Mitochondrial Bioenergetic Recovery in UVB-Irradiated Human Dermal Fibroblasts Mediated by Photostable Plant Polyphenols

Abstract

Ultraviolet B (UVB) is one of the most persistent environmental stresses to which the skin is exposed and the dermal fibroblast, located immediately below the epidermis, is burdened with a large part of the consequent oxidative stress. Much of that damage ends up in the mitochondrion and shows up as a drop in membrane potential, reduced respiration and depleted ATP. In this work we asked a really simple question: can a small group of plant polyphenols, selected precisely for their photostability, restore mitochondrial function in primary human dermal fibroblasts after a sub-lethal acute UVB dose? Cells were irradiated with 60mJ/cm2 and treated with quercetin, rutin or silibinin. A comparison, trans-Resveratrol, a photolabile polyphenol, was co-processed. We monitored photostability, viability, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (ΔΨm), ATP content, oxygen consumption rate and several biogenesis indicators. The three photostable compounds retained 83–91% of their starting material after a cumulative 150 mJ/cm² of exposure, while resveratrol decreased to approximately one quarter. Rutin and quercetin were the most effective in rescuing the cells, restoring basal and maximum respiration to near control levels, recovering ΔΨm, reducing ROS levels and partially restoring mtDNA copy number and PGC-1α expression. Resveratrol was not very active, similar to its degradation under light. The results show that photostability is not a trivial element but a real predictor of the usefulness of a polyphenol in a photo-oxidative situation.

Highlights
Mitochondrial Bioenergetic Recovery in UVB-Irradiated Human Dermal Fibroblasts Mediated by Photostable Plant Polyphenols
Quercetin, rutin and silibinin resist UVB photodegradation in vitro
Photostable polyphenols restore ΔΨm, ATP and respiration after UVB
Rutin produced the most complete recovery of mitochondrial function
Photolabile resveratrol protected weakly as it decayed under UVB
Photostability is a key determinant of polyphenol UV efficacy