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Introduction to Pharmacognosy

Pharmacognosy AND Phytochemistry

Definition

Pharmakon + Gnosis

Pharmacognosy is derived from two Greek words: Pharmakon & Gnosis

Pharmakon – means ‘drug’

Gnosis – means ‘knowledge’.

In brief, Pharmacognosy means ‘knowledge of drugs’. It is a study of drugs that originate in the plant & animal kingdoms.

What is Pharmacognosy

Pharmacognosy is a branch of pharmacy which deals with the basic resources of medicines from nature (plant & animal) and their uses as medicaments from ancient time to present day.

Pharmacognosy may be defined as an important branch of Pharmacy which deals with the study of structural, physical, chemical, biochemical and sensory characters of natural drugs of plant and animal origin. It also includes a study of their history, distribution, cultivation, collection, identification, preparation, evaluation, preservation, use and commerce.

At present pharmacognosy involves not only the crude drugs but also their natural derivatives (pure compounds or constituents). Digitalis leaf and its isolated glycoside, digitoxin; Rauwolfia root and its purified alkaloid, reserpine; and thyroid gland with its extracted hormone, thyroxine, are all part of the subject matter of pharmacognosy.

History of Pharmacognosy

History of pharmacognosy is actually the history of medicine that is medicinal plants.

Pre-history:

The first or beginning of pre-history on use of medicinal plants or herbs or animals, and the place where and how used were not well known, and those information were unwritten for a long time. As a result, the pre-history on herbs was almost lost.

However, some information was recorded by oral transmission from generation to generation.

Written History:

The written history has originated which was based on
region, religion and culture etc.
The written history was divided into the following:

  1. The western medicine
  2. The Unani (Islam)
  3. The Ayurveda (Indian)
  4. The orient
  5. The Greek History
  6. The African System

1. The western medicine:

  • This is originated in Mesopotamia and Egypt. Mesopotamia is considered as the first origin of human civilization. The Sumerians (peoples of ancient Mesopotamia) developed cuneiform tablet of herbal medicines. Those tablets is preserved in British museum.
  • In Egypt, information had written on paper – Papyrus ebers (1600BC). It consisted of 800 prescriptions, mentioning 700 drugs.
  • The first pharmacopoeia named London Pharmacopoeia was published in 1618 and then British Pharmacopoeia was published in 1864.

2. The Unani (Islam)

  • This herbal system was developed by Arabian Muslim Ibn Sina (980 – 1037 AD). He was a prince and ruler. He was a very brilliant pharmacist and physician who wrote a book – “Kitab-Al-Shifa”, means ‘Book of Healing’.
  • The book was written on Arabic language. This is a great contribution of Ibn Sina on medical and pharmaceutical sciences.

3.The Ayurveda (Indian, 2500-600 BC):

  • Ayurveda is the term for traditional medicine of ancient India.
  • The word “Ayur” means ‘Life’ and “veda” means ‘The study of’ that is “Study of Life”.
  • The Ayurvedic writings were divided into three systems:
    • Charaka Samhita
    • Sushruta Samhita
    • Astanga samhita.
  • The oldest writing was Charaka Samhita (six to seven century before Christ).
  • The book describes uses of many metallic drugs eg., iron, mercury, sulphur, cupper etc with herbs.

4. The orient (2700 BC):

  • This is originated from Chinese, Japanese and Tibet etc. The orient herbalism was very old (142 – 220 BC) and called “Kampo”. The written documents were made by the King ‘Shen Nung’ (2700 BC) and Shang (1766 – 1122 BC) etc.
  • Shen Nung investigated medicinal value of several herbs and written a book – “Pen T-Sao” or native herbal.

5. The Greek History:

Some of the early naturalists, scientists and physicians who contributed enormously to the development of human knowledge about medicinal plants include following:

  • Hippocrates (Father of Medicine, 460-370 BC): He was the first natural doctor who utilized simple remedies such as vinegar, honey, herbs etc in healing. He is also known to have collected and identified a number of medicinal plants.
  • Aristotle (384-322 BC): He gave the philosophy of medicine. He listed more than 500 plants of medicinal importance.
  • Theophrastus (340 BC): gave scientific basis of use of plants as medicine.
  • Galen (131-200 AD): A Greek pharmacist-physician. He developed the methods of preparing and compounding medicines by mechanical means. He was the originator of the formulae for a cold cream.

