General introduction and brief description about Volatile oils or Terpenoids
• Pharmacognostic profile of following drugs
INTRODUCTION Terpenoids are the hydrocarbons of plant origin having general formula (C5H8)n. They are also oxygenated, hydrogenated and dehydrogenated derivatives. Basically terpenoids are volatile substances which give fragrance or aroma to plants. They are also known as essential oils because they represent essence. They are mainly found in leaves and fruits of plants like conifers, citrus and eucalyptus. The term ‘terpene’ was assigned to the compounds after isolation of volatile liquid turpentine from pine trees. Volatile oils get vaporized or evaporates upon exposure to air at normal or ordinary temperature, so they are termed as etherel oil. Volatile oils generally occurs in plant families like Umbelliferae (examples Coriander, Fennel), Zingiberaceae (Ginger), Myrtacea (Clove), Piperaceae (black pepper), Rutaceae (Lemon, Orange) etc. 5.2 GENERAL PROPERTIES OF VOLATILE OILS OR TERPENOIDS 1. They are colourless, fragrant liquids lighter than water and volatile in nature. 2. A few of them are solids e.g. camphor. 3. They are soluble in organic solvents, alcohol and fixed oils and usually insoluble in water. 4. They are open chain or cyclic unsaturated compounds having one or more double bonds. 5. They give addition reaction with hydrogen, halogen, acids, etc and addition products possess antiseptic properties. 6. They undergo polymerization and dehydrogenation. 7. They are easily oxidized nearly by all the oxidizing agents.
CHEMICAL TEST 1. Volatile oil produces temporary stains when smeared on paper or cloth. The stain disappears after some time because the oil volatilizes. 2. Upon addition of Sudan III (alcoholic solution) to the thin section of volatile oil containing drug, red colour forms. 3. When few drops of Tincture alkana added on thin section of drug, red colour develops which indicates the presence of volatile oil. 5.5 EXTRACTION OF VOLATILE OILS Steam distillation, solvent extraction or mechanical means like ecuelle and enfleurage methods are employed for extraction purpose of volatile oils. These methods are as follows: 1. Hydro-distillation method: This method comprises of water distillation, water and steam distillation and steam distillation. These techniques are used for extraction of volatile oils from crude drugs. Hydro-distillation technique is used for fresh leaves and steam distillation uses for subterranean parts. 2. Enfleurage method: This method uses for the extraction of flavouring agents and perfumery. In this method, the fresh flowers (mainly petals) are taken and spreaded over layer of fatty material. Then it kept over fatty material for imbibition. After the imbibition the fresh petals are placed on fat layer and exhausted petals are removed. This process continues until saturation of fat layer with volatile constituents. This saturated fatty layer is extracted with lipid solvents. 3. Ecuelle method: This method is employed for citrus fruits which contains volatile principles. Here the oil containing ducts which contain oil cells are ruptured by mechanical means or manually. For this purpose special vessel are taken which contain pointed projections. The raw material is twisted over the projections in clockwise direction which rupture the cell and oil comes out. 5.6 ISOLATION OF VOLATILE OILS The oil obtained by distillation contains number of mono and sesqueterpenes. The monoterpenes hydrocarbons are distilled out first into their oxygenated derivatives by fractional distillation. Other methods like physical methods, chemical methods and chromatography also uses for their isolation. The chemical methods like treating the oil with sodium bisulphate, Phenylhydrazine, Tilden’s reagent and Grignard reagent isolates the compounds. Suitable adsorbents are used in chromatography for the elution of chromatogram of isolated compound. Uses: The utilization of terpenoids is mainly in perfumery, cosmetic industries, soaps manufacturing, incense-sticks manufacturing, food industries, pharmaceutical industries and beverage industries. They are also used as antiseptic, carminative, anthelmintic, stimulant, analgesic, antirheumatic, diuretic, aromatic, counter-irritant effect, insecticide, pesticide, insect repellant, and deodorant.
1. Define Volatile oil. Write its uses in therapy.
2. Classify terpenes with examples.
3. What are the chemical tests for Volatile oil identification?
4. What are the methods for extraction of volatile oil?
5. Write physicochemical properties of volatile oil.
6. Write synonym, biological source, family and geographical source of Mentha.
7. Write a detailed pharmacognostic note on Mentha.
8. What are the main constituents of Mentha oil? Draw it chemical structure.
9. Write chemical test and uses of Mentha.
10. Name out the adulterants of Mentha.
11. Write biological source, family and geographical source of Clove.
12. Write a note on cultivation and collection of Clove.
13. What are the main constituents of Clove? Draw it chemical structure.
14. Write chemical test and uses of Clove.
15. Name out the adulterants of Clove.
16. Write biological source, family and geographical source of Cinnamon.
17. What is the main constituent of Cinnamon? Draw it chemical structure.
18. Write chemical test and uses of Cinnamon.
19. How Cinnamon is adulterated?
20. Write biological source, family and geographical source of Cassia cinnamon.
21. What are the chemical constituents of Cassia cinnamon? Draw its chemical structure.
22. Write biological source, family and geographical source of Fennel.
23. Write method of cultivation and collection of Fennel.
24. Write in short about uses of Fennel.
25. What are the adulterants and substituent for Fennel?
26. Write synonym, biological source, family and geographical source of Coriander.
27. Write method of collection and preparation of Coriander.
28. What are the chemical constituents of Coriander? Draw it chemical structure.
29. Write in brief about uses of Coriander.
30. What are the adulterants and varieties for Coriander?