Rosmarinic acid showed protective effects when tested on mice due to its free radical scavenging potential and its ability to stimulate melanin synthesis, according to the research published in the journal Food and Chemical Toxicology.
According to the scientists from the University of Murcia, who were working in collaboration with Spanish botanical extracts company NutraFur, their in vitro tests confirmed the conclusions of previous studies regarding rosmarinic acid’s strong antioxidant potential.
The team then went on to investigate the effect of the antioxidant on tyrosinase activity in mice.
Some animal studies suggest that certain botanical extracts well known for their antioxidant capacity, such as green tea, interfere with melanin production in mice, according to the study authors.
As melanin provides an important line of defence against UV damage of the skin, if a compound is to be classed as a true photoprotective agent it must not interfere with melanin synthesis, they explain.
Increases tyrosinase activity
The team cultured B16 mouse melanoma cells, treating one culture with rosmarinic acid and leaving one as a control. After 48 hours treatment with the antioxidant, tyrosinase activity was increased in six independent assays.
In vivo studies were then performed on mice to investigate the effect oral administration had on UVA-induced dysplasia (abnormal cells that may lead to cancer).
A group of twenty female albino mice were exposed to 120 minutes of UVA rays (00-425nm) 3 times a week for 33 weeks. Ten of the mice had been treated daily with rosmarinic acid at 2 percent dose level in food and drink throughout the study period.
A majority of the samples (80 percent) taken from the mice exposed to UVA showed moderate dysplasia and 20 percent severe. In contrast, 70 percent of the samples taken from the treated mice showed no dysplasia and 30 percent light dysplasia.
The researchers conclude that concentrated rosmarinic acid extracts from rosemary leaves could protect against UV-induced oxidative stress when used in oral preparations and supplements.
More experiments are currently underway to investigate the specific antimutagenic activities of such extracts and their behavior in mammalian tissues after oral administration, according to the scientists.
Source: Food and Chemical ToxicologyIssue 47 (2009) 386-392Rosmarinic acid, a photo-protective agent against UV and other ionizing radiationsM. Sanchez-Campillo, J.A. Gabaldon, J.Castillo, O. Benavente-Garcia, M.J.Del Bano, M. Alcaraz, V. Vicente, N. Alvarez, J.A Lozano