Polypodium leucotomos (PL) is a tropical fern plant native to Central America and parts of South America. It grows in the rain forest and has a long history of use as an herbal medicine ingested for a variety of ailments by the indigenous people of Honduras. The Mayans even drank it as a tea. Historically, ferns have been used for medicinal purposes since ancient Europe. Commercial extracts of Polypodium leucotomos have been available since at least the 1970s.
Polypodium leucotomos is actually the common name for the herb known as Phlebodium aureum. Other names for PL include: calaguala (in Mexico and other Spanish-speaking countries), fougère, PLE, Polypodium, kalawalla, samambia, polypodiaceae, Polypodium aureum, Polypodium decumanum, Phlebodium decumanum, Golden Polypody, cabbage palm fern, golden serpent fern, Samambaia (in Brazil), and other synonyms in different parts of the world. It is also sold under a number of different brand names; for instance, Anapsos is a Spanish brand name for a psoriasis drug made from Polypodium leucotomos.
What Is Polypodium Leucotomos Used For?
Most commonly, Polypodium leucotomos is taken orally for the treatment of inflammation and a variety of skin ailments including psoriasis, vitiligo (the loss of pigment in patches of the skin), atopic dermatitis (eczema: inflammation of the skin), and melasma (over-pigmented patches of dark skin). It also serves as a protectant against sunburn (solar erythema) and helps prevent and relieve polymorphous light eruption (PMLE). In fact, much of the research that has been done on Polypodium leucotomos over the past 40+ years has been on its management of skin conditions and its photo-protective properties after it is ingested. Many of these clinical studies have shown extracts of Polypodium leucotomos to be surprisingly effective at defending skin against damage from the sun (ultraviolet radiation) when Polypodium leucotomos is taken orally, with some authors even calling it an “internal sunscreen.”
What Are The Active Ingredients In Polypodium Leucotomos Extract (PLE)?
Both the rhizomes (the stem of the plant that grows underground) and the leaf have been used in medicine. Research into the composition of the leaf extract of Polypodium leucotomos used today has shown it contains a number of active ingredients, many of which are antioxidant polyphenols. These polyphenols include the phenolic acids p-coumaric, ferulic, fumaric, vanillic (3-methoxy-4-hydroxybenzoic), quinic (4-hydroxycinnamoyl-quinic), caffeic (4-hydroxycinnamic), chlorogenic (3-caffeoylquinic), 3,4-dihydroxybenzoic, and 4-hydroxybenzoic, along with five phenolic chlorogenic acid isomers. Polypodium leucotomos leaf extract is rich in monosaccharides and flavonoids.
How Does Polypodium Leucotomos Work?
Clinical research has shown Polypodium leucotomos has a number of functions:
- Polypodium leucotomos has both antioxidant and anti-inflammatory properties, which may explain its ability to prevent damage caused by excessive sun exposure and its helpfulness in ameliorating certain skin conditions.
- The high percentage of antioxidant phenols in PL have been shown to protect skin from erythema by inhibiting the formation of free radicals from UV radiation (and thereby preventing oxidative damage). It has also been shown to help prevent sunburn and reduce the reddening of skin that can occur with sun exposure.
- By inhibiting free radicals such as reactive oxygen species in skin tissue, long-term DNA damage and photo-aging may be prevented.
- Part of the reason for its photo-protective effects is that PL is orally administered and so is working from the inside out, deep within skin where topically-applied products won’t reach.
- Polypodium leucotomos has also been shown to provide significant skin protection against UV radiation (sunlight) in people with polymorphous light eruption (also called polymorphic light eruption). These individuals, who are hypersensitive to sunlight, may benefit from PL with reduced itchiness and decreased skin redness.
This Supplement Contains Polypodium Leucotomos And Many Other Natural Ingredients That Protect Your Skin.
- PL’s anti-inflammatory effects in skin tissue help prevent immunosuppression: the inhibition of the immune system which can also lead to detrimental cellular changes.
