INTRODUCTION
Polypodium leucotomos is a tropical fern of the Polypodiaceae
family native to Central and South America. Polypodium leucotomos extract (PLE; Fernblock®, Ferndale Laboratories,
Ferndale, Michigan, USA) is a polyphenol-enriched
natural product derived from the leaves of the Polypodium leucotomos fern, and has long been known for its anti-inflammatory
and antitumor properties.1,2 Historically, Polypodium leucotomos was first introduced in Europe after the botanical
expedition of Ruiz funded by the Spanish Crown, and later
spread to other areas3. Several animal and human studies have
been performed in recent years that have helped elucidate PL’s
mechanisms of action, which may explain its observed clinical
effects of photoprotection and chemoprevention.
PLE has been used in various formulations for several years in
folk medicine for treatment of a variety of inflammatory ailments
including psoriasis, vitiligo, atopic dermatitis, and photosensitive
disorders. Fernblock® is currently distributed in over 26 countries
including the United States and Europe. It is available as a topical
gel, cream, spray, and compact makeup powder as well as a systemic
agent in the form of oral capsules. PL has been available as
a supplement in Europe since 2001, and as a topical product since
2000. PL has been an oral dietary supplement in the US since
2006. Currently, it is marketed as an oral dietary supplement to
help "protect against sun-related effects and aging", with a recommended
dose of one 240 mg capsule in the morning, and when
extensive sun exposure is anticipated, to take 240 mg one hour
before exposure, and another 240 mg 2-3 hours after. It is marketed
as Heliocareâ„¢ by Ferndale Healthcare, Ferndale, Michigan.
In regards to future developments, research is currently underway
to explore alternative extraction processes, which could
further enhance PL’s photoprotective and anti-oxidant activities
both topically and orally, as well as to investigate PL’s use in
combination with other agents, which could provide synergic
activity. It is hoped that this research will allow for the development
of targeted formulations for specific photoprotection
indications, for prevention of photoaging, and as adjuvant
treatment in sunlight induced or aggravated conditions such as
actinic keratosis and melasma.
PLE has been used to treat a variety of dermatologic disorders
including immunologically-mediated photodermatoses,
vitiligo, melasma, psoriasis, and atopic dermatitis. It has also
been used to minimize the development of photoaging and
skin cancers, and more recently, to decrease the development
of infectious disease in athletes. In this article, we will briefly
discuss its mechanisms of action as well as review its use in the
treatment of dermatologic diseases.
Mechanism of Action
It is well documented that chronic unprotected or excessive
ultraviolet (UV) radiation exposure induces a variety of damage
responses on cellular and molecular levels, including
the induction of stress proteins, indirect DNA damage due
to reactive oxygen species and direct DNA damage due to
formation of cyclobutane pyrimidine dimers; these lead to
immunosuppression and carcinogenesis, impaired immune
surveillance due to UV-induced decrease in epidermal Langer-
