Introduction and scope of pharmacognosy by Dr.U.Srinivasa, Professor, Srinivas college of pharmacy, Mangalore
TO N SY T IO NO C G U O D C O A TR RMIN HA P
DEFINITION : Pharmacy is the science of drugmaking / deals with their procurement(bring about), testing, storage andconversion into suitable forms ( tablets,capsules, emulsions etc)
DRUG :Any substance used in the treatment ofdisease or diagnosis is known as drug .Diagnosis is the determination of natureof disease.
CRUDE DRUG It is the simple drug ,crude drugs areplant, animal and their parts which aftercollection are subjected only to drying ormaking them into transverse orlongitudinal pieces or peeling (strippingoff skin or bark).They exist in naturalforms.
SOUCES OF DRUG Drugs used in medicine may be organic and inorganic innature. Organic drugs are essentially of 2 types .1. Purely synthetic : The product of man ‘s creation of newchemical entities ( structures) non – existent before theera of synthetic chemistry. 2.Drugs of biological origin : Produced in the livingcell, biogenic drugs (crude drugs)
PHARMACOGNOSYPharmacognosy is the science of drugs of biological origin( plant, animal, mineral) or The word pharmacognosy was coined in 1815by a German Scientist SEYDLER has been derived fromtwo Greek words , Pharmacon ---- ‘ a drug, gignosco – ‘acquire the knowledge of
Pharmacognosy is the subject of crude drugsobtained from the plants (vegetable), animal andmineral origin. Or It can also defined as theobjective study of crude drugs of the naturalsources processed scientifically.
The pharmacognosy is broadly defined as thescientific and systematic study of the structural,physical, chemical and sensory characters of crudedrugs of vegetable, animal and mineral origin alongwith their history, method of cultivation, collectionand preparation for the market.
Recently it includes:1- Modern isolation techniques.2- Pharmacological testing procedures to prepare purified substances.3- Cultivation and propagation by tissue culture
SCOPE OF PHARMACOGNOSY• Pharmacognosy has broad scope in the field of pharmacy such as :• 1. ISOLATION OR ANALYSIS OF PHYTOCHEMICAL :• Eg ; Strong acting substances such as glycosides from digitalis leaves,• Alkaloids from the plants of Belladonna, Hyocyamus, Rauwlofia• Morphine and other alkaloids from the plant opium were isolated and clinical uses studied
2. STRUCTURE ACTIVITY RELATIONSHIP :Eg : Tubocurarine and Toxiferine from curare plant have muscle relaxant properties because of quaternary ammonium groups. The hypotensive and tranquillizing actions of reserpine are due to the trimethoxy benzoic acid
3. DRUGS OBTAIN:ED BY PARTIAL SYNTHESIS OF NATURAL PRODUCTS:Eg : Preparation of Steroid hormones from diosgenin by acetolysis and oxidation and further preparation of cortisone by microbial reactions .4. NATURAL PRODUCTS AS MODELS FOR SYNTHESIS OF NEW DRUGS : Eg: Morphine is the model of a large group of potent drugs . Cocaine for local anaesthetics Atropine for certain spasmolytics
• 5. DRUGS OF DIRECT THERAPEUTIC USES :• Among the natural constituents which even now cannot be replaced are important group of antibiotics, steroids, ergot alkaloids, vincristine etc• 6. BIOSYNTHETIC PATHWAYS INVESTIGATION :• Biosynthetic pathways are of primary and secondary metabolites.• Some of the important pathways are Clavin ‘s cycle of photosynthesis,• Shikimic acid pathway of aromatic compounds
• Acetate hypothesis for antharacene glycosides• Isoprenoid hypothesis for terpens• 7.CULTIVATION AND COLLECTION OF MEDICINAL PLANTS :• clove, cinchona , cinnamon, senna, opium, etc• 8. PREPARATION OF HERBAL FORMULATIONS :• churnas, asvas, aristas, leha, etc• 9. DEVELOPMENT OF TISSUE CULTURED PLANTS
ASH VALUESThe residue remaining after incineration is the ash content of the drug.( inorganic salts of carbonates, phosphates, silicates of sodium, potassium, calcium and magnesium) is known as ash content.Ash value is a criterion to judge the identity OR purity of the crude drug
TYPES OF ASH VALUES1.Total ash value2.Acid insoluble ash value3.Sulphated ash value4. Water soluble ash value
