Fatty acids and vitamins generate singlet oxygen under UVB irradiation.
UVB radiation is already known as initiator and promoter of carcinogenesis in skin. UVB is well absorbed in proteins and DNA leading to products such as cyclobutane pyrimidine dimers. In contrast, UVA radiation generates reactive oxygen species such as singlet oxygen, which can initiate a variety of cellular damages and cellular signalling. It was the goal to investigate whether and to which extent UVB radiation is additionally able to cause oxidative damages via singlet oxygen. Potential endogenous photosensitizers such as vitamin B molecules or unsaturated fatty acids were irradiated in solution using monochromatic UVB radiation at 308 nm. Singlet oxygen was directly detected and quantified by its luminescence at 1270 nm. All investigated endogenous photosensitizers showed clear singlet oxygen signals with a quantum yield ranging from 5 to 40%. UVB radiation altered the photosensitizer molecules during irradiation yielding a change of absorption in the entire ultraviolet spectrum (280-400 nm). UVB irradiation of endogenous photosensitizers produced singlet oxygen that in turn changes the absorption of those molecules. Being an important prerequisite, the changed absorption may either reduce or increase singlet oxygen production. An increase in singlet oxygen generation may initiate a vicious cycle that has the potential to amplify UVB- or UVA-mediated effects in skin cells.
Department of Dermatology, University of Regensburg, Regensburg, Germany.
Johannes
J
Regensburger
Alena
A
Knak
Tim
T
Maisch
Michael
M
Landthaler
Wolfgang
W
Bäumler
D016718:Arachidonic Acid / Q000737:chemistry / Q000528:radiation effects; D005227:Fatty Acids / Q000737:chemistry / Q000528:radiation effects*; D019787:Linoleic Acid / Q000737:chemistry / Q000528:radiation effects; D008163:Luminescent Measurements; D009525:Niacin / Q000737:chemistry / Q000528:radiation effects; D010084:Oxidation-Reduction; D043803:Phenalenes / Q000737:chemistry / Q000528:radiation effects; D010782:Photolysis; D017319:Photosensitizing Agents / Q000737:chemistry / Q000528:radiation effects; D011166:Porphyrins / Q000737:chemistry / Q000528:radiation effects; D011736:Pyridoxine / Q000737:chemistry; D012256:Riboflavin / Q000737:chemistry / Q000528:radiation effects; D026082:Singlet Oxygen / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D014466:Ultraviolet Rays; D014815:Vitamins / Q000737:chemistry / Q000528:radiation effects*; D017962:alpha-Linolenic Acid / Q000737:chemistry / Q000528:radiation effects
D005227:Fatty Acids; D043803:Phenalenes; D017319:Photosensitizing Agents; D011166:Porphyrins; D014815:Vitamins; D017962:alpha-Linolenic Acid; D026082:Singlet Oxygen; D009525:Niacin; D016718:Arachidonic Acid; C021096:tetra(4-N-methylpyridyl)porphine; C038036:phenalen-1-one; D019787:Linoleic Acid; D011736:Pyridoxine; D012256:Riboflavin