Nootkatone encapsulation by cyclodextrins: Effect on water solubility and photostability

Area of Science:

• Food Chemistry
• Materials Science
• Pharmaceutical Sciences

Background:

• Nootkatone (NO) is a valuable sesquiterpenoid with applications in food, cosmetics, and pharmaceuticals, also exhibiting insect repellent properties.
• Current limitations in NO's application stem from its poor aqueous solubility and stability.
• Cyclodextrins (CDs) offer a potential solution for overcoming these limitations through encapsulation.

Purpose of the Study:

• To evaluate the encapsulation of nootkatone (NO) within cyclodextrins (CDs).
• To characterize the resulting inclusion complexes and assess their properties.
• To determine the potential of CDs as carriers for improving NO's characteristics.

Main Methods:

• Phase solubility studies, Isothermal Titration Calorimetry (ITC), Nuclear Magnetic Resonance (NMR) spectroscopy, and molecular modeling were employed.
• Solid CD/NO inclusion complexes were prepared and characterized for encapsulation efficiency and loading capacity using UV-Visible spectroscopy.
• Thermal properties were analyzed using thermogravimetric-differential thermal analysis (TG-DTA), and release studies were conducted via multiple headspace extraction.

Main Results:

• Phase solubility studies and ITC confirmed the formation of stable inclusion complexes between NO and CDs, with calculated formation constants (K_f).
• Characterization demonstrated successful encapsulation, with enhanced aqueous solubility, photo-stability, and thermal stability of NO within the CD complexes.
• Release studies confirmed that the NO can be effectively released from the solid complex in aqueous solutions.

Conclusions:

• Cyclodextrins (CDs) are effective carriers for nootkatone (NO), significantly enhancing its solubility and stability.
• The formation of stable inclusion complexes improves NO's properties, paving the way for expanded use.
• This encapsulation strategy holds promise for advancing the application of NO in food, cosmetic, pharmaceutical, and agrochemical preparations.