Juglon

Phylloquinone, which is found as a 1,4-naphthoquinone derivative (see also vitamin K), primarily in the green shells as well as in the green leaves and nutshells of walnuts. It is present there in glycosidic form (hydrojuglone glycoside). The substance is poorly soluble in water, but readily soluble in ether and benzene.

The walnut kernel does not contain juglone. The green nutshells and leaves contain hydrojuglone glycoside, the reduced and glucose-bound form of juglone, which is less reactive, non-toxic and colorless.

The actual juglone is produced by oxidizing hydrojuglone glycoside. The oxidized form is reactive, relatively toxic and polymerizes into a brown dye. This dye combines strongly with proteins and is difficult to remove (brownish discoloration of the hands when handling green walnuts). Juglone is also used to dye textiles.

Juglone has antibacterial, antifungal and antiproliferative effects. Furthermore, juglone inhibits angiogenesis and experimentally the tumor growth of various tumor cell lines. Juglone promotes wound healing (see below chronic wounds).

The name "juglone" is made up of the genus name "Juglans" and naphthoquinone). Juglone is a positional isomer of lawson, the colorant of henna leaves.

1. Avcı E et al. (2016) Investigation of juglone effects on metastasis and angiogenesis in pancreatic cancer cells. Genes 588:74-78.
2. Fang F et al (2015) Juglone exerts antitumor effect in ovarian cancer cells. Iran J Basic Med Sci 18:544-548.
3. Wahedi HM et al. (2016) Juglone ameliorates skin wound healing by promoting skin cell migration through Rac1/Cdc42/PAK pathway. Wound Repair Rain 24:786-794.
4. Wang J et al (2016) Antibacterial Activity of Juglone against Staphylococcus aureus: From Apparent to Proteomic. Int J Mol Sci 17(6). doi: 10.3390/ijms17060965.
5. Meskelevicius D et al (2016) Juglone Exerts Cytotoxic, Anti-proliferative and Anti-invasive Effects on Glioblastoma Multiforme in a Cell Culture Model. Anticancer Agents Med Chem.16:1190-1197.