Effect of streptomycin on melanogenesis and antioxidant status in melanocytes

Streptomycin is an aminoglycoside antibiotic with an antituberculosis activity commonly used in clinical practice due to its good antimicrobial characteristics. A well-known undesirable side effect of this drug is ototoxicity, which may be caused by overproduction of reactive oxygen species and loss of melanocytes in the inner ear. The aim of this study was to examine the effect of streptomycin on melanogenesis and antioxidant defense system in cultured normal human melanocytes (HEMa-LP). Streptomycin induced concentration-dependent loss in melanocytes viability. The value of EC₅₀ was determined to be ~5.0 mM. It has been shown that streptomycin causes inhibition of tyrosinase activity and reduces melanin content in human melanocytes in a concentration-dependent manner. Significant changes in the activity of cellular antioxidant enzymes: superoxide dismutase, catalase, and glutathione peroxidase were also stated. The results obtained in vitro may explain a potential role of melanocytes and melanin in the causative mechanisms of aminoglycosides ototoxic effects in vivo.