Page 68 - phytochemistry general program

A combination of extractive procedures and chromatographic separation
would allow the determination of alkaloids with a minimum percentage of error.
Assay of Hyoscyamus niger leaf (B.P. 1998)
Definition

Hyoscyamus leaf consists of the dried leaf or the dried leaf and flowering,
and occassionally fruit- bearing, tops of Hyoscyamus niger L. It contains not less
than 0.05 percent of total alkaloids, calculated as hyoscyamine (C17H23NO3, M wt
289.4) with reference to the drug dried at 100 0C to 105 0C. The alkaloids consist

mainly of hyoscyamine with varying proportion of hyoscine (scopolamine).
Principle of assay

1- Total alkaloids are liberated by maceration with a mixture of alcohol, ether and
ammonia.

2- Extraction is carried out by percolation with ether, chloroform mixture.
3- Total alkaloids are determined volumetrically by adding a known volume of
standard acid to the purified alkaloid residue and then back titration of the

excess acid with standard alkali.
Estimation of pure alkaloids

Pure alkaloids are evaluated by:
1- Colorimetric method

Atropine gives violet colour with Vitali-Morine’s reagent. The colour can be
measured colorimetrically at a wavelength of 550 nm.

2- Non-aqueous titration
Atropine, hyoscyamine and hyoscine and their medicinal preparations are

estimated potentiometrically and/or by non-aqueous titration.

Coca alkaloids

Coca leaves contain two types of alkaloids:

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