- PL has been shown to inhibit cytokines: immune system factors that are part of the inflammatory response and needed for proper healing of skin damage, but also implicated in autoimmune diseases. By properly inhibiting cytokines, PL may help prevent inflammation and tissue damage.
- Polypodium leucotomos also decreases the vasodilation that comes with inflammation.
- PL’s anti-inflammatory effects also have been shown to reduce itchy and inflamed skin in people with eczema and improve the symptoms of psoriasis.
- It also may decrease the incidence of phototoxicity in individuals undergoing UV treatments for skin conditions such as psoriasis and vitiligo. In people undergoing PUVA treatment (psoralen plus ultraviolet A light), PL may reduce side effects and skin damage.
- PL has also been shown to reduce the skin darkening that occurs in some people undergoing UV treatments for certain skin conditions.
- Interestingly enough though, research has also suggested that taking PL for months may help return some color (increase re-pigmentation) to the areas of skin with less pigment in people with vitiligo.
- PL may even be able to help stimulate collagen production by increasing the expression of a collagen promoter protein.
Mechanisms of Action
While the mechanisms of action of Polypodium leucotomos are complex and not completely elucidated, some of the details of how PL works are understood. These include:
- As an antioxidant, Polypodium leucotomos neutralizes free radicals, particularly superoxide anions, hydroxides, lipid peroxides, and reactive nitrogen species, thereby preventing these free radicals from directly damaging cells and other skin structures.
- PL has been shown to inhibit the depletion of Langerhans cells (one type of skin cell).
- Polypodium leucotomos inhibits the formation of cyclobutane pyrimidine dimers (a type of DNA damage) that are induced by UVB radiation, leading to less ultraviolet-induced DNA mutations.
- PL prevents inflammation and preserves skin tissue by inhibiting the infiltration of immune cells (which release chemicals as part of the inflammatory process, causing redness and itching)–such as mast cells, neutrophils, and macrophages–after UV exposure.
- Studies note a greater activation of p53 expression in skin cells, in response to UV radiation, in the presence of Polypodium leucotomos. This may be one of the main causes of PL’s protective effects. P53 is a tumor suppressor protein, whose activation may be one of the mechanisms affording PL’s genomic protection and anti-inflammatory effects, and the suppression of radiation-generated proliferation of skin cells.
- Other studies of PL have shown similar effects in the reduced of inflammatory response as measured by TNF-a (tumor necrosis factor alpha) and iNOS (inducible nitric oxide synthase) expression, which are both involved in systemic inflammation.
- PL has also been shown to have a protective effect in skin by inhibiting MMPs (matrix metalloproteinases), which degrade extracellular matrix proteins such as collagen in skin tissue. Interestingly, it may also stimulate the production of collagen.
- Laboratory experiments have also shown PL to increase the antioxidant capacity of blood (as measured by ORAC rating in plasma) by increasing the antioxidant enzymes superoxide dismutase (SOD), glutathione S transferase (GST), and glutathione peroxidase (GPX). This decreases genomic damage to skin and decreases mutations in DNA.
- In response to radiation, PL has also been shown to suppress the induction of cyclooxygenase-2 (COX-2), a key enzyme in the promotion of inflammation.
Research: Clinical Studies And The Effectiveness Of Polypodium Leucotomos
The key findings of a small selection of clinical trials, whose results have been published in scientific journals, are summarized below. These highlight some of the research that has been done on Poypodium leucotomos’s effects in the areas of sun protection, polymorphous light eruption (PMLE), photodermatitis, urticaria, psoriasis, skin aging, collagen production/preservation, and illness prevention in athletes.
The following studies demonstrate data for the protective effect of Polypodium leucotomos against the damage induced by ultraviolet radiation. The evidence suggests that PL can reduce reddening, the rate at which skin burns in sunlight, and many other markers of sun damage in skin.
