Adulteration of Drugs of Natural Origin: Adulteration means replacing a genuine drug, either completely or partially, with another substance that is inferior in quality, harmful, cheaper, or different from the original drug. Drugs of natural origin are obtained from plants, animals, minerals, and other natural sources. Examples include crude drugs such as Senna, Digitalis, Clove, Cinnamon, Ginger, Turmeric, Honey, Beeswax, and Tragacanth.
Adulteration is a major problem in pharmacognosy because it can reduce the quality, purity, safety, and therapeutic activity of natural drugs.
Why are Natural Drugs Adulterated?
The main reasons include:
- High cost of genuine drug – Cheap materials are substituted to increase profit.
- Scarcity of genuine drug – When the original drug is not easily available, substitutes may be used.
- Difficulty in identification – Some adulterants closely resemble the genuine drug.
- Poor collection practices – Wrong plant parts may be collected along with the drug.
- Improper storage – Moisture, insects, fungi, and microorganisms can damage the drug.
- Lack of knowledge – Collectors may not be able to distinguish genuine and adulterated materials.
- Intentional adulteration – Inferior or cheaper substances may deliberately be mixed with the genuine drug.
- Accidental adulteration – Unwanted materials may get mixed during collection, transportation, or processing.
Types of Adulteration
Adulteration of natural drugs can be broadly classified into intentional and unintentional adulteration.
1. Intentional Adulteration
This is also called deliberate adulteration. In this type, an inferior, cheaper, or different substance is intentionally added to or substituted for the genuine drug.
Examples
- Clove may be adulterated with exhausted cloves after removal of volatile oil.
- Saffron may be adulterated with coloured materials.
- Black pepper may be adulterated with papaya seeds.
- Ginger may be mixed with other cheaper materials.
- Senna may be substituted with other leaves.
The main purpose is usually economic gain.
2. Unintentional Adulteration
This occurs accidentally because of improper collection, transportation, storage, identification, or processing.
Examples
- Collection of the wrong plant species due to similarity.
- Mixing of foreign plant material during harvesting.
- Contamination with soil, stones, dust, insects, or other impurities.
- Growth of fungi and microorganisms because of improper storage.
- Mixing of different plant parts during collection.
Common Methods of Adulteration
1. Substitution with Inferior Commercial Varieties
The genuine drug is replaced by a cheaper or inferior variety.
Example: Genuine drugs may be substituted with closely related species having lower therapeutic value.
2. Substitution with Superficially Similar Materials
An adulterant is selected because it looks similar to the genuine drug.
For example, papaya seeds may be mixed with black pepper because their appearance can be similar.
3. Substitution with Exhausted Drugs
After removing the active constituents from a drug, the remaining material may be sold as genuine drug.
Example: Clove after removal of its volatile oil may be mixed with genuine cloves.Such material has reduced therapeutic value.
4. Addition of Foreign Organic Matter
Unwanted plant or animal materials may be added.
Examples include:
- Leaves
- Stems
- Seeds
- Bark
- Fibres
- Other plant parts
5. Addition of Inorganic Matter
Heavy or cheap inorganic materials may be added to increase the weight of the drug.
Examples:
- Sand
- Stones
- Chalk
- Earth
- Mineral matter
6. Addition of Artificially Manufactured Materials
Artificial materials may be prepared to resemble the genuine drug. This type of adulteration is particularly difficult to detect by simple visual examination.
7. Addition of Harmful Substances
Sometimes substances that can be toxic or harmful are added to improve the appearance, weight, or other properties of the drug. This is a serious form of adulteration because it can cause adverse health effects.
Examples of Adulteration of Important Natural Drugs
| Genuine Drug | Common Adulterant | Basis of Adulteration |
| Black pepper | Papaya seeds | Similar appearance |
| Clove | Exhausted cloves | Similar appearance but reduced volatile oil |
| Saffron | Coloured fibres/other materials | Colour and appearance |
| Honey | Sugar syrup | Similar sweetness |
| Senna | Other leaves | Similar appearance |
| Cinnamon | Cassia | Similar appearance |
| Isabgol | Other seeds/husks | Similar appearance |
| Tragacanth | Acacia/gum materials | Similar appearance |
| Ginger | Inferior/foreign rhizomes | Substitution |
| Turmeric | Artificially coloured materials | Appearance |
Adulteration vs. Substitution
These terms are related but should be understood separately.
Adulteration: Addition or mixing of an inferior, foreign, or harmful material with the genuine drug.
Substitution: Complete or partial replacement of the genuine drug with another material, often because it is cheaper or more easily available.
Example: Replacing genuine Cinnamon with Cassia is considered substitution.
Factors Used to Detect Adulteration
Adulteration can be detected by different methods.
1. Organoleptic Evaluation
The drug is examined using the senses.
Parameters include:
- Colour
- Odour
- Taste
- Shape
- Size
- Texture
- Appearance
Example:
Black pepper and papaya seeds can be differentiated by careful examination of their external characteristics.
2. Microscopic Examination
The drug is examined under a microscope to identify characteristic structures.
Important features may include:
- Stomata
- Trichomes
- Fibres
- Vessels
- Starch grains
- Calcium oxalate crystals
- Epidermal cells
- Oil glands
Microscopy is particularly useful when the adulterant looks similar to the genuine drug.
3. Physical Evaluation
Physical properties can be determined, such as:
- Moisture content
- Ash value
- Extractive value
- Specific gravity
- Melting point
- Refractive index
- Volatile oil content
Abnormal values may indicate adulteration or poor quality.
4. Chemical Evaluation
Chemical tests are performed to identify characteristic chemical constituents.
Examples:
- Alkaloids
- Glycosides
- Tannins
- Flavonoids
- Volatile oils
- Resins
The absence or unusually low concentration of characteristic constituents may indicate adulteration.
5. Chromatographic Methods
Modern techniques such as:
- TLC – Thin Layer Chromatography
- HPTLC – High-Performance Thin Layer Chromatography
- HPLC – High-Performance Liquid Chromatography
- GC – Gas Chromatography
can be used to identify and compare chemical constituents.
These methods are more accurate than simple visual examination.
6. Spectroscopic Methods
Advanced techniques include:
- UV-Visible spectroscopy
- IR spectroscopy
- Mass spectroscopy
- NMR spectroscopy
These techniques can help in authentication and quality control of natural drugs.
Effects of Adulteration
Adulteration can produce several problems:
- Reduction in therapeutic activity
- Variation in drug potency
- Treatment failure
- Toxicity or adverse effects
- Change in chemical composition
- Poor quality of pharmaceutical preparations
- Economic loss to consumers
- Loss of confidence in herbal and natural medicines
Prevention of Adulteration
Adulteration can be minimized by:
- Correct identification of the source plant.
- Proper collection and harvesting.
- Use of authenticated raw materials.
- Proper drying and storage.
- Protection from moisture, insects, and microorganisms.
- Pharmacopoeial testing of crude drugs.
- Proper packaging and labelling.
- Microscopic and chemical evaluation.
- Use of chromatographic fingerprinting.
- Purchasing raw materials from reliable suppliers.
- Following Good Agricultural and Collection Practices (GACP).
- Maintaining proper quality-control records.
Editorial Note
This article has been carefully researched and written by Deepak Rajput with a focus on accuracy, clarity, and evidence-based healthcare information. Pharmaacademias.com
