Page 98 - phytochemistry general program

- relaxing bronchial smooth muscle.
- increasing heart muscle contractility and efficiency.

- increasing heart rate.
- increasing blood pressure.
- increasing renal blood flow.
- central nervous system stimulatory effect mainly on the medullary respiratory center.
However its main therapeutic use is as smooth muscle relaxant, particularly for the
upper respiratory tract. Thus it is used in therapy for respiratory diseases under a

variety of brand names.

Test for purine alkaloids

Murexide test
In a porcelain dish containing about 10 mg of xanthine alkaloid, add 1ml of
mg of solid potassium chlorate. Evaporate the mixture to 10 conc. HCl and about
dryness on a water bath, a yellow residue is left which becomes crimson on further
heating. The color turns purple when residue is exposed to ammonia vapor. The

color is destroyed by solution of fixed alkali.

Separation of purine alkaloids

Separation of mixture of caffeine, theobromine and theophylline depends on
the solubility of caffeine in chloroform or benzene and insolubility of the other two
alkaloids (theophylline and theobromine) in these solvents. Ammonia solution is
then used for isolation of theophylline for theobromine.

Quantitative estimation of purine alkaloids
-Non- aqueous titration.
-Potentiometric.
-Colorimetric methods.

96