PHARAMACOLOGY

TANNINS ::

They are non nitrogenous plant constituents and have an astringent action They are of two types : (a) pyrogallol tannins which are glycosides of glucose and occur in oak galls (b) pyrocatechol tannins which are sugar free derivatives of catechol and occur in catechu and eucalyptus Tannin are used for treating burns and diarrhoea 

Gums ::

They are chemically polysaccharides which on hydrolysis yield simple sugars upon addition of water some of them swell up and form adhesive muscilagenous masses and some remain unchanged in the gut they act as hydrophillic colloids and function as bulk laxatives e.g. agar and psyllium seeds TRagacanth gum in the form of an emulsion is used for chapped skin Acacia is used as a suspending agent in making emulsions and mixtures like bismuth kaolin mixture for diarrhoea 

Resins ::

They are ill defined solid substances found on plants and are produced by oxidation and polymerization of volatile oils Resins are of many types : oleoresins (aspidium) Gum-resins (asafoetida) oleo-gum-resin (myrrh) balsams (benzoin tolu peru) Balsams are used in the treatment of cough and bronchitis for their antiseptic and protective properties podophyllum resin is an irritant purgative 

Antibiotics ::

They are chemical substances produced or derived from living cells which have a lethal (bactericidal) or inhibitory (bacteriostatic) action on micro-organisms The main sources of antibiotics are moulds yeasts and bacteria 

Hormones ::

They are specialized chemicals generally derived from animal endocrine glands hormones are largely used in medicine as substitution therapy They vary in their chemical structure e.g. insulin is a polypeptide sex hormones and corticosteroids are steroids thyroxine is an iodine derivative of the amino acid tyrosine