European ferns as rich sources of antioxidants in the human diet.

Wild edible plants have become an attractive variation of the human diet, especially in East Asia, North America, and Oceania. However, their potential in nutrition is only rarely considered in Europe. This study aims to reveal the nutritional and antioxidant potential of mature fern leaves from 13 families grown in Europe. We found that most of the examined fern species displayed a high antioxidant capacity, exceeding 0.5 g Trolox equivalent per gram of extract dry weight in ORAC assay and reaching IC50 values lower than 30 µg·mL-1 in DPPH assay (with the value for Trolox 7 µg·mL-1). Most of the species also appeared to be a good source of carotenoids, especially of lutein (205 µg·g-1 DW on average) and β-carotene (161 µg·g-1 DW on average) when compared to the reference leafy vegetables spinach and rocket. A cytotoxicity test using ovine hepatocytes showed a non-toxicity effect of fern leaf extracts.