Design of Ascorbic Acid Eutectic Mixtures With Sugars to Inhibit Oxidative Degradation

Area of Science:

• Pharmaceutical Science
• Food Science
• Materials Science

Background:

• L-Ascorbic acid (vitamin C) is a potent antioxidant widely used in pharmaceuticals and food.
• Its primary limitation is poor aqueous stability due to oxidative degradation.
• This instability hinders its application in various formulations.

Purpose of the Study:

• To enhance the aqueous stability and shelf-life of L-Ascorbic acid.
• To explore co-crystallization with mono- and di-saccharides as a stabilization strategy.
• To investigate the impact of pH on the stability of these eutectic compositions.

Main Methods:

• Co-crystallization of L-Ascorbic acid with glucose, sucrose, lactose, and mannitol.
• Characterization using melting point analysis, Powder X-ray diffraction (PXRD), and Fourier transform Infrared spectroscopy (FT-IR).
• Assessment of aqueous stability and shelf-life in buffer solutions across a pH range (3.3-7) using Scanning Electron Microscopy (SEM).

Main Results:

• Binary eutectic compositions of L-Ascorbic acid with sugars were successfully formed.
• Co-crystals exhibited improved aqueous stability, with shelf-life increases of 2-5 fold at pH 5 and 7.
• Stabilizing effect decreased with increasing medium acidity; disaccharide eutectics showed higher stability at neutral pH.

Conclusions:

• Co-crystallization with sugars is an effective method to improve L-Ascorbic acid's aqueous stability and extend its shelf-life.
• The stabilizing effect is pH-dependent, with better performance in neutral and weakly acidic conditions.
• Disaccharide co-crystals demonstrate superior stability due to enhanced non-bonded interactions.