Bio-guided fractionation of extracts of Geranium robertianum L.: Relationship between phenolic profile and biological activity

Geranium robertianum L. is used in folk medicine and herbalism practice for the treatment of a variety of ailments. Recently, we studied the bioactivity of several aqueous and organic extracts of this plant. In this work, the more active extracts were fractionated and the fractions evaluated for their antioxidant activity and cytotoxicity against several human tumor cell lines and non-tumor porcine liver primary cells. Some of the fractions from the acetone extract consistently displayed low EC50 and GI(50) values and presented the higher contents of total phenolic compounds in comparison to other fractions. The phenolic compounds profile of the fractions was determined. The bio-guided fractionation of the extracts resulted in several fractions with improved bioactivity relative to the corresponding extracts. Their lower compositional complexity allowed the identification of more than two dozen compounds, to the best of our knowledge, so far not reported in G. robertianum.