In 2004, Harvard researchers conducted a study in which healthy volunteers were tested to see whether Polypodium leucotomos would protect fair to light-skinned individuals from sun damage. Some subjects were given oral doses of PL extract, and some were not. All were exposed to varying doses of ultraviolet radiation, and after 24 hours the researchers took skin biopsies to measure the amount of skin redness due to erythema (inflammation caused by ultraviolet radiation, i.e. sunburn).
The results demonstrated a remarkable decrease in UV-induced skin damage in those who had taken the PL extract. Those taking the PL extract had significantly fewer sunburned cells (a sign of tissue damage) and less cyclobutane pyrimidine dimers (a marker of DNA damage). The PL extract also inhibited the infiltration of mast cells (which cause inflammation, redness, and itching). Furthermore, the PL extract had a protective effect on Langerhans cells: sensitive immune cells, found throughout the many layers of the skin, that help fight infections. The researchers concluded that Polypodium leucotomos is an effective oral photoprotective agent which offers “significant protection of skin against UV radiation.”
[Middelkamp-Hup M, Pathak MA, Parrado C, et.al. Oral Polypodium leucotomos extract decreases ultraviolet-induced damage of human skin. J Am Acad Dermatol. 2004 Dec;51(6):910-8.]
A 2010 publication reported the results of a clinical trial in which 10 healthy volunteers were given either 240mg oral Polypodium leucotomos 8 hours and again 2 hours before UVA exposure, or not given anything at all before UVA exposure. Prior to exposure, each individual was measured to determine his or her baseline skin histology and how much UVA radiation it took to cause erythema (MED: minimal erythema dose). After exposure, skin samples were again taken and tested for CD (common deletion: a type of DNA damage and a marker of chronic UVA radiation). At 2 times the MED the non-PL group had increases of CD of 217% over baseline, while the group taking PL had decreases of 84%. At 3 times the MED, the non-PL group had increases of CD of 760% over baseline, while the group taking PL only had a 61% increase on average. These trends were determined “very strong” by the researchers, and while the data was not statistically significant (due in part to the small sample size), the researchers concluded that Polypodium leucotomos “may prevent UVA-induced skin photodamage possibly by preventing UVA-dependent mitochondrial DNA damage.”
[Villa A, Viera M, Amini S, et al. Decrease of ultraviolet A light–induced “common deletion” in healthy volunteers after oral Polypodium leucotomos extract supplement in a randomized clinical trial. J Am Acad Dermatol. 2010 Mar;62(3);511-3.]
Polymorphous Light Eruption (PMLE), Photodermatitis, And Urticaria
In 2007, a study found that Polypodium leucotomos extract was beneficial to individuals who are extremely sensitivity to the sun. The individuals all had either polymorphic light eruption (itchy red rashes from sun exposure) or solar urticaria (a form of hives caused by sunlight), but had not responded well to other available therapies. These patients’ response to sunlight was measured both before and after taking an oral dose of 480 mg of Polypodium leucotomos.
The researchers reported that after taking Polypodium leucotomos and being exposed to sunlight, patients had a relevant and statistically significant reduction of skin reactions and subjective symptoms as compared to exposure without PL. The researchers concluded that the “photoprotective activity of Polypodium leucotomos was significant,” and furthermore, the tolerance of PL was excellent and administration was shown to be effective and safe.
[Caccialanza M, Percivalle S, Piccinno R, Brambilla R. Photoprotective activity of oral polypodium leucotomos extract in 25 patients with idiopathic photodermatoses. Photodermatol Photoimmunol Photomed. 2007 Feb;23(1):46-7.]
Another study in 2012 tested 30 patients with polymorphic light eruption. These patients were exposed to UVA and UVB light both before taking Polypodium leucotomos and after two weeks of oral treatment with Polypodium leucotomos. After taking Polypodium leucotomos, 30% of patients did not get polymorphic light eruptions at all when exposed to UVA, and in the remaining patients the number of UVA irradiations needed to elicit polymorphic light eruptions increased on average from 1.95 to 2.62. Similarly, 28% of patients did not get polymorphic light eruptions at all when exposed to UVB, and in the remaining patients the number of UVB irradiations needed to elicit polymorphic light eruptions increased on average from 2.38 to 2.92. The researchers concluded that Polypodium leucotomos treatment might be beneficial for the prevention of PMLE.
