Adulteration of Drugs of Natural Origin: Adulteration and substitution are major problems in growing herbal industries. It causes a major threat in the research on commercial natural products. The deforestation and extinction of many species and incorrect identification of many plants have resulted in adulteration and substitution of raw herbal drugs. In ancient times most of the drugs used for the cure of health problems were of plant origin but lack of proper description and proper authentication has made it difficult to provide the correct identity of the herbal drugs. Not only that, due to the lack of standardization method, the herbal drugs are still in confusion and controversies for choice of the allied species, which results in adulteration of the herbal drugs. The term is derived from the Latin adultery, which in its various inflections signifies to defile, to debase, to corrupt, to sophisticate, to falsify, to counterfeit. Ultimately it is defined as a practice of substituting original crude drug, partially or wholly, with other similar looking substances, but the latter is either free from or inferior in chemical or therapeutic properties or adulteration is defined as mixing or substituting the original drug material with other spurious, inferior, defective, spoiled, useless other parts of same or different harmful substances or drug that do not comply with the official standards. The constituents that are added to the original substances are known as adulterants and the practice or process is known as adulteration. The whole admixed products are known as adulterated products. The plant-based drugs are adulterated by substitution with sub-standard commercial varieties, inferior drugs, or artificially manufactured commodities.
- To increase the bulk or weight of the article.
- To improve its appearance.
- To give it a false strength.
- To rob it of its most valuable constituents.
- To make product cost-benefit.
- Scarcity of drugs.
Conditions of Adulteration:
Deterioration: It is the impairment in the quality of a drug. This condition is due to the destruction or abstraction of valuable constituents by bad treatment or aging or to the deliberate extraction of the constituents and the sale of the residue as the original drugs. Apart from this condition, crude drugs are also prone to deterioration in storage. The shelf-life of crude drugs is influenced by many factors which include not only the quality of storage conditions but also the stability of the secondary metabolites present. Several factors are to be considered for the detrimental effects on the stored products.
Admixture: It is the addition of one article to another due to ignorance or carelessness or accidentally. Example: inclusion of soil on an underground organ or the co-collection of two similar species.
Sophistication: It is the intentional type of adulteration by adding spurious or inferior material with intent to defraud. Such materials are carefully produced and may appear at first sight to be genuine. E.g., powder ginger may be diluted with starch with the addition of little coloring material to give the correct shade of yellow color.
Substitution: It occurs when some different substance is added in place of the original drug. e.g., supply of cheap cottonseed oil in place of olive oil.
Inferiority: It refers to any sub-standard drug. This condition is like a crop is taken whose natural constituent is below the minimum standard for that particular drug. It can be avoided by a more careful selection of the plant material.
Spoilage: The deterioration due to the attack of microorganisms. This condition makes the product unfit for consumption, which can be avoided by careful attention to the drying and storage conditions.
Adulteration generally takes place either directly (intentionally) or indirectly (unintentionally).
Direct adulteration: This type of practice is mainly encouraged by traders who are reluctant to pay premium prices for herbs of superior quality and hence are inclined to purchase only the cheaper products. Therefore producers and traders sell the herbs of inferior quality. In this type of adulteration, a herbal drug is substituted partially or fully with other inferior products which have a morphological resemblance to the authentic herb and many other inferior commercial varieties.
They may or may not have any chemical or therapeutic potential. This practice is most common in the case of volatile oil-containing materials. Foreign matters like any other parts of the same plant with no active ingredients, fine sand and stones, dust, dried clay, manufactured artifacts, and synthetic inferior principles are used as substitutes (Fig. 1).
Indirect adulteration: This type of adulteration is also known as unintentional or undeliberate adulteration that accidentally occurs without any intention of the manufacturer or supplier. Sometimes due to improper evaluation, an authentic drug is partially or fully replaced with the active ingredient which enters the market. Generally, this practice happens at geographical sources, growing conditions, processing and storage conditions that influence the quality of the drug.
Fig. 1: Types of direct adulterations
Fig. 2: Types of Indirect adulterations
Types of Adulteration:
1. With artificially manufactured substances: This type of adulteration is done for costlier drugs. Artificially prepared substances resemble the original drug and are not separated or identified by naked eyes and these products are used as substitutes. Generally, they are colored substances. Examples: Compressed Chicory in place of coffee, yellow-colored paraffin wax for the beeswax, properly cut and shaved basswood for nutmeg, artificial invert sugar for honey, Musk is adulterated with dust and dried blood; Tinospora cordifolia extract adulterated with arrowroot powder.
