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Category  Bitter

        Gentian consists of the dried underground organs of Gentiana lutea L. (Family Gentianaceae).

Origin of plant  Gentian is native to Central and Southern Europe. 

Constituents  Gentian contains bitter secoiridoid monoterpenes including gentiopicroside swirtiamarin, sweroside, and its acyl glucoside derivatives, amarogentin.  It also contains xanthones (e.g., gensitin, isogensitin, gentianose, gentioside), alkaloid gentianine, volatile oil, etc.

Description  Odour, characteristic; taste, sweet, followed by persistently bitter aftertaste.
      Macroscopical  Single or branched subcylindrical of underground parts, varied in length, usually 5 to 40 mm in diameter; externally yellowish brown or greyish brown; internally yellowish or reddish yellow. Root brittle, longitudinally wrinkled and occasionally bearing rootlet scars.  Rhizome brittle; rhizome branch usually bearing terminal bud and encircled by closely arranged root scars.
     Microscopical  Powdered drug of Gentian shows cork, fragments of dermal tissue, parenchyma, vessels, and xylem.  Cork:  yellowish brown, thin-walled, polygonal cells.  Fragments of dermal tissue:  yellowish brown thin-wall cork cells and thick-walled collenchyma.  Parenchyma:  moderately thick-walled cells containing oil droplets and small prismatic and minute needle-shaped crystals of calcium oxalate.  Vessels:  lignified reticulate or spiral vessels.  Xylem:  vessels and moderately thick-walled parenchyma containing oil droplets.   

Other relevant information
     1.  It is contra-indicated in pregnant, nursing women, young children, and in patients with gastric or duodenal ulcer, hypertension and hyperacidity.
     2.  Overdose may result in nausea and vomiting.

Packaging and storage  Gentian shall be kept in well-closed containers, protected from light.

Identification  Carry out the test as described in the “Thin-Layer Chromatography” (Appendix 3.1).
      Standard solution  Dissolve 5 mg of hyperoside, and 5 mg of phenazone in 10 mL of methanol.
      Test solution  To 1 g, in No. 355 powder, add 25 mL of methanol, shake for 15 minutes and filter.  Evaporate the filtrate to dryness under reduced pressure at a temperature not exceeding 50°.  Dissolve the residue with a small portions of methanol to obtain 5 mL of a solution, which may contain a sediment.
     Adsorbent  Silica gel F254.
     Mobile phase  Water, anhydrous formic acid, ethyl formate (4:8:88).
     Application  Apply 20 µL each of Standard solution and Test solution as 10-mm bands.
     Development and drying  Allow the solvent front to ascend 8 cm above the line of application in an unsaturated tank.  Dry the developed plate in air.
     Detection A  Examine the plate under ultraviolet light (254 nm).
     Results A  When examined under ultraviolet light (254 nm), the test solution shows a prominent quenching band due to gentiopicroside in the lower third of the chromatogram, corresponding in R_f to the quenching band of hyperoside shown by the standard solution.  There is also a weak quenching band due to amarogentin in the middle and a prominent quenching band in the upper third of the chromatogram.
     A quenching band of phenazone obtained from the standard solution appears also in the upper third with R_f value between that of amarogentin and of the prominent quenching band from the test solution.
    Detection B  Spray the plate with a 10 per cent w/v of potassium hydroxide in methanol and then spray with a freshly prepared 0.2 per cent w/v solution of fast blue B salt in a mixture of equal volumes of anhydrous ethanol and water.  Examine the plate under visible light.
    Results B   When examined under visible light, the test solution shows a weak light brown band due to gentiopicroside in the lower third of the chromatogram, corresponding in R_f to the brownish red band due to hyperoside shown by the standard solution.  A violet-red band due to amarogentin and a dark violet band of higher R_f value in the upper third of the chromatogram are present.

Acid-insoluble ash  Not more than 3.0 per cent w/w (Appendix 7.6).

Total ash  Not more than 6.0 per cent w/w (Appendix 7.7).

Water-soluble extractive  Not less than 33.0 per cent w/w (Appendix 7.12).  Use 5.0 g, in No. 710 powder, add 200 mL of boiling water, allow to stand for 10 minutes, shake occasionally.  Allow to cool, dilute to 200.0 mL with water and filter.  Evaporate 20.0 mL of the filtrate to dryness on a water-bath.  Dry the residue at 105°.

GENTIAN, POWDERED

Complies with the requirements for Packaging and storage, Identification, Acid-insoluble ash, Total ash, and Water-soluble extractive stated under Gentian, and with the following requirement.

Description  Yellowish brown to brown.  Diagnostic structures:  a small number of lignified, reticulately thickened vessels; small acicular crystals of calcium oxalate; droplets of oil, parenchymatous cells, numerous; starch granules rare.