Astilbin is a flavanonol, a type of flavonoid.

[2] Astilbin can be found in St John's wort (Hypericum perforatum, Clusiaceae, subfamily Hypericoideae, formerly often considered a full family Hypericaceae), in Dimorphandra mollis[3] (Fava d'anta, Fabaceae), in the leaves of Harungana madagascariensis (Hypericaceae),[4] in the rhizome of Astilbe thunbergii,[5] in the root of Astilbe odontophylla[6](Saxifragaceae), in the rhizome of Smilax glabra[7] (Chinaroot, Smilacaceae) and in the bark of Hymenaea martiana.

[8] It can be isolated from Kohki tea processed from Engelhardtia chrysolepis (huang-qui).

[9] Astilbin can act as an insecticide against Anticarsia gemmatalis and Spodoptera frugiperda.

3'-O-Methylastilbin shows an immunosuppressive activity against contact dermatitis.