Another Reason for Using Caffeine in Dermocosmetics: Sunscreen Adjuvant

Abstract

The excessive exposure to ultraviolet (UV) radiation is the main cause of skin cancer, the most commonly diagnosed cancer in the world. In this context, the development of innovative and more effective sunscreens, with bioactive compounds like caffeine, displaying antioxidant and anticancer potential, is required. This research work assessed in vitro and in vivo the efficacy and safety of topical sunscreen formulations containing caffeine as an adjuvant of the UV filters. Sunscreens were prepared with 2.5% w/w caffeine or in the absence of this compound. In order to evaluate the safety of these formulations, stratum corneum hydration, skin barrier and colorimetry were assessed in vivo in healthy subjects before and after skin treatment with the samples. The efficacy of the sunscreens was assessed in vitro , using PMMA plates and a spectrophotometer equipped with an integrating sphere; and in vivo by the determination of the sun protection factor (SPF). None of the formulations caused erythema or impaired the skin barrier function. The in vitro functional characterization showed higher SPF values for the caffeine formulation. The in vivo studies also confirmed the higher SPF value of the formulation combining caffeine with the filters, compared to the caffeine-free sample. This improvement contributed to an increase of, approximately, 25% in the in vivo anti-UVB protection. In conclusion, caffeine was well tolerated by the skin and increased the photoprotective activity, being a new alternative adjuvant in sunscreens formulation.

In vivo SPF from multifunctional sunscreen systems developed with natural compounds—A review

“…12 Ethanolic (1.0%) and aqueous extracts (1.0%) of Bauhinia microstachya were associated with UV filters, such as BP (5.0%), EHMC after topical application with concomitant formation of metabolites that enhanced photoprotection in vivo. 49 In another contribution, Cabernet sauvignon pomace extract (10.0%) was associated with BMDBM, EHMC, and EHDP. The concentration of total phenolic compounds was higher than flavonoids in the extract.…”

“…52 Generally, in the literature summarized in this study, in vivo SPF values were the highest when a natural compound was included into the sunscreen system. 12,49 After a rigorous search in specialized journals regarding in vivo SPF values, we found the studies described in lower than the commercial product used as control. L sericea extract has achieved significant performance as sunscreen, considering that this extract was the only anti-UVB active used, which suggests further investigation to obtain higher values of SPF.…”

“…Therefore, in vivo biocompatibility evaluation led us to establish the safety of these samples with no evidence of skin irritation, dermal sensitivity, photoirritation, or potential photosensitivity when compared with placebos. 11,49,52,53 We investigated the in vivo safety and efficacy of formulations 53 Moreover, it was also demonstrated good cutaneous biocompatibility of gelatin-based rutin-loaded nanoparticles. 57 In another approach, a phenolic compound named ferulic acid Additionally, some plant extracts have also been incorporated into sunscreens with promising results, as summarized in Table 2.…”

“…Therefore, in vivo biocompatibility evaluation led us to establish the safety of these samples with no evidence of skin irritation, dermal sensitivity, photoirritation, or potential photosensitivity when compared with placebos. 11,49,52,53 We investigated the in vivo safety and efficacy of formulations containing gelatin-based rutin-loaded nanoparticles associated with EHDP, ethylhexyl methoxycinnamate (EHMC), and BMDBM. It is worth pointing out that the degradation mechanism of EHMC and BMDBM, a photoinstability model, involves light and free radicals, and antioxidants that can scavenge these reactive species are able to reduce photoinstability of EHMC and BMDBM association.…”

“…The natural ingredient acted by delaying erythema formation, significantly contributing with sample efficacy. It was suggested that caffeine may have been metabolized after topical application with concomitant formation of metabolites that enhanced photoprotection in vivo 49.…”