Investigation of Anticholinesterase Activity of Chemically Characterised Hieracium s. str. Methanol Extracts and Their Selected Metabolites

Abstract

The composition and anticholinesterase activity of the dried MeOH extracts of Hieracium scheppigianum and H. naegelianum underground parts (rhizomes and roots), as well as the anticholinesterase activity of the dried, previously chemically characterised MeOH extracts of the flowering aerial parts of these two and 26 other Hieracium species in the strict sense (s. str.), were investigated. Furthermore, the anticholinesterase activity of 12 selected secondary metabolites of these extracts was evaluated. Using semi-preparative LC-MS, five caffeoylquinic acids and the sesquiterpene lactone crepiside E were isolated from H. scheppigianum underground parts extract. All these compounds were also identified in the underground parts extract of H. naegelianum. Quantitative LC-MS analysis showed that the analysed underground parts extracts were rich in both caffeoylquinic acids (139.77 and 156.62 mg/g of extract, respectively) and crepiside E (126.88 and 116.58 mg/g). In the Ellman method, the tested extracts showed an interesting anti-AChE and/or anti-BChE activity (IC50=0.56–1.58 mg/mL), which can be explained, at least partially, by the presence of some of their constituents. Among the metabolites tested, the best activity was revealed for the flavonoids apigenin, luteolin and diosmetin, and the sesquiterpene lactone 8-epiixerisamine A (IC50=68.09–299.37 μM).