2. Superficially similar inferior drugs: These drugs are with or without chemical or therapeutic values as that of the original drug. Due to their morphological resemblance to authentic drugs, they are marketed as adulterants. Ailanthus leaves are used to substitute belladonna leaves, Carthamus tinctorious flowers are mixed with costly saffron flowers and beeswax is substituted with Japan wax and mother clove with original clove, Strychnous nux-blanda or S.potatorum in place of S. nux-vomica, Capsicum annuum in place of C.minimum, Indian senna is substituted with Arabian senna (Cassia Angustifolia) or dog senna (Cassia obovata), medicinal ginger (Zingiber officinale) is substituted with Zingiber myoga or Cochin ginger.
3. Exhausted materials: The exhausted material may be used entirely or in part as a substituent for the genuine drug. e.g., umbelliferous fruits and cloves (without volatile oils) are adulterated with exhausted (without volatile oils) drugs, exhausted jalap and Indian hemp (without resins) are used as an adulterant.
4. Use of synthetic chemicals: They are sometimes used to enhance the natural character as in the case of the addition of benzyl benzoate to balsam of Peru, citral to citrus oils like oil of lemon and orange oil, etc.
5. Substitution with the exhausted drug: The same drug is admixed but is devoid of any medicinally active constituents as they are already extracted out. This practice is common with volatile oil-containing drugs like fennel, clove, coriander, caraway, etc. The Colour and odor of exhausted drugs are manipulated by adding other additives and then it is substituted. e.g., exhausted gentian made bitter with aloes, the artificial coloring of exhausted saffron, almond oil adulterated with groundnut oil and cottonseed oil, etc.
6. Harmful adulterants: In this type of adulteration, the waste from the market is collected and admixed with the authentic drug. This practice is noticed in the case of liquids or unorganized drugs. Examples include pieces of amber-colored glass in colophony, limestones in asafoetida, lead shot in opium, white oil in coconut oil, cocoa butter mixed with stearin or paraffin. The addition of rodent fecal matter to cardamom seed is a very harmful adulteration.
7. Adulteration of powders: The powdered forms are frequently found to be adulterated with original drugs. Examples: dextrin in ipecacuanha, powered licorice or gentian admixed with powdered olive stones, exhausted ginger powder in powdered colocynth or ginger, red-sanders wood in capsicum, Mallotus Philippines is mixed with fine brick powder, etc.
8. Faulty collection: Herbal adulteration sometimes occurs due to the carelessness of herbal collectors and suppliers. The correct part of the genuine plant should be collected. Moreover, the collection should be carried out at a proper season and time when the active constituents reach maximum. Examples: Datura strumarium leaves should be collected during the flowering stage and wild cherry bark in autumn etc. Collection from other plants by ignorance, due to the similarity in the appearance, color, lack of knowledge may lead to adulteration. Examples: In place of Aconitum napellus, the other Aconitum deinorhizum may be collected, or in place of Rhamnus purshiana (cascara bark) Rhamnus California is generally collected. Often in different states, the same plant is known by different vernacular names, while quite different drugs are known by the same name. This creates confusion which is best illustrated by Punarnava and Brahmi. The Indian pharmacopeia drugs Trianthema portulacastrum L. and Boerhavia diffusa L. are both known by the same vernacular name “Punarnava”. Sometimes lack of authentic sources may lead to adulteration. Example: Nagakesar is one of the important drugs in Ayurveda. The original drug, Mesua ferrea is adulterated with flowers of Calophyllum inophyllum and is sold as Nagakesar in the market. Authentic flowers can be easily identified by the presence of a two-celled ovary, whereas in the case of spurious flowers they are single-celled.
9. Imperfect preparation: The collection of the plant parts should be clear by the collectors. Sometimes stems are collected with leaves, flowers, fruits which are not necessary. Sometimes undesirable parts should not be collected, like cork should be removed from the ginger rhizome. Sometimes neglected drying process may lead to unintentional adulteration. e.g. if digitalis leaves are dried above 65°C, decomposition of glycosides by enzymatic hydrolysis occurs. Use of excessive heat in separating the cod liver oil from livers but the proportion of vitamins, odor, and color, etc. are adversely affected.
10. Incorrect storage: Deterioration, especially during storage, leads to the loss of active ingredients and the production of non-active toxic metabolites. Physical factors such as oxygen, humidity, light, and temperature can bring about deterioration directly or indirectly. These factors also help in the development the growth of organisms such as molds, mites, and bacteria. Oxidation of essential oils can lead to rancid. Moisture or humidity and elevated temperatures can accelerate enzymatic activities, leading to changes in the physical appearance and decomposition of the herb. For example, volatile oils should be protected from light and stored in well-closed containers in a cool place. Belladonna leaf should be stored in moisture-free containers, which may cause enzymatic action leading to decomposition of medicinally active constituents.
