Impact of cytotoxic plant naphthoquinones, juglone, plumbagin, lawsone and 2-methoxy-1,4-naphthoquinone, on Chlamydomonas reinhardtii reveals the biochemical mechanism of juglone toxicity by rapid depletion of plastoquinol.

Hydrophilic, untethered 1,4-naphthoquinones (1,4-NQs) are plant secondary metabolites that are often excreted into the environment and play a role in various plant-microbial, plant-fungal, plant-insect and plant-plant interactions. The biological activity of 1,4-NQs is mainly related to their redox properties, i.e.