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Basic Tests for Drugs - Pharmaceutical Substances, Medicinal Plant Materials and Dosage Forms
(1998; 100 pages) [French] [Spanish] View the PDF document
Table of Contents
View the documentPreface
View the document1. Introduction
View the document2. Other collections of simple tests
View the document3. Test procedures for pharmaceutical substances
View the document4. Test procedures for medicinal plant materials
View the document5. Test procedures for pharmaceutical dosage forms
View the document6. Reagents
View the documentAcknowledgements
View the documentOther WHO publications on pharmaceuticals
View the documentBack cover
 

4. Test procedures for medicinal plant materials

IPECACUANHA ROOT

Composition. Ipecacuanha root is the dried rhizome and roots of the shrub Cephaëlis ipecacuanha (Brotero) A. Richard (family Rubiaceae) or of C. acuminata Karsten, or of a mixture of both species. The principal alkaloids are emetine and cephaëline.

Identity tests

Description. Odour, slight; taste, bitter, nauseous and acrid.

Macroscopic characteristics

C. ipecacuanha. Dark brick-red to very dark brown. A somewhat tortuous root, seldom more than 15 cm in length or 6 mm in diameter; the root is closely annulated externally, with rounded ridges that completely encircle it; the fracture is short in the bark and splintery in the wood; a transversely cut surface shows a wide greyish bark and a small uniformly dense wood. The rhizomes are short lengths attached to the roots; they are cylindrical, up to 2 mm in diameter, finely wrinkled longitudinally, and with pith occupying approximately one-sixth of the whole diameter.

C. acuminata. In general, resembles the root of C. ipecacuanha, but differs in the following particulars: often up to 9 mm in diameter; external surface greyish brown or reddish brown with transverse ridges at intervals of about 1-3 mm; the ridges are about 0.5-1 mm wide, extending about half-way round the circumference and fading at the extremities into the general surface level.

Colour and other reactions

1. Coarsely powder the root, mix 0.05 g with about 2 ml of hydrochloric acid (~420 g/l) TS and 1 drop of hydrogen peroxide (~330 g/l) TS and warm the mixture; an orange colour is produced (rubremetine).

2. Coarsely powder the root, mix about 0.2 g with 2 drops of ammonia (~260 g/l) TS and 2 ml of dichloromethane R, shake and filter. Evaporate to dryness about 1 ml of the filtrate (keep the unused portion for test 3), dissolve the residue in about 0.2 ml of water and add 3 drops of potassium iodobismuthate/acetic acid TS; an orange precipitate is produced.

3. To the remaining filtrate from test 2 add 0.5 ml of ethanol (~750 g/l) TS and transfer to a small test-tube, 100 × 10 mm. Dip vertically into the tube a strip of filter-paper, 100 × 6 mm, and allow the solution to ascend 70 mm. Dry the paper strip in air and expose it to iodine vapours for 30 seconds. Observe under ultraviolet light at 365 nm; a blue fluorescence appears.

Degradation test

Discoloration of the test material usually indicates gross degradation.

PODOPHYLLUM RESIN

Composition. Podophyllum resin is a mixture of resins obtained from the rhizomes and roots of the herbaceous plant Podophyllum hexandrum Royle (P. emodi Wall.) or P. peltatum L. after percolation with ethanol and precipitation from water or very dilute acids.

Identity tests

Description. Light brown to greenish yellow or brownish grey masses or an amorphous powder. Darkens when exposed to light or stored at temperatures above 25°C.

Note. This material is very toxic and should be handled with care.

Colour and other reactions

1. Finely powder the resin, dissolve about 0.2 g in 10 ml of potassium hydroxide (~55 g/l) TS; a clear, yellow solution is formed which darkens on standing. Acidify with hydrochloric acid (~70 g/l) TS; the resin precipitates.

2. Finely powder the resin, add 0.4 g to 2 ml of ethanol (~750 g/l) TS, then add 0.5 ml of potassium hydroxide (~55 g/l) TS, shake gently and allow to stand; the resin of P. hexandrum produces a stiff jelly whereas that of P. peltatum does not gelatinize.

3. Dissolve 10 mg in 2 ml of ethanol (~750 g/l) TS and add 1 drop of ferric chloride (25 g/l) TS; a deep, dark green colour is produced and the solution appears black in reflected light.

4. Dissolve 10 mg in 1 ml of ethanol (~750 g/l) TS, add 4 ml of water and about 1 ml of sulfuric acid (~1760 g/l) TS and cool; the resin of P. hexandrum forms an orange to brownish red solution whereas that of P. peltatum forms a yellowish green solution.

SENNA FRUIT

Composition. Alexandrian or Khartoum senna fruit is the dried ripe fruit of Cassia senna L. (C. acutifolia Delile) and Tinnevelly senna fruit is the dried ripe fruit of C. angustifolia Vahl.