6. The African System (Tropical Africa, North and South America):

  • They keep information in their groups or tribes. The information transmitted from one generation to another.
  • These regions are richest sources of medicinal plants and needs to explore for new drug discovery.

Scope of Pharmacognosy

Pharmacognosy deals primarily with information on the sources and constituents of natural drugs.

  1. Primary source of medicines (from ancient time to present day), for example – hyoscine, morphine, ergotamine, ouabain etc.
  2. Providing Template/guide for the discovery of new drugs, for example – Pathidine (analgesic drug) designed from morphine.
  • Pharmacognosy is critical in development of different disciplines of science. The knowledge of plant taxonomy, plant breeding, plant pathology and plant genetics is helpful in the development of cultivation technology for medicinal and aromatic plants.
  • Plant chemistry (phytochemistry) has undergone significant development in recent years as a distinct discipline. It is concerned with the enormous variety of substances that are synthesized and accumulated by plants and the structural elucidation of these substances. Extraction, isolation, purification and characterization of phytochemicals from natural sources are important for advancement of medicine system.
  • The knowledge of chemotaxonomy, biogenetic pathways for formation of medicinally active primary and secondary metabolites, plant tissue culture and other related fields is essential for complete understanding of Pharmacognosy. One should have the basic knowledge of biochemistry and chemical engineering is essential for development of collection, processing and storage technology of crude drugs.
  • Pharmacognosy is important branch of pharmacy which is playing key role in new drug discovery and development by using natural products.
  • Pharmacognosy has given many leads for new drug discovery and development.
  • It is an important link between modern medicine systems (allopathy) and traditional system of medicine.
  • It is part medicinal system which is affordable as well as accessible to common man.
  • As part of integrative system of medicine, pharmacognosy can help to increase effectiveness of modern medicine system.
  • It is acting as bridge between pharmacology, medicinal chemistry and pharmacotherapeutics and also pharmaceutics. It also bridges pharmaceutics with other pharmacy subjects.
  • More than 60 percent of world population is still using natural product for their primary healthcare needs. Pharmacognosy can provide safe and effective drugs in combination with modern medicine system.
  • Pharmacognosy includes knowledge about safe use of herbal drugs including toxicity, side effects, drug interaction thereby increasing effectiveness of modern medicine.
  • Pharmacognosy is an important link between pharmacology and medicinal chemistry. As a result of rapid development of phytochemistry and pharmacological testing methods in recent years, new plant drugs are finding their way into medicine as purified phytochemicals, rather than in the form of traditional galenical preparations.
  • Pharmacognosy is the base for development of novel medicines. Most of the compounds obtained from natural product serve as prototype or base for development of new drug which are more active and less toxic.
  • By means of pharmacognosy, natural products can be dispensed, formulated and manufactured in dosage forms acceptable to modern system of medicine.
  • There are vast number of plant and animal species which are not studied systematically.
  • Development of pharmacognosy also leads to development of botany, taxonomy, plant biotechnology, plant genetics, plant pathology, pharmaceutics, pharmacology, phytochemistry and other branches of science.

Source of Drugs

Sources of drugs of natural origin (DONO)

Plants, animals, minerals, marines and plant tissue culture Plants Plant source is the oldest source of drugs. Most of the drugs in ancient times were derived from plants. Almost all parts of the plants are used i.e.leaves, stem, bark, fruits and roots etc Leaves: The leaves of Digitalis purpurea are the source of Digitoxin and Digoxin, which are cardiac glycosides. Leaves of Eucalyptus give oil of Eucalyptus, which is important component of cough syrup. Tobacco leaves give nicotine. Atropa belladonna gives atropine. Sources of drugs of natural origin

Plant source

  • Flowers: Clove gives eugenol Vinca rosea gives vincristine and vinblastine Rose gives rose water used as tonic. Fruits Senna pod gives anthracine, which is a purgative (used in constipation) Calabar beans give physostigmine, which is cholinomimetic agent.
  • Seeds: Seeds of Nux Vomica give strychnine, which is a CNS stimulant. Castor seeds give castor oil. Calabar beans give Physostigmine, which is a cholinomimetic drug.
  • Roots: Ipecacuanha root gives Emetine, used to induce vomiting as in accidental poisoning. It also has amoebicidal properties Rauwolfia serpentina gives reserpine, a hypotensive agent. Reserpine was used for hypertension treatment.
  • Bark: Cinchona bark gives quinine and quinidine, which are antimalarial drugs. Quinidine also has antiarrythmic properties.
  • Stem: Kalmegh Hepatoprotective

