A Comprehensive Strategy to Annotate and Evaluate Galloylated Polyphenols of Rhodiola crenulata Based on Improved...

Rhodiola crenulata (Hook. f. et Thoms.) H. Ohba (R. crenulata) is widely acknowledged as a traditional medicine in both Asia and Europe, renowned for its exceptional health-promoting properties. Currently, galloylated polyphenols are distinguished by their high structural similarity and notable isomerism, presenting considerable challenges in their annotation and evaluation. However, there is currently a lack of detailed information on the galloylated polyphenols of R. crenulata.

We optimized the extraction conditions for galloylated polyphenols based on single-factor and response surface experiments. The galloylated polyphenol components were enriched and isolated via HP-20 macroporous resin column chromatography. To this end, we proposed a comprehensive annotation and evaluation of the galloylated polyphenols in R. crenulata by utilizing an improved precursor ion list (PIL)-data dependent acquisition (DDA)/mass spectrometry (MS) combined with the biogenetic building block strategy, along with the preparation and evaluation of the refined fractions.

An acetone concentration of 65% and a solid-liquid ratio of 1:29 were employed to extract galloylated polyphenols at 50°C for 46 min, which facilitated the maximum extraction of these compounds. The galloylated polyphenols were characteristically enriched in a 30% ethanol elution using an HP-20 macroporous resin column chromatography. Subsequently, we annotated 56 galloylated polyphenols from R. crenulata, including 24 galloyl catechins, 17 gallotannins, 7 gallic acid esters, 4 galloyl salidrosides, 3 gallic acids, and 1 ellagitannin. These galloylated polyphenols and their fine fractions all showed significant nitric oxide inhibitory activity and exhibited potential anti-inflammatory effects.

Based on this study, galloylated polyphenols are demonstrated to be a class of abundant and bioactive constituents in R. crenulata, thereby providing a foundation for further elucidating the material basis of its medicinal effects.