From chemical composition to biological impact

Plant oils are widely used in cosmetic and pharmaceutical formulations due to their bioactive constituents and antioxidant properties; however, their safety and biological effects require systematic evaluation. This study aimed to conduct an integrated chemical, antioxidant and biological assessment of selected plant oils namely, calendula (Calendula officinalis), echium (Echium plantagineum or Echium vulgare), sea buckthorn (Hippophae rhamnoides L., Elaeagnaceae), and spelt (Triticum spelta L.) with potential cosmetic relevance. Oil composition was characterized using GC–MS, antioxidant activity was assessed by DPPH radical scavenging, and in silico toxicity prediction was applied to major constituents and suggested that while several major constituents showed low predicted toxicity, certain compounds anywhere predicted to be safe (i, e., no risk profile). Biological effects were evaluated in two Drosophila melanogaster strains (Lancaster and wDah) using lifespan and negative geotaxis (climbing) assays. GC-MS analysis confirmed the presence of antioxidant constituents in the oils. The DPPH radical scavenging assay experimentally verified their activity, showing that the antioxidant potency follows the order: Sea Buckthorn > Calendula > Echium > Spelt. Survival analyses revealed pronounced strain-dependent responses. In the Lancaster strain, calendula and echium oils caused a clear reduction in survival at all tested concentrations, whereas sea buckthorn and spelt oils showed limited toxicity at low doses but induced reduced survival at higher concentrations. In contrast, none of the oils significantly affected survival in the wDah strain. Locomotor analysis demonstrated oil-, dose-, and time-dependent effects. In the Lancaster strain, sea buckthorn oil preserved climbing performance at early time points, while prolonged exposure to all oils resulted in a marked decline in negative geotaxis performance. Spelt oil caused a dose-dependent reduction in climbing ability, whereas calendula and echium oils consistently impaired locomotor function. In the wDah strain, early climbing performance was largely maintained, with declines over time driven primarily by exposure duration rather than dose. Overall, this study demonstrates that the biological effects of plant-based oils are strongly concentration-dependent and are modulated by both their chemical composition and the genetic background of Drosophila melanogaster flies. The integrated approach employed provides a comprehensive framework for evaluating both efficacy and safety of plant oils, supporting their informed application in cosmetic and related formulations.