11. Presence of vegetative matter in the same plant: In the same field, sometimes other miniature plants are grown along with medicinal plants that are admixed accidentally with the authentic drug due to their morphological resembling i.e. color, odor, etc. The lower plants like moss, liverworts, and epiphytes are grown on the bark portion and are mixed with cascara or cinchona. The stem portions are mixed along with leaf drugs like stramonium, lobelia, and senna. Mucuna pruriens is adulterated with other similar Papilionaceae seeds having similarities in morphology. M. utilize and M. deeringiana are popular adulterants. Apart from this, M. cochinchinensis, Canavalia virosa, and C. ensiformis are also sold in Indian markets.
Pharmacognostically, it is defined as the “whole replacement of an entirely different article that is used or sold in place of the original article”. Examples: Cottonseed oil substituted in place of olive oil, American saffron substituted in place of Spanish saffron, etc.
Reasons for Substitution:
1. Non-availability of the drug: If the part of the plant is not available, then a similar-looking part of another plant is used as a replacement. Example: In the case of nonavailability of leaf of the Abies webbiana (Talisa Patra), leaf of the Abies baccata is used.
2. Uncertain identity of the drug: Sometimes due to the confusion of the authenticity of the plant, drug identity becomes uncertain. Like Chichona bark it has different species like Cinchona calisaya, C. officinalis, C. ledgeriana, etc. are considered.
3. Cost of the drug: Some costly drugs are not always available in the market and hence similar types of drugs are sold in the market at a lesser price than original drugs. Examples: Kumkuma (Crocus sativas) being a costly herb is substituted by Kusumbha (Carthamus tinctorius).
4. Geographical distribution of the drug: Depending on the geographical location and plant distribution, the different plants are sold in the same name in the market. For example, in North India Premna integrifolia is used as Agnimantha, whereas in South India, Arani (Clerodendrum phlomidis) is used as Agnimantha.
5. The adverse reaction of the drug: Vasa is a well-known drug that cures bleeding disorder, but due to its abortifacient activity, its utility in pregnant women is limited, instead drugs such as Laksha, Ashoka, etc. are substituted for similar therapeutic effects.
6. Seasonal availability of drugs: Some drugs are available in a specific season so other drugs can be introduced in their absence which has the same action. For example, Trianthema portulacastrum can be used in the seasonal absence of Boerhavia diffusa.
Types of Substitutions:
Substitution with totally different drugs: This practice is generally done in the case of oil. Like cottonseed oil in place of olive oil. Sometimes barks also substitute original bark.
Substitution of species in the same family: This practice is done in the case of dried leaves, roots, or stems. Example: Dog senna in place of Indian seena, but both have the same family (Leguminosae), Leaves of Natural metal with D. stramonium (family: Solanaceae), Cinchona bark can be easily substituted with other species of the same family (Rubiaceae) i.e., Cinchona ledgeriana, C. succirubra.
Substitution of different species: Dried fruits, flowers, and leaves are easily substituted with different species with different family but the genus is the same. For example, Brahmi, which has two species like Centella Asiatica and Baccopa monerii, and both belong to different families of Umbelliferae and Scrophulariaceae, respectively. Two types of Gokhru viz. Tribulus Terrestris (Zygophyllaceae) and Pedalium murex (Pedaliaceae) of which, T. Terrestris has chemical constituents like chlorogenic, diosgenin, rutin, rhamnose, and alkaloids. While P. murex has sitosterol, ursolic acid, vanillin, flavonoids, and alkaloids. Both the species have proved lithotriptic, diuretic, and hepatoprotective activities.
Substitution of different parts of the same plant: Depending on the pharmacological activities and therapeutic active principles present, the substitution of the plant parts is practiced. Example: The root of Sida cordifolia and the whole plant of Sida cordifolia. Root has chemical constituents such as sitoindoside, acylsteryglycoside, while the whole plant has alkaloids, hydrocarbons, fatty acids, and ephedrine. Various extracts of the whole plant showed antibacterial, antioxidant, hypoglycemic, hepatoprotective, and cardiotonic activities.
Substitution of the plant parts due to the same action: Based on the pharmacological activities, this practice is carried out for the substitution of the plants. Different plant sources have the same action but have the same part of the plant. Like leaves of Datura, Belladona, Hyoscyamus, etc. They belong to tropane alkaloids but have different biological sources. They possess anticholinergic activities with the same useful plant part of leaves and flowers.
Some of the examples of original drugs that are adulterated and substituted in the market, depicted in table 3.
Table 3: Adulteration and substitution of natural crude drugs
Method of Detection of Adulteration and Substitution
Generally, adulterants and substituents are detected in the original drug morphologically, microscopically, chemical tests, physical evaluation method, microbiological techniques, and instrumental methods. These all are have been explained in detail in the evaluation method in earlier chapters. Oils are detected by odor, viscosity, color, clarity, followed by specific gravity, optical rotation, refractive index, and finally by gas chromatography (GC) analysis.
Some of the detection tests for the original crude drugs with adulterants are given in table 4.
Table 4: Test for detection of original natural drugs with their adulterants
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