Formulation and Characterisation of an Edible Functional Elderflower Extract Gel for Upper Respiratory Tract Soothing

The increasing demand for natural functional products for soothing the upper respiratory tract has stimulated interest in plant-based bioactive formulations with antioxidant and cytoprotective properties. This study aimed to develop and characterise an edible gel containing elderflower extract and to evaluate its physicochemical properties and biological activity in an in vitro inflammatory model. The extract was characterised in terms of total phenolic content (TPC), antioxidant capacity (FRAP, ABTS, DPPH), and compound composition using chromatographic analysis. The gel formulation was assessed for texture parameters and pH. Biological activity was evaluated using HBEC-3 cells exposed to lipopolysaccharide (LPS, 1 µg/mL) for 24 h, followed by treatment with the extract in free or gel-incorporated form at different concentrations. The elderflower extract exhibited high TPC and strong antioxidant activity, with chlorogenic acid, rutin, and quercetin derivatives identified as major phenolic compounds. The formulated gel showed suitable firmness, consistency, cohesiveness, and a mildly acidic pH. LPS exposure reduced cell viability by approximately 48%, whereas treatment with the extract significantly increased viability in a concentration-dependent manner. At the highest tested concentration (50 mg/mL), the gel increased cell viability by 36% compared to LPS alone and markedly reduced necrotic cell death. These results indicate that the formulated edible elderflower extract gel combines favourable physicochemical properties with concentration-dependent cytoprotective effects, supporting its potential application for upper respiratory tract soothing.