Importance of Genetic Identification of Medicinal Plants
Importance
of Genetic Identification of Medicinal Plants
Dr.
Hemant Vinze (M. S.)
Bhoomyaamalakee
(Phyllanthus niruri-Phyllanthus
amarus)
Thyagarajan’s
landmark paper published in ‘The Lancet’ on eradication of Hepatitis B surface
antigen by using ‘Bhoomyaamalakee’ or ‘Bhuiaawalaa’ (Phyllanthus amarus)
in HBV carriers stirred the medical fraternity. Bloomberg et al added value to
Thyagarajan’s paper, for their results were much better than Thyagarajan’s.
Inspired by this data many researchers, clinicians and specialists in Ayurveda
started using ‘Bhoomyaamalakee’ or ‘Bhuiaawalaa’ (then called Phyllanthus
niruri) to treat jaundice in general and viral hepatitis B in particular;
but in vain, for they did not get the desired results.
Despite
the uncertain, unconvincing and inconclusive results, the trade of
‘Bhoomyaamalakee’ or ‘Bhuiaawalaa’ (so called Phyllanthus niruri)
reached its zenith.
I
had an opportunity to discuss this issue with a professor of pharmacology. The
professor stunned me by saying ‘the results of the Chinese Phyllanthus
amarus are much superior in this regard to the Indian Phyllanthus amarus’.
As I asked the explanation, ‘Purity of the plant’, the professor replied.
Since
ancient times, herbs of the genus Phyllanthus have been in use in
traditional European, Chinese and Indian medicine mainly for treating jaundice.
Modern research with Phyllanthus focuses on its potential for fighting
hepatitis B virus and malaria parasite.
The
species Phyllanthus niruri is an American species and not at all found
in India. In India Phyllanthus amarus, Phyllanthus fraternus, Phyllanthus
debilis and Phyllanthus urinaria grow sympatrically (in the same
geographical region or zone). Morphologically they bear a remarkable semblance
to Phyllanthus niruri. (See images at https:
//sites.google.com/site/ayurvinze/ ). Earlier researchers therefore grouped
them in a single group of species Phyllanthus niruri which was later
described as ‘niruri complex’. However taxonomically this is incorrect. Each
species must be identified separately and individually with a specific
taxonomical (botanical) name.
Phyllanthus niruri Phyllanthus
amarus
Phyllanthus
fraternus Phyllanthus
debilis
,
Phyllanthus pulcher Phyllanthus talbotii
Phyllanthus tenellus
The
confusion still exists because of morphological similarities. This implies
inadvertent or deliberate adulteration of crude drugs lowering the efficiency
or efficacy of the medication for its intended purpose. Secondly, incorrect
identification may also lead to erroneous reports on actions of the herb. These
may be some of the reasons why researchers could not emulate the results
reported by Thyagarajan and Bloomberg et al.
To
overcome this problem in crude drug and compliment morphological identification
in live plant, scientists offered genetic identity for each species. This is
based on SCAR (Sequence Characterized Amplified Region) markers of DNA. The
genetic identification of Phyllanthus species mentioned above is:
Phyllanthus amarus: 1150 bp
Phyllanthus fraternus: 317 bp
Phyllanthus debilis: 980 bp
Phyllanthus urinaria: 550 bp (2), (3)
Bhringaraaja
(Eclipta alba)
In
Ayurveda, Bhringaraaja was extolled as ‘hair tonic’ (Kesharaaja). Later it was
described to be useful for the disorders of liver and spleen. According to the colors of the flowers the herb bears; in Ayurveda
three varieties of Bhringaraaja are described: White, Yellow and Neela Bhringaraaja or Neeli Bhringaraaja.
Shweta Bhringaraaja Peeta
Bhringaraaja
(Eclipta alba) (Wedelia
calendulacea)
Neela
Bhringaraaja (Indigofera tinctoria) 4.
Although
they have some similar Ayurvedic and pharmacological actions; taxonomically
they are three different plants:
Shweta
(white) Bhringaraaja: Eclipta alba
Peeta
(yellow) Bhringaraaja: Wedelia calendulacea
Neela
(blue) Bhringaraaja: Indigofera tinctoria
(For
more details see below: Confusion
due to taxonomical synonyms)
Daaru-Haridraa (Berberis aristata)
In field, usually
more than one species of Berberis (Daaruharidraa) grow together.
Morphologically many of them resemble each other. In 1999 Rao et al. reported
pollen morphologic studies in solving taxonomic confusion. However during
harvesting, in the field, it becomes difficult to distinguish one species from
the other. Thus species other than Berberis aristata are also harvested.
Berberis aristata Berberis vulgaris
Berberis evergreen
Berberis aquefolium Berberis julianne
Berberis thunbergii
Berberis stenophylla Berberis-hedge
Berberis darwini
Since stems of the
plant are used for medicinal purpose, it becomes even more challenging to
obtain authentic collections and assure quality. Conventional Pharmacognosy
techniques based on macro and micro-morphological characters of plant
identification may not be effective in distinguishing Berberis aristata
because some species may share similar histological characteristics, making
microscopic identification inaccurate. Different species of the same genus may
have totally different or weaker pharmacological action compared with the
authentic species. DNA-based markers have therefore become a popular means of
definitive identification of plants because genetic composition is unique for
each individual species irrespective of physical form, age, physiological
condition, environmental factors, storage and processing.
