Ratanjot / रतनजोत / Alkanet / Onosma echioides

Alkanet is traditionally used in Indian food under the name ratan jot, and lends its red colour to some versions of the curry dish rogan josh. In Australia, alkanet is approved for use as a food colouring, but in the European Union, it is not.

It has been used as colorant for lipstick and rouge (cosmetics).

In alkaline environments, alkanet dye has a blue color, with the color changing again to crimson on addition of an acid.The colour is red at pH 6.1, purple at 8.8 and blue at pH 10. Hence, it can be used to do alkali-acid litmus tests (but the usual litmus test paper does not use alkanet as the agent and its color change is closer to pH 7).

The colouring agent in A. tinctoria root has been chemically isolated and named alkannin.

In folk medicine, it is also used to treat abscesses and inflammations.