Quality control & standardization of herbal extracts

Standardization and quality control are necessary to guarantee consistent levels of active principles in the extract. To this end most of the plants intended for industrial or medicinal applications are now produced under controlled agricultural conditions.

Advantages of cultivated plants in terms of standardization :
  • they grow in a soil with optimal characteristics
  • they grow at the same altitude, in the same climate
  • they are harvested at the right time
  • Plants can be dried quickly
Quality control

Quality control is a multistep process stretching from the growing phase of the plant to the chemical assay of the extract. Many factors determine the extract quality :

  • the correct identity of the plant
  • the quality of the plant somehow related to environmental factors under which it was cultivated
  • plants part used and time of harvesting
  • the processing (drying, transportation, storage)
  • the extraction method
  • the purety
  • the level of biologically actives compounds
  • level of contaminants must be kept within limits

Standardization is essential to ensure that customers are provided with high quality botanicals. Extracts made directly from crude plant material show wide variation in composition, quality, and therapeutic effects. Standardized extracts are high-quality extracts containing consistent levels of specified compounds. They are subjected to strict quality controls during all phases of the growing, harvesting, and manufacturing processes. Standardization can be defined as a requirement to have a minimum amount of one or several compounds in the extract. When the active principles are unknown, marker substances are established for analytical purposes and standardization. Marker substances are chemically defined substances that are important for the quality of the finished product. Ideally, the chemical markers chosen would also be the active constituents. The content in marker substances are given as percentage of a class of compounds expressed in a specific compound of this group. For example, an extract could have to contain at least 60% of alkaloids expressed in sanguinarine.