The protective effect of a novel sunscreen against blue light

Abstract

Background and objective: Premature skin ageing, and skin hyperpigmentation are influenced by exogenous factors, such as ultraviolet radiation and blue light. In this study, we assess the protective effect of a sunscreen (TDF ® Blu Voile Sunscreen) in protecting the skin against the harmful effects of blue light irradiation in vivo and through the in situ quantitative and qualitative evaluation of protein carbonylation in human skin explants. Methodology:The protective effect of the test product against blue light was first evaluated ex vivo on human skin explants. The treated and non-treated explants were exposed to 14 J/cm 2 of blue light 460 nm following which the protein carbonylation was evaluated by in situ epifluorescence imaging and separation by high-resolution gel electrophoresis. To determine whether the test product could also protect against the immediate and persistent pigmenting effect of blue light, two randomized in vivo studies were conducted, which included respectively 17 subjects with a skin phototype of IV and V (Fitzpatrick classification) and 22 subjects with a skin phototype of IV, V, and VI (Fitzpatrick classification).The duration of the study for each subject was 2 days (D1 and D2) for immediate observations and 5 days (D1-D5) for persistent observations. Specific zones on the subjects' back were either left non-treated or treated with the test product and were then exposed to a unique dose of blue light 415 nm. The onset of pigmentation between the treated and exposed zones was then assessed relative to the non-exposed treated zone through colorimetric measurements of the Individual Typology Angle (ITA o ).Results: Human skin explants treated with test product showed significantly lower levels of accumulated carbonylated proteins, with a protection of 82%, following exposure to blue light 460 nm. Findings of the in vivo studies also indicated that the test product presented significantly better protective efficacy against immediate and persistent pigmentation induced by blue light 415 nm.

Broad‐spectrum sunscreens containing the TriAsorB™ filter: In vitro photoprotection and clinical evaluation of blue light‐induced skin pigmentation

“…Moreover, although the degree of pigmentation rapidly decreased in the 24 h post‐exposure, it did not return to baseline. Similar findings have been described in several previously reported clinical studies 9,20,26,27 …”

“…Similar findings have been described in several previously reported clinical studies. 9,20,26,27 Sunscreens containing the broad-spectrum PBDT filter have good cosmetic properties and represent valuable alternatives to sunscreens containing mineral filters, which often appear white after application. Moreover, the nontinted PBDT products can be widely used according to consumer preferences, skin tones and usage conditions, without the need to include coloured pigments.…”

“…12,31 Other formulations containing iron oxide, or specific BL-blocking agents combined with mineral UV filters with pigmentation preventing properties, have also been recently developed to extend topical photoprotection beyond UV radiation. 18,26 At present, there are no rules or regulatory constraints surrounding the inclusion of indications of BL photoprotection on product labels. Only the SPF and UVA-PF are required in the EU, and must follow stringent regulations for testing (ISO 24444:2019 and ISO 24443:2021 norms) and labelling.…”

“…Moreover, it has been shown that sunscreens containing pigments can provide greater attenuation of the BL and HEV radiation reaching the skin than non‐pigmented products 12,31 . Other formulations containing iron oxide, or specific BL‐blocking agents combined with mineral UV filters with pigmentation preventing properties, have also been recently developed to extend topical photoprotection beyond UV radiation 18,26 …”

“…The sample size estimation (15-20 subjects) was based on previous studies comparing sunscreen formulations and using similar colorimetric measurements. [24][25][26] Eligible participants were healthy adult females, aged from 18 to 50 years, with Fitzpatrick phototypes ranging from III to V. Other eligibility criteria included the presence of a uniform skin colour all over the back, use of a reliable form of contraception, absence of sun or UV exposure on the back within the 3 months before inclusion, absence of sunburn (erythema) or other skin disorders on the back, and no use of any medication or topical treatments known to cause abnormal responses to UV exposure. All concomitant medications and adverse events (including local intolerance) were reported throughout the study.…”