Dittrichia viscosa Methanol Extract-Containing Nanoemulsion and Nanoemulsion-Based Gel Formulations: Preparation and in vitro Characterization Studies

Dittrichia viscosa (L.) Greuter (Dv) has antimicrobial, analgesic, antioxidant, anti-inflammatory, cytotoxic, and wound-healing properties. We aimed to prepare the methanol extract (Dv-Me) of the aerial parts of Dv and to determine its antioxidant capacity by FRAP, CUPRAC, and DPPH methods. In addition, we prepared nanoemulsion (NE) and NE-based gel (NEG) formulations containing Dv-Me for topical application to the skin for wound healing and characterized these formulations in vitro. The antioxidant capacity of Dv-Me was determined by CUPRAC, FRAP, and DPPH methods. Then, NE formulations with/without extract (B-NE and Dv-Me-NE) were developed and in vitro characterized [morphological analysis; centrifuge test; viscosity and pH measurements; FT-IR analysis; the determination of zeta potential, droplet size and polydispersity index (PDI)]. Besides, B-NEG and Dv-Me-NEG were prepared and in vitro characterized [FT-IR analysis; viscosity and pH measurements]. The droplet size and zeta potential values of NE formulations were smaller than 185 nm and around -30 mV, respectively. PDI values were found to be less than 0.3. The pH values of Dv-Me-NE and Dv-Me-NEG were found to be 5.13±0.01 and 5.87±0.02, respectively. The NE and NEG formulations showed Newtonian and pseudoplastic behaviors, respectively. As a result, Dv-Me-NEG exhibits the desired pseudoplastic behavior for topical application to the skin.