Promising Developments in Sunscreen Technology
By Larisa M. Lehmer, MD, MA
Iron. The element hailed for its essential role in the red blood cell’s oxygen-carrying compound, hemoglobin, is less of a knight-in-shining-armor and more of a reckless barbarian when it comes to sun exposure in the skin. When solar energy in the form of UVA-rays interacts with excess iron stored up in skin cells, toxic free radicals are formed that damage or even destroy the cells. The effect of this microscopic process of cell damage and death is what we observe as a sunburn or, over time, photo-aging. Our bodies use antioxidants like Vitamin C and E, gleaned naturally from a diet rich in fruits and vegetables, to combat the low levels of stress that cells face on a daily basis. However, all too painful experience indicates that these basic defenses are no match for the veritable oxidative onslaught incurred by a mid-day trip to the beach largely because these antioxidants help neutralize free radicals once they form, but cannot prevent them from happening in the first place.
In a set of elegant experiments performed on skin cells in a lab, researchers at the University of Bath and King’s College of London have shown it is possible to disable the iron responsible for cellular damage through a process of targeted chelation. “But wait — ” you may say, “What about the iron the cell needs?” The catechol-based hexadentate iron chelator chosen by the researchers scavenges the excess iron from the cells “labile iron pools” without interfering with the iron being used in cellular processes.
So, what happened when they put it to the test? The cells exposed to the compound before being hit with the UVA equivalent of 140 minutes of uninterrupted sun exposure were 100% protected from its harmful effect – it was as if nothing had happened, whereas the “control cells,” i.e., those with no treatment, showed extensive signs of damage and/or death. They further tested the iron-UVA interaction by applying a compound half as good at soaking up the cellular iron to another set of cells before shining UVA on them and this group suffered 50% more damage than with the ideal compound.
A big reason why removing a key component for free radical formation, i.e., the labile iron, is so effective is because the cell requires a large amount of energy to generate the compounds that neutralize the free radicals and then repair the damage that has been done. The researchers showed that exposing cells to UVA depletes their energy store by 80%, but with the addition of the iron chelator, the same dose of UVA only costs the cell 40% of its energy store which leaves enough around for full regeneration to occur.
While more testing has to be done to ensure the use of targeted iron chelation that is strong enough to block UVA damage is safe for use on our summer vacations, don’t be surprised if iron edges-out zinc and titanium to become the new “It-metal” of skin care discussion forums.