Researchers here demonstrate that molecules designed to supply hydrogen sulfide to mitochondria in skin cells can slow the progression of photoaging, the damage done to skin tissue by UV radiation. This offers some insight into the role of mitochondria in the reaction to UV radiation that produces lasting structural damage in skin. The publicity materials speculate on the ability to reverse existing photoaging damage, but that is unsupported by the work presented in the paper, which only shows the outcome of the topical application of the treatment to skin prior to exposure to ultraviolet radiation.
Two new molecules, AP39 and AP123, that generate minute amounts of the gas hydrogen sulfide have been found to prevent skin from ageing after being exposed to ultraviolet light found in sunlight. Researchers exposed adult human skin cells and the skin of mice to ultraviolet radiation (UVA). UVA is the part of natural sunlight which damages unprotected skin and can penetrate through windows, and even through some clothes. It causes skin to age prematurely by turning on skin digesting enzymes called collagenases. These enzymes eat away at the natural collagen, causing the skin to lose elasticity and sag, resulting in wrinkles
In the experiments, the compounds AP39 and AP123 did not protect the skin in the same way traditional sun creams prevent sunburn, but instead penetrated the skin to correct how skin cells' energy production and usage was turned off by UVA exposure. This then prevented the activation of skin-degrading collagenase enzymes and subsequent skin damage.
The compounds AP39 and AP123 specifically target the energy generating machinery inside our cells, the mitochondria, and supply them with minute quantities of alternative fuel, hydrogen sulfide, to use when skin cells are stressed by UVA. The direct result of this was the activation of two protective mechanisms. One is a protein call PGC-1α, which controls mitochondria number inside cells and regulates energy balance. The other is Nrf2, which turns on a set of protective genes that mitigate UVA damage to skin and turn off the production of collagenase, the main enzyme that breaks down collagen in damaged skin tissue and causes skin to look significantly more "aged".