juglone

Juglone is a naturally occurring **naphthoquinone derivative** with the chemical formula C10H6O3, mainly found in the black walnut (Juglans nigra) and other plants in the Juglandaceae family[1][2][4][8]. Its primary physiological role in nature is as an **allelopathic agent**—it inhibits the growth of surrounding plants. Juglone has been studied for several bioactivities, notably as an **irreversible inhibitor of peptidyl-prolyl cis/trans isomerases of the parvulin family** (including human Pin1)[2][3]. It also inhibits **RNA polymerases I, II, and III** at low micromolar concentrations[2]. Juglone exerts complex oxidative effects, acting as both a **pro-oxidant and, at some concentrations, an antioxidant**. It also chelates metal ions, such as iron, which can modulate oxidative stress[3]. Juglone is toxic to many organisms and has seen occasional use as an herbicide, anthelmintic, dye (C.I. Natural Brown 7), and, experimentally, as an antibacterial and antifungal agent[1][4][5]. It is not an approved pharmaceutical and is mainly of research interest.

Other names

5-hydroxy-1,4-naphthalenedione5-hydroxy-1,4-naphthoquinone5-hydroxynaphthalene-1,4-dioneregianinC.I. Natural Brown 7C.I. 75500