Prenylated acetophenones from the roots of Calendula officinalis and their anti-inflammatory activity

ABSTRACT Calendula officinalis is a medicinal plant in the Asteraceae family, and it has a broad range of biological activities. In this study, we focused on the roots of C. officinalis, which have remarkable anti-inflammatory properties. By using a bioassay-guided fractionation approach, prenylated acetophenones 1 and 2—of which 1 was previously unknown—were isolated, and their structures were determined by spectroscopic analysis. Both compounds decreased lipopolysaccharide-stimulated NO production in J774.1 cells. This study could lead to the use of the Calendula roots as a natural source of inflammatory mediators. Graphical Abstract Graphical Abstract Prenylated acetophenones with anti-inflammatory activity were isolated and determined their structures from the roots of Calendula officinalis.