Chestnut shell is the exocarp of chestnut, which is sweet, astringent and flat. It has the effect of lowering adverse flow and stopping bleeding, and is mainly used for nausea, epistaxis and hematochezia.

In the final analysis, it is still Chinese medicine. It's hard to say why in chemistry-it may be the following.

Chestnut shell pigment extracted from chestnut shell belongs to flavonoids and belongs to brown pigment series which is difficult to obtain in general plant materials. It can not only be widely used as a colorant for food, daily chemicals and medicine, but also has certain medicinal value.