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.