[Tanew A, et al Oral administration of a hydrophilic extract of Polypodium leucotomos for the prevention of polymorphic light eruption . J Am Acad Dermatol. (2012)]
In another study of patients with idiopathic photodermatoses (53 with polymorphic light eruption and 4 with urticaria), the basal skin condition was clinically evaluated in the patients both before and after sunlight exposure while taking Polypodium leucotomos. 74% of patients taking 480mg of Polypodium leucotomos daily for 15 days reported a benefit, with a significant reduction of skin reaction to the sun and subjective symptoms. No side effects were reported. The researchers concluded that Polypodium leucotomos is an effective and safe treatment for photoprotection in those with polymorphic light eruption and urticaria.
[Caccialanza M, Recalcati S, Piccinno R Oral polypodium leucotomos extract photoprotective activity in 57 patients with idiopathic photodermatoses . G Ital Dermatol Venereol. (2011)]
In a placebo-controlled study of 37 patients affected by psoriasis, 13 took a placebo and 22 patients finished treatments of Polypodium leucotomos (anapsos) in capsules of 120mg. 9 out of 22 of the psoriasis patients who used Polypodium leucotomos obtained complete relief of symptoms (called “whitenings” by the authors: complete treatments of the areas of affected skin), 5 patients obtained relief of symptoms in 40% to 80% of the affected surface, 5 patients obtained a maximum of 40% relief of symptoms, and 3 patients had null results. The authors concluded that, due to the absence of side effects and minimum intolerance, and the amount of success obtained by the patients, the treatment of psoriasis with Polypodium leucotomos is a viable option.
[Del Pino, Gamboa J., De Sambricio, Guiu F., and Colomo, Gomez C. [Comparative study between 120 mg. of anapsos and a placebo in 37 psoriasis patients]. Med Cutan Ibero.Lat.Am 1982;10(3):203-208.]
In another study, 495 patients affected by several forms of psoriasis were given daily doses of between 80mg and 720mg of Polypodium leucotomos, depending on age, weight, and treatment phase. After 6 months, 304 patients (61%) achieved between 80% and 100% whitenings of the affected skin. 46 patients achieved between 30% and 80% whitenings of their lesions. 15 patients obtained null results, and only 11 had relapses. 119 patients (24%) abandoned treatment, probably mainly due to the length of time of the study and slowness of process. There was also a positive association with PUVA (psoralen plus ultraviolet A) therapy, which shortened psoriasis treatment.
[Pineiro, Alvarez B. [2 years personal experience in anapsos treatment of psoriasis in various clinical forms]. Med Cutan Ibero.Lat.Am 1983;11(1):65-72.]
Skin Aging And Collagen Production
In a 2009 study it was found that Polypodium leucotomos had the potential to be an important anti-aging agent. In the study, researchers measured a variety of effects of Polypodium leucotomos on fibroblasts and melanoma cells both with and without UVA and UVB irradiation.
The results demonstrated a number of effects:
- Matrix metalloproteinases (MMPs) are enzymes capable of degrading the extracellular matrix (ECM: the structure between cells that includes many different substances including collagen), but are also implicated in skin aging/photoaging, and cancer. Polypodium leucotomos inhibited both the expression and activity of MMPs in dermal fibroblasts and melanoma cells.
- Tissue inhibitors of matrix metalloproteinases (TIMPs) inhibit MMPs (and thereby preserve the extracellular matrix of the skin). Polypodium leucotomos stimulated the expression of TIMPs in fibroblasts and melanoma cells, thereby aiding the health of the skin.
- Polypodium leucotomos stimulated collagen in both UV radiated and non-irradiated fibroblasts.
