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In Sight—UVA Protection Through Strawberry Anthocyanins
By: Katie Anderson
Posted: October 1, 2012, from the October 2012 issue of Cosmetics & Toiletries.
Francesca Giampieri, center, is a doctoral student at the Università Politecnica delle Marche’s department of odontostomatologic and specialized clinical sciences. She conducted the research with fellow students Luca Mazzoni, left, and José Miguel Alvarez Suarez, right.
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Before testing the photoprotective benefits of the extract, preliminary experiments were carried out to determine the optimal range of extract concentrations in terms of cell viability and the exposure time. “We incubated cells with different concentrations of extracts for six and 24 hours, and we chose the concentrations of strawberry extract that gave the best results in terms of vitality,” said Giampieri.
To test the protoprotective effect of the strawberry extract, the team added it at 0.05, 0.25 and 0.5 mg/mL to fibroblast cell cultures. The team capped the dosage at 0.5 mg, as a higher dosage appeared to be toxic to cells. There was also a control, where the fibroblast cell culture was not treated. The cultures were then exposed to UVA radiation and assessed using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Control cells and cells pre-treated with different concentrations of strawberry extract were analyzed to determine the photoprotective activity of the strawberry extract and to observe if its protection was dose-dependent. “We found that cells pre-incubated with the lower concentration of the extract exhibited vitality similar to the control, while the cells pre-incubated with higher concentrations of the extract showed higher survivabilty. In particular, cells treated with 0.5 mg/mL exhibited a significant difference in vitality,” reported Giampieri. Cells did not show significant difference in vitality at higher UV exposures, according to Giampieri. She explained, “This outcome is likely due to the depletion of the protective capacity of strawberry extracts after high UV treatments.” She adds that many studies have also found anthocyanin-rich extracts to be capable of protecting cells such as fibroblasts against UVB radiation; although her work focused on UVA.
UVA radiation causes oxidative damage through generation of reactive oxygen species (ROS), which can interact with cellular biomolecules such as nucleic acids, proteins, fatty acids and saccharides (5), altering the redox status of the intracellular location, according to Giampieri. Therefore, the team believed that anthocyanins, due to their antioxidant capacity, could decrease the amount of intracellular ROS caused by the UVA radiation and reduce the damage to cell structures, including DNA. Therefore, the team assessed whether the strawberry extract could provide DNA protection.Control cells and cells pre-incubated with the extract were exposed to UVA radiation for 15 min and processed according to the Comet assay protocol.
“Consistent with the vitality assay, DNA damage was observed in control cells and cells pre-incubated with the lower concentrations of the extract (0.05 mg/mL),” explained Giampieri. “Conversely, cells pre-treated with 0.25 mg/mL and 0.5 mg/mL showed a significant decrease in DNA damage in comparison with the control.”
Giampieri finds great value in her team’s results and believes that they could lead to the prevention of cancer and skin-related inflammatory and degenerative illnesses.