Identity tests

Description. Odour, slight; taste, first mucilaginous and sweet, then slightly bitter.

Macroscopic characteristics

Leaflike, flat and thin pods, yellowish green to yellowish brown with a dark brown central area, oblong or reniform.

Alexandrian senna fruit. Pale to greyish green; length, about 40-50 mm; width, 20-25 mm; stylar point at one end; containing 6-7 obovate green to pale brown seeds, with prominent longitudinal ridges on the testa.

Tinnevelly senna fruit. Brown to greyish black; length, about 35-60 mm; width, 14-18 mm; stylar point at one end; containing up to 10 obovate green to pale brown seeds, with indefinite transverse ridges on the testa.

Colour and other reactions

Before carrying out any tests, crush the fruit to a fine powder.

1. Mix about 0.2 g of the powdered fruit with 5 ml of hydrochloric acid (~250 g/l) TS and warm for 2 minutes. Cool and filter, shake the filtrate with 5 ml of toluene R and evaporate 1 ml of the yellowish coloured toluene extract to dryness. Dissolve the residue in 0.5 ml of ammonia (~100 g/l) TS and warm the solution; a pink to red-violet colour is produced.

2. Sprinkle 10 mg of the powdered fruit on the surface of about 1 ml of sulfuric acid (~1760 g/l) TS without stirring; within 5 minutes a greenish to brownish colour appears (other colours such as red indicate the presence of other species, e.g. C. auriculata L., C. goratensis Fres.).

Degradation test

Discoloration of the test material usually indicates gross degradation.

SENNA LEAF

Composition. Senna leaf consists of the dried leaflets of Cassia senna L., known as Alexandrian or Khartoum senna (C. acutifolia Delile), and Tinnevelly senna (C. angustifolia Vahl), or a mixture of both species.

Identity tests

Description. Odour, slight; taste, first mucilaginous and sweet, then slightly bitter.

Macroscopic characteristics

Alexandrian senna leaf. Pale greyish green, thin, fragile leaflets; lanceolate, mucronate; length, 20-40 mm; width, 5-15 mm, the maximum width being at a point slightly below the centre; lamina, slightly undulant; both surfaces covered with fine, short trichomes; pinnate venation, slightly prominent midrib with lateral veins leaving the midrib at an angle of about 60° and anastomosing to form a ridge parallel to the margin.

Tinnevelly senna leaf. Yellowish green leaflets; elongated and lanceolate; length, 25-50 mm; width at the centre, 7-20 mm; lamina, flat; both surfaces are smooth, with a very small number of trichomes, and marked with impressed transverse or oblique lines.

Colour and other reactions

Before carrying out any tests, powder the leaves to a particle size that allows them to pass through a sieve no. 45 (nominal aperture size, 0.045 mm).

1. To 0.5 g of powdered leaves add 10 ml of ethanol (~375 g/l) TS, warm in a water-bath for 5 minutes and filter while hot. To the filtrate add about 1 ml of hydrochloric acid (~420 g/l) TS, heat in a water-bath for 10 minutes and cool. Mix with 5 ml of ethyl acetate R, shake and allow to stand. Separate the ethyl acetate layer, add 2 ml of sodium hydrogen carbonate (40 g/l) TS and shake; a reddish yellow colour is produced in the aqueous layer. Remove the ethyl acetate layer, add 1 drop of hydrogen peroxide (~330 g/l) TS and heat in a water-bath; the colour of the solution changes to red.

2. Heat 0.10 g of powdered leaves with 10 ml of water in a water-bath for 30 minutes and filter. To the filtrate add 1 drop of hydrochloric acid (~420 g/l) TS, shake with 2 quantities, each of 5 ml, of dichloromethane R and discard the dichloromethane layer. Adjust the pH of the aqueous layer to 7-8, adding sodium carbonate (50 g/l) TS and testing with pH-indicator paper R. Add 10 ml of a solution composed of 4 ml of ferric chloride (25 g/l) TS and 6 ml of water, mix and heat in a water-bath for 20 minutes. Add about 1 ml of hydrochloric acid (~420 g/l) TS and continue to heat for a further 20 minutes, shaking the flask frequently. Filter, extract the filtrate with 10 ml of dichloromethane R, evaporate the dichloromethane extract to dryness over a water-bath and dissolve the residue in 2 ml of potassium hydroxide (~55 g/l) TS; a red-orange colour is produced.

3. Sprinkle 10 mg of the powdered leaves on the surface of about 1 ml of sulfuric acid (~1760 g/l) TS without stirring; within 5 minutes a greenish to brownish colour appears (other colours such as red indicate the presence of other species, e.g. C. auriculata L., C. goratensis Fres.).

Degradation test

Discoloration of the test material usually indicates gross degradation.

 

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