<i>Kadsura coccinea</i> Seed Oil Nanoemulsion: Preparation, Characterization, Antioxidant Activity, and Cytoprotective Effect

ABSTRACT This study investigates the preparation, characterization, antioxidant activity and cytoprotective effect of Kadsura coccinea seed oil nanoemulsion (KSO‐NE) from four varieties. The characteristics of these varieties, including particle size, polydispersity index (PDI), and stability were compared. Through optimizing the homogenization frequency, homogenization pressure, oil content, and Tween ratio, the optimal conditions were found to be an oil concentration of 8% (w/w), a Tween‐80 concentration of 1.5% (w/w), and a homogenized pressure of 100 MPa applied 5 times. Under these conditions, the nanoemulsion showed a unimodal size distribution (149–159 nm), a PDI below 0.2, and a zeta potential of −19.1 mV. It also exhibited excellent apparent viscosity (0.0005–0.0055 Pa s), as well as stability for dilution (no stratification in dilutions ranging from 50 to 1000 times), centrifugation (the Ke value was less than 5.81 after centrifugation at 2000 g for 20 min), storage (stable for 25 days at 4°C and 25°C), and antioxidant (68.07%–100% of initial antioxidant activities were preserved). Moreover, the cytoprotective effect of KSO‐NE on an in vitro human umbilical vein endothelial cell (HUVEC) injury model induced by H 2 O 2 demonstrated that KSO‐NE was non‐toxic to the cells, and could significantly improve the survival rate of H 2 O 2 ‐injured cells, with the survival rate reaching up to 96.4%. In addition, a decrease in reactive oxygen species (ROS) content and lactate dehydrogenase (LDH) efflux was observed. This study clarified the key formulation and processing factors governing KSO‐NE's physicochemical stability and antioxidative cytoprotection, highlighting its potential for development in the food and cosmetic industries.