The genetic identity
of Berberis aristata is determined by “Direct sequencing of complete ITS
region” 5
This
reveals that, from traditional herbalists, Ayurvedic physicians to taxonomists
it seems there exists confusion regarding ‘appropriate’ identification of
medicinal plants.
The factors
producing confusion in appropriate identity of Ayurvedic plants are:
1. Confusion due to
morphological similarities:
Phyllanthus niruri and Phyllanthus amarus both look
alike. Hence they are confused with each other. However P. niruri is not
an Indian plant but P. amarus is!
2. Confusion due to
taxonomical synonyms:
The aim of Carl
Linnaeus a Swedish botanist, zoologist and physician in developing a system of
botanical nomenclature (taxonomy) was to avoid confusion in identification of
plants (and animals) and impart one universal scientific name to each species.
Because of this taxonomical system any given species, be it a plant or an
animal, is appropriately identifiable world over.
But, even today taxonomically there exist many
synonyms of Bhringaraaja, such as Eclipta alba, Eclipta prostrata, Eclipta
erecta and many more. This must not happen.
3. Confusion due to
similarities in pharmacological actions:
Shweta (white)
Bhringaraaja, Peeta (yellow) Bhringaraaja, and Neela (blue) Bhringaraaja have
very similar pharmacological actions. All the three plants have similar leaves
and similar ‘morphological look’. Hence in Ayurveda three varieties of Bhringaraaja are described. Taxonomically
however, they are three different plants; three different species: Eclipta
alba, Wedelia calendulacea and Indigofera tinctoria.Again,
Wedelia calendulacea and Wedelia chinensis are used as synonyms.
Surprisingly, even today Wedelia calendulacea is known as Peeta (yellow)
Bhringaraaja and is used in place of Eclipta alba. Scientifically this
is adulteration!
Myrsine
africana
Linn is sold as Widnga but it is NOT Widnga it is an
adulterant.
(See below)
Hence there is an
absolute need for ‘genetic identification’ of Ayurvedic plants!
Currently various
methods and techniques are used for genetic identification. The detailed
discussion is beyond the scope of this work. Hence the authors prefer to
mention some commonly used types of genetic markers.
RFLP (Restriction
Fragment Length Polymorphism)
AFLP (Amplified
Fragment Length Polymorphism)
RAPD (Random
Amplification of Polymorphic DNA)
VNTR (Variable
Number Tandem Repeat)
MSP (Micro
Satellite Polymorphism)
SNP (Single
Nucleotide Polymorphism)
STR (Short Tandem
Repeat)
SPF (Single Feature
Polymorphism)
SCAR
(Sequence Characterized Amplified Region) (6), (7)
Widanga
(Embelia ribes)
In
Ayurveda Widanga (Embelia ribes Burm. f.) is famous for antimicrobial
activity. However another species of Widanga is also used for antimicrobial
activity. Taxonomically it is Embeliaro busta auct. Nonroxb. Therefore
though this other species shows antimicrobial activity similar to that
of Widanga (Embelia ribes Burm. f.); scientifically the other species is
an adulterant. Researchers have proved Widanga (Embelia ribes Burm.
f.) has more potent antimicrobial activity than the adulterant
species Embeliaro busta auct. Nonroxb. [8]
Different
Varieties: At
present Embelia Tsjeriam -Cottom-R et S, Embelia
robusta are supplied as Widanga (Embelia ribes) in India, but
taxonomically they are not Widanga (Embelia ribes). P. V.
Sharmaji reported that Myrsine africana Linn is sold as Widnga but it
is NOT Widnga it is an adulterant.
True Widanga (Embelia ribes)
True
Widanga (Embelia ribes)
Embelia Tsjeriam -Cottom Embelia robusta
Myrsine africana Linn
[9]
Hence
the absolute need and importance of chromosomal and genetic identification of
herbs for effective pharmacological actions.
For
more details visit:
References:
1.
Images from Wikipedia and google images
3.
Jain N, Shasany AK, Singh S, Khanuja SP, Kumar S; SCAR markers for correct
identification of Phyllanthus amarus, P. fraternus, P. debilis and P. urinaria
used in scientific investigations and dry leaf bulk herb trade; Planta Med,
2008 Feb; 74 (3): 296-301
4.
Google images
5. Subramani Paranthaman Balasubramani, Gurinder Singh
Goraya and Padma Venkata Subramanian; Development of ITS sequence-based markers to distinguish Berberis aristata
DC from B. lyceum Royale and B. asiatica Roxb.; Biotech. 2011
February 25; 1(1): 57
6. K Semagen, A. Bjornstad and M. N. Ndjiondjop, An
overview of molecular marker methods for plants; American Journal of
Biotechnology Vol. 5 (25) pp2540-2568 December, 2006
7. P. Kumar, V.K. Gupta, A. K. Misra, D. R. Modi and
B. K. Pandey, Potential of Molecular Markers in Plant Biotechnology; Plant Omics
Journal Southern Cross Journals, 2 (4):141-162 (2009)
8. Malvika
Saini, Gaurav Sharma, Mita Kotecha, A comparative Antimicrobial Evaluation of
Embelia ribes Burm. f. and Embeliaro Busta auct. Nonroxb. Fruits,
International Journal of Pharmaceutical Sciences and Research, 2015; 1, 11:
90.24
9.
google images
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