Taxonomical Classification of Crude Drug

Crude drugs are any natural occurring, unrefined substance derived from organic or inorganic sources such as plant, animal  bacteria, organs or whole organisms intended for use in the diagnosis, cure, mitigation, treatment, prevention of disease in man or other animals .

Crude drug generally applies to the products from plant & animal origin found in a raw form. The term also applied to include pharmaceutical products from mineral kingdom in original form and not necessary only of organic origin such as kaolin, bentonite etc

To follow the study of the individual drugs, one must adopt some particular sequence of arrangement and this is referred to a system of classification of drugs. 
A method of classification should be simple and easy to use, and free from confusion & ambiguities .
Because of their wide distribution, each arrangement of classification has its own merits and demerits, but for the purpose of study the drugs are classified in the following different ways :


Classification of Crude Drugs:

1. Alphabetical classification: In this system the crude drugs are arranged in alphabetical order.
Examples: Acacia, Benzoin, Cinchona, Dill, Ergot, Fennel, Gentian, Hyoscyamus, Ipecacuanha, Jalap, Kurchi, Liquorice, Mints, Nuxvomica, Opium, Podophyllum, Quassia, Rauwolfia, Senna, Vasaka, Wool fat, Yellow bees wax, Zeodary.
2. Morphological classification: In this system the crude drugs are classified according to their morphological characters like leaves, barks, seeds, fruits, roots, flowers etc.,
Here, crude drugs are grouped into organized drug (parts of plant like root, rhizome, flower, leaf, fruit, bark, seed, wood etc) and unorganized drug (dried lattices, dried juice, gum, wax, oil etc).
Example: Leaves- (Senna, digitalis, vasaka, eucalyptus), Barks- (Cinchona, kurchi, cinnamon, quaillia), Woods- (Quassia, sandal-wood) etc.

3. Chemical classification: This classification gives logical reasoning to biological activities of crude drugs. It is purely based on chemistry of major active constituents.
4. Chemo-taxonomic classification: The chemical examinations of several plants photochemical evaluation have established that there is close link between their chemical constituents and taxonomical status. 
This classification establishes relation between chemistry and taxonomy by exact choice of group, sound sampling, and analysis of chemical content, interpretation and comparison.
Example: Solanaceae family contains Tropane alkaloids, Umbelliferae family contains Volatile oil, Pinaceae family contains Oleo-resin.

5. Pharmacological or biological classification: The classification shows that a quick review therapeutic effects or pharmacological activity of crude drugsCrude drugs are arranged according to taxonomic order i.e., phylum, division, class, sub-class, orders, families, genus and species.
6. Taxonomical classification: Taxonomical classification is based on principles of natural relationship & evolutionary developments. It is Purely Botanical classification. This method of classification is based on the consideration of natural relationship or phylogeny among plant and animal.  
They are grouped in (Kingdom, Phylum, Order, Family, and Genus & Species). Sometimes not all the entire plants are used as drug but only parts of plant are used as a drug, e.g. Cinnamon bark so in this case it has no significance from identification point of view to put these plants in a taxonomic order.



For Example:
Phylum - Spermatophyta Division - Angiospermae Class - Dicotyledons Sub-class - Sympetalae Order - Tubiflorae Family - Solanaceae Genus – Atropa  Species – belladonna

Another example:

Division
Angiospermae
Class
Dicotyledoneae
Subclass
Sympetalae
Order
Tubiflorae
Suborder
Verbenineae
Family
Labiatae (Lamiaceae)
Subfamily
Stachydoideae
Tribe
Satureieae
Genus
Mentha
Species
Mentha piperita Linnaeus (Peppermint)
Varieties
Mentha piperita var. officinalis Sole (White Peppermint), Mentha piperita var. vulgaris Sole (Black Peppermint



[Here we shall only discuss about Taxonomical Classification]

Taxonomy, in a broad sense the science of classification, but more strictly the classification of living and extinct organisms—i.e., biological classification. 
The term is derived from the Greek taxis (“arrangement”) and nomos (“law”).

Taxonomy is, therefore, the methodology and principles of systematic botany and zoology and sets up arrangements of the kinds of plants and animals in hierarchies of superior and subordinate groups.

The taxonomic classification system (also called the Linnaean system after its inventor, Carl Linnaeus, a Swedish botanist, zoologist, and physician) uses a hierarchical model. Moving from the point of origin, the groups become more specific, until one branch ends as a single species.

