This group contains some of the most poisonous compounds known, so should not be handled by the amateur. Tannins Are found in a wide range of plant families. They break animal proteins up so that they don't rot and are therefore used to tan leather. They were used to treat cuts, wounds and rashes externally. They are also used internally for inflammation of the stomach or intestines.
Flavonoids are mainly yellow coloured and normally bound to sugars.
They have an unusual affect on the walls of fine blood vessels and are therefore used in mainstream medicine for treating veins, high blood pressure and arteriosclerosis. Bitters Are a group of bitter tasting compounds. They are used to aid digestion and appetite. They also speed up fermentation and putrefaction. They are commonly found in the mint and gentian families.