Protective effects of the seaweed phlorotannin polyphenolic compound dieckol on gentamicin-induced damage in auditory hair cells

Objectives: Drug-induced ototoxicity from compounds such as aminoglycosides and platinum can damage the inner ear resulting in hearing loss, tinnitus or balance problems and may be caused by the formation of reactive oxygen species (ROS). Dieckol is a phlorotannin polyphenolic compound with strong antioxidant effects found in edible brown algae. This study investigated the protective effects of dieckol on drug-induced ototoxicity in cochlear cultures obtained from neonatal mice. Methods: Cochlear explants were pretreated with dieckol and exposed to gentamicin for 48 h. The explants were then fixed and stained with fluorescein isothiocyanate-phalloidin and the intact hair cells counted. The free radical scavenging activity of dieckol was assessed using a 1,1-diphenyl-2-picrylhydrazyl assay. E. coli (Escherichia coli) cultures were used to evaluate the effect of dieckol on the antibiotic activity of gentamicin. Results: Gentamicin treatment resulted in dose-dependent hair cell loss that was partially protected by dieckol. Moreover, at concentrations >67 mu M dieckol had significant radical scavenging activity. Dieckol did not compromise the antibiotic effect of gentamicin. Conclusions: These findings suggest that dieckol can be used as a therapeutic agent that reduces the damage caused by drug-induced ototoxicity. (C) 2016 Elsevier Ireland Ltd. All rights reserved.