For example, after the common beginning of all life, scientists divide organisms into three large categories called a domain: Bacteria, Archaea, and Eukarya. Within each domain is a second category, called a kingdom. After kingdoms, the subsequent categories of increasing specificity are: phylum, class, order, family, genus, and species.



In taxonomical classification crude drugs are arranged according to taxonomic order i.e., phylum, division, class, sub-class, orders, families, genus and species. Also In this system crude drugs are arranged according to the natural groups (e.g. families) of their sources. 
Thus all the drugs obtained from plants of the family. Umbelliferae are grouped together as umbelliferous drugs, those from Solanaceae are grouped together as Solanaceous drugs and so on.

This system of classification reflects the natural relationship or phylogeny of the sources, which are also in many instances found to contain similar chemical constituents.
For example, volatile oils are the main constituents of the Umbelliferous fruit drugs, while tropane alkaloids are characteristics of Solanaceous drugs. 
As all the entire plants are not used as drugs, part of the plant is used as a drug, for example, cinnamon bark.

Thus it is of no significance from identification point of view to put plants in a taxonomic order.
Table 1 give the account of main characters of various taxon that contribute crude drugs while as Table 2 gives the taxonomical classification of some drugs.

                      

 

Table 1: Main Characters of Various Taxon that Contribute Crude Drugs

                                                 Plant kingdom
Thallophyta
Pteridophyta
Gymnosperm
        Angiosperm
• Alage and 
fungi are 
consider 
together 
• They differ in 
mode of 
nutrition 
• Alage exhibit 
autotropic and 
fungi exhibit 
heterotrophic 
nutrition.
Example: 
Rhodophyta 
(Red algae)
This group of plant 
derives its name 
from the fern, Pteris
which also represent 
salient features of 
group (Pterido-
pteris, Phyton-
plant) 
• They occur is humid 
and tropical 
climates and usually 
ground on soil, 
rocks, in ponds etc. 
• These plant are also 
raised in pots as 
ornamentals 
Example: Male fern
• The gymnosperm 
(Gymnos-naked and 
sperma-seed i.e. plant 
with a naked seeds) 
are comparatively 
more ancient than the 
angiosperm in 
evolutionary terms 
• The living 
gymnosperms are 
widely distributed in 
the cold climates 
• The plant body is 
sporophyte and 
differentiated into 
roots, stem and 
leaves. 
Example: Ephedra, 
Colophony
• The term angiosperm means 
enclosed seed because the 
ovules or potential seed are 
enclosed within a hallow 
ovary. 
• The angiosperms constitute 
the most dominant and 
ubiquitous vascular plants 
of present day flora 
• Dicots and monocots are its 
sub divisions

Dicot
Monocot
They have 
two 
cotyledons 
Example: 
Coriander, 
Capsicum
They have 
one 
cotyledons 
Example: 
Vanilla, Colchicum



                       

Table2:  Taxonomical Classification of Some Crude Drugs:


   Phylum
   Order
    Family
    Drugs
Thallophyta (Bacteria, 
fungi, Lichens) 
Rhodophyta 

       
     Gelidiales

   
     Gelidiaceae

          
         Agar
Pteridophyta (Liverhorts, 
Mosses and Ferns) 


     Filicales


  Polypodiaceae

      
      Male fern
Gymnosperms
  Genetales
  Coniferae
    Ephedraceae
        Pinaceae
      Ephedra 
    Colophony
Angiosperms (Moncotyledons)  
     Liliflorae,  Microspermae
      Liliaceae 
  Dioscoreaceae 
   Orchidaceae 
     Colchicum 
     Dioscorea 
        Vanilla
Angiosperms 
(Dicotyledons)
Papaverales 
   Rosales  
  Papaveraceae 
      Rosaceae 
   Leguminosae
Opium 
Almond, Rose oil 
Balsam of Tolu

 

The main feature of the taxonomical classification:

• Uses the botanical classification: Drugs are arranged according to the source of the plants.
• Thus, using; classes, orders, families, genera and species.
• It allows quick and precise arrangement that is devoid of ambiguities.
• Its use is decreasing with decreasing the knowledge of the practitioners mainly pharmacists.

Taxonomical classification is helpful for studying evolutionary developments. Though this classification is easy for study but it has some bad issues. This system is criticized for its failure to recognized/unrecognized nature of crude drugs in their morphological studies. Again, the system fails to face into an account chemical nature of active constituent and therapeutic significance of crude drugs.
Finally, the drugs obtained from plants having alternate leaves, flowers, seeds, capsules (Hyocyamus, Datura, Belladonna, Stramonium) are considered with other members of Solanaceae.





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