Fernblock (R), an aqueous extract of the aerial parts of the fern Polypodium leucotomos, used as raw, material for topical and oral photoprotective formulations, was fractioned by HPLC and the main components with antioxidant capability were identified by means of UV spectra, electrochemical detection, and MS". Phenolic compounds were identified as 3,4-dihydroxyhenzoic acid, 4-hydroxybenzoic acid, vanillic acid, caffeic acid, 4-hydroxycinnamic acid, 4-hydrosycinnamoyl-quinic acid, ferulic acid, and five chlorogenic acid isomers. Total firric antioxidant capacity (FRAP) of HPLC eluted fractions was measured. The results suggest that the herein identified compounds support, at least partially, the antioxidant and radical scavenging capacities of Fernblock. (c) 2006 Prous Science. All rights reserved.