Basic Test For Medicinal Plants: Basic tests describe procedures for testing pharmaceutical substances, medicinal plant materials, and pharmaceutical dosage forms. Basic tests are not, intended to replace the requirements of The International Pharmacopoeia or other pharmacopoeial monographs. These give an assurance of quality whereas, basic tests merely confirm identity.
Basic tests need not be carried out by fully qualified pharmacists or chemists, but they should be performed by people with some understanding of analytical chemistry such that acquired in courses for pharmaceutical assistants.
1. Ipecacuanha Root
Table of Contents
Composition: Ipecacuanha root is the dried rhizome and roots of the shrub Cephaelis ipecacuanha (Brotero) A. Richard (family Rubiaceae) or of C. acuminata Karsten, or a mixture of both species. The principal alkaloids are emetine and cephaeline.
Identity tests:
Description: Slightly bitter taste, Odour – 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 hole diameter.
C. acuminate: It resembles the root of C. ipecacuanha, but differs in the following. particulars: often up to 9 mm in diameter, the external surface is 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 halfway round the circumference and fading at the extremities into the general surface level.
Procedures:
- Coarsely powder the root, mix 0.05 gm with about 2 ml of hydrochloric acid (-420 gm/L) TS and 1 drop of hydrogen peroxide (-330 gm/L) TS, and warm the mixture. Orange color is produced (rubremetine).
- Coarsely powder the root, mix about 0.2 gm with 2 drops of ammonia (-260 gm/L) TS and 2 ml of dichloromethane, 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.
- To the remaining filtrate from test 2, add 0.5 ml of ethanol (~750 gm/L) TS and transfer to a small test tube, 100 x 10 mm. Dip a strip of filter paper of 100 x 6 mm into the test tube vertically and allow the solution to ascend 70 mm. Dry the paper. strip in air and expose it to iodine vapors 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.
2. 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.
Melting point: About 184°C.
Procedures:
- Finely powder the resin, dissolve about 0.2 gm in 10 ml of potassium hydroxide (~55 gm/L) TS; a clear, yellow solution is formed which darkens on standing. Acidify with hydrochloric acid (-70 gm/L) TS; the resin precipitates.
- Finely powder the resin, add 0.4 gm to 2 ml of ethanol (-750 gm/L) TS, then add 0.5 ml of potassium hydroxide (~55 gm/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.
- Dissolve 10 mg in 2 ml of ethanol (-750 gm/L) TS and add 1 drop of ferric chloride (25 gm/L) TS; a deep, dark green color is produced and the solution appears black in reflected light.
- Dissolve 10 mg in 1 ml of ethanol (~750 gm/L) TS, add 4 ml of water and about 1 ml of sulfuric acid (-1760 gm/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.
Degradation test: Darkens when exposed to light or stored at temperatures above 25°C.
3. 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:
- Leaf-like, 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; the astylar 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; the astylar point at one end; containing up to 10 obovate green to pale brown seeds, with indefinite transverse ridges on the testa.
Procedures:
Before carrying out any tests, crush the fruit to a fine powder.
- Mix about 0.2 gm of the powdered fruit with 5 ml of hydrochloric acid (-250 gm/L) TS and warm for 2 minutes. Cool and filter, shake the filtrate with 5 ml of toluene, and evaporate 1 ml of the yellowish colored toluene extract to dryness. Dissolve the residue in 0.5 ml of ammonia (~100 gm/L) TS and warm the solution; a pink to red-violet color is produced.
- Sprinkle 10 mg of the powdered fruit on the surface of about 1 ml of sulfuric acid (~1760 gm/L) TS without stirring; within 5 minutes a greenish to brownish color appears (other colors such as; red indicate the presence of other species. Eg. C. auriculata L., C. goratensis Fres.).
Degradation test: Discoloration of the test material usually indicates gross degradation.
4. 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 is slight; the taste is first mucilaginous and sweet and 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 center; 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 center, 7-20 mm; lamina flat; both surfaces are smooth, with a very small number of trichomes and marked with impressed transverse or oblique lines.
Procedures:
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, 0.354 mm)
- To 0.5 gm of powdered leaves add 10 ml of ethanol (-375 gm/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 gm/L) TS, heat in a water bath for 10 minutes, and cool. Mix with 5 ml of ethyl acetate, shake, and allow to stand. Separate the ethyl acetate layer, add 2 ml of sodium hydrogen carbonate (40 gm/L) TS, and shake; a reddish yellow color is produced in the aqueous layer. Remove the ethyl acetate layer, add 1 drop of hydrogen peroxide (-330 gm/L) TS, and heat in a water bath; the color of the solution changes to red.
- Heat 0.10 gm 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 gm/L) TS, shake with 2 quantities; each of 5 ml of dichloromethane, and discard the dichloromethane layer. Adjust the pH of the aqueous layer to 7-8, adding sodium carbonate (50 gm/L) TS and testing with pH-indicator paper. Add 10 ml of a solution composed of 4 ml of ferric chloride (25 gm/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 gm/L) TS and continue to heat for a further 20 minutes, shaking the flask frequently. Filter, extract the filtrate with 10 ml of dichloromethane, evaporate the dichloromethane extract to dryness over a water bath and dissolve the residue in 2 ml of potassium hydroxide (-55 gm/L) TS; a red-orange color is produced.
- Sprinkle 10 mg of the powdered leaves on the surface of about 1 ml of sulfuric acid (-1760 gm/L) TS without stirring; within 5 minutes a greenish to brownish color appears (other colors 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.
Make sure you also check our other amazing Article on : Basic Test For Pharmaceutical Substances