A 28-day oral toxicology study of an aqueous extract of Polypodium leucotomos (Fernblock ®)

Toxicol Rep. 2017 Sep 12;4:494-501. doi: 10.1016/j.toxrep.2017.09.002. eCollection 2017.


Fernblock® is a standardized commercial aqueous extraction of the leaves of the tropical fern Polypodium leucotomos promoted as an orally active photoprotective substance. In a previous battery of toxicological tests on Fernblock®, no genotoxicy was observed and no oral toxicity was observed up to 1200 mg/kg bw/day. The current study was conducted in Hsd.Han Wistar rats using doses of 0, 2000, 3500, and 5000 mg/kg bw/day Fernblock® by gavage for 28 consecutive days. No mortality or toxic effects were observed and no target organs were identified. The no observed adverse effect level was determined to be 5000 mg/kg bw/day, the highest dose tested.

Keywords: A/G ratio, albumin to globulin ratio; ANOVA, analysis of variance; BALT, bronchus associated lymphoid tissue; FOB, functional observation battery; Fernblock; MTD, maximum tolerated dose; NOAEL; NOAEL, no observed adverse effect level; OECD, Organisation for Economic Cooperation and Development; Photoprotection; Polypodium leucotomos; SPF, specific pathogen free; Toxicity; Toxicology.