A treatise published two centuries ago (in 1820) on adulterations in food and culinary materials is a proof for this practice as an age-old one. Due to adulteration, faith in herbal drugs has declined. Adulteration in market samples is one of the greatest drawbacks in promotion of herbal products.
ADULTERATION
A treatise published two centuries ago (in 1820) on
adulterations in food and culinary materials is a proof for this practice as
an age-old one. Due to adulteration, faith in herbal drugs has declined.
Adulteration in market samples is one of the greatest drawbacks in promotion of
herbal products. Many researchers have contributed in checking adulterations
and authenticating them. It is invariably found that the adverse event reports
are not due to the intended herb, but rather due to the presence of an
unintended herb. Medicinal plant dealers have discovered the ‘scientific’
methods in creating adulteration of such a high quality that without
microscopic and chemical analysis, it is very difficult to trace these
adulterations.
Definition: The term adulteration is defined as substituting original
crude drug partially or wholly with other similar-looking substances. The
substance, which is mixed, is free from or inferior in chemical and therapeutic
property.
Types of Adulterants
Adulteration in simple terms is debasement of an article.
The motives for intentional adulteration are normally commercial and are
originated mainly with the intension of enhancement of profits. Some of the
reasons that can be cited here are scarcity of drug and its high price
prevailing in market. The adulteration is done deliberately, but it may occur
accidentally in some cases. Adulteration involves different conditions such as
deterioration, admixture, sophistication, substitution, inferiority and
spoilage. Deterioration is impairment in the quality of drug, whereas admixture
is addition of one article to another due to ignorance or carelessness or by
accident. Sophistication is the intentional or deliberate type of adulteration.
Substitution occurs when a totally different substance is added in place of
original drug. Inferiority refers to any substandard drug, and spoilage is due
to the attack of microorganisms.
Unintentional Adulteration
Unintentional adulteration may be due to the following
reasons:
1. confusion in vernacular names
between indigenous systems of medicine and local dialects
2. lack of knowledge about the
authentic plant
3. nonavailability of the authentic
plant
4. similarity in morphology and or
aroma
5. careless collection
6. other unknown reasons
Name
confusion
In ayurveda, ‘Parpatta’ refers to Fumaria parviflora. In siddha, ‘Parpadagam’ refers to Mollugo pentaphylla. Owing to the
similarity in the names in traditional systems of medicine, these two herbs are
often interchanged or adulterated or substituted. Because of the popularity of
siddha medicine in some parts of south India, traders in these regions supply M. pentaphylla as Parpatta/Parpadagam
and the north Indian suppliers supply
F. parviflora. These two can be
easily identified by the presence of pale yellow to mild brown-coloured, thin
wiry stems and small simple leaves of M.
pentaphylla and black to dark brown-coloured, digitate leaves with narrow
segments of F. parviflora. Casuarina equisetifolia for Tamarix indica and Aerva lanata for Bergenia ciliata are some other examples of adulterations due to
confusion in names.
Lack
of knowledge about authentic source
‘Nagakesar’ is one of the important drugs in ayurveda. The
authentic source is Mesua ferrea.
However, market samples are adulterated with flowers of Calophyllum inophyllum. Though the authentic plant is available in
plenty throughout the Western Ghats and parts of the Himalayas, suppliers are
unaware of it. There may also be some restrictions in forest collection. Due to
these reasons, C. inophyllum (which
is in the plains) is sold as Nagakesar. Authentic flowers can be easily
identified by the presence of two-celled ovary, whereas in case of spurious
flowers they are single celled.
Similarity
in morphology
Mucuna pruriens is the best example for unknown
authentic plant and similarity in
morphology. It is adulterated with other similar papilionaceae seeds. M. utilis (sold as white variety) and M. deeringiana (sold as bigger variety)
are popular adulterants. Apart from this, M.
cochinchinensis, Canavalia virosa and C. ensiformis are also sold in Indian markets. Authentic seeds are up to 1 cm
in length with shining mosaic pattern of black and brown colour on their
surface. M. deeringiana and M. utilis are bigger (1.5–2 cm) in size.
M. deeringiana is dull black, whereas
M. utilis is white or buff coloured.
Lack
of authentic plant
Hypericum perforatum is cultivated and sold in European markets. In India, availability of this
species is very limited. However, the abundant Indo-Nepal species H. patulum is sold in the name of H. perforatum. Market sample is a whole
plant with flowers, and it is easy to identify them taxonomically.
Anatomically, stem transverse section of H.
perforatum has compressed thin
phloem, hollow pith and absence of
calcium oxalate crystals. On the otherhand, H.
patulum has broader phloem, partially hollow pith and presence of calcium oxalate crystals.
Similarity
in colour
It is well known that in course of time, drug materials get
changed to or substituted with other plant species. ‘Ratanjot’ is a recent-day
example. On discussion with suppliers and nontimer forest product (NTFP)
contractors, it came to be known that in the past, roots of Ventilago madraspatana were collected
from Western Ghats, as the only source of ‘Ratanjot’. However, that is not the
practice now. It is clearly known that Arnebia
euchroma var euchroma is the present source. Similarity in yielding a red
dye, A. euchroma substitutes V. madraspatana. The description to
identify these two is unnecessary because of the absence of V. madraspatana in market. Whatever is
available in the market, in the name of Ratanjot, was originated from A. euchroma.
