Polypodium leucotomos extract
Polypodium leucotomos extract (PLE) comes from a tropical fern plant grown in Central and South America. Native Americans have used the plant extract for centuries for the treatment of inflammatory disorders and skin diseases. Clinical research has shown that it has antioxidant and photoprotective properties and taken orally provides protection against the harmful effects of ultraviolet (UV) radiation from the sun and other sources.
How does PLE work?
To gain a better understanding of how PLE works, you need to understand the effects of UV radiation on the body. These are described in the article on sunburn.
The mechanism of action of PLE is fairly complex but has been summarized into the following main points:
- PLE acts as a scavenger to mop up free radicals and reactive oxygen species (ROS), particularly superoxide anions (these high energy molecules cause direct cell damage and have long been associated with all types of cancer)
- PLE inhibits the depletion of Langerhans cells
- PLE reduces the number of sunburn cells
- PLE protects DNA by inhibiting the formation of cyclobutane pyrimidine dimers (cancer-causing cells) induced by UVB radiation
- PLE preserves skin tissue structure by inhibiting the infiltration of mast cells into skin (mast cells release chemicals in the body that cause inflammation, redness and itching)
What is PLE used for?
PLE is an addition to the armamentarium against the damaging effects of UV radiation exposure. It should be considered as another layer of protection and used in conjunction with a good sunscreen and protective clothing.
PLE is particularly suitable for people whom are photosensitive, especially those with polymorphous light eruption. Clinical trials have been performed in people with skin types II to IV and results show that PLE provides significant protection of skin against UV radiation.
PLE can also be used as a chemophotoprotector against PUVA-induced skin phototoxicity. Extensive PUVA treatment results in premature aging changes in the skin (i.e. increased dryness, freckling and wrinkling) and can increase the chance of skin cancer. Fair skinned individuals or those with previous sun or radiation damage are most at risk. In clinical trials, PLE has proven to be the first oral agent effective in reducing the harmful side effects of PUVA treatment.
How is PLE given?
PLE is marketed as a dietary supplement containing a combination of the antioxidants (Heliocare®, Antioxidine®). These are rapidly absorbed and provide early protection that lasts up to 2 hours after administration, against the initial signs of sunburn (erythema). However, the photoprotective effect of PLE extends beyond just decreasing erythema. The antioxidant properties of orally administered PLE work at protecting the skin at a deeper cellular level that is not achieved with topically applied antioxidants.
PLE has not been clinically tested in patients less than 18 years, and in pregnant or breastfeeding women. Hence there is no data to support its use in these groups.
Side effects of PLE
PLE supplements have been used over the last 20 years in Europe without any side effects being reported.
PLE has not been thoroughly tested for interactions with other supplements and drugs. Some concern has been expressed that it may interact with medications that affect the function of the heart or blood pressure, as cardiac effects have been demonstrated with a related fern species, Polypodium vulgare.