Abstract

(3R)-1,7-diphenyl-(4E,6E)-4,6-heptadien-3-ol (DPHD), a diarylheptanoid, is the primary phytoestrogen found in Curcuma comosa Roxb. (CC). The potential uses of this compound include alleviation of menstrual pain and menopausal symptoms. However, its poor solubility hinders extraction, formulation, and pharmacological action. This study aimed to create hydrophobic deep eutectic solvents (HDESs) and their microemulsions as solvents for the extraction process, ultimately resulting in ready-to-deliver DPHD. The HDES comprised of lactic acid and L-menthol in a 1:2 mol ratio (La1M2) exhibits DPHD solubility (34.75 ± 0.13 mg/mL), surpassing that achieved using ethanol and methanol. When La1M2 as the oil phase was combined with a surfactant mixture of Tween 20 and propylene glycol (1:1), and water, the solubility significantly increased to 59.82 ± 0.24 mg/mL. Particle sizes of microemulsions with CC extract ranged from 17.2 to 30.8 nm. The microemulsions were physically stable under ambient temperature and freeze–thaw cycles. Microwave-assisted extraction from CC rhizome utilizing an HDES-based microemulsion as solvent yielded a DPHD of 2.02 ± 0.01 µg/mg dry weight. Extraction of DPHD using methanol and ethanol yielded 2.60 ± 0.02 and 2.49 ± 0.01 µg/mg, respectively. The CC extract retained its estrogenic activity in the La1M2-based microemulsion, indicating biocompatibility. Therefore, since the La1M2 components are consumable, La1M2 and its microemulsion may serve as edible solvents for microwave-assisted extraction and drug delivery formulation compatibility.