Animal Sources

  • Pancreas is a source of Insulin, used in treatment of Diabetes.
  • Sheep thyroid is a source of thyroxin, used in hypertension.
  • Cod liver is used as a source of vitamin A and D.
  • Blood of animals is used in preparation of vaccines.
  • Cochineal (dried full grown female insects) consist of carminic acid used as colouring agent for foods, drugs and for cosmetic products.

Mineral Sources

Metallic and Non metallic sources: Iron is used in treatment of iron deficiency anemia. Mercurial salts are used in Syphilis. Zinc is used as zinc supplement. Zinc oxide paste is used in wounds and in eczema. Iodine is antiseptic. Iodine supplements are also used. Gold salts are used in the treatment of rheumatoid arthritis. ii)Miscellaneous Sources: Fluorine has antiseptic properties. Borax has antiseptic properties as well. Selenium as selenium sulphide is used in anti dandruff shampoos. Petroleum is used in preparation of liquid paraffin.

Marines

The greater part of the earth surface is covered by seas and ocean, which contains about 5,00,000 species of marine organisms. Many of these compounds have shown pronounced biological activity. In the western medicine agar, alginic acid, carrageenan, protamine sulphate, spermaceti & cod and halibut liver oils are the established marine medicinal products. Macroalgae or seaweeds have been used as crude drugs in the treatment of iodine deficiency states such as goitre, etc. Some seaweed have also been utilized as sources of additional vitamins and in the treatment of anaemia during pregnancy. During the last 30–40 years numerous novel compounds have been isolated from marine organisms having biological activities such as antibacterial, antiviral, antitumour, antiparasitic, anticoagulants, antimicrobial, antiinflammatory and cardiovascular active products. Ara-A Semisynthetic antiviral agent Bryostatin Anticancer agents Octopamine Cardiovascular agent Bio-indol derivatives Antiinflammatory.

Plant tissue culture

Tissue culture is in vitro cultivation of plant cell or tissue under aseptic and controlled environmental conditions, in liquid or on semisolid well-defined nutrient medium for the production of primary and secondary metabolites or to regenerate plant. This technique affords alternative solution to problems arising due to current rate of extinction and decimation of flora and ecosystem. The whole process requires a well-equipped culture laboratory and nutrient medium. This process involves various steps, viz. preparation of nutrient medium containing inorganic and organic salts, supplemented with vitamins, plant growth hormone(s) and amino acids as well as sterilization of explant (source of plant tissue), glassware and other accessories inoculation and incubation.

Applications:

  • Production of Phytopharmaceuticals
  • Biochemical Conversions
  • Clonal Propagation (Micro-propagation)
  • Production of Immobilized Plant Cell

Synthetic/ Semi synthetic Sources

Synthetic Sources:

  • When the nucleus of the drug from natural source as well as its chemical structure is altered, we call it synthetic.
  • Examples include Emetine Bismuth Iodide.

Semi Synthetic Source:

  • When the nucleus of drug obtained from natural source is retained but the chemical structure is altered, we call it semi-synthetic.
  • Examples include Apomorphine, Diacetyl morphine, Ethinyl Estradiol, Homatropine, Ampicillin and Methyl testosterone.
  • Most of the drugs used nowadays (such as antianxiety drugs, anti convulsants) are semisynthetic forms.

Microbiological Sources

  • Penicillium notatum is a fungus which gives penicillin.
  • Actinobacteria give Streptomycin.
  • Aminoglycosides such as gentamicin and tobramycin are obtained from streptomycis and micromonosporas.
  • Viral Vaccines:
    • Smallpox Vaccine is a virus of vaccinia (cow pox).
    • Rabies vaccines
    • Influenza virus vaccine
    • Poliomyelitis vaccine
    • Measles vaccine
    • Yellow fever vaccine
    • Hepatitis virus vaccine
  • Rickettsial vaccine: a group of very small gram negative microorganism.
  • Bacterial vaccines: Typoid vaccine, BCG vaccine
  • Toxoids: tetanus and diptheria toxoid.

