Most sunscreens in the market protect the skin well against solar UV-B (shortwave) radiation but have limited effectiveness against damage induced by UV-A (long-wave), relying on the reflective properties of creams to defend against dangerous UV-A rays, which can cause photo-ageing -- premature ageing of the skin -- and cell damage as well as skin cancer.
The new compound, named by the team as "mitoiron claw", offers strong protection within our cells precisely where the greatest damage from UV-A occurs, and doesn't interfere with rest of the cell.
"Our mitochondria-targeted compound can address an unmet need in the skincare and sunscreen fields. This mitoiron claw is a highly effective compound, offering unprecedented protection against UVA-induced mitochondrial damage," said Charareh Pourzand from the University of Bath in Britain.
Free iron concentration is particularly high within mitochondria -- the powerhouse of the cell -- where it is needed for several vital functions. However, upon exposure to UV-A in sunlight, excess free iron acts as a catalyst for the production of toxic reactive oxygen species (ROS), damaging cell components such as DNA, fat and proteins thereby increasing the risk of cell death and cancer.
This custom-designed iron chelator -- a molecule that binds to an iron atom like a claw -- moves directly to mitochondria where it safely binds the excess free iron, preventing it from reacting upon exposure to UV-A rays, the researchers noted.
Tests with human skin fibroblast cells exposed to UV-A radiation equivalent to 140 minutes of uninterrupted sun exposure at sea level, showed that cells treated with the mitoiron claw were completely protected against cell death.
However, the cells untreated with the mitoiron claw suffered significant cell death.
"The role of iron-mediated damage induced upon exposure of skin cells to UV-A has been underestimated for many years. For efficient protection against UVA-induced iron damage of skin strong chelators are needed, but until now these risked toxic effects caused by non-targeted iron starvation of cells," added Pourzand.
The researchers hope to see the mitoiron claw compound added to sunscreens and skin care products within 3-4 years.
The findings were published in the Journal of Investigative Dermatology.
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