Introduction to Pharmacognosy Lecture 2

Learning outcomes of the lecture By the end of the lecture, the students should be able to: 1- Identify types, uses and values of natural products. 2- Identify different types of crude drugs. 3- Describe the items used to study details of medicinal plants. 4- Recognize binomial system of nomenclature. 5- Characterize terms related to biological and geographical origin of crude drugs.

What is Natural Product? A natural product is a substance obtained from a natural source. It includes: 1. A crude drug , e.g. Senna, Cascara, Cinchona, etc. 2. A galenical preparation of a crude drug, e.g. extracts and tinctures, etc. 3. A pure compound, e.g. morphine, atropine, digoxin, etc. 4. A semithynthetic product, e.g. etoposide, teniposide, hyoscine butyl bromide etc.

Uses of Natural Products As drugs for the treatment of a wide range of diseases, e.g. morphine, atropine, digoxin, hormones, antibiotics, etc.. As pharmaceutical aids in pharm. industry, e.g. suspending & emulsifying agents, suppository bases, binders, excipients, sweetening & colouring agents, etc..

Uses of Natural Products In cosmetics as flavouring & colouring agents, etc. In culture media for the propagation of M.O. in microbiology laboratories & biotechnology (e.g. Gelidium). General uses e.g. in food industries: as falvouring agent (e.g. vanilla pods), colouring agent (e.g. saffron), fragrants (e.g. cinnamon), cooling agent (e.g. mentha) and in perfumery (e.g. rose).

Value of Natural Products Compounds from natural sources play four significant roles in modern medicine: They provide a number of extremely useful drugs that are difficult, if not impossible, to produce commercially by synthetic means. Natural sources also supply basic compounds (Leads) that may be modified slightly to render them more effective or less toxic

3. Their utility as prototypes or models for synthetic drugs possessing physiologic activities similar to the originals.

4. Some natural products contain compounds that demonstrate little or no activity themselves but which can be modified by chemical or biological methods to produce potent drugs not easily obtained by other methods Baccatin III  Taxol

Types of Crude Drugs Derived from Plants 1- herbal drugs derived from specific parts of a medicinal plant: they are known as “herbal medicinal products”, “herbal remedies” or “phytomedicines”. Entire plants : Mentha, Lobelia. Entire organs of plants : Senna, Clove, Fennel, Linseed, Quassia, Cinchona, Liquorice.

2- Natural products or compounds isolated from nature (unorganized): opium, aloes, tragacanth, resins, musk, beeswax, gelatin etc. 3- Nutraceuticals, or “functional foods”: garlic, spices, anthocyanin or flavonoid containing foods and carotenoid- containing plants

For detailed description of each individual drug the following points are to be considered 1- Origin: including biological and geographical sources, a knowledge of the history and name of the drug. 2- Cultivation and preparation: including details of cultivation of the medicinal plants, methods of collection, drying, packing and other treatment of the drug during its preparation for the market.

3- Characters: including the physical characters such as dimensions, surface characters, fracture and the sensory characters such as colour, odour and taste. The histological characters which help in the identification of the drug in powdered form, are of fundamental importance.

4- Constituents and tests: constituents include both the reputed active constituents and also other constituents and reserve food materials. Chemical identity tests are based on the nature of constituents. 5- Adulterants: including materials added fraudulently and matter which has become associated with the drug owing to carelessness in handling during collection, preparation, packing and transport. 6- Evaluation of the physical and chemical characters of the drug. 7- Uses and application of the drug in medicine.

Pharmacopoeia Government is aiming to standardize herbal drugs: Quality, Efficacy and Safety of drugs in order that many traditional herbs meet legal requirements of different countries. Pharmacopoeia is a book recognized by the government as legal authority for standardization of drugs, e.g. British Herbal Pharmacopoeia, 1996. The British Herbal Compendium Vol. 1& 2, 1993. The United States Herbal Pharmacopoeia. German Commission E Monographs. The Chinese Herbal Pharmacopoeia.

Monograph The descriptive material pertaining to any of the drugs in the Pharmacopoeia is known as the monograph. In the monograph of a crude drug, the following information are generally covered: English, Arabic, Latin, French names, definition, description, special condition for collection or prepn for the market, identity tests, tests for adulterants, method of assay, special storage requirements, dose , natural or biological origin.

