in soil, and hydrolysis-in the Pesticides in Flooded Applications Model to simulate CAP dissipation in a model California (USA) rice field. The model estimates an environmental half-life of 26 d in the aqueous phase, but the bulk of applied CAP remains in the benthic zone and degrades, with estimated half-lives of 29 and 92 d in flooded and drained fields, respectively. Environ Toxicol Chem 2020;39:1929-1935. © 2020 SETAC.

Scale Effect of a Fluorescent Waveguide in Organic Micromaterials: A Case Study Based on Coumarin Microfibers.

The classical method for evaluating the waveguide ability only focuses on the optical loss coefficient. However, for the micro- or submicroscale, an organic waveguide is demonstrated by the present study whose scale effect should not be neglected. We found that the optical loss coefficient increased remarkably when decreasing the sectional size of the microfibers. Furthermore, simulations based on Finite-Difference Time-Domain also demonstrated the size-dependent effect of the waveguide. Both the experimental and simulating results showed that the optical loss coefficient converges to a certain value, which means that the scale effect can be neglected as the sectional size is large enough. On the basis of the present study, we suggest that the scale-dependent effect on the sectional size of the waveguide should be investigated by evaluating the waveguide ability by the optical loss coefficient.

A New Fluorogenic Probe for the Detection of endo-ß-N-Acetylglucosaminidase.

We developed a fluorescence-quenching-based assay system to determine the hydrolysis activity of endo-ß-N-acetylglucosaminidases (ENGases). The pentasaccharide derivative 1 was labeled with an N-methylanthraniloyl group as a reporter dye at the non-reducing end and with a 2,4-dinitrophenyl group as a quencher molecule at the reducing end. This derivative is hydrolyzed by ENGase, resulting in an increase in fluorescence intensity. Thus, the fluorescence signal is directly proportional to the amount of the tetrasaccharide derivative, hence allowing ENGase activity to be evaluated easily and quantitatively. Using this system, we succeeded in measuring the hydrolysis activities of ENGases and thus the inhibitory activities of known inhibitors. We confirmed that this assay system is suitable for high-throughput screening for potential inhibitors of human ENGase that might serve as therapeutic agents for the treatment of N-glycanase 1 (NGLY1) deficiency.

Tolfenamic acid degradation by direct photolysis and the UV-ABC/H2O2 process: factorial design, kinetics, identification of intermediates, and toxicity evaluation.

This study employed direct UV-ABC photolysis and the UV-ABC/H2O2 process to investigate the degradation of tolfenamic acid (TA), a common anti-inflammatory drug used in both human and veterinary medicine. A 23 factorial design with added center point was used to evaluate the effect of three independent variables-namely, H2O2 concentration ([H2O2]), TA concentration ([TA]), and experiment time (time)-on TA degradation and H2O2 photolysis during UV-ABC/H2O2 treatment using a high-pressure mercury vapor lamp (photon flux of 2.6307 × 104 J s-1) as the UV irradiation source. The responses yielded similar values, revealing a linear behavior, with correlation coefficients R = 0.9968 and Radj = 0.9921 for TA degradation and R = 0.9828 and Radj = 0.9570 for H2O2 photolysis. The most efficient combination of variables was [H2O2] = 255 mg L-1 and [TA] = 25 mg L-1, resulting in 100% TA degradation and 98.87% H2O2 photolysis by 90 min of treatment. Additionally, the second-order kinetic constant of the reaction between TA and HO● was determined using a competitive kinetic model, employing 2,4-dichlorophenoxyacetic acid (2,4D) as the reference compound. The kinetic constant was 1.9 × 1010 M-1 s-1 in alkaline medium. TA degradation by direct photolysis generated quinone imines as by-products, responsible for the formation of a dark red "internal filter" that increased the value of acute toxicity to Artemia salina. The UV-ABC/H2O2 process did not promote formation of quinone imines by 90 min of treatment and therefore did not increase acute toxicity values. Several by-products generated during TA degradation were identified and possible degradation pathways for the UV-ABC and UV-ABC/H2O2 processes were proposed.