- Transforming growth factor-beta (TGF-beta) is a protein that regulates the ECM. It is inhibited in aging/photoaging but stimulated in carcinogenesis. Polypodium leucotomos had stimulatory effects on TGF-beta expression in non-irradiated and UV radiated fibroblasts, and inhibited TGF-beta expression in melanoma cells.
It is extremely interesting to note that Polypodium leucotomos protected the ECM via two different types of effects: the inhibition of ECM proteolytic enzymes (that break down the ECM) and the stimulation of different types of structural ECM collagens (that build up the ECM).
The researchers concluded that Polypodium leucotomos may be beneficial to skin health—in preventing aging and preventing or treating cancer—via its antioxidant, anti-inflammatory, and photoprotective properties.
[Philips N, Conte J, Chen YJ, et al. Beneficial regulation of matrixmetalloproteinases and their inhibitors, fibrillar collagens and transforming growth factor-beta by Polypodium leucotomos, directly or in dermal fibroblasts, ultraviolet radiated fibroblasts, and melanoma cells. Arch Dermatol Res. 2009 Aug;301(7):487-95.]
Bacterial Infections In Athletes
Intense and prolonged physical activity can cause adverse changes to the immune system, increasing the chances of respiratory infections. In a 2012 study, 100 high performance athletes were given either 240mg of Polypodium leucotomos twice a day, or a placebo, for 3 months. At the end of the trial, only 14% of athletes taking Polypodium leucotomos got an infection, whereas 56% of the athletes taking a placebo got an infection. Furthermore, only one athlete (14%) in the Polypodium leucotomos group that did get an infection relapsed, versus 38% of the control group. The researchers concluded that Polypodium leucotomos extract has been shown to be useful in the prevention of infectious illnesses, as well as reducing recurring infections, in athletes.
[Solivellas BM, Martín TC Polypodium leucotomos Extract use to prevent and reduce the risk of infectious diseases in high performance athletes . Infect Drug Resist. (2012)]
Combinations Work Even Better Than Polypodium Leucotomos By Itself
While Polypodium leucotomos has many beneficial properties, taking a combination of different types of antioxidants can have an even stronger effect. Combinations of antioxidants have been found to have synergistic effects, providing greater benefits than any individual compound used alone, and enumerable studies have shown this. For instance, a number of different classes of antioxidant compounds have been demonstrated to help defend skin against free radicals and sun damage including various polyphenols (such as those found in green tea), carotenes (for instance: lycopene), xanthophylls (like lutein and astaxanthin), polyphenols, Vitamin C, Vitamin E, and the minerals zinc and selenium—which function as cofactors in certain antioxidant enzymes. Combining these ingredients can offer greater health benefits to skin and increased photoprotection.
One formulation that takes advantage of research into the benefits of a combination of efficacious antioxidants is Sunsafe Rx. Sunsafe Rx is an oral capsule with a proprietary formulation of Polypodium leucotomos and a number of other antioxidants from plants and foods that have all been clinically shown to protect your skin. The anti-aging ingredients in Sunsafe Rx are also healthy for your skin and eyes.
How Do You Use It?
Polypodium leucotomos leaf extract has shown benefits when taken via oral supplementation, and even to a certain degree when applied topically. For its photoprotective benefits it is often recommended to take it orally 30 to 60 minutes prior to sun exposure, once or several times per day. For other conditions that don’t involve sun exposure, it can be taken at any time. For some skin conditions, benefits may take weeks or even months to be fully realized. It doesn’t seem to matter if PLE extract is consumed with or without food.
Most of the research on Polypodium leucotomos leaf extract has been done with dosages of approximately 240mg to 480mg per day, although various studies have been done with results seen at dosages of 80mg or 120mg, and other experiments at 720mg per day or higher. A common guideline seems to be daily dosages of approximately 7.5mg per kg of an individual’s body weight. For a 150 pound person, this would be approximately 511mg per day.
