Sunburn, immune suppression, photoaging, and skin cancers result from uncontrolled overexposure of human skin to solar ultraviolet radiation (UVR). Preventive measures, including photoprotection, are helpful and can be achieved by topical sunscreening agents. Polypodium leucotomos (PL) has been used for the treatment of inflammatory diseases and has shown some in vitro and in vivo inmunomodulating properties. Its beneficial photoprotective effects in the treatment of vitiligo and its antioxidant properties encouraged us to evaluate in vivo the potentially useful photoprotective property of natural extract of PL after topical application or oral ingestion. Twenty-one healthy volunteers [either untreated or treated with oral psoralens (8-MOP or 5-MOP)] were enrolled in this study and exposed to solar radiation for evaluation of the following clinical parameters: immediate pigment darkening (IPD), minimal erythema dose (MED), minimal melanogenic dose (MMD), and minimal phototoxic dose (MPD) before and after topical or oral administration of PL. Immunohistochemical assessment of CD1a-expressing epidermal cells were also performed. PL was found to be photoprotective after topical application as well as oral administration. PL increased UV dose required for IPD (P < 0.01), MED (P < 0.001) and MPD (P < 0.001). After oral administration of PL, MED increased 2.8 +/- 0.59 times and MPD increased 2.75 +/- 0.5 and 6.8 +/- 1.3 times depending upon the type of psoralen used. Immunohistochemical study revealed photoprotection of Langherhans cells by oral as well as topical PL. The observed photoprotective activities of oral or topical PL reveal a new avenue in examining the potentially useful field of systemic photoprotection and suggests that PL can be used as adjunct treatment and can make photochemotherapy and phototherapy possibly safe and effective when the control of cutaneous phototoxicity to PUVA or UVB is a limiting factor in such phototherapies.

5-Methoxypsoralen↗

PubMedDate not supplied

An extract of Polypodium leucotomos appears to minimize certain photoaging changes in a hairless albino mouse animal model. A pilot study.

Chronic ultraviolet B (UVB) exposure of human or murine skin is known to induce cutaneous photoaging and enhanced carcinogenic risk. An extract of Polypodium leucotomos (PL), a tropical fern plant, has been known to exhibit interesting antioxidant and photoprotective properties against acute exposure to ultraviolet radiation. The objective of this preliminary (or pilot) study was to determine the photoprotective role of topically applied Polypodium leucotomos extract in the prevention or amelioration of cutaneous changes of photoaging in hairless mice. PL-treated mice showed significant reduction of skinfold thickness than those observed in PL-untreated controls. Additionally, PL-treated mice showed a significantly lower degree of histologic parameters of photoaging damage, including dermal elastosis, compared with positive control mice. Interestingly, PL treatment also showed reduction in the number of mice showing skin tumors at 8 weeks after the cessation of the UVB exposure protocol. The results of this preliminary study illustrate that PL treatment helped to ameliorate and to partially inhibit some of the histologic damage associated with photoaging of skin and appeared to contribute to a decrease in the prevalence of UVB-induced skin tumors in mice.

Animals↗