As the link between skin cancer and UV radiation strengthens, the use of sunscreen is increasing. Problem is many current sunscreens cause skin allergies. Enter scytoenemin—cyanobacteria that have the potential to offer a UV-protecting pigment in sun care products, including sunscreen, minus the skin allergens.
"Unfortunately, several of the chemical UV filters used in sunscreens cause contact allergy, either of themselves or when they are exposed to sunlight," said Isabella Karlsson, research student in the Department of Chemistry at the University of Gothenburg. “We have therefore studied a UV filter, scytonemin, found in certain bacteria. We have managed to produce this substance artificially in the laboratory."
Rewind to 1993, researchers at the University of Oregon, Eugene, were investigating scytonemin—which was first shown to be an effective, photo-stable UV shield in prokaryotes—as a possible UV screening strategy far more ancient than plant flavonoids and animal melanins (Cellul Molecul Life Sci. 1993; 49(9):825-829). It provided significant protection to cyanobacteria against damage by UV radiation.
UVA rays, skin’s biggest offender, are typically combated in sun creams with the chemical UVA filter 4-tert-butyl-4'-methoxy dibenzoylmethane (BM-DBM), which is known to cause photocontact allergy when it reacts on the skin. According to Karlsson, BM-DBM breaks down in UV light to form several different products, including the potent contact allergens—arylglyoxals. Another popular UV filter is octocrylene; but again, this chemical filter has several reports of causing skin allergies.
Therefore, scientists at the University of Gothenburg and Chalmers University of Technology are spearheading efforts to find a natural UV filter that doesn’t cause contact skin allergies. The 1993 study reported the pigment’s ability to absorb UVA, UVB and UVC. And another study conducted at NASA Ames Research Center, reported, “Scytonemin is known to absorb in the UV regions of the light spectrum, protecting cells from its devastating effects. Higher exposures create a need for scytonemin to react and absorb, protecting the organism from cellular and molecular damage."
Karlsson and her team are hopeful for scytonemin as a natural ingredient in sunscreen; but more research will be required, she said.