Protective Role of Vernonia Amygdalina Leaf Aqueous Extract Against Neomycin-Induced Hair Cell Damage in Transgenic Zebrafish

Aminoglycoside treatment increases the loss of hair cells in the inner ear. Once the hair cells are lost, they are unable to regenerate spontaneously, and the resulting hearing loss is profound and irreversible in humans. The aqueous extract from the leaves of Vernonia amygdalina has been reported to have antioxidant properties. In this study, we evaluated whether the aqueous extracts of Vernonia amygdalina leaf could protect hair cells from aminoglycoside-induced damage using a transgenic zebrafish line. Our results showed that the EC50 of 1,1-Diphenyl-2 picrylhydrazyl radical scavenging and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulphonate), a measure of antioxidant capacity, of the aqueous extracts of Vernonia amygdalina leaf was 11.31 mg/mL and 2.73 mg/mL, respectively. Moreover, the total phenolic and flavonoids contents were 11.48 ± 3.12 mg gallic acid/g and 6.89 ± 0.65 mg catechin/g, respectively. In the toxicology study, the larval survival rate was significantly decreased and was dependent on the dosage of aqueous extracts of Vernonia amygdalina leaf, whereas it had no significant toxicity at doses below 2.5 mg/mL concentration (survival rate = 100%). Furthermore, a hair cell survival study shows that aqueous extracts of Vernonia amygdalina leaf decreased neomycin-induced hair cell death in a dose-dependent manner (survival rate = ~94.1 ± 3.1% at 2 mg/mL concentration). Overall, these results suggest that the aqueous extracts of Vernonia amygdalina leaf possess the antioxidant effect and protects against hair cell loss caused by toxic side effects of neomycin. An optimal aqueous extract of Vernonia amygdalina leaf can be consumed as an herbal medicine without probable toxicity to body tissues and organs.