Valorisation of hydrodistillation by-products from Damask Rose ( <i>Rosa damascena</i> ): extraction, characterization, and bioactivity of phenolic compounds with biological properties

The present study focuses on the valorization of aqueous waste generated from the essential oil distillation of Damask rose (<i>Rosa damascena</i>) petals through the extraction and characterization of their bioactive compounds having potential antioxidant and anti-inflammatory properties. The aqueous waste, referred to as rose water, was subjected to liquid-liquid extraction using ethyl acetate, followed by solvent evaporation and methanol solubilization. The final extract shows a significant bioactivity, with a total phenolic content of 255.45 µg GAE/g dry extract (DE) and a total flavonoid content of 320.86 µg QE/g DE. The antioxidant capacity, assessed via the DPPH radical scavenging assay, revealed an IC₅₀ value of 18.23 µg/mL, indicating potent activity. HPLC-DAD analysis identified key phenolic compounds, including protocatechuic acid, gallic acid, syringic acid, ferulic acid, isorhamnetin-3-<i>O</i>-glucoside, quercetin-3-<i>O</i>-rutinoside, ellagic acid, and quercetin. The extract also exhibited dose-dependent anti-inflammatory effects, as evidenced by the inhibition of nitric oxide production in LPS-stimulated RAW 264.7 macrophage cells. The valorization of rose water not only contributes to the discovery of bioactive compounds but also promotes the sustainable management of distillation by-products, reducing waste and minimizing environmental impact.