Total ash value:Useful for detecting low grade productsUseful for detecting exhausted productsUseful for detecting excess of sandyUseful for detecting earthy matter with drug
DETERMINATION1.Weigh accurately about 3gms of the powdered drug in a tared silica crucible2.Incinerate the powdered drug by gradually increasing the heat until free from carbon and cool. Keep it in desiccators3. Weigh the ash and calculate the % of the total ash with reference to the air dried sample
Acid insoluble ash value :1. Used for the determination of earthy matter present on roots, rhizomes, and also on the leaves2. Crude drugs contain calcium oxalate crystals the amount may varies depending on the environmental conditions
DETERMINATION1. Boil the total ash obtained as above for 5 minutes with 25ml of dilute HCL2.Filter and collect the insoluble matter on the ashless filter paper , wash the filter paper with hot water, ignite in tared crucible, cool and kept in desiccators3.Weigh the residue and calculate the acid insoluble ash of the drug
Sulphated ash value :Used for the detection of low grade productsWater soluble ash value :Used to detect either material exhausted by water or not( Tea leaves, Ginger rhizomes)
SWELLING FACTORSignificances :Useful in the evaluation of crude drugs containing mucilageUseful for the detection of purity of the crude drug
DETERMINATION1. Transfer 1 gm of the seeds to a 25ml stoppered cylinder2. Fill up to the 20ml mark on the cylinder with water. Agitate gently and occasionally during 24 hours and allowed to stand3.Measure the volume occupied by the swollen seeds
EXTRACTIVE VALUESSignificances :1.Useful for the evaluation especially when the constituents of the drugs can not be readily estimated by any other means2.It also helps to indicate the nature of chemical constituents present in the drug3. Also helps in the identification of adulterants
1.Water soluble extractive value is applied for the drugs which contain water soluble constituents such as tannins, sugars, plant acids and mucilage.2.Alcohol soluble extractive value is applied for the drugs which contain alcohol soluble constituents such as tannins, resins and alkaloids Official method for the assay of myrrh & asafoetida
3.Ether soluble extractive value is applied for the extraction of volatile oils, fixed oils and resins.1.Volatile ether soluble extractive value2.Non volatile ether soluble extractive value
DETERMINATIONWater soluble extractive value:1. Macerate about 5gm of the accurately weighed coarse powder with 100ml of chloroform water in a 100ml volumetric flask for 24 hours .2. Shake frequently for first 6 hours3. Filter rapidly through filter paper and evaporate 25ml of water extract to dryness in a tared flat-bottomed shallow dish.
4. Dry the residue at 105 and weigh. Keep it in a desiccators5. Dry the extract to constant weight ,finally , calculate the % W/W of Water soluble extractive value with reference to the air dried drug.
• Alcohol soluble extractive values• Macerate about 5gm of the accurately weighed coarse powder with 100ml of 90% alcohol in a 100ml stoppered flask for 24 hours .• Shake frequently for first 6 hours• Filter rapidly through filter paper and collect the filtrate evaporate 25ml of alcohol extract to dryness in a tared flat- bottomed shallow dish.
• Dry the residue at 105 and weigh. Keep it in a desiccators• Dry the extract to constant weight ,finally , calculate the % w/w of alcohol soluble extractive value with reference to the air dried drug.
SIGNIFICANCE:1.The method is generally used when standardization is not done satisfactory by chemical or physical methods2.When the quantity of the drug /sample are very less then the drugs are evaluated by biological methods
These methods are performed on living animals,isolating living organ and tissue, animal preparation, andmicro-organism( Bioassay)
Following method is used as1.Anti inflammatory activity2.Analgesic activity3.Antipyretic activity4.Anti ulcer activity5.Antidiabetic activity6.Anthelmintic activity on earth worms
7.Cardiac activity- on frog and pigeon8.Microbiological methods- living bacteria, yeast, molds are used for the assaying vitamins and to determine the activity of antibiotic drugs