Understand the stated amount of botanical extracts
Introduction
When it comes to the manufacture of dietary supplements, good manufacturing practice (cGMP) plays a central role in ensuring the quality of the product. A crucial part of this is establishing and verifying specifications for the ingredients, particularly plant extracts. But there is one area that often leads to misunderstanding and confusion: plant-to-extract ratios. This article aims to clarify what plant-to-extract ratios mean and their relevance to quality control and product labeling.
What are the Plant to Extract Ratios?
"Plant-to-extract ratios" represent the amount of plant material required to produce a given amount of extract. It is a measure of the yield from the raw material and gives an indication of the strength of the extract. A common misconception is that a higher ratio would mean a stronger extract. However, this is not always the case, as the ratio is also affected by factors such as the quality of the raw material, the type of solvent used, and the parameters of the extraction process.
Plant Extracts: Types and Forms
Plant extracts can be divided into different types based on their physical form, as shown in Table 1 below:
| extract type | Extract form | Definition | Examples of USP monographs |
|---|---|---|---|
| Liquid extract | Fluid | A liquid extract containing aqueous ethanol as a solvent or preservative, where each 1 ml contains extract from 1 g of dry material. | Garlic extract |
| tincture | Fluid | A liquid extract prepared with ethanol or hydroethanolic mixtures by maceration or percolation. | Rosemary tincture, Valerian tincture |
| Soft extracts & Oleoresins | Semi-solid or viscous | Extract with a consistency between liquid and dry, often due to incomplete evaporation of solvent or natural water content. | Capsicum oleoresin (Chili extract) |
| Torrt extract | Fast | Dry extracts are solid articles, for example powder, flakes or granules, produced by evaporation of the solvent used in production. | Guarana seed extract (dry) |
Standardization of Plant Extracts
To ensure consistent quality and effect of plant extracts, standardization is used. This means controlling and optimizing production processes to minimize natural variation in the raw material and ensure that the extract contains a defined amount of active or marker compounds. Examples of standardized extracts include senna extract, which is standardized to a specific content of sennosides, and milk thistle extract, which is standardized for silymarin.
Challenges with Plant-to-Extract Ratios
One of the major challenges in using plant-to-extract ratios as a measure of extract strength is the variation in extractive content of different plant materials. For example, the same plant, depending on origin and processing, can give different yields even under identical extraction conditions. This means that conditions can vary from batch to batch, complicating comparisons between products.
Labeling of Plant-to-Extract Ratios
In many countries, plant-to-extract ratios are required to be listed on the product label, especially to help consumers and regulatory authorities understand the strength and quality of the product. An example of correct labeling according to the European Medicines Agency (EMA) is shown in Table 2 below:
| Ingredients | Finished Product (Capsule) |
|---|---|
| Torrt extrakt från valerianarot | Amount of dry extract (genuine plant preparation and other excipients) in the herbal medicine: 200 mg/capsule |
| Amount of genuine extract: 80% genuine extract | THE genuine: 3–6:1 |
| Other auxiliary substances: 20% | Label: Each capsule contains 160 mg extract (as dry extract) of Valeriana officinalis L s.l., radix |
Conclusion
Plant-to-extract ratios are an important component in the description of plant extracts, but they should be used with caution. For these ratios to give a fair picture of the quality and potency of the extract, it is crucial to also consider the entire composition of the extract, including added excipients and extraction methods. By understanding and correctly using plant-to-extract ratios, manufacturers can improve the accuracy of labeling their products and support consumers in their decision-making.
Source: National Library of Medicine
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