Antioxidant activity and phenolic content of Bergenia crassifolia, B. x ornata and B. ciliata.

This study focused on a phytochemical analysis of Bergenia crassifolia (L.) Fritsch., B. ciliata (Haw.) Sternb., and B. x ornata Stein. and evaluation of their free radical scavenging properties. Arbutin and total tannin contents of the leaves of the Bergenia species were determined during different seasons. The present study also aimed at analyzing, for the first time, environmental influence on concentrations of phenolic metabolites in Bergenia leaves. The highest total tannin content was found in the leaves of B. crassifolia (24.9-48.7 mg x g(-1) DW) and B. x ornata (36.9 mg.g(-1) DW). The highest amount of arbutin was in the leaves of B. x ornata (35.8-51.0 mg.g(-1) DW) and B. crassifolia (24.6-41.7 mg x g(-1) DW). Autumn was better than spring for the collection of Bergenia leaves for the highest amount of arbutin (B. x ornata: 51.0 mg x g(-1) DW). Free radical scavenging potential, in DPPH and ABTS assays, of the water leaf extracts revealed that extracts of B. crassifolia and B. x ornata are the most active radical scavengers. Antioxidant activity correlated well with the content of total tannin, especially in the ABTS assay, which suggests an important role for these compounds in antioxidant activity. It was shown that phenolic concentrations in Bergenia leaves are affected by seasonal factors. A significant correlation was found between arbutin and tannin contents and the average humidity.