Resins
- They cannot be defined clearly.
- They can be described as mixtures of organic acids, alcohols, and esters.
- Physical Properties:
- They are amorphous, non- crystallizable, transparent, solids or semi-solids.
- They are insoluble in water & soluble in organic solvents.
- When heated they melt & burn with a sooty flame.
- They are produced in plants in the special type of glands.
- On boiling with alkalis they form resin soaps.
- They are nonnitrogenous.
- They are hard, heavier than water and nonconductive.
- On trituration with water they form emulsion
Classification: -
- According to the principal components present, they can be classified as follows:-
| Class. | Drug. | Examples. |
| 1 Acid Resin. | Colophony, Myrrh. | Abietic acid, Commiphoric acid. |
| 2. Ester Resin. | Benzoin, Storax. | Benzyl benzoate. Benzyl cinnamate. |
| 3. Resin alcohols. | Balsam of Peru, Gurjanbalsam | Peruresinotannol, Gurjuresinol. |
Resin Combinations: -
1) Oleoresins: -
- Homogenous mixtures of volatile oils & resins are called as oleoresins.
- e.g. Oleoresin of Ginger.
2) Oleo- gum- Resin: -
- Homogenous mixtures of volatile oils, gums & resin.
- e.g. Myrrh, Asafoetida.
3) Glyco resins: -
- Homogenous mixtures of sugars & resins.
- e.g. Jalap, Resin of Ipomoea
4) Balsams: -
- If the resin contains cinnamic &/ or benzoic acid it is called as balsam.
- e.g. Benzoin, Balsam of Tolu.
Isolation Of Resins: -
- By heating the crude drug. Ex. Guaiacum.
- By collecting the fossil resins. Ex. Kauri
- By making incisions on the plant. Ex. Asafoetida, Myrrh.
- By distillation. Ex. Colophony
- By extraction with alcohol. Ex. Oleoresin of Ginger & oleoresin of capsicum.
Chemical Tests:
A) Benzoin (Styrax benzoin Styraceae.)
1. Heat a small amount of benzoin slowly in a dry test tube -----> melts and white fumes are produced.
2. Benzoin when heated with potassium permanganate solution -----> odor of benzaldehyde. (Sumatra benzoin)
3. Benzoin is extracted with alcohol and to the extract add water ------>milky white solution is formed.4. Digest benzoin with few drops of petroleum ether for 5
B) Asafoetida: (Ferula foetida Umbelliferae.)
- Powdered drug triturated with water –--> yellowish emulsion is produced.
- Combined umbelliferone test –The drug is boiled with HCL for 5 minutes, it is filtered and ammonia is added to the filtrate –----> A blue fluorescence is observed.
- The drug is treated with few drops of 50% HNO3 –---> green color is produced.
- The drug is treated with few drops of sulphuric acid – red color is produced which changes to violet on washing with water.