Addition of rosmarinic acid, a natural antioxidant, to sunscreens alongside conventional UV filters, reduced the amount of sunscreen required for protection and reduced the amount of synthetic chemicals released into the environment, according to a research published in the journal Cosmetics.
The addition of rosmarinic acid at a rate of a mere 0.1 percent reduced the amount of sunscreen required to protect the skin, increased the sun protection factor by more than 41%, and combined photoprotection with antioxidant activity.
In a published article in the journal Cosmetics, a researcher investigates the effects of including rosmarinic acid, an active antioxidant, in a sunscreen along with two conventional ultraviolet light filters, ethylhexoxycinnamate (against UVB) and avobenzone (against UVA).
The researchers found that adding rosmarinic acid at 0.1 percent increased the sunscreen's photoprotective ability, compared to the use of conventional UV filters. Their findings suggest that including natural molecules with antioxidant activities into sunscreens might reduce the amount of conventional UV filters in the final product, with the advantage of providing other functional attributes.
The performance of the product was improved without the need to increase active principle doses, reducing both the amount of sunscreen needed to protect the same skin area and the amount of synthetic chemicals discharged into the environment.
The sun protection factor (SPF) increased by 41% in in vitro and clinical studies.
Another advantage of including rosmarinic acid was its ability to enhance photoprotection, for example, by using the compound in antiaging cosmetics.
"Our research on photoprotective systems primarily focuses on developing possible sunscreen enhancement strategies. We're particularly interested in enhancing sunburn protection while also preserving the product's durability, according to André Rolim Baby, the last author of the paper and a professor at the University of So Paulo's School of Pharmaceutical Sciences.
“We’re also interested in looking for alternatives to conventional filters that are less harmful to the environment, such as natural ingredients that enhance the formulation.”
The investigation was part of a FAPESP-sponsored program to study the chemopreventive properties of various UV filters.
Rosmarinic acid, a natural polyphenol antioxidant found in rosemary, sage, peppermint, and many other medicinal plants, has antiviral, anti-inflammatory, immunomodulatory, antibiotic, and anti-cancer properties.
The research group presented a review article in the journal Nutrients in 2022 that examined the beneficial effects of rosmarinic acid as a food supplement, such as improvements in skin firmness and wrinkle reduction.
"We found potential benefits of rosmarinic acid for skin surface hydration in another investigation," said Baby.
Mara de Oliveira Bispo, Ana Luca Morocho-Jácome, Renata Miliani Martinez, Claudinéia Aparecida Sales of Oliveira Pinto, Catarina Rosado, Maria Valéria Robles Velasco, and André Rolim Baby, 6 January 2023, Cosmetics. DOI: 10.3390/cosmetics10010011.
SPF and critical wavelength were tested in a Labsphere UV2000S Ultraviolet Transmittance Analyzer purchased with FAPESP's financing.
Mara de Oliveira Bispo, Ana Lucia Morocho-Jácome, Renata Miliani Martinez, Claudinéia Aparecida Sales of Oliveira Pinto, and Maria Valéria Robles Velasco, all affiliated with USP, are the other authors; Cassiano Carlos Escudeiro of IPclin, a private laboratory located in Jundia, South-West state; and Catarina Rosado of the Lu