Identification of a Riboflavin–Boric Acid Complex by Electrospray Ionization Mass Spectrometry
Year: 2026
Type: article
Abstract: Boric acid ingestion in children and adults has been shown to increase urinary riboflavin excretion ( 1 ), while high intakes of riboflavin reduce symptoms of boron toxicity in rats, guinea pigs, and chicks ( 2 ). Boric acid, the physiological form of boron, exhibits an affinity for molecules containing vicinal diols. Esterification of vicinal diols by boric acid has been reported for NAD + , the active form of vitamin B 3 , and cADPR, a signaling molecule derived from NAD + that functions in the Ca 2+ signaling pathway and oxidative stress ( 3 , 4 , 5 ). Riboflavin (vitamin B 2 ) contains a ribityl side chain with vicinal diols, and although indirect evidence suggests an interaction with boron, direct evidence has been lacking. In this study, electrospray ionization mass spectrometry (ESI-MS) was used to investigate complex formation between riboflavin and boric acid. In negative-ion mode at pH 10.3, riboflavin produced a dominant ion at m/z 375.3, and the addition of boric acid resulted in a new signal at m/z 401.3, corresponding to a + 26 Da increase relative to riboflavin and assigned to the formation of a 1:1 riboflavin-boric acid complex through boron-diol esterification. This species accounted for approximately 8% of the riboflavin signal, indicating a weak yet measurable binding. These findings provide direct analytical evidence for riboflavin-boric acid complexation. Together with previously reported interactions in humans and animals, these findings highlight the need to define a safe range of boric acid/riboflavin intake, as both are beneficial, but excessive intake of one may impact the status of the other.
Authors: Danny H. Kim, Curtis D. Eckhert
Language: English
Subfield: Spectroscopy
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,290
OpenAlex ID: W7155068429