Visualization of the distribution of anthocyanin species in mice eyeball by matrix-assisted laser desorption/ionization mass spectrometry imaging.

RATIONALE: Anthocyanins, which belong to a class of molecules called flavonoids, are known to have beneficial effects for both humans and animals. Many physiological functions have been attributed to anthocyanins since ancient times. The most important function is the relief of eyestrain, but the biodistribution of anthocyanins remains unknown. In this study, we analyzed the kinetics of anthocyanin species in mice eyeballs and surrounding tissues.

METHODS: We used mice that were administered bilberry extract solution intraperitoneally. After harvesting eyeballs, cross-sections were prepared using a cryostat and analyzed using matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI).

RESULTS: Various ions of anthocyanin species, m/z 419, 449, 463, 465, 479, and 493, were observed in MALDI-MSI spectra. Most of these peaks corresponded to places considered to be extraocular muscles with the outer layer of the retina.

CONCLUSIONS: Through MALDI-MSI and MALDI-MS/MS analyses, we demonstrated that anthocyanin species are distributed at muscle tissues with the outer layer of the retina. It is speculated that anthocyanin species directly improve eyestrain at the extraocular muscles.