Comparative HPLC-DAD-ESI(+)MS Fingerprint and Quantification of Phenolic and Flavonoid Composition of Aqueous Leaf Extracts of Cornus mas and Crataegus monogyna, in Relation to Their Cardiotonic Potential

Abstract

Our study aimed to compare the phenolic and flavonoid composition of two medicinal plants from the wild flora of Romania, traditionally known to be efficient in preventing cardiotoxicity: Cornus mas and Crataegus monogyna. As most previous studies have focused on fruits, our investigations aimed to fingerprint and quantify the two classes of compounds in aqueous leaf extracts, based on HPLC-DAD-ESI(+)MS analysis. The specific HPLC-DAD fingerprint was coupled with UV spectra at 280 and 340 nm to discriminate between three subclasses of compounds: two hydroxycinnamic acids and a flavonoid glycoside. While the C. monogyna extract contained more than 98% vitexin isomers (2'- and 4'-O-rhamnoside), the C. mas extract was very complex, containing a mixture of phenolic derivatives and flavonoid glycosides. The spectral patterns of C. mas, combined with the molecular mass and specific fragmentations allowed the identification of epi-catechin, coumaric and caffeic acids and quercetin derivatives. Based on LC-MS peak area and parallel calibrations with gallic acid and rutin, the mean concentration for flavonoids in C. mas was 13 mg/100 ml, while aprox. 65 mg/100 ml in C. monogyna extracts. Using the Folin method, the total phenol content was 105 mg/100 ml in C. mas and around three times less in the C. monogyna extract, while the antioxidant activity was increased only 1.5-1.7 times in C. mas extract compared to C. monogyna. These findings suggest a higher stability and potential of flavonoids to act as antioxidants in hydrophilic environment.