Pigment Melanin Scavenges Nitric Oxide In Vitro: Possible Relevance to Keloid Formation

摘要

Recently, nitric oxide (NO) has been implicated in the formation of keloids, preferentially formed in dark-skinned persons, and we suspected that pigment melanin itself may play a direct role by adsorbing NO. We tested the ability of cuttlefish sepia melanin to scavenge (adsorb) NO, generated in situ by 2-(N.N Diethylamino) diazeneolate-2-oxide (DEA/NO), through a dialysis membrane. NO was measured asNO2_andNO3_by the Griess method and asN2O3by trapping experiments with the fluorogenic substrate 4,5-diaminofluorescein (DAF-2). InitialNO2_andNO3_concentrations were significantly lower in the test dialyzates than in controls. Scavenging of NO was rapid enough to compete with DAF adduct formation. Both analytical methods gave comparable results. Adsorbed NO and/or its oxidized products may undergo interactions with melanin, adsorbedO2, and/or dermal material that may lead to keloid formation.