Enhancing solubility and bioavailability of octacosanol: Development of a green O/W nanoemulsion synthesis process

Octacosanol, a naturally occurring higher fatty alcohol, possessed numerous biological effects. However, octacosanol limited solubility in water due to its lipophilic nature and large structure, resulting in poor absorption and low bioavailability. To overcome this challenge, we developed a simple, environmentally friendly, and energy-efficient O/W nanoemulsion synthesis process. The nanoemulsion achieved an average droplet size of approximately 30 nm, exhibited excellent dispersibility and stability at room temperature for 60 days, and showcased robust storage properties insensitive to ambient temperature, pH, NaCl, and sucrose. Remarkably, the preparation process of the nanoemulsion maintained the biological activity of octacosanol while demonstrating significantly enhancing antioxidant activity compared to octacosanol suspension. Additionally, the nanoemulsion displayed negligible cytotoxic effects on Caco-2 cells. Significantly, the octacosanol nanoemulsion exhibited a 5.4-fold enhancement in transmembrane transport efficiency when compared to the suspension in Caco-2 cell monolayers. Additionally, in an in vivo experiment, there was a notable 2.9-fold increase in rat intestinal absorption. These findings could provide valuable insights into the development of octacosanol nanoemulsion, supporting its future applications and paving the way for the design of stable nanoemulsion systems for other lipophilic and sparingly soluble substances.