PLE supplements have been commonly used for over 20 years in Europe, and other parts of the world, without any side effects being reported. There are no known side effects associated with PLE taken orally as a dietary supplement.
PLE has not, however, been extensively tested in children, pregnant, or breast-feeding women, and there have not been published clinical trials testing PLE for interactions with various drugs.
Since PLE is not technically considered a sunscreen by the FDA (since it is not a lotion that is put on the skin and does not contain certain specific chemicals legally required for a lotion to be called a sunscreen), care should be taken when you are in the sun. As always, be very careful to avoid extensive sun exposure, cover exposed skin, and use a natural sunscreen lotion if sun exposure can’t be avoided. After all, the sun ages your skin more than just about anything else.
Where Can You Get Polypodium Leucotomos?
Much of the research on Polypodium leucotomos has been done on extracts of the leaf. Polypodium leucotomos leaf extract is difficult to source, but it is sold in Europe and the United States and other parts of the world by a few different companies. It is sold both by itself and in combination with other ingredients, including in this anti-aging product.
While more research is always useful, the research to date has shown Polypodium leucotomos to be safe and efficacious for a variety of conditions and uses, and there is substantial clinical evidence to recommend its use for photoprotection and a variety of skin conditions including psoriasis, vitiligo, atopic dermatitis (eczema), melasma, polymorphous light eruption, and various other inflammatory ailments of the skin.
Alcaraz, M. V., Pathak, M. A., Rius, F., Kollias, N., and Gonzalez, S. An extract of Polypodium leucotomos appears to minimize certain photoaging changes in a hairless albino mouse animal model. A pilot study. Photodermatol.Photoimmunol.Photomed. 1999;15(3-4):120-126.
Alvarez XA, et al Double-blind, randomized, placebo-controlled pilot study with anapsos in senile dementia: effects on cognition, brain bioelectrical activity and cerebral hemodynamics . Methods Find Exp Clin Pharmacol. (2000)
Dea-Ayuela, M., Rodero, M., Rodriguez-Bueno, R., Bolas-Fernandez, F., and Martinez-Fernandez, A. R. Modulation by Anapsos (Polypodium leucotomos extract) of the antibody responses against the nematode parasite Trichinella spiralis. Phytother Res 1999;13(7):566-570.
Edlich RF, Winters KL, Lim HW et al. Photoprotection by sunscreens with topical antioxidants and systemic antioxidants to reduce sun exposure. Journal of Long-Term effects of Medical Implants 2004;14(4):317-340
Fernandez-Novoa, L., Alvarez, X. A., Sempere, J. M., Miguel-Hidalgo, J. J., Diaz, J., Franco-Maside, A., and Cacabelos, R. Effects of anapsos on the activity of the enzyme Cu-Zn-superoxide dismutase in an animal model of neuronal degeneration. Methods Find.Exp Clin Pharmacol 1997;19(2):99-106.
Fosslien E Review: molecular pathology of cyclooxygenase-2 in cancer-induced angiogenesis . Ann Clin Lab Sci. (2001)
Garcia F, Pivel JP, Guerrero A, et al. Phenolic components and antioxidant activity of Fernblock, an aqueous extract of the aerial parts of the fern Polypodium leucotomos. Methods Find Exp Clin Pharmacol 2006;28:157-60.
Gomes, A. J., Lunardi, C. N., Gonzalez, S., and Tedesco, A. C. The antioxidant action of Polypodium leucotomos extract and kojic acid: reactions with reactive oxygen species. Braz.J Med Biol Res 2001;34(11):1487-1494.
Gonzalez S, Alcaraz MV, Cuevas J, Perez M, Jaen P, Alvarez-Mon M, Villarrubia VG. An extract of the fern Polypodium leucotomos (Difur) modulates Th1/Th2 cytokines balance in vitro and appears to exhibit anti-angiogenic activities in vivo: pathogenic relationships and therapeutic implications. Anticancer Res. (2000) 20.3A: 1567-1575.
