Extracellular Vesicles and PlantCrystals for Improved Bioavailability of Curcumin as a BCS Class IV Drug

The limited water solubility of active compounds remains a significant challenge for efficient dermal drug delivery, particularly for BCS class IV drugs such as curcumin. This study aimed to enhance curcumin's dermal penetration using two strategies: extracellular vesicles (EVs) and plantCrystals derived from soybeans. EVs were isolated using classical methods. However, plantCrystals containing extracellular vesicles (PCEVs) were formed during the preparation of plantCrystals through bead milling. Curcumin was either added after PCEVs were formed, resulting in curcumin-added PCEVs, or added to the soybean dispersion before bead milling, forming curcumin-loaded PCEVs. The formulations were characterized for their physicochemical properties and assessed for dermal penetration efficacy using quantitative dermatokinetic and semi-quantitative ex vivo porcine ear models. The results indicated that curcumin-loaded PCEVs achieved higher penetration efficacy compared to curcumin-added PCEVs and curcumin-loaded EVs, with approximately 1.5-fold and 2.7-fold increases in penetration efficacy, respectively. Additionally, curcumin-loaded PCEVs showed superior penetration depth, while curcumin from the curcumin-loaded EVs remained in the stratum corneum. These findings suggest that the plantCrystals strategy via bead milling offers a more effective approach than the classical EVs strategy for improving the topical delivery of class IV drugs like curcumin.