Background/Objectives: The extraction and encapsulation of Tanacetum parthenium L. (feverfew) represent highly relevant approaches for maximizing the recovery and protection of its bioactive phytocomplexes, particularly the main active compound, parthenolide (PAR). The present study aimed to develop and optimize a cyclodextrin-based extraction and encapsulation method for T. parthenium to improve the chemical and physicochemical properties and biological activity of bioactive-rich phytocomplexes. Methods: The extraction process was optimized by comparing conventional maceration (ME) and ultrasound-assisted extraction (UE), using different ethanol–water mixtures as extractants, with and without hydroxypropyl-β-cyclodextrin (CD) as an extraction enhancer. The highest PAR yield (approximately 6.3 mg/g dried biomass), combined with enhanced total polyphenol and flavonoid contents, was achieved using 50% (v/v) ethanol with 0.5% CD under UE. The optimized extract was spray-dried to produce powder formulations, with or without carrier material, which have been characterized for their technological, chemical, physicochemical, structural, and biological properties. Results: The inclusion of CD significantly improved process yield (approximately 65% compared to 47% for the non-encapsulated extract) and reduced residual moisture content, indicating enhanced drying efficiency and improved powder stability. Furthermore, the encapsulated formulation demonstrated preserved antioxidant and anti-inflammatory activity in cell-based assays. Conclusions: The developed CD-based encapsulation method represents a promising strategy for stabilizing feverfew bioactives and enhancing their potential applicability in pharmaceutical and dermo-cosmetic formulations.

Designing ionic liquids (ILs) where a single functional group orchestrates a suite of enhanced properties remains a key challenge in materials science. Here, we introduce 1-butyl-3-methylimidazolium mandelate, [Bmim][Man], a novel IL where the hydroxyl group on the mandelate anion simultaneously enhances hydrogen bonding, thermal stability, antimicrobial activity, and extraction selectivity. The structure-property relationships of [Bmim][Man] were investigated through measurements of density, viscosity, and conductivity and were compared with analogous ILs. The presence of the hydroxyl group on the mandelate anion resulted in the highest density and viscosity among the series, attributed to strong hydrogen bonding and efficient ion packing. Notably, [Bmim][Man] exhibited a high molar conductivity that decouples from its high viscosity, suggesting an unusual degree of ion dissociation facilitated by the hydroxyl group. Thermogravimetric analysis revealed superior thermal stability. Furthermore, the investigated ionic liquid demonstrated a low critical aggregation concentration (CAC = 0.01982 mol·dm⁻³) in water, indicating a strong propensity for self-aggregation. [Bmim][Man] showed synergistic, enhanced antibacterial activity against E. coli and P. aeruginosa. Finally, the functional utility of this designed liquid was demonstrated in separation science, where [Bmim][Man]-based aqueous biphasic systems showed selective extraction capabilities for transition metals, a process driven by the same hydrogen-bonding and coordination interactions that define its bulk properties. These findings establish [Bmim][Man] as a promising multifunctional material where the mandelate anion concurrently dictates liquid microstructure, thermal resilience, antimicrobial performance, and application in extraction.