Metabolomic analysis of bioactive compounds in dill (Anethum graveolens L.) extracts

Dill (Anethum graveolens L.) is a functional herb known for its dietary, medicinal, and health-promoting agents, as it enriches antioxidants that help to protect cells from oxidative stress and may reduce the risk of several chronic diseases. The daily consumption of active components from dill, achieved through methods such as tea preparation and incorporation into soups and salads, relies on aqueous extraction techniques. The aim of this work was to investigate the metabolic profile of dill leaves extracted with water in various conditions. We also assessed the antioxidant and longevity properties of dill leaf extracts. The availability of aqueous-extracted chemicals from dill promotes therapeutic usage and nutritional supplements, showing its potential as a culinary and medicinal herb.

The metabolic profiles of dill leaves extracted with water at 27 °C and 90 °C were analyzed using untargeted proton nuclear magnetic resonance spectroscopy (¹H NMR). The one-dimensional (1D) followed by two-dimensional (2D) J-resolved ¹H NMR were employed. The antioxidant activities of dill leaf extracts were measured using four methods: total phenolic content (TPC), ferric-reducing antioxidant power (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and oxygen radical absorbance capacity (ORAC) assays. The correlation between antioxidant properties and metabolites was analyzed using heatmap analysis. Reactive oxygen species (ROS) activity assays were conducted. The longevity effect of dill leaf extracts on human dermal fibroblasts (HDFs) was also examined using western blotting.

The ¹H NMR analysis identified 41 metabolites in dill leaf extracts, including 39 primary and two secondary metabolites. The antioxidant tests showed that an aqueous extraction of dill leaves with hot water at 90 °C resulted in much stronger antioxidant activities compared to using water at 27 °C. Antioxidant activities were positively correlated with the levels of five metabolites: pyridoxal, indole-3-lactate, adenine, inosine, and folate. β-Hydroxybutyrate, cellobiose, and α-glucose were the three metabolites that showed negative relationships with antioxidant activities. We also demonstrated that dill leaf extracts significantly reduced cytosolic oxidation and altered longevity markers in human dermal fibroblasts (HDFs) by increasing FOXO3, SIRT6, and AMPK while diminishing levels of mTOR and Akt proteins.

Results indicated that dill leaf extracts contain antioxidant and anti-aging potential, especially in aqueous extracts at 90 °C. Key metabolites contributing to these effects might facilitate oxidative protection and cellular longevity in fibroblasts, supporting the value of dill as a dietary and medicinal herb.