Evaluation of the anti-inflammatory and antioxidative potential of four fern species from China intended for use as food supplements.
Inflammation plays a major role in many diseases, for instance in arteriosclerosis, rheumatoid arthritis, autoimmune disorders and cancer. Since many plants contain compounds with anti-inflammatory activity, their consumption may be able to prevent the development of inflammatory-based diseases. Edible ferns are some of the most important wild vegetables in China and have traditionally been used both for dietary and therapeutic purposes. In this study we investigated the anti-inflammatory and antioxidant potential of fern extracts from Matteuccia struthiopteris, Osmundajaponica, Matteuccia orientalis and Pteridium aquilinum intended for use as nutraceuticals. Two modes of action were investigated the inhibition of the pro-inflammatory gene expression of interleukin-1 beta (IL1-β) and interleukin-6 (IL6), and the gene expression of iNOS by LPS-elicited macrophages. The results showed a decrease of IL1-β gene expression for the five fern extracts. This effect was more pronounced for the extracts prepared from the roots of O. japonica (IC50 of 17.8 µgmL) and the young fronds of M orientalis (50.0 µgmL). Regarding the indirect measurement of NO, via iNOS gene expression, an interesting decrease of 50% was obtained with the extract of M. orientalis fronds at a low concentration (20 µgmL) compared with P. aquilinum fronds (160 µgmL) and leaves of O. japonica. The latter showed a higher decrease but at a high concentration of extract (160 µgmL). The five fern extracts were also evaluated for their ability to scavenge 2,2-diphenyl-l-picrylhydrazyl (DPPH) radicals and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). All fern extracts exhibited antioxidant effects but the roots of O. japonica and the fronds of M orientalis were most efficient. The HPLC-MS analysis of the constituents of the fern extracts confirmed the presence of chlorogenic acid, caffeic acid, p-coumaric acid, ferulic acid, kaempferol and apigenin, molecules known to exhibit antiinflammatory andor antioxidant properties.