Riboflavin Plays a Pivotal Role in the UVA-Induced Cytotoxicity of Fibroblasts as a Key Molecule in the Production of H2O2 by UVA Radiation in Collaboration with Amino Acids and Vitamins

Abstract

To investigate environmental factors that contribute to ultraviolet A (UVA)-induced oxidative stress, which accelerates the senescence and toxicity of skin cells, we irradiated human fibroblasts cultured in commonly used essential media with UVA and evaluated their viability and production of reactive oxygen species. The viability of fibroblasts exposed to a single dose of 3.6 J/cm2 UVA was not reduced when cultured in Hanks balanced salt solution, but it was significantly decreased when cultured in Dulbecco’s modified Eagle’s medium (DMEM), which contains various amino acids and vitamins. Furthermore, cell viability was not reduced when fibroblasts were cultured in DMEM and treated with a hydrogen peroxide (H2O2) scavenger such as glutathione or catalase added after UVA irradiation. In addition, we confirmed that the production of H2O2 was dramatically increased by UVA photosensitization when riboflavin (R) coexisted with amino acids such as tryptophan (T), and found that R with folic acid (F) produced high levels of H2O2 after UVA irradiation. Furthermore, we noticed that R and F or R and T have different photosensitization mechanisms since NaN3, which is a singlet oxygen quencher, suppressed only R and T photosensitization. Lastly, we examined the effects of antioxidants (L-ascorbic acid, trolox, L-cysteine, and L-histidine), which are singlet oxygen or superoxide or H2O2 scavengers, on R and F or on R and T photosensitization, and found that 1 mM ascorbic acid, Trolox, and L-histidine were strongly photosensitized with R, and produced significant levels of H2O2 during UVA exposure. However, 1 mM L-cysteine dramatically suppressed H2O2 production by UVA photosensitization. These data suggest that a low concentration of R-derived photosensitization is elicited by different mechanisms depending on the coexisting vitamins and amino acids, and regulates cellular oxidative stress by producing H2O2 during UVA exposure.

Electroporation does not affect human dermal fibroblast proliferation and migration properties directly but indirectly via the secretome

“…These results are in agreement with those reported in the literature showing the deleterious effects of H2O2 on dermal fibroblasts [59,60].…”

Revisiting food-sourced vitamins for consumer diet and health needs: a perspective review, from vitamin classification, metabolic functions, absorption, utilization, to balancing nutritional requirements

“…This reaction suggests the increased rate of vitamin C degradation (loss) in food products like milk in the presence of sunlight ( Ottaway, 1993 ; de La Rochette et al, 2000 ). This implies that photo-oxidation of vitamin C is significantly reduced in the absence of riboflavin ( Yoshimoto et al, 2020 ). Riboflavin-folic acid: …”

Photocatalysis in the Skin Related to UVA Photoaging

“…On the other hand, some research groups have shown that the coexistence of multiple components induces stronger cytotoxicity than a single photosensitizer condition [44,51]. It has been reported that a low concentration of photocatalyst, about 0.4 μg/mL riboflavin, can induce cell damage in coexisting conditions with amino acids and vitamins [52]. On the other hand, in single riboflavin conditions, it takes about 100 μg/mL of riboflavin to induce cell toxicity in vitro [53].…”

“…Those results indicate that the oxidative degradation of folic acid proceeds only very slowly in HBSS containing folic acid alone, but occurs rapidly in the presence of the photosensitizer riboflavin. Since this reaction was not inhibited by NaN 3 , a singlet oxygen scavenger, it was thought that the oxidative degradation of folic acid was possibly promoted via photosensitization of type I generated by riboflavin photosensitization [52]. Therefore, it is considered that the superoxide quencher is effective for these types of reactions.…”