Official and Unofficial Drugs OFFICIAL DRUG is one that is listed and described as being a definite therapeutic agent in the pharmacopoeia. UNOFFICIAL DRUG is that one that are not recognized in the pharmacopoeia and is used as therapeutic agent (e.g. Folkloric medicine)

Classification of drugs for study Vegetable drugs are usually classified for study in one of the following ways: 1- Alphabetical: using either Latin or English names; the drugs are arranged in an alphabetical order. 2- Taxonomic: using one of the accepted systems of botanical classification; the drugs are according to the plants from which they are obtained in phyla, orders, families. Genera and species. 3- Morphological: dividing the drugs into groups e.g. leaves, flowers, fruits, seeds,..... which are referred to as "organized drugs", and groups as dried lattices, extracts, gums, resins, oils, fats and waxes which are known as "unorganized drugs“.

4- Chemical: the drugs are divided into groups according to their most important constituents e.g. drugs containing volatile oils, glycosides, alkaloids, bitter principles, tannins, saponins,...... 5- Pharmacological and therapeutic effects: grouping of drugs according to the pharmacological action of their most important constituents or their therapeutic use. e.g. astringent, irritant, drugs affecting the gastrointestinal tract, drugs promoting systemic effects on the muscle and nervous system, drugs affecting the circulatory system, drugs used chemotherapeutically for the treatment of infectious diseases, etc....

Origin of Drugs There are two origins for each drug; the natural or biological, as well as, the geographical origin. The commercial origin is also of interest in case of certain drugs.

The Natural or Biological Origin (Source) The natural origin of a drug is the plant or animal yielding it, if a plant, botanical origin or botanical source and if an animal, zoological origin or source.

The Binomial System Is due to Swedish biologist Linnaus, in this system the first name, which is always spelt with Capital letter, denotes the genus. whilst the second name denotes the species. It is however, still equally correct to use capital where the species is named after a person. Thus the species of Cinchona named after Charles Ledger, who brought its seed from Brazil 1865, is known as Cinchona Ledgeriana.

The specific name is usually chosen to indicate: 1- Some striking characteristics of the plant: a- Conium maculatum (maculate = spotted) (stem with reddish, spotted patches). b- Glycyrrhiza glabra (glabrous = smooth). Refers to the fruit of this species which is a smooth pod. c- Hyoscyamus muticus (muticus = short). The plant being short. d- Atropa belladonna (bella = beautiful, donna = lady) the juice of the berry placed in the eyes causes dilatation of the pupils, thus giving a striking appearance).

2- A characteristic colour: a- Piper nigrum (= black) b- Veratrum viride (= green) c- Citrus aurantium (= golden yellow) d- Digitalis purpurea (= purple) e- Digitalis lutea (= yellow) 3- An aromatic plant or certain aroma: a- Myristica fragrans (having a fragrant, nice aroma) b- Caryophyllus aromaticus (refers to the aroma)

4- A geographical source or history of a drug: a- Salvia aegyptica (growing in Egypt) b- Tamarinds indica (India). c- Olea arabica (in Arabic region). d- Uriginia maritima (near the coast) 5- A Pharmaceutical activity or an active constituents: a- Papaver somniferum (sleep inducing) b- Strychnos nux vomica (from two latin words, nut causing vomiting) c- Ipomoea purga (laxative). 6- A general meaning or a special indication a- Allium sativum (= cultivated) b- Triticum vulgare (= wild) c- Linum usitatissimum (most useful).

The generic name may also allude to certain characters of the plant: Atropa, from Atrops, meaning flexile, the name of the Greek fate who cuts the thread of life, alluding to the poisonous characters of the drugs. Glycyrrhiza is from glucose= sweet, riza = root.

Geographical sources of drugs The geographical source or Habitat is the region in which the plant or animal yielding the drug grows. Plants growing in their native countries are said to be indigenous to these regions, e.g. Aconitum napellus of the mountainous regions of Europe, Hyoscyamus muticus of Egypt, Cannabis sativa of India. Plants are said to be naturalized when they grow in a foreign land or in locality other than their native home.

Commercial origin The commercial origin of a drug refers to its production and its channels of trade.