Preparation, characterization, and solubility enhancement of octenyl succinate anhydride debranched starch/1-Octacosanol nanocomplex

Abstract

1-Octacosanol (1-Octa) is recognized worldwide as a functional anti-fatigue agent with additional anti-inflammatory and energy-boosting benefits. However, it has low bioavailability owing to the poor water solubility and instability in the gastrointestinal tract; this limits its use in food, medical, and health care products. To address this, we aimed to prepare a water-soluble octenyl succinate anhydride debranched starch (OSD)-Octa complex and investigate the effects of degree of substitution of OSD and reaction temperature on the drug loading, structure, and water solubility of the complex. The contact angle of free 1-Octa was 110.3°, which decreased to <55° in the complex, and the solubility of 1-Octa in the complex ranged from 0.329 ± 0.008 to 1.532 ± 0.023 mg/mL, which indicated a notable increase in the aqueous solubility of 1-Octa. Furthermore, 1-Octa was found to penetrate the amylose helical cavity of OSD and form exohydrophilic and endohydrophobic nanoparticles with OSD through hydrophobic interaction. Finally, OSD-Octa effectively mitigated the degradation of 1-Octa under extreme pH conditions and in the presence of digestive enzymes compared to that of free 1-Octa. These findings suggest that the OSD system is an effective approach to enhancing the solubility and stability of hydrophobic functional factors.