Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative stress caused by excess or fluctuating light conditions.
Humans and other animals have also developed photoprotective mechanisms to avoid UV photodamage to the skin, prevent DNA damage, and minimize the downstream effects of oxidative stress.
In organisms that perform oxygenic photosynthesis, excess light may lead to photoinhibition, or photoinactivation of the reaction centers, a process that does not necessarily involve chemical damage.
When photosynthetic antenna pigments such as chlorophyll are excited by light absorption, unproductive reactions may occur by charge transfer to molecules with unpaired electrons.
[2] Another unique, albeit poorly-understood, cyanobacterial strategy involves the IsiA chlorophyll-binding protein, which can aggregate with carotenoids and form rings around the PSI reaction center complexes to aid in photoprotective energy dissipation.
[3] Some other cyanobacterial strategies may involve state-transitions of the phycobilisome antenna complex[4] , photoreduction of water with the Flavodiiron proteins,[5] and futile cycling of CO2[6] .
To better understand this phenomenon, Waterman et al. conducted an experiment to analyze the photoprotective qualities of UVACs (Ultraviolet Absorbing Compounds) and red pigmentation in antarctic mosses.
Moss specimens of species Ceratodon purpureus, Bryum pseudotriquetrum and Schistidium antarctici were collected from an island region in East Antarctica.
All specimens were then grown and observed in a lab setting under constant light and water conditions to assess photosynthesis, UVAC and pigmentation production.
Many factors including soil nutrient richness, ambient temperature fluctuation and water availability all impact the photoprotection process in plants.
Plants exposed to high light intensity coupled with water deficits displayed a significantly inhibited photoprotection response.
[14][15][16] Afamelanotide is also being investigated as a method of photoprotection from in the treatment of polymorphous light eruption, actinic keratosis and squamous cell carcinoma (a form of skin cancer).
Oxybenzone, titanium oxide and octyl methoxycinnamate are photoprotective agents used in many sunscreens, providing broad-spectrum UV coverage, including UVB and short-wave UVA rays.