An extract is a preparation of plant -- ethnobotanical or herbal -- using a solvent to release the active compounds from the plant material. Extracts made with alcohol are referred to as tinctures, while those produced with glycerin are glycerites. It is believed that an herbal extract is often more effective than pills or capsules containing the same herbs. The fresh or dried herbal material is macerated, placed in the solvent for a specific time and filtered to produce an extract containing the active constituents of the herb.
Alcohol/water based extracts have a number of advantages. Because they are concentrated, a smaller amount of extract is needed; the alcohol acts as a preservative, so these extracts have a long shelf life; and the method of preparation allows for more accurate dosing.
Dry extracts have been developed to make the constituents appropriate for use in tablets, capsules, and other medicinal forms.