Recombinant DNA technology

Recombinant DNA technology involves cleavage of DNA by enzyme restriction endonucleases. The desired gene is coupled to rapidly replicating DNA (viral, bacterial or plasmid) The new genetic combination is inserted into the bacterial cultures which allow production of vast amount of genetic material.

Advantages: Huge amounts of drugs can be produced. Drug can be obtained in pure form. It is less antigenic.

Disadvantages: Well equipped lab is required. Highly trained staff is required. It is a complex and complicated technique.

Significance of Pharmacognosy

Ayurveda

Ayurveda is accepted to be the oldest medical system. The word Ayurveda means Ayur meaning life and Veda meaning science. Thus, Ayurveda literally means science of life. Theory & Basic principal Pamchamahabhuta Sidhanta – Every substance in the universe is composed of five basic elements viz. solid (pruthvi) ,liquid (Jal) energy (Agni), air (Vayu), and space (Akash) (Panchamahabhuta ). They exist in the human body in combined forms like vata (space and air), pitta (energy and liquid) and kapha (liquid and solid). Vata, pitta and kapha together are called Tridosha (three pillars of life).The body has a perfect balance of these element and when balance is disturbed,an unhealthy condition called illness developed. Charaka Samhita (1900 B.C.) is the first recorded book with the concept of practice of Ayurveda. This describes 341 plants and plant products used in medicine. Sushruta Samhita (600 B.C.) was the next ayurvedic literature that has special emphasis on surgery. It described 395 medicinal plants, 57 drugs of animal origin, 4 minerals and metals as therapeutic agents.

Unani

The Unani system of medicine is based on the Hippocratic theory of 4 humours (blood,phlegm,yellow bile and black bile) and Pythogorian theory of 4 proximates qualities (hot, cold, moist and dry) Health is decribed as primary state in which 4 humors are present in correct proportion. The Materia Medica of Unani system consist of drugs of vegetable, animal and mineral origin.Vegetable drugs include various morphological parts of plants or the products such as latex,gums which are secretions. Around 3000 such drugs are recognised. Drugs of animal origin derived from living beings,animal organs and their flesh,hair,hoofs,excreta or bones.Minerals includes metal like gold, silver, lead, zinc, copper, iron, heavy metals like arsenic and antimony.Minerals such as talc,mica,precious stones suchas emerald,sapphire,are also used as drugs.

Homeopathy

The ‘Similia Similibus Curantur’ (lets like treated by likes is the basic principle of Homeopathic medicine. It is system of treating ailments by administration of drugs which has capacity to produce disease state in healthy individuals.This is known as proving the medicine. If same symptoms are evelpoed in patient,then medicine act as curative agent. Unique features of homoepatic medicine are its small dose amd methodology of serial dilutionby which all the energy og drug is liberated and transfered to the medium base suger or alcohol. Seven principles :Principles of , Individualisation (No 2 individuals in the world are alike and therefore disease affecting the 2 individuals cannot be similar) Similia Similibus Curantur ((the treatment of the disease by medicine which produces similar symptoms in healthy individuals by proving the drugs) ,Simplex (Only single simple medicine at one time and no combination is allowed),Minimum dose,(Min.medicine at a time which is just sufficient to arouse vital force as a dynamic power which preserves life force and its normal state indicate good health) law of proving, law of dymamisation,and vital force Source of Homeopathic medicines Plant Kingdom Various morphological plant parts,fungi etc. Animal kingdom Secretion ,Saliva, poisons and whole animals etc. Minerals and chemicals Inorganic salts,nonmetal acids and mixtures etc.

Siddha

The Siddha system of medicine is based on 3 principles of the body ,namely Vata ,Pitta,Kapha which are known as Trigunas Siddha physucians begins keeps the knoledge of thousansd of hebs . Siddha formulary extensively incorporates drugs of vegetable,animal and mineral origin.It decribes the drugs from metals and nonmetals. The use of mercury,gold,silver,sulphur,zinc,copper sulphate, alu, borax,mica,asbetos and arsenuc is widespread.Ut also mention drugs from secretions of animals like civet and musk,shell and bones of aquatic animals,deer,horns aanimal flesh.

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