Gonzalez S, Pathak MA, Cuevas J, et al. Topical or oral administration with an extract of Polypodium leucotomos prevents acute sunburn and psoralen-induced phototoxic reactions as well as depletion of Langerhans cells in human skin. Photodermatol Photoimmunol Photomed 1997;13:50-60.
Gonzalez S, Pathak MA. Inhibition of ultraviolet-induced formation of reactive oxygen species, lipid peroxidation, erythema and skin photosensitization by polypodium leucotomos. Photodermatol Photoimmunol Photomed 1996;12:45-56.
Middelkamp-Hup MA, et al Treatment of vitiligo vulgaris with narrow-band UVB and oral Polypodium leucotomos extract: a randomized double-blind placebo-controlled study . J Eur Acad Dermatol Venereol. (2007)
Middelkamp-Hup MA, Pathak MA, Parrado C et al. Oral Polydium leucotomos extract decreases ultraviolet-induced damage of human skin. J AM Acad Dermatol 2004;51:910-8 http://www.ncbi.nlm.nih.gov/pubmed/15583582
Middelkamp-Hup MA, Pathak MA, Parrado C, et al. Orally administered Polypodium leucotomos extract decreases psoralen-UVA-induced phototoxicity, pigmentation, and damage of human skin. J Am Acad Dermatol 2004;50:41-9.
Middelkamp-Hup, M. A., Bos, J. D., Rius-Diaz, F., Gonzalez, S., and Westerhof, W. Treatment of vitiligo vulgaris with narrow-band UVB and oral Polypodium leucotomos extract: a randomized double-blind placebo-controlled study. J Eur Acad Dermatol Venereol 2007;21(7):942-950.
Navarro-Blasco, F. J. and Sempere, J. M. Modification of the inflammatory activity of psoriatic arthritis in patients treated with extract of Polipodium leucotomos (Anapsos). Br J Rheumatol. 1998;37(8):912.
Philips N, et al Beneficial regulation of matrixmetalloproteinases and their inhibitors, fibrillar collagens and transforming growth factor-beta by Polypodium leucotomos, directly or in dermal fibroblasts, ultraviolet radiated fibroblasts, and melanoma cells . Arch Dermatol Res. (2009)
Philips N, Smith J, Keller T, Gonzalez S. Predominant effects of Polypodium leucotomos on membrane integrity, lipid peroxidation, and expression of elastin and matrixmetalloproteinase-1 in ultraviolet radiation exposed fibroblasts, and keratinocytes. J Dermatol Sci. 2003 Jun;32(1):1-9.
Rayward, J., Villarrubia, V. G., Guillen, C., Prieto, A., Rodriguez-Zapata, M., Sada, G., and Alvarez-Mon, M. An extract of the fern Polypodium leucotomos inhibits human peripheral blood mononuclear cells proliferation in vitro. Int J Immunopharmacol. 1997;19(1):9-14.
Smith ML, Fornace AJ Jr p53-mediated protective responses to UV irradiation . Proc Natl Acad Sci U S A. (1997)
Solivellas BM, Martín TC Polypodium leucotomos Extract use to prevent and reduce the risk of infectious diseases in high performance athletes . Infect Drug Resist. (2012)
Vasange, M., Rolfsen, W., and Bohlin, L. A sulphonoglycolipid from the fern Polypodium decumanum and its effect on the platelet activating-factor receptor in human neutrophils. J Pharm Pharmacol 1997;49(5):562-566.
Vasange-Tuominen, M., Perera-Ivarsson, P., Shen, J., Bohlin, L., and Rolfsen, W. The fern Polypodium decumanum, used in the treatment of psoriasis, and its fatty acid constituents as inhibitors of leukotriene B4 formation. Prostaglandins Leukot.Essent.Fatty Acids 1994;50(5):279-284.
Villa A, et al Decrease of ultraviolet A light-induced “common deletion” in healthy volunteers after oral Polypodium leucotomos extract supplement in a randomized clinical trial . J Am Acad Dermatol. (2010)