title: Effect of biotransformation by liver S9 enzymes on the mutagenicity and cytotoxicity of melanin extracted from Aspergillus nidulans.
abstract: BACKGROUND
  A mutant that exhibited increased melanin pigment production was isolated from Aspergillus nidulans fungus. This pigment has aroused biotechnological interest due to its photoprotector and antioxidant properties. In a recent study, we showed that melanin from A. nidulans also inhibits NO and TNF-α production.
  
  
  OBJECTIVE
  The present study evaluates the mutagenicity and cytotoxicity of melanin extracted from A. nidulans after its exposure to liver S9 enzymes.
  
  
  METHODS
  The cytotoxicity of multiple concentrations of melanin (31.2-500 μg/mL) against the McCoy cell line was evaluated using the Neutral Red assay, after incubation for 24 h. Mutagenicity was assessed using the Ames test with the Salmonella typhimurium strains TA98, TA97a, TA100, and TA102 at concentrations ranging from 125 μg/plate to 1 mg/plate after incubation for 48 h.
  
  
  RESULTS
  The cytotoxicity of A. nidulans melanin after incubation with S9 enzymes was less than (CI50 value= 413.4 ± 3.1 μg/mL) that of other toxins, such as cyclophosphamide (CI50 value = 15 ± 1.2 μg/mL), suggesting that even the metabolised pigment does not cause significant damage to cellular components at concentrations up to 100 μg/mL. In addition, melanin did not exhibit mutagenic properties against the TA 97a, TA 98, TA 100, or TA 102 strains of S. typhimurium, as shown by a mutagenic index (MI)  <2 in all assays.
  
  
  CONCLUSIONS
  The significance of these results supports the use of melanin as a therapeutic reagent because it possesses low cytotoxicity and mutagenic potential, even when processed through an external metabolising system.
authors.affiliation: a Department of Pharmaceutical Sciences , Espirito Santo Federal University - UFES , Vitoria , Brazil .
authors.forename: Rita
authors.initials: R
authors.lastname: de Cássia Ribeiro Gonçalves
authors.affiliation: a Department of Pharmaceutical Sciences , Espirito Santo Federal University - UFES , Vitoria , Brazil .
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Rezende Kitagawa
authors.affiliation: b Faculty of Pharmaceutical Sciences , São Paulo State University - UNESP , Araraquara , Brazil , and.
authors.forename: Eliana
authors.initials: E
authors.lastname: Aparecida Varanda
authors.affiliation: b Faculty of Pharmaceutical Sciences , São Paulo State University - UNESP , Araraquara , Brazil , and.
authors.forename: Maria
authors.initials: M
authors.lastname: Stella Gonçalves Raddi
authors.affiliation: c Department of Biochemistry and Technology Chemistry , Institute of Chemistry, São Paulo State University - UNESP , Araraquara , Brazil.
authors.forename: Carla
authors.initials: C
authors.lastname: Andrea Leite
authors.affiliation: c Department of Biochemistry and Technology Chemistry , Institute of Chemistry, São Paulo State University - UNESP , Araraquara , Brazil.
authors.forename: Sandra
authors.initials: S
authors.lastname: Regina Pombeiro Sponchiado
mesh_terms: D000818:Animals; D001233:Aspergillus nidulans / Q000737:chemistry*; D001711:Biotransformation; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000187:drug effects / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008543:Melanins / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology*; D051379:Mice; D008862:Microsomes, Liver / Q000187:drug effects / Q000201:enzymology; D009152:Mutagenicity Tests; D017207:Rats, Sprague-Dawley; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics
chemical_list: D008543:Melanins
keywords: Cytotoxic; fungi; mutagenic; pigment