Careless
collections
Some of the herbal adulterations are due to the carelessness
of herbal collectors and suppliers. Parmelia
perlata is used in ayurveda, unani and siddha. It is also used as grocery.
Market samples showed it to be admixed with other species (P. perforata and P. cirrhata).
Sometimes, Usnea sp. is also mixed with them. Authentic plants can be
identified by their thallus nature.
Unknown
reasons
‘Vidari’ is another example of unknown authentic plant. It
is an important ayurvedic plant used extensively. Its authentic source is Pueraria tuberosa, and its substitute is
Ipomoea digitata. However, market
samples are not derived from these two. It is interesting to know that an
endangered gymnosperm Cycas circinalis is
sold in plenty as Vidari. The adulterated
materials originated from Kerala, India. Although both the authentic plant
and its substitute are available in plenty throughout India, how C. circinalis became a major source for
this drug is unknown. P. tuberosa can
be easily identified by the presence of papery flake-like tubers, I. digitata by the presence of its
concentric rings of vascular bundles and their adulterant C. circinalis by its leaf scars and absence of vessel elements.
Intentional Adulteration
Intentional adulteration may be due to the following reasons:
1. adulteration using manufactured
substances
2. substitution using inferior
commercial varieties
3. substitution using exhausted drugs
4. substitution of superficially
similar inferior natural substances
5. adulteration using the vegetative
part of the same plant
6. addition of toxic materials
7. adulteration of powders
8. addition of synthetic principles
Adulteration
using manufactured substances
In this type of adulteration the original substances are
adulterated by the materials that are artificially manufactured. The materials
are prepared in a way that their general form and appearance resemble with
various drugs. Few examples are cargo of ergot from Portugal was adulterated
with small masses of flour dough moulded to the correct size and shape and
coloured, first using red ink, and then into writing ink. Bass-wood is cut
exactly the required shape of nutmegs and used to adulterate nutmegs.
Compressed chicory is used in place of coffee berries. Paraffin wax is coloured
yellow and is been substituted for beeswax, and artificial invert sugar is used
in place of honey.
Substitution
using inferior commercial varieties
In this type, the original drugs are substituted using
inferior quality drugs that may be similar in morphological characters,
chemical constituents or therapeutic activity. For example hog gum or hog
tragacanth for tragacanth gum, mangosteen fruits for bael fruits, Arabian
senna, obovate senna and Provence senna are used to adulterate senna, ginger
being adulterated with Cochin, African and Japanese ginger. Capsicum annuum fruits and Japanese
chillies are used for fruits of C.
minimum.
Substitution
using exhausted drugs
In this type of substitution the active medicaments of the
main drugs are extracted out and are used again. This could be done for the
commodities that would retain its shape and appearance even after extraction,
or the appearance and taste could be made to the required state by adding
colouring or flavouring agents. This technique is frequently adopted for the
drugs containing volatile oils, such as: clove, fennel etc. After extraction,
saffron and red rose petals are recoloured by artificial dyes. Another example
is balsam of tolu that does not contain cinnamic acid. The bitterness of
exhausted gentian is restored by adding aloes.
Substitution
of superficially similar inferior natural substances
The substituents used may be morphologically similar but
will not be having any relation to the genuine article in their constituents or
therapeutic activity. Ailanthus leaves are substituted for belladona, senna,
etc. saffron admixed with saff flower; peach kernels and apricot kernels for
almonds; clove stalks and mother cloves with cloves; peach kernel oil used for
olive oil; chestnut leaves for hamamelis leaves and Japan wax for beeswax are
few examples for this type of adulteration.
Adulteration
using the vegetative part of the same plant
The presence of vegetative parts of the same plant with the
drug in excessive amount is also an adulteration. For example, epiphytes, such
as mosses, liverworts and lichens that grow over the barks also may occur in
unusual amounts with the drugs, e.g. cascara or cinchona. Excessive amount of
stems in drugs like lobelia, stramonium, hamamelis leaves, etc. are few example
for this type of adulteration.
Addition
of toxic materials
In this type of adulteration the materials used for
adulteration would be toxic in nature. A big mass of stone was found in the
centre of a bale of liquorice root. Limestone pieces with asafetida, lead shot
in opium, amber-coloured glass pieces in colophony, barium sulphate to
silvergrain cochineal and manganese dioxide to blackgrain cochineal, are few
examples in this adulteration.
Adulteration
of powders
Powdered drugs are found to be adulterated very frequently.
Adulterants used are generally powdered waste products of a suitable colour and
density. Powdered olive stones for powdered gentian, liquorice or pepper; brick
powder for barks; red sanders wood to chillies; dextrin for powdered
ipecacuanha, are few adulterants.
Addition
of synthetic principles
Synthetic pharmaceutical principles are used for market and
therapeutic value. Citral is added to lemon oil, whereas benzyl benzoate is
added to balsam of Peru. Apart from these, the herbal products labelled to
improve sexual performance in men, when analysed, contained sildenafil. Brand
names included Actra-Rx, Yilishen, Hua Fo, Vinarol and Vasx, Sleeping Buddha
containing estazolam, Diabetes Angel containing glyburide and phenformin are
few examples under this category.
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