Resins

Resins:

Resin may be defined as complex amorphous product of more or less solid characteristics, which, on heating, first soften and then melts. Resins form an ill-defined group of plant products which are produced normally during growth or secreted as a result of injury to the plant. General properties of resins: 1. Hard, transparent or translucent brittle materials. 2.Amorphous materials but rarely crystallisable in nature. 3.Resins are bad conductors of electricity. 4.Specific gravity ranging from 0.9-1.25. 

Occurrence: Resins are plant products with the exception of shellac, insect secretion. They are formed in the schizogenous ducts / cavities . The resinous exudation may consist almost entirely of resin e.g. Benzoin; Resin when associated with gum ; it is an gum-resin Resin when associated with volatile oil ; it is an oleo-resin when a considerable proportion of volatile oil also present it is called an oleo-gum-resin eg. Myrrh. Those resins or oleo-resins which contain benzoic or cinnamic acid either free or combined are commonly called balsmas. e.g. Benzoin Balasam of Tolu.

Classification: . Basis of their occurrence in combination Balsams: . e.g : Tolubalsam , Benzoin . Oleo-gum resins: e.g : Asafoetida , Myrrh. Glycoresins ( Glucoresins ): e.g. Podophyllum , Jalap. Oleoresins: e.g. Ginger, Male Fern. Gum-resins: e.g. Ammoniacum . Basis of the constituents of the resin: Acid resins: e.g:Colophony ( abetic acid), Copaiba ( copalvic and oxy- copalvic acid). Ester resins: e.g : Benzoin and Storax . Benzoin Resin alcohols: e.g : Balsam of Peru with perureslonotannol . Resin phenols: e.g : The resinotannols are found in balsam of Peru as Peruresinotannol . Resenes : e.g : Asafoetida Taxaonomical classification: Coniferous Resins: e.g.Colophony,Sandarac . Berberidaceae Resins: e.g.: Podophyllum . Zygophyllaceae Resins: e.g.: Guaiacum

Identification tests: Dissolve 0.1 gm of powdered drug in 10 ml acetic anhydride in a dry test tube. Add a drop of concentrated sulphuric acid to the cold solution. Purple colour appears which quickly changes to dark violet on standing. Dissolve powdered drug in petroleum ether. To 5 ml of filtrate, add 10 ml of dilute solution of copper acetate. Petroleum ether layer develops green colour due to formation of abietic acid salt with copper . Isolation of Resins: By extraction with alcohol and precipitation with water. e.g. Jalap, Podophyllum , Ipomoea, Capsicum, Ginger etc. 2. By distillation for separation of oil: e.g. Copaiba, colophony etc. 3. By heating plant part. e.g. Guaiacum. 4. As plant exudates by incision. e.g. Myrrh, asafetida, balsams etc. 5. By collecting fossil resins. e.g. Copal, kauri etc

CHEMICAL COMPOSTION AND ISOLATION• complex mixture of acids, alcohols, phenols, esters, glycosides orhydrocarbons.• When associated with volatile oils, contains monoterpenoids,sesequiterpenoid and diterpenoids.• gums when associated with resin: acacia gum: oxidase enzymes.• gums when associated with resin: acacia gum: oxidase enzymes.ISOLATION:• difficult task due to presence of various combinations.• Extraction with alcoholic solvents and then the subsequentprecipitation by adding concentrated alcoholic extract to a largeproportion of water.• Hydro distillation or distillation can be used for separation of volatileoils from resins. (separation of resin from turpentine)