2-Hydroxy-1,4-naphthoquinone

2-Hydroxy-1,4-naphthoquinone (Lawsone) is a naphthoquinone dye isolated from leaves of Lawsonia inermis, the Henna plant used for preparing decorative hair and skin dyes. In addition to strong light interaction which underlies the aesthetic properties of Henna, 2-Hydroxy-1,4-naphthoquinone also demonstrates antimicrobial and antioxidant effects. The observations that 2-Hydroxy-1,4-naphthoquinone participates in radical scavenging and in redox cycling with the hypoxanthine/xanthine oxidase system are attributable to the electronics of the naphthoquinone structure. This naphthoquinone structure also imparts cytotoxic properties to 2-Hydroxy-1,4-naphthoquinone and is conserved across many antibiotics, though this particular mechanism of cytotoxicity is not thought to involve redox cycling. In vitro 2-Hydroxy-1,4-naphthoquinone is shown to suppress the formation of hydrogen peroxide and superoxide radical anion by aldehyde oxidase-catalyzed reactions.