From traditional uses to phytochemical study of a Polynesian healing plant: Constituents and properties of “Metuapua'a”

“Metuapua'a” is the vernacular name attributed to distinct fern species (Microsorum großum) (Polypodiaceae) used in a great number of remedies in Polynesian traditional medicine. Fronds and/or rhizomes are usually prescribed to treat stomach ache, gonorrhoea, pneumonia, leucorrhoea, sterility, dislocations, fractures, etc [1]. Phytochemical studies of these species led to establishing their chemical composition, showing that the main components are purportedly adaptogenic phytoecdysteroid such as ecdysone and 20-hydroxyecdysone. Their complex phytoecdysteroid composition and distribution differs between species and plant organs [2 – 5]. The list of biological properties of the main phytoecdysteroid constituents whose benefits on health are well known [6 – 8] justify their medicinal uses. The skin-active effect of M. großum extract was investigated in two ways on human dermal fibroblasts: a transcriptomic study with c-DNA array for gene expression modulation and a stress induced premature senescence (SIPS) test. The total extract of M. großum up regulates Heme Oxygenase 1 (HO1), an enzyme which protects cells from oxidative stress and which is responsible for skin photoimmunoprotection. We report that premature senescence of human skin induced by repeated UV irradiations can be prevented by an exdysteroid fraction of M. großum. It seems therefore that extracts of this fern could protect skin against oxidative stresses and that so could be used as innovative active cosmetic ingredient [9].

Acknowledgements: Financial support from the “Délégation de la Recherche” of French Polynesia and from the “Ministère de l'Outre-Mer” (M.O.M.) of France are deeply acknowledged.

Keywords: Microsorum großum, ethnopharmacology, medicinal plant, phytoecdysteroids, dermal fibroblast, cellular senescence.

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