Ecdysteroids in ferns: Distribution, Diversity, Biosynthesis, and functions

Abstract

Phytoecdysteroids are plant analogs of insect molting hormones, which were first discovered in a gymnosperm in 1966 and almost simultaneously in the fern Polypodium vulgare in 1967. Many fern species were investigated for ecdysteroid presence soon afterwards, and a large number of different ecdysteroids has been isolated, including several unique molecular structures. Ecdysteroids are not found in all fern families, but in some (e.g., Polypodiaceae) almost all investigated species contain these molecules, sometimes at very high concentrations. Ecdysteroid biosynthesis from sterols has been little investigated in plants, but available data indicate that it probably does not proceed by the same pathway as in insects. Ecdysteroid accumulation is precisely regulated, as shown with prothalli of P. vulgare. Ecdysteroids are believed to contribute to phytophagous insect deterrency, but in addition they exert various pharmacological effects on mammals/humans, and extracts from several ferns containing large amounts of ecdysteroids are used in traditional medicines.