Novel crystalline solid dispersion of tranilast with high photostability and improved oral bioavailability.

Tranilast (TL) is an anti-allergic agent and widely used in the clinical treatment of bronchial asthma, atopic rhinitis, atopic dermatitis and keloids. However, therapeutic potential of TL could be partly limited because of its poor solubility, bioavailability, and photostability. To overcome these drawbacks, crystalline solid dispersion of TL (CSD/TL) was prepared by wet-milling technique with aim of improving physicochemical and pharmacokinetic properties. Physicochemical properties of the formulations prepared were characterized by laser diffraction and dynamic light scattering for particle size analysis, scanning electron microscope for morphological analysis, and powder X-ray diffraction and differential scanning calorimetry for crystallinity assessment. TL particles in CSD/TL appeared to be crystalline with diameter of 122 nm, and CSD/TL exhibited marked improvement in the dissolution behavior as compared to crystalline TL. Under irradiation of UVA/B (250 W/m(2)), solution and amorphous solid dispersion of TL were found to be highly photodegradable, whereas high photochemical stability was seen in CSD/TL. After oral administration of CSD/TL, enhanced TL exposure was observed with increase of C(max) and AUC by 60- and 32-fold, respectively, as compared to crystalline TL. According to these observations, taken together with dissolution and pharmacokinetic behaviors, crystalline solid dispersion strategy would be efficacious to enhance bioavailability of TL with high photochemical stability.

The photophysical properties of menthyl anthranilate: a UV-A sunscreen.

The results of a comprehensive investigation of the photophysical properties of the sunscreen agent menthyl anthranilate in various solvent systems are reported. Luminescence studies reveal that this ester is highly fluorescent (phi f = 0.64 +/- 0.06 in ethanol) and has a solvent-dependent emission maximum in the range of 390-405 nm. Phosphorescence has also been detected in low-temperature glasses with an emission maximum at 445 nm and a lifetime of 2.5 s. Kinetic UV-visible absorption measurements revealed a transient species with absorption maxima at 480 nm and solvent-dependent lifetimes of 26-200 microseconds that are attributed to the triplet state. The triplet state is efficiently quenched by oxygen, leading to the formation of singlet oxygen in all of the solvent systems studied. The singlet-oxygen quantum yields (phi delta) determined by time-resolved near-infrared luminescence measurements were determined to be in the range 0.09-0.12 for all systems.

Effect of UV-absorbing agents on photodegradation of tranilast in oily gels.

Tranilast (TL) oily gels containing UV-absorbing agents (UV absorber) were prepared, and the effect of the agents against photodegradation of TL was investigated. When 0.1% TL oily gel without UV absorber was exposed to light, TL was photochemically decomposed to the extent of 74.1% of its initial content at the end of the first hour. Although there were differences in the preventive effect on photodegradation of TL depending on the UV absorbers employed, 2-(2-benzotriazolyl)-p-cresol (BTPC) was the most effective absorber. The addition of UV absorbers to the oily gel did not affect the release of TL from the gel, the skin permeation, or the skin concentration of TL following topical application. UV absorbers added to TL oily gel penetrated into skin; however, their concentration in skin was similar to that following application of commercial sunscreen. These results suggest that the addition of UV absorbers to the oily gel of TL may be useful in preventing photodegradation of TL in the gel.

[Study of the kinetics of chlorophyll photosensitized dye reduction by photopolarography]. / Izuchenie kinetiki fotosensibilizirovannogo khlorofillom vosstanovleniia krasitelei metodom fotopoliarografii.

It has been shown by photopolarographic method that under stationary illumination chlorophyll-photosensitized reduction of dyes with ascorbic acid proceeds according to the first kinetic order. Rate constants of photoreduction of vitamin K3, methelene red, safranin-T and methylviologen were found in the course of sensitization which proceeded by oxidative and reduction mechanisms. Similarity of kinetics at both sensitization mechanisms was shown. Results obtained by polarographic and spectroscopic methods were compared.