What it is
This extract is obtained from the leaves and stems of Polygonum tinctorium, the plant traditionally used in Japan to produce indigo dye. In cosmetics it is included as a plant-derived conditioning agent and is associated with antioxidant-type polyphenols rather than with any coloring function at use levels. It typically appears at low concentrations as a marketing-forward botanical alongside the main functional ingredients.
Safety & warnings
Botanical extracts can occasionally cause sensitization in susceptible individuals, but this extract is not a commonly reported allergen. As with any plant extract, the actual composition depends on the source and processing.
Origin & sourcing
Natural extract from the leaves and stems of the Japanese indigo plant (Polygonum tinctorium, also classified as Persicaria tinctoria).
History
Polygonum tinctorium has a long history in Japan as a source of indigo dye, where it is known as ai.
Questions everyone asks
Is this the plant used to make indigo dye?
Yes. Polygonum tinctorium is the Japanese indigo plant traditionally used for dyeing, though in skin care the extract is used for conditioning, not coloring.
Will it stain or tint the skin?
At the low levels used in these formulas it functions as a conditioning extract and is not intended to color the skin.