Phototoxicity Evaluation of Pharmaceutical Substances with a Reactive Oxygen Species Assay Using Ultraviolet A

Abstract

With ultraviolet and visible light exposure, some pharmaceutical substances applied systemically or topically may cause phototoxic skin irritation. The major factor in phototoxicity is the generation of reactive oxygen species (ROS) such as singlet oxygen and superoxide anion that cause oxidative damage to DNA, lipids and proteins. Thus, measuring the generation of ROS can predict the phototoxic potential of a given substance indirectly. For this reason, a standard ROS assay (ROS assay) was developed and validated and provides an alternative method for phototoxicity evaluation. However, negative substances are over-predicted by the assay. Except for ultraviolet A (UVA), other UV ranges are not a major factor in causing phototoxicity and may lead to incorrect labeling of some non-phototoxic substances as being phototoxic in the ROS assay when using a solar simulator. A UVA stimulator is also widely used to evaluate phototoxicity in various test substances. Consequently, we identified the applicability of a UVA simulator to the ROS assay for photoreactivity. In this study, we tested 60 pharmaceutical substances including 50 phototoxins and 10 non-phototoxins to predict their phototoxic potential via the ROS assay with a UVA simulator. Following the ROS protocol, all test substances were dissolved in dimethyl sulfoxide or sodium phosphate buffer. The final concentration of the test solutions in the reaction mixture was 20 to 200 μM. The exposure was with 2.0~2.2 mW/cm2 irradiance and optimization for a relevant dose of UVA was performed. The generation of ROS was compared before and after UVA exposure and was measured by a microplate spectrophotometer. Sensitivity and specificity values were 85.7% and 100.0% respectively, and the accuracy was 88.1%. From this analysis, the ROS assay with a UVA simulator is suitable for testing the photoreactivity and estimating the phototoxic potential of various test pharmaceutical substances.

Comparative analysis of the phototoxicity induced by BRAF inhibitors and alleviation through antioxidants

“…UVA light plays a more significant role in causing phototoxicity than other UV ranges. 22,23 This is consistent with the results of the ROS assay that was performed in this study with UVA and UVB light. Only 3 out of with UVB light compared with 9 agents which generated ROS after UVA light absorption.…”

“…The generation of reactive oxygen species following UV light irradiation can lead to oxidative damage to the cell. UVA light plays a more significant role in causing phototoxicity than other UV ranges . This is consistent with the results of the ROS assay that was performed in this study with UVA and UVB light.…”

Antioxidantes producidos por microorganismos acuáticos y terrestres con uso potencial en cosméticos

“…Los ensayos de fototoxicidad evalúan la respuesta fotoinducida cuando una sustancia fotoreactiva es activada por la luz solar produciendo químicos excitados que pueden transferir la energía adsorbida y generar especies reactivas que podrían causar irritación sobre la piel (Reis-Mansur et al, 2019). Se pueden realizar disolviendo la sustancia evaluada en un buffer de fosfato de sodio, analizando el espectro de absorción UV/VIS con un espectrofotómetro y evaluando las especies reactivas de oxígeno formadas (Lee et al, 2017).…”

Phototoxicity of traditional chinese medicine (TCM)

“…However, negative substances are over-predicted by this assay. 48 Derivatives of reactive oxygen metabolites assay include a capillary gel electrophoresis-based photocleavage assay and an IBP assay. Combined use of photochemical/photobiological and PK data have also been proposed as a new screening strategy for predicting in vivo phototoxic risk.…”