title: Gentamicin affects melanogenesis in normal human melanocytes.
abstract: BACKGROUND
  Aminoglycoside antibiotics, including gentamicin, despite their ability to induce adverse effects on pigmented tissues, remain valuable and sometimes indispensable for the treatment of various infections. It is known that gentamicin binds to melanin biopolymers, but the relation between this drug affinity to melanin and its toxicity is not well documented. The aim of this work was to examine the impact of gentamicin on viability and melanogenesis in HEMa-LP (light pigmented) and HEMn-DP (dark pigmented) normal human melanocytes.
  
  
  RESULTS
  The effect of gentamicin on cell viability was determined by 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1) assay; melanin content and tyrosinase activity were measured spectrophotometrically. It has been demonstrated that gentamicin induces concentration-dependent loss in melanocytes viability. The application of antibiotic in concentration of 10 mM causes higher reduction in viability of the light pigmented melanocytes (by about 74%) when compared with the dark pigmented ones (by about 62%). The value of the concentration of a drug that produces loss in cell viability by 50% (EC50) for both cell lines was found to be ∼7.5 mM. It has been shown that gentamicin causes inhibition of tyrosinase activity and reduces melanin content in light pigmented melanocytes significantly more than in the dark pigmented cells.
  
  
  CONCLUSIONS
  We have found that gentamicin modulates melanization process in melanocytes in vitro, what may explain the potential role of melanin biopolymer in the mechanisms of undesirable toxic effects of this drug in vivo, as a result of its accumulation in pigmented tissues. We have also stated that the melanogenesis process in light pigmented melanocytes is more sensitive to the inhibitory effect of gentamicin than in the dark pigmented cells.
authors.affiliation: Department of Pharmaceutical Chemistry, Medical University of Silesia in Katowice , Sosnowiec , Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Wrześniok
authors.forename: Artur
authors.initials: A
authors.lastname: Beberok
authors.forename: Michał
authors.initials: M
authors.lastname: Otręba
authors.forename: Ewa
authors.initials: E
authors.lastname: Buszman
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005839:Gentamicins / Q000494:pharmacology*; D006801:Humans; D008543:Melanins / Q000096:biosynthesis*; D008544:Melanocytes / Q000187:drug effects* / Q000378:metabolism
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D005839:Gentamicins; D008543:Melanins
keywords: Gentamicin; melanin; melanization; melanocytes; tyrosinase