Water-Soluble Formulations of Curcumin and Eugenol Produced by Spray Drying

Background/Objectives: In this study, we present a green, scalable platform for the production of water-dispersible powders co-encapsulating the lipophilic bioactives curcumin (Cur) and eugenol (Eug) within the amphiphilic polymer Soluplus^® (SP) via low-temperature spray drying. Methods: The amount of Cur (1%, 5%, and 10%) and Eug (5%, 10%, 15%, and 20%) was varied to achieve single- and double-loaded water-soluble powders with the maximum amount of active substances. The powders containing a higher loading of Cur, 5% and 10% (and Eug), were obtained from water/ethanol mixtures (2:1 and 5:1 v/v ratio), while the formulation with 1% of Cur was spray-dried by using water as a solvent. Results: By leveraging aqueous or aqueous-ethanolic feed systems, we achieved high loading of the bioactive substances-up to 10% Cur and 20% Eug (w/w)-while minimizing organic solvent use. Myo-inositol was incorporated as a stabilizing excipient to modulate particle morphology, improve powder flowability, and enhance redispersibility. Physicochemical characterization revealed nanoscale micellization (53-127 nm), amorphization of both actives as confirmed by XRD and DSC, and the absence of crystalline residue. Encapsulation efficiencies exceeded 95% for Cur and 93% for Eug. Dissolution tests demonstrated a rapid release from the 5% Cur/5% Eug formulation (>85% in 5 min), while higher-loaded single-formulations showed progressively slower release (up to 45 min). Conclusions: This work demonstrates a robust and environmentally responsible encapsulation strategy, suitable for delivering poorly water-soluble phytochemicals with potential applications in oral nutraceuticals and pharmaceutical dosage forms.