Riboflavin Crystals with Extremely High Water Solubility.

Area of Science:

• Biochemistry and Pharmaceutical Sciences
• Material Science

Background:

• Riboflavin (Rf), or vitamin B2, exhibits potential therapeutic properties beyond supplementation, including anti-inflammatory, immunomodulatory, antioxidant, anticancer, and antiviral activities.
• Poor water solubility of riboflavin (0.1-0.3 g/L) limits its clinical application, hindering comparisons with its more soluble metabolites, flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD).

Purpose of the Study:

• To develop a method for significantly increasing the water solubility of riboflavin.
• To investigate the physicochemical properties and therapeutic potential of the new riboflavin form.

Main Methods:

• Recrystallization of type A riboflavin crystals into a new hydrophilic form, termed type P.
• Modification of Rf crystal structure via recrystallization from a dilute alkaline solution.
• Comprehensive analysis of the physicochemical properties of the type P riboflavin.

Main Results:

• Achieved an unprecedented water solubility for riboflavin, reaching 23.5 g/L.
• Type P riboflavin demonstrated enhanced photodynamic therapeutic activity against clinical isolates of *Staphylococcus aureus*, *Pseudomonas aeruginosa*, *Escherichia coli*, and *Salmonella typhimurium* compared to types A and B/C.
• The developed method is simple, inexpensive, and yields a highly soluble riboflavin form.

Conclusions:

• A novel, highly water-soluble crystal form of riboflavin (type P) has been successfully synthesized.
• This advancement is expected to increase riboflavin's bioactivity and expand its therapeutic applications, particularly in photodynamic therapy.
• The findings offer a cost-effective approach to improving vitamin B2's therapeutic utility.