The other form is called gallotannic acid and is found in oak galls.

In vitro interaction of neuroleptics and tricylic antidepressants with coffee, tea, and gallotannic acid.

The gallotannic acid was usually extracted from oak galls (also known as "oak apples"), or galls of other trees; hence the name.

Other important essential oil constituents of clove oil include acetyl eugenol, beta-caryophyllene and vanillin, crategolic acid, tannins such as bicornin, gallotannic acid, methyl salicylate (painkiller), the flavonoids eugenin, kaempferol, rhamnetin, and eugenitin, tri terpenoids like oleanolic acid, stigmasterol and campesterol and several sesquiterpenes.