Indole derivatives are widely distributed in nature. Many natural compounds contain indole rings. Some indole derivatives are closely related to life activities, so indole is also a very important heterocyclic compound. Indole is widely contained in essential oils such as bitter orange oil, sweet orange oil, lemon oil, white lemon oil, citrus oil, grapefruit peel oil, jasmine oil, etc. It can be widely used in jasmine, lilac, orange blossom, gardenia, honeysuckle , Lotus, narcissus, ylang-ylang, grass orchid, white orchid and other floral fragrances. A very small amount can be used in flavors such as chocolate, raspberry, strawberry, bitter orange, coffee, nuts, cheese, grape and fruity compounds.
