Hydrophilic and Lipophilic Antioxidant Activities of Mistletoe (Viscum album) as Determined by FRAP Method

Abstract

Phytochemical antioxidants, found in many medicinal plants, gained an increasing interest nowadays, because of their positive effect demonstrated by epidemiological and in vitro studies. Methanol and acetone extracts of European mistletoe (Viscum album) leaves and stems collected from five host trees (Acer campestre, Malus domestica, Fraxinus excelsior, Populus nigra and Robinia pseudoacacia) were subjected to antioxidant activity measurements. Considering the antioxidant potential of European mistletoe components (leaves and stems) due to their content in phenolic derivatives (phenolic acids and flavonoids) and carotenoids, and their specific hydrophilic and lipophilic character, respectively, the “lipophilic” (HAA) and “hydrophilic” (HAA) antioxidant capacity has been measured comparatively, based on the reducing power of such antioxidants against the ferric tripyridyltriazine (Fe(III)-TPTZ) complex (method FRAP). Among the selected plants, methanole extract of V. album leaves collected from Malus domestica (VAM) exhibited the highest antioxidant activity (0.14 ± 0.12 mg/l vitamin C equivalent / g of fresh leaves). A lipophilic antioxidant activity of mistletoe was around 100 times lower compared to hydrophilic antioxidant activities. HAA was positively correlated with total phenol concentration from leaves and stems (R2 = 0.9363, respectively R2 = 0.7337), but not with carotenoid content (R2 = 0.168). Meanwhile, the correlation of LAA with carotenoid was more significant (R2 = 0.6327). The antioxidant capacity proved to be dependent on the host trees, VAM being a recommendable good source, either in water or alcoholic extract. No significant differences were noticed between the antioxidant content and activity of different plant parts of mistletoe (stems versus leaves). The host tree of mistletoe may play a significant role in the elaboration of specific mistletoe antioxidants and becomes important parameter in the assessment of the mistletoe as a raw material for phytopharmaceutical formulas.