I have been looking up “Indigo naturalis” on the Internet for a while.
In China, “Indigo naturalis” is said to be effective against leukemia, atopy, and psoriasis. There is even a soap made from “Indigo naturalis” that is said to be effective against atopic dermatitis. I wonder if the color will not come off.
It seems that there are still many things that are not fully understood, including its efficacy against ulcerative colitis.