Beyond flowers: exploring Calendula officinalis aerial parts composition and biological potential

Calendula officinalis is a medicinal plant belonging to the Asteraceae family, widely recognized for its biological potential. Although C. officinalis flowers are traditionally the part of the plant used for medicinal and cosmetic applications, this study focuses on the aerial parts, including stems and leaves that are generally considered as a byproduct. An untargeted metabolomic approach on the hydroalcoholic extract of C. officinalis aerial parts correlated chemical composition with different biological activities. Liquid chromatography high-resolution tandem mass spectrometry analysis led to the annotation of several primary and secondary metabolites: along with well-known compounds of the flower extracts, luteolin and its derivatives were identified for the first time in C. officinalis aerial parts. Biological assays indicated that the plant extract was endowed with antioxidant and anti-inflammatory properties, which were evaluated on human immortalized keratinocytes and human monocyte cells, respectively. Furthermore, the C. officinalis extract showed selective antibacterial and antifungal properties on phytopathogenic strains, suggesting its potential use in agriculture. Overall, the results highlight C. officinalis aerial parts as an unexplored source of high-value bioactive compounds, offering new perspectives for their application in the nutraceutical, cosmetic, and agro-industrial sectors. Thus, this study contributes to circular bioeconomy by investigating underutilized plant tissues, providing a sustainable strategy for the valorization of residual biomass from a commercially exploited species.